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1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * lock.c
4 : : * POSTGRES primary lock mechanism
5 : : *
6 : : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
7 : : * Portions Copyright (c) 1994, Regents of the University of California
8 : : *
9 : : *
10 : : * IDENTIFICATION
11 : : * src/backend/storage/lmgr/lock.c
12 : : *
13 : : * NOTES
14 : : * A lock table is a shared memory hash table. When
15 : : * a process tries to acquire a lock of a type that conflicts
16 : : * with existing locks, it is put to sleep using the routines
17 : : * in storage/lmgr/proc.c.
18 : : *
19 : : * For the most part, this code should be invoked via lmgr.c
20 : : * or another lock-management module, not directly.
21 : : *
22 : : * Interface:
23 : : *
24 : : * LockManagerShmemInit(), GetLocksMethodTable(), GetLockTagsMethodTable(),
25 : : * LockAcquire(), LockRelease(), LockReleaseAll(),
26 : : * LockCheckConflicts(), GrantLock()
27 : : *
28 : : *-------------------------------------------------------------------------
29 : : */
30 : : #include "postgres.h"
31 : :
32 : : #include <signal.h>
33 : : #include <unistd.h>
34 : :
35 : : #include "access/transam.h"
36 : : #include "access/twophase.h"
37 : : #include "access/twophase_rmgr.h"
38 : : #include "access/xlog.h"
39 : : #include "access/xlogutils.h"
40 : : #include "miscadmin.h"
41 : : #include "pg_trace.h"
42 : : #include "storage/lmgr.h"
43 : : #include "storage/proc.h"
44 : : #include "storage/procarray.h"
45 : : #include "storage/spin.h"
46 : : #include "storage/standby.h"
47 : : #include "utils/memutils.h"
48 : : #include "utils/ps_status.h"
49 : : #include "utils/resowner.h"
50 : :
51 : :
52 : : /* GUC variables */
53 : : int max_locks_per_xact; /* used to set the lock table size */
54 : : bool log_lock_failures = false;
55 : :
56 : : #define NLOCKENTS() \
57 : : mul_size(max_locks_per_xact, add_size(MaxBackends, max_prepared_xacts))
58 : :
59 : :
60 : : /*
61 : : * Data structures defining the semantics of the standard lock methods.
62 : : *
63 : : * The conflict table defines the semantics of the various lock modes.
64 : : */
65 : : static const LOCKMASK LockConflicts[] = {
66 : : 0,
67 : :
68 : : /* AccessShareLock */
69 : : LOCKBIT_ON(AccessExclusiveLock),
70 : :
71 : : /* RowShareLock */
72 : : LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock),
73 : :
74 : : /* RowExclusiveLock */
75 : : LOCKBIT_ON(ShareLock) | LOCKBIT_ON(ShareRowExclusiveLock) |
76 : : LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock),
77 : :
78 : : /* ShareUpdateExclusiveLock */
79 : : LOCKBIT_ON(ShareUpdateExclusiveLock) |
80 : : LOCKBIT_ON(ShareLock) | LOCKBIT_ON(ShareRowExclusiveLock) |
81 : : LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock),
82 : :
83 : : /* ShareLock */
84 : : LOCKBIT_ON(RowExclusiveLock) | LOCKBIT_ON(ShareUpdateExclusiveLock) |
85 : : LOCKBIT_ON(ShareRowExclusiveLock) |
86 : : LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock),
87 : :
88 : : /* ShareRowExclusiveLock */
89 : : LOCKBIT_ON(RowExclusiveLock) | LOCKBIT_ON(ShareUpdateExclusiveLock) |
90 : : LOCKBIT_ON(ShareLock) | LOCKBIT_ON(ShareRowExclusiveLock) |
91 : : LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock),
92 : :
93 : : /* ExclusiveLock */
94 : : LOCKBIT_ON(RowShareLock) |
95 : : LOCKBIT_ON(RowExclusiveLock) | LOCKBIT_ON(ShareUpdateExclusiveLock) |
96 : : LOCKBIT_ON(ShareLock) | LOCKBIT_ON(ShareRowExclusiveLock) |
97 : : LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock),
98 : :
99 : : /* AccessExclusiveLock */
100 : : LOCKBIT_ON(AccessShareLock) | LOCKBIT_ON(RowShareLock) |
101 : : LOCKBIT_ON(RowExclusiveLock) | LOCKBIT_ON(ShareUpdateExclusiveLock) |
102 : : LOCKBIT_ON(ShareLock) | LOCKBIT_ON(ShareRowExclusiveLock) |
103 : : LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock)
104 : :
105 : : };
106 : :
107 : : /* Names of lock modes, for debug printouts */
108 : : static const char *const lock_mode_names[] =
109 : : {
110 : : "INVALID",
111 : : "AccessShareLock",
112 : : "RowShareLock",
113 : : "RowExclusiveLock",
114 : : "ShareUpdateExclusiveLock",
115 : : "ShareLock",
116 : : "ShareRowExclusiveLock",
117 : : "ExclusiveLock",
118 : : "AccessExclusiveLock"
119 : : };
120 : :
121 : : #ifndef LOCK_DEBUG
122 : : static bool Dummy_trace = false;
123 : : #endif
124 : :
125 : : static const LockMethodData default_lockmethod = {
126 : : MaxLockMode,
127 : : LockConflicts,
128 : : lock_mode_names,
129 : : #ifdef LOCK_DEBUG
130 : : &Trace_locks
131 : : #else
132 : : &Dummy_trace
133 : : #endif
134 : : };
135 : :
136 : : static const LockMethodData user_lockmethod = {
137 : : MaxLockMode,
138 : : LockConflicts,
139 : : lock_mode_names,
140 : : #ifdef LOCK_DEBUG
141 : : &Trace_userlocks
142 : : #else
143 : : &Dummy_trace
144 : : #endif
145 : : };
146 : :
147 : : /*
148 : : * map from lock method id to the lock table data structures
149 : : */
150 : : static const LockMethod LockMethods[] = {
151 : : NULL,
152 : : &default_lockmethod,
153 : : &user_lockmethod
154 : : };
155 : :
156 : :
157 : : /* Record that's written to 2PC state file when a lock is persisted */
158 : : typedef struct TwoPhaseLockRecord
159 : : {
160 : : LOCKTAG locktag;
161 : : LOCKMODE lockmode;
162 : : } TwoPhaseLockRecord;
163 : :
164 : :
165 : : /*
166 : : * Count of the number of fast path lock slots we believe to be used. This
167 : : * might be higher than the real number if another backend has transferred
168 : : * our locks to the primary lock table, but it can never be lower than the
169 : : * real value, since only we can acquire locks on our own behalf.
170 : : *
171 : : * XXX Allocate a static array of the maximum size. We could use a pointer
172 : : * and then allocate just the right size to save a couple kB, but then we
173 : : * would have to initialize that, while for the static array that happens
174 : : * automatically. Doesn't seem worth the extra complexity.
175 : : */
176 : : static int FastPathLocalUseCounts[FP_LOCK_GROUPS_PER_BACKEND_MAX];
177 : :
178 : : /*
179 : : * Flag to indicate if the relation extension lock is held by this backend.
180 : : * This flag is used to ensure that while holding the relation extension lock
181 : : * we don't try to acquire a heavyweight lock on any other object. This
182 : : * restriction implies that the relation extension lock won't ever participate
183 : : * in the deadlock cycle because we can never wait for any other heavyweight
184 : : * lock after acquiring this lock.
185 : : *
186 : : * Such a restriction is okay for relation extension locks as unlike other
187 : : * heavyweight locks these are not held till the transaction end. These are
188 : : * taken for a short duration to extend a particular relation and then
189 : : * released.
190 : : */
191 : : static bool IsRelationExtensionLockHeld PG_USED_FOR_ASSERTS_ONLY = false;
192 : :
193 : : /*
194 : : * Number of fast-path locks per backend - size of the arrays in PGPROC.
195 : : * This is set only once during start, before initializing shared memory,
196 : : * and remains constant after that.
197 : : *
198 : : * We set the limit based on max_locks_per_transaction GUC, because that's
199 : : * the best information about expected number of locks per backend we have.
200 : : * See InitializeFastPathLocks() for details.
201 : : */
202 : : int FastPathLockGroupsPerBackend = 0;
203 : :
204 : : /*
205 : : * Macros to calculate the fast-path group and index for a relation.
206 : : *
207 : : * The formula is a simple hash function, designed to spread the OIDs a bit,
208 : : * so that even contiguous values end up in different groups. In most cases
209 : : * there will be gaps anyway, but the multiplication should help a bit.
210 : : *
211 : : * The selected constant (49157) is a prime not too close to 2^k, and it's
212 : : * small enough to not cause overflows (in 64-bit).
213 : : *
214 : : * We can assume that FastPathLockGroupsPerBackend is a power-of-two per
215 : : * InitializeFastPathLocks().
216 : : */
217 : : #define FAST_PATH_REL_GROUP(rel) \
218 : : (((uint64) (rel) * 49157) & (FastPathLockGroupsPerBackend - 1))
219 : :
220 : : /*
221 : : * Given the group/slot indexes, calculate the slot index in the whole array
222 : : * of fast-path lock slots.
223 : : */
224 : : #define FAST_PATH_SLOT(group, index) \
225 : : (AssertMacro((uint32) (group) < FastPathLockGroupsPerBackend), \
226 : : AssertMacro((uint32) (index) < FP_LOCK_SLOTS_PER_GROUP), \
227 : : ((group) * FP_LOCK_SLOTS_PER_GROUP + (index)))
228 : :
229 : : /*
230 : : * Given a slot index (into the whole per-backend array), calculated using
231 : : * the FAST_PATH_SLOT macro, split it into group and index (in the group).
232 : : */
233 : : #define FAST_PATH_GROUP(index) \
234 : : (AssertMacro((uint32) (index) < FastPathLockSlotsPerBackend()), \
235 : : ((index) / FP_LOCK_SLOTS_PER_GROUP))
236 : : #define FAST_PATH_INDEX(index) \
237 : : (AssertMacro((uint32) (index) < FastPathLockSlotsPerBackend()), \
238 : : ((index) % FP_LOCK_SLOTS_PER_GROUP))
239 : :
240 : : /* Macros for manipulating proc->fpLockBits */
241 : : #define FAST_PATH_BITS_PER_SLOT 3
242 : : #define FAST_PATH_LOCKNUMBER_OFFSET 1
243 : : #define FAST_PATH_MASK ((1 << FAST_PATH_BITS_PER_SLOT) - 1)
244 : : #define FAST_PATH_BITS(proc, n) (proc)->fpLockBits[FAST_PATH_GROUP(n)]
245 : : #define FAST_PATH_GET_BITS(proc, n) \
246 : : ((FAST_PATH_BITS(proc, n) >> (FAST_PATH_BITS_PER_SLOT * FAST_PATH_INDEX(n))) & FAST_PATH_MASK)
247 : : #define FAST_PATH_BIT_POSITION(n, l) \
248 : : (AssertMacro((l) >= FAST_PATH_LOCKNUMBER_OFFSET), \
249 : : AssertMacro((l) < FAST_PATH_BITS_PER_SLOT+FAST_PATH_LOCKNUMBER_OFFSET), \
250 : : AssertMacro((n) < FastPathLockSlotsPerBackend()), \
251 : : ((l) - FAST_PATH_LOCKNUMBER_OFFSET + FAST_PATH_BITS_PER_SLOT * (FAST_PATH_INDEX(n))))
252 : : #define FAST_PATH_SET_LOCKMODE(proc, n, l) \
253 : : FAST_PATH_BITS(proc, n) |= UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l)
254 : : #define FAST_PATH_CLEAR_LOCKMODE(proc, n, l) \
255 : : FAST_PATH_BITS(proc, n) &= ~(UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l))
256 : : #define FAST_PATH_CHECK_LOCKMODE(proc, n, l) \
257 : : (FAST_PATH_BITS(proc, n) & (UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l)))
258 : :
259 : : /*
260 : : * The fast-path lock mechanism is concerned only with relation locks on
261 : : * unshared relations by backends bound to a database. The fast-path
262 : : * mechanism exists mostly to accelerate acquisition and release of locks
263 : : * that rarely conflict. Because ShareUpdateExclusiveLock is
264 : : * self-conflicting, it can't use the fast-path mechanism; but it also does
265 : : * not conflict with any of the locks that do, so we can ignore it completely.
266 : : */
267 : : #define EligibleForRelationFastPath(locktag, mode) \
268 : : ((locktag)->locktag_lockmethodid == DEFAULT_LOCKMETHOD && \
269 : : (locktag)->locktag_type == LOCKTAG_RELATION && \
270 : : (locktag)->locktag_field1 == MyDatabaseId && \
271 : : MyDatabaseId != InvalidOid && \
272 : : (mode) < ShareUpdateExclusiveLock)
273 : : #define ConflictsWithRelationFastPath(locktag, mode) \
274 : : ((locktag)->locktag_lockmethodid == DEFAULT_LOCKMETHOD && \
275 : : (locktag)->locktag_type == LOCKTAG_RELATION && \
276 : : (locktag)->locktag_field1 != InvalidOid && \
277 : : (mode) > ShareUpdateExclusiveLock)
278 : :
279 : : static bool FastPathGrantRelationLock(Oid relid, LOCKMODE lockmode);
280 : : static bool FastPathUnGrantRelationLock(Oid relid, LOCKMODE lockmode);
281 : : static bool FastPathTransferRelationLocks(LockMethod lockMethodTable,
282 : : const LOCKTAG *locktag, uint32 hashcode);
283 : : static PROCLOCK *FastPathGetRelationLockEntry(LOCALLOCK *locallock);
284 : :
285 : : /*
286 : : * To make the fast-path lock mechanism work, we must have some way of
287 : : * preventing the use of the fast-path when a conflicting lock might be present.
288 : : * We partition* the locktag space into FAST_PATH_STRONG_LOCK_HASH_PARTITIONS,
289 : : * and maintain an integer count of the number of "strong" lockers
290 : : * in each partition. When any "strong" lockers are present (which is
291 : : * hopefully not very often), the fast-path mechanism can't be used, and we
292 : : * must fall back to the slower method of pushing matching locks directly
293 : : * into the main lock tables.
294 : : *
295 : : * The deadlock detector does not know anything about the fast path mechanism,
296 : : * so any locks that might be involved in a deadlock must be transferred from
297 : : * the fast-path queues to the main lock table.
298 : : */
299 : :
300 : : #define FAST_PATH_STRONG_LOCK_HASH_BITS 10
301 : : #define FAST_PATH_STRONG_LOCK_HASH_PARTITIONS \
302 : : (1 << FAST_PATH_STRONG_LOCK_HASH_BITS)
303 : : #define FastPathStrongLockHashPartition(hashcode) \
304 : : ((hashcode) % FAST_PATH_STRONG_LOCK_HASH_PARTITIONS)
305 : :
306 : : typedef struct
307 : : {
308 : : slock_t mutex;
309 : : uint32 count[FAST_PATH_STRONG_LOCK_HASH_PARTITIONS];
310 : : } FastPathStrongRelationLockData;
311 : :
312 : : static volatile FastPathStrongRelationLockData *FastPathStrongRelationLocks;
313 : :
314 : :
315 : : /*
316 : : * Pointers to hash tables containing lock state
317 : : *
318 : : * The LockMethodLockHash and LockMethodProcLockHash hash tables are in
319 : : * shared memory; LockMethodLocalHash is local to each backend.
320 : : */
321 : : static HTAB *LockMethodLockHash;
322 : : static HTAB *LockMethodProcLockHash;
323 : : static HTAB *LockMethodLocalHash;
324 : :
325 : :
326 : : /* private state for error cleanup */
327 : : static LOCALLOCK *StrongLockInProgress;
328 : : static LOCALLOCK *awaitedLock;
329 : : static ResourceOwner awaitedOwner;
330 : :
331 : :
332 : : #ifdef LOCK_DEBUG
333 : :
334 : : /*------
335 : : * The following configuration options are available for lock debugging:
336 : : *
337 : : * TRACE_LOCKS -- give a bunch of output what's going on in this file
338 : : * TRACE_USERLOCKS -- same but for user locks
339 : : * TRACE_LOCK_OIDMIN-- do not trace locks for tables below this oid
340 : : * (use to avoid output on system tables)
341 : : * TRACE_LOCK_TABLE -- trace locks on this table (oid) unconditionally
342 : : * DEBUG_DEADLOCKS -- currently dumps locks at untimely occasions ;)
343 : : *
344 : : * Furthermore, but in storage/lmgr/lwlock.c:
345 : : * TRACE_LWLOCKS -- trace lightweight locks (pretty useless)
346 : : *
347 : : * Define LOCK_DEBUG at compile time to get all these enabled.
348 : : * --------
349 : : */
350 : :
351 : : int Trace_lock_oidmin = FirstNormalObjectId;
352 : : bool Trace_locks = false;
353 : : bool Trace_userlocks = false;
354 : : int Trace_lock_table = 0;
355 : : bool Debug_deadlocks = false;
356 : :
357 : :
358 : : inline static bool
359 : : LOCK_DEBUG_ENABLED(const LOCKTAG *tag)
360 : : {
361 : : return
362 : : (*(LockMethods[tag->locktag_lockmethodid]->trace_flag) &&
363 : : ((Oid) tag->locktag_field2 >= (Oid) Trace_lock_oidmin))
364 : : || (Trace_lock_table &&
365 : : (tag->locktag_field2 == Trace_lock_table));
366 : : }
367 : :
368 : :
369 : : inline static void
370 : : LOCK_PRINT(const char *where, const LOCK *lock, LOCKMODE type)
371 : : {
372 : : if (LOCK_DEBUG_ENABLED(&lock->tag))
373 : : elog(LOG,
374 : : "%s: lock(%p) id(%u,%u,%u,%u,%u,%u) grantMask(%x) "
375 : : "req(%d,%d,%d,%d,%d,%d,%d)=%d "
376 : : "grant(%d,%d,%d,%d,%d,%d,%d)=%d wait(%d) type(%s)",
377 : : where, lock,
378 : : lock->tag.locktag_field1, lock->tag.locktag_field2,
379 : : lock->tag.locktag_field3, lock->tag.locktag_field4,
380 : : lock->tag.locktag_type, lock->tag.locktag_lockmethodid,
381 : : lock->grantMask,
382 : : lock->requested[1], lock->requested[2], lock->requested[3],
383 : : lock->requested[4], lock->requested[5], lock->requested[6],
384 : : lock->requested[7], lock->nRequested,
385 : : lock->granted[1], lock->granted[2], lock->granted[3],
386 : : lock->granted[4], lock->granted[5], lock->granted[6],
387 : : lock->granted[7], lock->nGranted,
388 : : dclist_count(&lock->waitProcs),
389 : : LockMethods[LOCK_LOCKMETHOD(*lock)]->lockModeNames[type]);
390 : : }
391 : :
392 : :
393 : : inline static void
394 : : PROCLOCK_PRINT(const char *where, const PROCLOCK *proclockP)
395 : : {
396 : : if (LOCK_DEBUG_ENABLED(&proclockP->tag.myLock->tag))
397 : : elog(LOG,
398 : : "%s: proclock(%p) lock(%p) method(%u) proc(%p) hold(%x)",
399 : : where, proclockP, proclockP->tag.myLock,
400 : : PROCLOCK_LOCKMETHOD(*(proclockP)),
401 : : proclockP->tag.myProc, (int) proclockP->holdMask);
402 : : }
403 : : #else /* not LOCK_DEBUG */
404 : :
405 : : #define LOCK_PRINT(where, lock, type) ((void) 0)
406 : : #define PROCLOCK_PRINT(where, proclockP) ((void) 0)
407 : : #endif /* not LOCK_DEBUG */
408 : :
409 : :
410 : : static uint32 proclock_hash(const void *key, Size keysize);
411 : : static void RemoveLocalLock(LOCALLOCK *locallock);
412 : : static PROCLOCK *SetupLockInTable(LockMethod lockMethodTable, PGPROC *proc,
413 : : const LOCKTAG *locktag, uint32 hashcode, LOCKMODE lockmode);
414 : : static void GrantLockLocal(LOCALLOCK *locallock, ResourceOwner owner);
415 : : static void BeginStrongLockAcquire(LOCALLOCK *locallock, uint32 fasthashcode);
416 : : static void FinishStrongLockAcquire(void);
417 : : static ProcWaitStatus WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner);
418 : : static void waitonlock_error_callback(void *arg);
419 : : static void ReleaseLockIfHeld(LOCALLOCK *locallock, bool sessionLock);
420 : : static void LockReassignOwner(LOCALLOCK *locallock, ResourceOwner parent);
421 : : static bool UnGrantLock(LOCK *lock, LOCKMODE lockmode,
422 : : PROCLOCK *proclock, LockMethod lockMethodTable);
423 : : static void CleanUpLock(LOCK *lock, PROCLOCK *proclock,
424 : : LockMethod lockMethodTable, uint32 hashcode,
425 : : bool wakeupNeeded);
426 : : static void LockRefindAndRelease(LockMethod lockMethodTable, PGPROC *proc,
427 : : LOCKTAG *locktag, LOCKMODE lockmode,
428 : : bool decrement_strong_lock_count);
429 : : static void GetSingleProcBlockerStatusData(PGPROC *blocked_proc,
430 : : BlockedProcsData *data);
431 : :
432 : :
433 : : /*
434 : : * Initialize the lock manager's shmem data structures.
435 : : *
436 : : * This is called from CreateSharedMemoryAndSemaphores(), which see for more
437 : : * comments. In the normal postmaster case, the shared hash tables are
438 : : * created here, and backends inherit pointers to them via fork(). In the
439 : : * EXEC_BACKEND case, each backend re-executes this code to obtain pointers to
440 : : * the already existing shared hash tables. In either case, each backend must
441 : : * also call InitLockManagerAccess() to create the locallock hash table.
442 : : */
443 : : void
444 : 6 : LockManagerShmemInit(void)
445 : : {
446 : 6 : HASHCTL info;
447 : 6 : int64 init_table_size,
448 : : max_table_size;
449 : 6 : bool found;
450 : :
451 : : /*
452 : : * Compute init/max size to request for lock hashtables. Note these
453 : : * calculations must agree with LockManagerShmemSize!
454 : : */
455 : 6 : max_table_size = NLOCKENTS();
456 : 6 : init_table_size = max_table_size / 2;
457 : :
458 : : /*
459 : : * Allocate hash table for LOCK structs. This stores per-locked-object
460 : : * information.
461 : : */
462 : 6 : info.keysize = sizeof(LOCKTAG);
463 : 6 : info.entrysize = sizeof(LOCK);
464 : 6 : info.num_partitions = NUM_LOCK_PARTITIONS;
465 : :
466 : 6 : LockMethodLockHash = ShmemInitHash("LOCK hash",
467 : 6 : init_table_size,
468 : 6 : max_table_size,
469 : : &info,
470 : : HASH_ELEM | HASH_BLOBS | HASH_PARTITION);
471 : :
472 : : /* Assume an average of 2 holders per lock */
473 : 6 : max_table_size *= 2;
474 : 6 : init_table_size *= 2;
475 : :
476 : : /*
477 : : * Allocate hash table for PROCLOCK structs. This stores
478 : : * per-lock-per-holder information.
479 : : */
480 : 6 : info.keysize = sizeof(PROCLOCKTAG);
481 : 6 : info.entrysize = sizeof(PROCLOCK);
482 : 6 : info.hash = proclock_hash;
483 : 6 : info.num_partitions = NUM_LOCK_PARTITIONS;
484 : :
485 : 6 : LockMethodProcLockHash = ShmemInitHash("PROCLOCK hash",
486 : 6 : init_table_size,
487 : 6 : max_table_size,
488 : : &info,
489 : : HASH_ELEM | HASH_FUNCTION | HASH_PARTITION);
490 : :
491 : : /*
492 : : * Allocate fast-path structures.
493 : : */
494 : 6 : FastPathStrongRelationLocks =
495 : 6 : ShmemInitStruct("Fast Path Strong Relation Lock Data",
496 : : sizeof(FastPathStrongRelationLockData), &found);
497 [ - + ]: 6 : if (!found)
498 : 6 : SpinLockInit(&FastPathStrongRelationLocks->mutex);
499 : 6 : }
500 : :
501 : : /*
502 : : * Initialize the lock manager's backend-private data structures.
503 : : */
504 : : void
505 : 806 : InitLockManagerAccess(void)
506 : : {
507 : : /*
508 : : * Allocate non-shared hash table for LOCALLOCK structs. This stores lock
509 : : * counts and resource owner information.
510 : : */
511 : 806 : HASHCTL info;
512 : :
513 : 806 : info.keysize = sizeof(LOCALLOCKTAG);
514 : 806 : info.entrysize = sizeof(LOCALLOCK);
515 : :
516 : 806 : LockMethodLocalHash = hash_create("LOCALLOCK hash",
517 : : 16,
518 : : &info,
519 : : HASH_ELEM | HASH_BLOBS);
520 : 806 : }
521 : :
522 : :
523 : : /*
524 : : * Fetch the lock method table associated with a given lock
525 : : */
526 : : LockMethod
527 : 2 : GetLocksMethodTable(const LOCK *lock)
528 : : {
529 : 2 : LOCKMETHODID lockmethodid = LOCK_LOCKMETHOD(*lock);
530 : :
531 [ + - ]: 2 : Assert(0 < lockmethodid && lockmethodid < lengthof(LockMethods));
532 : 4 : return LockMethods[lockmethodid];
533 : 2 : }
534 : :
535 : : /*
536 : : * Fetch the lock method table associated with a given locktag
537 : : */
538 : : LockMethod
539 : 0 : GetLockTagsMethodTable(const LOCKTAG *locktag)
540 : : {
541 : 0 : LOCKMETHODID lockmethodid = (LOCKMETHODID) locktag->locktag_lockmethodid;
542 : :
543 [ # # ]: 0 : Assert(0 < lockmethodid && lockmethodid < lengthof(LockMethods));
544 : 0 : return LockMethods[lockmethodid];
545 : 0 : }
546 : :
547 : :
548 : : /*
549 : : * Compute the hash code associated with a LOCKTAG.
550 : : *
551 : : * To avoid unnecessary recomputations of the hash code, we try to do this
552 : : * just once per function, and then pass it around as needed. Aside from
553 : : * passing the hashcode to hash_search_with_hash_value(), we can extract
554 : : * the lock partition number from the hashcode.
555 : : */
556 : : uint32
557 : 2415065 : LockTagHashCode(const LOCKTAG *locktag)
558 : : {
559 : 2415065 : return get_hash_value(LockMethodLockHash, locktag);
560 : : }
561 : :
562 : : /*
563 : : * Compute the hash code associated with a PROCLOCKTAG.
564 : : *
565 : : * Because we want to use just one set of partition locks for both the
566 : : * LOCK and PROCLOCK hash tables, we have to make sure that PROCLOCKs
567 : : * fall into the same partition number as their associated LOCKs.
568 : : * dynahash.c expects the partition number to be the low-order bits of
569 : : * the hash code, and therefore a PROCLOCKTAG's hash code must have the
570 : : * same low-order bits as the associated LOCKTAG's hash code. We achieve
571 : : * this with this specialized hash function.
572 : : */
573 : : static uint32
574 : 0 : proclock_hash(const void *key, Size keysize)
575 : : {
576 : 0 : const PROCLOCKTAG *proclocktag = (const PROCLOCKTAG *) key;
577 : 0 : uint32 lockhash;
578 : 0 : Datum procptr;
579 : :
580 [ # # ]: 0 : Assert(keysize == sizeof(PROCLOCKTAG));
581 : :
582 : : /* Look into the associated LOCK object, and compute its hash code */
583 : 0 : lockhash = LockTagHashCode(&proclocktag->myLock->tag);
584 : :
585 : : /*
586 : : * To make the hash code also depend on the PGPROC, we xor the proc
587 : : * struct's address into the hash code, left-shifted so that the
588 : : * partition-number bits don't change. Since this is only a hash, we
589 : : * don't care if we lose high-order bits of the address; use an
590 : : * intermediate variable to suppress cast-pointer-to-int warnings.
591 : : */
592 : 0 : procptr = PointerGetDatum(proclocktag->myProc);
593 : 0 : lockhash ^= DatumGetUInt32(procptr) << LOG2_NUM_LOCK_PARTITIONS;
594 : :
595 : 0 : return lockhash;
596 : 0 : }
597 : :
598 : : /*
599 : : * Compute the hash code associated with a PROCLOCKTAG, given the hashcode
600 : : * for its underlying LOCK.
601 : : *
602 : : * We use this just to avoid redundant calls of LockTagHashCode().
603 : : */
604 : : static inline uint32
605 : 471709 : ProcLockHashCode(const PROCLOCKTAG *proclocktag, uint32 hashcode)
606 : : {
607 : 471709 : uint32 lockhash = hashcode;
608 : 471709 : Datum procptr;
609 : :
610 : : /*
611 : : * This must match proclock_hash()!
612 : : */
613 : 471709 : procptr = PointerGetDatum(proclocktag->myProc);
614 : 471709 : lockhash ^= DatumGetUInt32(procptr) << LOG2_NUM_LOCK_PARTITIONS;
615 : :
616 : 943418 : return lockhash;
617 : 471709 : }
618 : :
619 : : /*
620 : : * Given two lock modes, return whether they would conflict.
621 : : */
622 : : bool
623 : 25516 : DoLockModesConflict(LOCKMODE mode1, LOCKMODE mode2)
624 : : {
625 : 25516 : LockMethod lockMethodTable = LockMethods[DEFAULT_LOCKMETHOD];
626 : :
627 [ + - ]: 25516 : if (lockMethodTable->conflictTab[mode1] & LOCKBIT_ON(mode2))
628 : 25516 : return true;
629 : :
630 : 0 : return false;
631 : 25516 : }
632 : :
633 : : /*
634 : : * LockHeldByMe -- test whether lock 'locktag' is held by the current
635 : : * transaction
636 : : *
637 : : * Returns true if current transaction holds a lock on 'tag' of mode
638 : : * 'lockmode'. If 'orstronger' is true, a stronger lockmode is also OK.
639 : : * ("Stronger" is defined as "numerically higher", which is a bit
640 : : * semantically dubious but is OK for the purposes we use this for.)
641 : : */
642 : : bool
643 : 2096109 : LockHeldByMe(const LOCKTAG *locktag,
644 : : LOCKMODE lockmode, bool orstronger)
645 : : {
646 : 2096109 : LOCALLOCKTAG localtag;
647 : 2096109 : LOCALLOCK *locallock;
648 : :
649 : : /*
650 : : * See if there is a LOCALLOCK entry for this lock and lockmode
651 : : */
652 [ + - - + : 2096109 : MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
# # # # #
# ]
653 : 2096109 : localtag.lock = *locktag;
654 : 2096109 : localtag.mode = lockmode;
655 : :
656 : 2096109 : locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
657 : : &localtag,
658 : : HASH_FIND, NULL);
659 : :
660 [ + + - + ]: 2096109 : if (locallock && locallock->nLocks > 0)
661 : 1255519 : return true;
662 : :
663 [ + + ]: 840590 : if (orstronger)
664 : : {
665 : 543961 : LOCKMODE slockmode;
666 : :
667 [ + - ]: 824384 : for (slockmode = lockmode + 1;
668 : 824384 : slockmode <= MaxLockMode;
669 : 280423 : slockmode++)
670 : : {
671 [ + + ]: 824384 : if (LockHeldByMe(locktag, slockmode, false))
672 : 543961 : return true;
673 : 280423 : }
674 [ + - ]: 543961 : }
675 : :
676 : 296629 : return false;
677 : 2096109 : }
678 : :
679 : : #ifdef USE_ASSERT_CHECKING
680 : : /*
681 : : * GetLockMethodLocalHash -- return the hash of local locks, for modules that
682 : : * evaluate assertions based on all locks held.
683 : : */
684 : : HTAB *
685 : 4523 : GetLockMethodLocalHash(void)
686 : : {
687 : 4523 : return LockMethodLocalHash;
688 : : }
689 : : #endif
690 : :
691 : : /*
692 : : * LockHasWaiters -- look up 'locktag' and check if releasing this
693 : : * lock would wake up other processes waiting for it.
694 : : */
695 : : bool
696 : 0 : LockHasWaiters(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock)
697 : : {
698 : 0 : LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
699 : 0 : LockMethod lockMethodTable;
700 : 0 : LOCALLOCKTAG localtag;
701 : 0 : LOCALLOCK *locallock;
702 : 0 : LOCK *lock;
703 : 0 : PROCLOCK *proclock;
704 : 0 : LWLock *partitionLock;
705 : 0 : bool hasWaiters = false;
706 : :
707 [ # # ]: 0 : if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
708 [ # # # # ]: 0 : elog(ERROR, "unrecognized lock method: %d", lockmethodid);
709 : 0 : lockMethodTable = LockMethods[lockmethodid];
710 [ # # ]: 0 : if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
711 [ # # # # ]: 0 : elog(ERROR, "unrecognized lock mode: %d", lockmode);
712 : :
713 : : #ifdef LOCK_DEBUG
714 : : if (LOCK_DEBUG_ENABLED(locktag))
715 : : elog(LOG, "LockHasWaiters: lock [%u,%u] %s",
716 : : locktag->locktag_field1, locktag->locktag_field2,
717 : : lockMethodTable->lockModeNames[lockmode]);
718 : : #endif
719 : :
720 : : /*
721 : : * Find the LOCALLOCK entry for this lock and lockmode
722 : : */
723 [ # # # # : 0 : MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
# # # # #
# ]
724 : 0 : localtag.lock = *locktag;
725 : 0 : localtag.mode = lockmode;
726 : :
727 : 0 : locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
728 : : &localtag,
729 : : HASH_FIND, NULL);
730 : :
731 : : /*
732 : : * let the caller print its own error message, too. Do not ereport(ERROR).
733 : : */
734 [ # # # # ]: 0 : if (!locallock || locallock->nLocks <= 0)
735 : : {
736 [ # # # # ]: 0 : elog(WARNING, "you don't own a lock of type %s",
737 : : lockMethodTable->lockModeNames[lockmode]);
738 : 0 : return false;
739 : : }
740 : :
741 : : /*
742 : : * Check the shared lock table.
743 : : */
744 : 0 : partitionLock = LockHashPartitionLock(locallock->hashcode);
745 : :
746 : 0 : LWLockAcquire(partitionLock, LW_SHARED);
747 : :
748 : : /*
749 : : * We don't need to re-find the lock or proclock, since we kept their
750 : : * addresses in the locallock table, and they couldn't have been removed
751 : : * while we were holding a lock on them.
752 : : */
753 : 0 : lock = locallock->lock;
754 : : LOCK_PRINT("LockHasWaiters: found", lock, lockmode);
755 : 0 : proclock = locallock->proclock;
756 : : PROCLOCK_PRINT("LockHasWaiters: found", proclock);
757 : :
758 : : /*
759 : : * Double-check that we are actually holding a lock of the type we want to
760 : : * release.
761 : : */
762 [ # # ]: 0 : if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
763 : : {
764 : : PROCLOCK_PRINT("LockHasWaiters: WRONGTYPE", proclock);
765 : 0 : LWLockRelease(partitionLock);
766 [ # # # # ]: 0 : elog(WARNING, "you don't own a lock of type %s",
767 : : lockMethodTable->lockModeNames[lockmode]);
768 : 0 : RemoveLocalLock(locallock);
769 : 0 : return false;
770 : : }
771 : :
772 : : /*
773 : : * Do the checking.
774 : : */
775 [ # # ]: 0 : if ((lockMethodTable->conflictTab[lockmode] & lock->waitMask) != 0)
776 : 0 : hasWaiters = true;
777 : :
778 : 0 : LWLockRelease(partitionLock);
779 : :
780 : 0 : return hasWaiters;
781 : 0 : }
782 : :
783 : : /*
784 : : * LockAcquire -- Check for lock conflicts, sleep if conflict found,
785 : : * set lock if/when no conflicts.
786 : : *
787 : : * Inputs:
788 : : * locktag: unique identifier for the lockable object
789 : : * lockmode: lock mode to acquire
790 : : * sessionLock: if true, acquire lock for session not current transaction
791 : : * dontWait: if true, don't wait to acquire lock
792 : : *
793 : : * Returns one of:
794 : : * LOCKACQUIRE_NOT_AVAIL lock not available, and dontWait=true
795 : : * LOCKACQUIRE_OK lock successfully acquired
796 : : * LOCKACQUIRE_ALREADY_HELD incremented count for lock already held
797 : : * LOCKACQUIRE_ALREADY_CLEAR incremented count for lock already clear
798 : : *
799 : : * In the normal case where dontWait=false and the caller doesn't need to
800 : : * distinguish a freshly acquired lock from one already taken earlier in
801 : : * this same transaction, there is no need to examine the return value.
802 : : *
803 : : * Side Effects: The lock is acquired and recorded in lock tables.
804 : : *
805 : : * NOTE: if we wait for the lock, there is no way to abort the wait
806 : : * short of aborting the transaction.
807 : : */
808 : : LockAcquireResult
809 : 97668 : LockAcquire(const LOCKTAG *locktag,
810 : : LOCKMODE lockmode,
811 : : bool sessionLock,
812 : : bool dontWait)
813 : : {
814 : 97668 : return LockAcquireExtended(locktag, lockmode, sessionLock, dontWait,
815 : : true, NULL, false);
816 : : }
817 : :
818 : : /*
819 : : * LockAcquireExtended - allows us to specify additional options
820 : : *
821 : : * reportMemoryError specifies whether a lock request that fills the lock
822 : : * table should generate an ERROR or not. Passing "false" allows the caller
823 : : * to attempt to recover from lock-table-full situations, perhaps by forcibly
824 : : * canceling other lock holders and then retrying. Note, however, that the
825 : : * return code for that is LOCKACQUIRE_NOT_AVAIL, so that it's unsafe to use
826 : : * in combination with dontWait = true, as the cause of failure couldn't be
827 : : * distinguished.
828 : : *
829 : : * If locallockp isn't NULL, *locallockp receives a pointer to the LOCALLOCK
830 : : * table entry if a lock is successfully acquired, or NULL if not.
831 : : *
832 : : * logLockFailure indicates whether to log details when a lock acquisition
833 : : * fails with dontWait = true.
834 : : */
835 : : LockAcquireResult
836 : 3804548 : LockAcquireExtended(const LOCKTAG *locktag,
837 : : LOCKMODE lockmode,
838 : : bool sessionLock,
839 : : bool dontWait,
840 : : bool reportMemoryError,
841 : : LOCALLOCK **locallockp,
842 : : bool logLockFailure)
843 : : {
844 : 3804548 : LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
845 : 3804548 : LockMethod lockMethodTable;
846 : 3804548 : LOCALLOCKTAG localtag;
847 : 3804548 : LOCALLOCK *locallock;
848 : 3804548 : LOCK *lock;
849 : 3804548 : PROCLOCK *proclock;
850 : 3804548 : bool found;
851 : 3804548 : ResourceOwner owner;
852 : 3804548 : uint32 hashcode;
853 : 3804548 : LWLock *partitionLock;
854 : 3804548 : bool found_conflict;
855 : 3804548 : ProcWaitStatus waitResult;
856 : 3804548 : bool log_lock = false;
857 : :
858 [ + - ]: 3804548 : if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
859 [ # # # # ]: 0 : elog(ERROR, "unrecognized lock method: %d", lockmethodid);
860 : 3804548 : lockMethodTable = LockMethods[lockmethodid];
861 [ + - ]: 3804548 : if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
862 [ # # # # ]: 0 : elog(ERROR, "unrecognized lock mode: %d", lockmode);
863 : :
864 [ - + # # ]: 3804548 : if (RecoveryInProgress() && !InRecovery &&
865 [ # # ]: 0 : (locktag->locktag_type == LOCKTAG_OBJECT ||
866 [ # # ]: 0 : locktag->locktag_type == LOCKTAG_RELATION) &&
867 : 0 : lockmode > RowExclusiveLock)
868 [ # # # # ]: 0 : ereport(ERROR,
869 : : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
870 : : errmsg("cannot acquire lock mode %s on database objects while recovery is in progress",
871 : : lockMethodTable->lockModeNames[lockmode]),
872 : : errhint("Only RowExclusiveLock or less can be acquired on database objects during recovery.")));
873 : :
874 : : #ifdef LOCK_DEBUG
875 : : if (LOCK_DEBUG_ENABLED(locktag))
876 : : elog(LOG, "LockAcquire: lock [%u,%u] %s",
877 : : locktag->locktag_field1, locktag->locktag_field2,
878 : : lockMethodTable->lockModeNames[lockmode]);
879 : : #endif
880 : :
881 : : /* Identify owner for lock */
882 [ + + ]: 3804548 : if (sessionLock)
883 : 873 : owner = NULL;
884 : : else
885 : 3803675 : owner = CurrentResourceOwner;
886 : :
887 : : /*
888 : : * Find or create a LOCALLOCK entry for this lock and lockmode
889 : : */
890 [ + + - + : 3804548 : MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
# # # # #
# ]
891 : 3804546 : localtag.lock = *locktag;
892 : 3804546 : localtag.mode = lockmode;
893 : :
894 : 3804546 : locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
895 : : &localtag,
896 : : HASH_ENTER, &found);
897 : :
898 : : /*
899 : : * if it's a new locallock object, initialize it
900 : : */
901 [ + + ]: 3804546 : if (!found)
902 : : {
903 : 2316920 : locallock->lock = NULL;
904 : 2316920 : locallock->proclock = NULL;
905 : 2316920 : locallock->hashcode = LockTagHashCode(&(localtag.lock));
906 : 2316920 : locallock->nLocks = 0;
907 : 2316920 : locallock->holdsStrongLockCount = false;
908 : 2316920 : locallock->lockCleared = false;
909 : 2316920 : locallock->numLockOwners = 0;
910 : 2316920 : locallock->maxLockOwners = 8;
911 : 2316920 : locallock->lockOwners = NULL; /* in case next line fails */
912 : 2316920 : locallock->lockOwners = (LOCALLOCKOWNER *)
913 : 4633840 : MemoryContextAlloc(TopMemoryContext,
914 : 2316920 : locallock->maxLockOwners * sizeof(LOCALLOCKOWNER));
915 : 2316920 : }
916 : : else
917 : : {
918 : : /* Make sure there will be room to remember the lock */
919 [ + + ]: 1487626 : if (locallock->numLockOwners >= locallock->maxLockOwners)
920 : : {
921 : 2 : int newsize = locallock->maxLockOwners * 2;
922 : :
923 : 2 : locallock->lockOwners = (LOCALLOCKOWNER *)
924 : 4 : repalloc(locallock->lockOwners,
925 : 2 : newsize * sizeof(LOCALLOCKOWNER));
926 : 2 : locallock->maxLockOwners = newsize;
927 : 2 : }
928 : : }
929 : 3804546 : hashcode = locallock->hashcode;
930 : :
931 [ + + ]: 3804546 : if (locallockp)
932 : 3706879 : *locallockp = locallock;
933 : :
934 : : /*
935 : : * If we already hold the lock, we can just increase the count locally.
936 : : *
937 : : * If lockCleared is already set, caller need not worry about absorbing
938 : : * sinval messages related to the lock's object.
939 : : */
940 [ + + ]: 3804546 : if (locallock->nLocks > 0)
941 : : {
942 : 1487626 : GrantLockLocal(locallock, owner);
943 [ + + ]: 1487626 : if (locallock->lockCleared)
944 : 1477003 : return LOCKACQUIRE_ALREADY_CLEAR;
945 : : else
946 : 10623 : return LOCKACQUIRE_ALREADY_HELD;
947 : : }
948 : :
949 : : /*
950 : : * We don't acquire any other heavyweight lock while holding the relation
951 : : * extension lock. We do allow to acquire the same relation extension
952 : : * lock more than once but that case won't reach here.
953 : : */
954 [ + - ]: 2316920 : Assert(!IsRelationExtensionLockHeld);
955 : :
956 : : /*
957 : : * Prepare to emit a WAL record if acquisition of this lock needs to be
958 : : * replayed in a standby server.
959 : : *
960 : : * Here we prepare to log; after lock is acquired we'll issue log record.
961 : : * This arrangement simplifies error recovery in case the preparation step
962 : : * fails.
963 : : *
964 : : * Only AccessExclusiveLocks can conflict with lock types that read-only
965 : : * transactions can acquire in a standby server. Make sure this definition
966 : : * matches the one in GetRunningTransactionLocks().
967 : : */
968 [ + + ]: 2316920 : if (lockmode >= AccessExclusiveLock &&
969 [ + + ]: 43805 : locktag->locktag_type == LOCKTAG_RELATION &&
970 [ + - + + ]: 26337 : !RecoveryInProgress() &&
971 : 26337 : XLogStandbyInfoActive())
972 : : {
973 : 634 : LogAccessExclusiveLockPrepare();
974 : 634 : log_lock = true;
975 : 634 : }
976 : :
977 : : /*
978 : : * Attempt to take lock via fast path, if eligible. But if we remember
979 : : * having filled up the fast path array, we don't attempt to make any
980 : : * further use of it until we release some locks. It's possible that some
981 : : * other backend has transferred some of those locks to the shared hash
982 : : * table, leaving space free, but it's not worth acquiring the LWLock just
983 : : * to check. It's also possible that we're acquiring a second or third
984 : : * lock type on a relation we have already locked using the fast-path, but
985 : : * for now we don't worry about that case either.
986 : : */
987 [ + + + + : 2316920 : if (EligibleForRelationFastPath(locktag, lockmode) &&
+ + + + +
+ + + ]
988 : 2100571 : FastPathLocalUseCounts[FAST_PATH_REL_GROUP(locktag->locktag_field2)] < FP_LOCK_SLOTS_PER_GROUP)
989 : : {
990 : 2100411 : uint32 fasthashcode = FastPathStrongLockHashPartition(hashcode);
991 : 2100411 : bool acquired;
992 : :
993 : : /*
994 : : * LWLockAcquire acts as a memory sequencing point, so it's safe to
995 : : * assume that any strong locker whose increment to
996 : : * FastPathStrongRelationLocks->counts becomes visible after we test
997 : : * it has yet to begin to transfer fast-path locks.
998 : : */
999 : 2100411 : LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
1000 [ + + ]: 2100411 : if (FastPathStrongRelationLocks->count[fasthashcode] != 0)
1001 : 27590 : acquired = false;
1002 : : else
1003 : 4145642 : acquired = FastPathGrantRelationLock(locktag->locktag_field2,
1004 : 2072821 : lockmode);
1005 : 2100411 : LWLockRelease(&MyProc->fpInfoLock);
1006 [ + + ]: 2100411 : if (acquired)
1007 : : {
1008 : : /*
1009 : : * The locallock might contain stale pointers to some old shared
1010 : : * objects; we MUST reset these to null before considering the
1011 : : * lock to be acquired via fast-path.
1012 : : */
1013 : 2072821 : locallock->lock = NULL;
1014 : 2072821 : locallock->proclock = NULL;
1015 : 2072821 : GrantLockLocal(locallock, owner);
1016 : 2072821 : return LOCKACQUIRE_OK;
1017 : : }
1018 [ + + ]: 2100411 : }
1019 : :
1020 : : /*
1021 : : * If this lock could potentially have been taken via the fast-path by
1022 : : * some other backend, we must (temporarily) disable further use of the
1023 : : * fast-path for this lock tag, and migrate any locks already taken via
1024 : : * this method to the main lock table.
1025 : : */
1026 [ + + + + : 244099 : if (ConflictsWithRelationFastPath(locktag, lockmode))
+ + + + ]
1027 : : {
1028 : 33094 : uint32 fasthashcode = FastPathStrongLockHashPartition(hashcode);
1029 : :
1030 : 33094 : BeginStrongLockAcquire(locallock, fasthashcode);
1031 [ + - + - ]: 66188 : if (!FastPathTransferRelationLocks(lockMethodTable, locktag,
1032 : 33094 : hashcode))
1033 : : {
1034 : 0 : AbortStrongLockAcquire();
1035 [ # # ]: 0 : if (locallock->nLocks == 0)
1036 : 0 : RemoveLocalLock(locallock);
1037 [ # # ]: 0 : if (locallockp)
1038 : 0 : *locallockp = NULL;
1039 [ # # ]: 0 : if (reportMemoryError)
1040 [ # # # # ]: 0 : ereport(ERROR,
1041 : : (errcode(ERRCODE_OUT_OF_MEMORY),
1042 : : errmsg("out of shared memory"),
1043 : : errhint("You might need to increase \"%s\".", "max_locks_per_transaction")));
1044 : : else
1045 : 0 : return LOCKACQUIRE_NOT_AVAIL;
1046 : 0 : }
1047 [ - + ]: 33094 : }
1048 : :
1049 : : /*
1050 : : * We didn't find the lock in our LOCALLOCK table, and we didn't manage to
1051 : : * take it via the fast-path, either, so we've got to mess with the shared
1052 : : * lock table.
1053 : : */
1054 : 244099 : partitionLock = LockHashPartitionLock(hashcode);
1055 : :
1056 : 244099 : LWLockAcquire(partitionLock, LW_EXCLUSIVE);
1057 : :
1058 : : /*
1059 : : * Find or create lock and proclock entries with this tag
1060 : : *
1061 : : * Note: if the locallock object already existed, it might have a pointer
1062 : : * to the lock already ... but we should not assume that that pointer is
1063 : : * valid, since a lock object with zero hold and request counts can go
1064 : : * away anytime. So we have to use SetupLockInTable() to recompute the
1065 : : * lock and proclock pointers, even if they're already set.
1066 : : */
1067 : 488198 : proclock = SetupLockInTable(lockMethodTable, MyProc, locktag,
1068 : 244099 : hashcode, lockmode);
1069 [ + - ]: 244099 : if (!proclock)
1070 : : {
1071 : 0 : AbortStrongLockAcquire();
1072 : 0 : LWLockRelease(partitionLock);
1073 [ # # ]: 0 : if (locallock->nLocks == 0)
1074 : 0 : RemoveLocalLock(locallock);
1075 [ # # ]: 0 : if (locallockp)
1076 : 0 : *locallockp = NULL;
1077 [ # # ]: 0 : if (reportMemoryError)
1078 [ # # # # ]: 0 : ereport(ERROR,
1079 : : (errcode(ERRCODE_OUT_OF_MEMORY),
1080 : : errmsg("out of shared memory"),
1081 : : errhint("You might need to increase \"%s\".", "max_locks_per_transaction")));
1082 : : else
1083 : 0 : return LOCKACQUIRE_NOT_AVAIL;
1084 : 0 : }
1085 : 244099 : locallock->proclock = proclock;
1086 : 244099 : lock = proclock->tag.myLock;
1087 : 244099 : locallock->lock = lock;
1088 : :
1089 : : /*
1090 : : * If lock requested conflicts with locks requested by waiters, must join
1091 : : * wait queue. Otherwise, check for conflict with already-held locks.
1092 : : * (That's last because most complex check.)
1093 : : */
1094 [ + + ]: 244099 : if (lockMethodTable->conflictTab[lockmode] & lock->waitMask)
1095 : 20 : found_conflict = true;
1096 : : else
1097 : 488158 : found_conflict = LockCheckConflicts(lockMethodTable, lockmode,
1098 : 244079 : lock, proclock);
1099 : :
1100 [ + + ]: 244099 : if (!found_conflict)
1101 : : {
1102 : : /* No conflict with held or previously requested locks */
1103 : 244042 : GrantLock(lock, proclock, lockmode);
1104 : 244042 : waitResult = PROC_WAIT_STATUS_OK;
1105 : 244042 : }
1106 : : else
1107 : : {
1108 : : /*
1109 : : * Join the lock's wait queue. We call this even in the dontWait
1110 : : * case, because JoinWaitQueue() may discover that we can acquire the
1111 : : * lock immediately after all.
1112 : : */
1113 : 57 : waitResult = JoinWaitQueue(locallock, lockMethodTable, dontWait);
1114 : : }
1115 : :
1116 [ - + ]: 244099 : if (waitResult == PROC_WAIT_STATUS_ERROR)
1117 : : {
1118 : : /*
1119 : : * We're not getting the lock because a deadlock was detected already
1120 : : * while trying to join the wait queue, or because we would have to
1121 : : * wait but the caller requested no blocking.
1122 : : *
1123 : : * Undo the changes to shared entries before releasing the partition
1124 : : * lock.
1125 : : */
1126 : 0 : AbortStrongLockAcquire();
1127 : :
1128 [ # # ]: 0 : if (proclock->holdMask == 0)
1129 : : {
1130 : 0 : uint32 proclock_hashcode;
1131 : :
1132 : 0 : proclock_hashcode = ProcLockHashCode(&proclock->tag,
1133 : 0 : hashcode);
1134 : 0 : dlist_delete(&proclock->lockLink);
1135 : 0 : dlist_delete(&proclock->procLink);
1136 [ # # # # ]: 0 : if (!hash_search_with_hash_value(LockMethodProcLockHash,
1137 : 0 : &(proclock->tag),
1138 : 0 : proclock_hashcode,
1139 : : HASH_REMOVE,
1140 : : NULL))
1141 [ # # # # ]: 0 : elog(PANIC, "proclock table corrupted");
1142 : 0 : }
1143 : : else
1144 : : PROCLOCK_PRINT("LockAcquire: did not join wait queue", proclock);
1145 : 0 : lock->nRequested--;
1146 : 0 : lock->requested[lockmode]--;
1147 : : LOCK_PRINT("LockAcquire: did not join wait queue",
1148 : : lock, lockmode);
1149 [ # # ]: 0 : Assert((lock->nRequested > 0) &&
1150 : : (lock->requested[lockmode] >= 0));
1151 [ # # ]: 0 : Assert(lock->nGranted <= lock->nRequested);
1152 : 0 : LWLockRelease(partitionLock);
1153 [ # # ]: 0 : if (locallock->nLocks == 0)
1154 : 0 : RemoveLocalLock(locallock);
1155 : :
1156 [ # # ]: 0 : if (dontWait)
1157 : : {
1158 : : /*
1159 : : * Log lock holders and waiters as a detail log message if
1160 : : * logLockFailure = true and lock acquisition fails with dontWait
1161 : : * = true
1162 : : */
1163 [ # # ]: 0 : if (logLockFailure)
1164 : : {
1165 : 0 : StringInfoData buf,
1166 : : lock_waiters_sbuf,
1167 : : lock_holders_sbuf;
1168 : 0 : const char *modename;
1169 : 0 : int lockHoldersNum = 0;
1170 : :
1171 : 0 : initStringInfo(&buf);
1172 : 0 : initStringInfo(&lock_waiters_sbuf);
1173 : 0 : initStringInfo(&lock_holders_sbuf);
1174 : :
1175 : 0 : DescribeLockTag(&buf, &locallock->tag.lock);
1176 : 0 : modename = GetLockmodeName(locallock->tag.lock.locktag_lockmethodid,
1177 : 0 : lockmode);
1178 : :
1179 : : /* Gather a list of all lock holders and waiters */
1180 : 0 : LWLockAcquire(partitionLock, LW_SHARED);
1181 : 0 : GetLockHoldersAndWaiters(locallock, &lock_holders_sbuf,
1182 : : &lock_waiters_sbuf, &lockHoldersNum);
1183 : 0 : LWLockRelease(partitionLock);
1184 : :
1185 [ # # # # ]: 0 : ereport(LOG,
1186 : : (errmsg("process %d could not obtain %s on %s",
1187 : : MyProcPid, modename, buf.data),
1188 : : errdetail_log_plural(
1189 : : "Process holding the lock: %s, Wait queue: %s.",
1190 : : "Processes holding the lock: %s, Wait queue: %s.",
1191 : : lockHoldersNum,
1192 : : lock_holders_sbuf.data,
1193 : : lock_waiters_sbuf.data)));
1194 : :
1195 : 0 : pfree(buf.data);
1196 : 0 : pfree(lock_holders_sbuf.data);
1197 : 0 : pfree(lock_waiters_sbuf.data);
1198 : 0 : }
1199 [ # # ]: 0 : if (locallockp)
1200 : 0 : *locallockp = NULL;
1201 : 0 : return LOCKACQUIRE_NOT_AVAIL;
1202 : : }
1203 : : else
1204 : : {
1205 : 0 : DeadLockReport();
1206 : : /* DeadLockReport() will not return */
1207 : : }
1208 : : }
1209 : :
1210 : : /*
1211 : : * We are now in the lock queue, or the lock was already granted. If
1212 : : * queued, go to sleep.
1213 : : */
1214 [ + + ]: 244099 : if (waitResult == PROC_WAIT_STATUS_WAITING)
1215 : : {
1216 [ + - ]: 42 : Assert(!dontWait);
1217 : : PROCLOCK_PRINT("LockAcquire: sleeping on lock", proclock);
1218 : : LOCK_PRINT("LockAcquire: sleeping on lock", lock, lockmode);
1219 : 42 : LWLockRelease(partitionLock);
1220 : :
1221 : 42 : waitResult = WaitOnLock(locallock, owner);
1222 : :
1223 : : /*
1224 : : * NOTE: do not do any material change of state between here and
1225 : : * return. All required changes in locktable state must have been
1226 : : * done when the lock was granted to us --- see notes in WaitOnLock.
1227 : : */
1228 : :
1229 [ + - ]: 42 : if (waitResult == PROC_WAIT_STATUS_ERROR)
1230 : : {
1231 : : /*
1232 : : * We failed as a result of a deadlock, see CheckDeadLock(). Quit
1233 : : * now.
1234 : : */
1235 [ # # ]: 0 : Assert(!dontWait);
1236 : 0 : DeadLockReport();
1237 : : /* DeadLockReport() will not return */
1238 : : }
1239 : 42 : }
1240 : : else
1241 : 244057 : LWLockRelease(partitionLock);
1242 [ + - ]: 244099 : Assert(waitResult == PROC_WAIT_STATUS_OK);
1243 : :
1244 : : /* The lock was granted to us. Update the local lock entry accordingly */
1245 [ + - ]: 244099 : Assert((proclock->holdMask & LOCKBIT_ON(lockmode)) != 0);
1246 : 244099 : GrantLockLocal(locallock, owner);
1247 : :
1248 : : /*
1249 : : * Lock state is fully up-to-date now; if we error out after this, no
1250 : : * special error cleanup is required.
1251 : : */
1252 : 244099 : FinishStrongLockAcquire();
1253 : :
1254 : : /*
1255 : : * Emit a WAL record if acquisition of this lock needs to be replayed in a
1256 : : * standby server.
1257 : : */
1258 [ + + ]: 244099 : if (log_lock)
1259 : : {
1260 : : /*
1261 : : * Decode the locktag back to the original values, to avoid sending
1262 : : * lots of empty bytes with every message. See lock.h to check how a
1263 : : * locktag is defined for LOCKTAG_RELATION
1264 : : */
1265 : 1268 : LogAccessExclusiveLock(locktag->locktag_field1,
1266 : 634 : locktag->locktag_field2);
1267 : 634 : }
1268 : :
1269 : 244099 : return LOCKACQUIRE_OK;
1270 : 3804546 : }
1271 : :
1272 : : /*
1273 : : * Find or create LOCK and PROCLOCK objects as needed for a new lock
1274 : : * request.
1275 : : *
1276 : : * Returns the PROCLOCK object, or NULL if we failed to create the objects
1277 : : * for lack of shared memory.
1278 : : *
1279 : : * The appropriate partition lock must be held at entry, and will be
1280 : : * held at exit.
1281 : : */
1282 : : static PROCLOCK *
1283 : 244383 : SetupLockInTable(LockMethod lockMethodTable, PGPROC *proc,
1284 : : const LOCKTAG *locktag, uint32 hashcode, LOCKMODE lockmode)
1285 : : {
1286 : 244383 : LOCK *lock;
1287 : 244383 : PROCLOCK *proclock;
1288 : 244383 : PROCLOCKTAG proclocktag;
1289 : 244383 : uint32 proclock_hashcode;
1290 : 244383 : bool found;
1291 : :
1292 : : /*
1293 : : * Find or create a lock with this tag.
1294 : : */
1295 : 488766 : lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
1296 : 244383 : locktag,
1297 : 244383 : hashcode,
1298 : : HASH_ENTER_NULL,
1299 : : &found);
1300 [ + - ]: 244383 : if (!lock)
1301 : 0 : return NULL;
1302 : :
1303 : : /*
1304 : : * if it's a new lock object, initialize it
1305 : : */
1306 [ + + ]: 244383 : if (!found)
1307 : : {
1308 : 219939 : lock->grantMask = 0;
1309 : 219939 : lock->waitMask = 0;
1310 : 219939 : dlist_init(&lock->procLocks);
1311 : 219939 : dclist_init(&lock->waitProcs);
1312 : 219939 : lock->nRequested = 0;
1313 : 219939 : lock->nGranted = 0;
1314 [ + - + - : 1319634 : MemSet(lock->requested, 0, sizeof(int) * MAX_LOCKMODES);
+ - - + +
+ ]
1315 [ - + # # : 219939 : MemSet(lock->granted, 0, sizeof(int) * MAX_LOCKMODES);
# # # # #
# ]
1316 : : LOCK_PRINT("LockAcquire: new", lock, lockmode);
1317 : 219939 : }
1318 : : else
1319 : : {
1320 : : LOCK_PRINT("LockAcquire: found", lock, lockmode);
1321 [ + - ]: 24444 : Assert((lock->nRequested >= 0) && (lock->requested[lockmode] >= 0));
1322 [ + - ]: 24444 : Assert((lock->nGranted >= 0) && (lock->granted[lockmode] >= 0));
1323 [ + - ]: 24444 : Assert(lock->nGranted <= lock->nRequested);
1324 : : }
1325 : :
1326 : : /*
1327 : : * Create the hash key for the proclock table.
1328 : : */
1329 : 244383 : proclocktag.myLock = lock;
1330 : 244383 : proclocktag.myProc = proc;
1331 : :
1332 : 244383 : proclock_hashcode = ProcLockHashCode(&proclocktag, hashcode);
1333 : :
1334 : : /*
1335 : : * Find or create a proclock entry with this tag
1336 : : */
1337 : 488766 : proclock = (PROCLOCK *) hash_search_with_hash_value(LockMethodProcLockHash,
1338 : : &proclocktag,
1339 : 244383 : proclock_hashcode,
1340 : : HASH_ENTER_NULL,
1341 : : &found);
1342 [ + - ]: 244383 : if (!proclock)
1343 : : {
1344 : : /* Oops, not enough shmem for the proclock */
1345 [ # # ]: 0 : if (lock->nRequested == 0)
1346 : : {
1347 : : /*
1348 : : * There are no other requestors of this lock, so garbage-collect
1349 : : * the lock object. We *must* do this to avoid a permanent leak
1350 : : * of shared memory, because there won't be anything to cause
1351 : : * anyone to release the lock object later.
1352 : : */
1353 [ # # ]: 0 : Assert(dlist_is_empty(&(lock->procLocks)));
1354 [ # # # # ]: 0 : if (!hash_search_with_hash_value(LockMethodLockHash,
1355 : 0 : &(lock->tag),
1356 : 0 : hashcode,
1357 : : HASH_REMOVE,
1358 : : NULL))
1359 [ # # # # ]: 0 : elog(PANIC, "lock table corrupted");
1360 : 0 : }
1361 : 0 : return NULL;
1362 : : }
1363 : :
1364 : : /*
1365 : : * If new, initialize the new entry
1366 : : */
1367 [ + + ]: 244383 : if (!found)
1368 : : {
1369 : 227043 : uint32 partition = LockHashPartition(hashcode);
1370 : :
1371 : : /*
1372 : : * It might seem unsafe to access proclock->groupLeader without a
1373 : : * lock, but it's not really. Either we are initializing a proclock
1374 : : * on our own behalf, in which case our group leader isn't changing
1375 : : * because the group leader for a process can only ever be changed by
1376 : : * the process itself; or else we are transferring a fast-path lock to
1377 : : * the main lock table, in which case that process can't change its
1378 : : * lock group leader without first releasing all of its locks (and in
1379 : : * particular the one we are currently transferring).
1380 : : */
1381 [ + + ]: 227043 : proclock->groupLeader = proc->lockGroupLeader != NULL ?
1382 : 227043 : proc->lockGroupLeader : proc;
1383 : 227043 : proclock->holdMask = 0;
1384 : 227043 : proclock->releaseMask = 0;
1385 : : /* Add proclock to appropriate lists */
1386 : 227043 : dlist_push_tail(&lock->procLocks, &proclock->lockLink);
1387 : 227043 : dlist_push_tail(&proc->myProcLocks[partition], &proclock->procLink);
1388 : : PROCLOCK_PRINT("LockAcquire: new", proclock);
1389 : 227043 : }
1390 : : else
1391 : : {
1392 : : PROCLOCK_PRINT("LockAcquire: found", proclock);
1393 [ + - ]: 17340 : Assert((proclock->holdMask & ~lock->grantMask) == 0);
1394 : :
1395 : : #ifdef CHECK_DEADLOCK_RISK
1396 : :
1397 : : /*
1398 : : * Issue warning if we already hold a lower-level lock on this object
1399 : : * and do not hold a lock of the requested level or higher. This
1400 : : * indicates a deadlock-prone coding practice (eg, we'd have a
1401 : : * deadlock if another backend were following the same code path at
1402 : : * about the same time).
1403 : : *
1404 : : * This is not enabled by default, because it may generate log entries
1405 : : * about user-level coding practices that are in fact safe in context.
1406 : : * It can be enabled to help find system-level problems.
1407 : : *
1408 : : * XXX Doing numeric comparison on the lockmodes is a hack; it'd be
1409 : : * better to use a table. For now, though, this works.
1410 : : */
1411 : : {
1412 : : int i;
1413 : :
1414 : : for (i = lockMethodTable->numLockModes; i > 0; i--)
1415 : : {
1416 : : if (proclock->holdMask & LOCKBIT_ON(i))
1417 : : {
1418 : : if (i >= (int) lockmode)
1419 : : break; /* safe: we have a lock >= req level */
1420 : : elog(LOG, "deadlock risk: raising lock level"
1421 : : " from %s to %s on object %u/%u/%u",
1422 : : lockMethodTable->lockModeNames[i],
1423 : : lockMethodTable->lockModeNames[lockmode],
1424 : : lock->tag.locktag_field1, lock->tag.locktag_field2,
1425 : : lock->tag.locktag_field3);
1426 : : break;
1427 : : }
1428 : : }
1429 : : }
1430 : : #endif /* CHECK_DEADLOCK_RISK */
1431 : : }
1432 : :
1433 : : /*
1434 : : * lock->nRequested and lock->requested[] count the total number of
1435 : : * requests, whether granted or waiting, so increment those immediately.
1436 : : * The other counts don't increment till we get the lock.
1437 : : */
1438 : 244383 : lock->nRequested++;
1439 : 244383 : lock->requested[lockmode]++;
1440 [ + - ]: 244383 : Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
1441 : :
1442 : : /*
1443 : : * We shouldn't already hold the desired lock; else locallock table is
1444 : : * broken.
1445 : : */
1446 [ + - ]: 244383 : if (proclock->holdMask & LOCKBIT_ON(lockmode))
1447 [ # # # # ]: 0 : elog(ERROR, "lock %s on object %u/%u/%u is already held",
1448 : : lockMethodTable->lockModeNames[lockmode],
1449 : : lock->tag.locktag_field1, lock->tag.locktag_field2,
1450 : : lock->tag.locktag_field3);
1451 : :
1452 : 244383 : return proclock;
1453 : 244383 : }
1454 : :
1455 : : /*
1456 : : * Check and set/reset the flag that we hold the relation extension lock.
1457 : : *
1458 : : * It is callers responsibility that this function is called after
1459 : : * acquiring/releasing the relation extension lock.
1460 : : *
1461 : : * Pass acquired as true if lock is acquired, false otherwise.
1462 : : */
1463 : : static inline void
1464 : 4674304 : CheckAndSetLockHeld(LOCALLOCK *locallock, bool acquired)
1465 : : {
1466 : : #ifdef USE_ASSERT_CHECKING
1467 [ + + ]: 4674304 : if (LOCALLOCK_LOCKTAG(*locallock) == LOCKTAG_RELATION_EXTEND)
1468 : 47556 : IsRelationExtensionLockHeld = acquired;
1469 : : #endif
1470 : 4674304 : }
1471 : :
1472 : : /*
1473 : : * Subroutine to free a locallock entry
1474 : : */
1475 : : static void
1476 : 2316921 : RemoveLocalLock(LOCALLOCK *locallock)
1477 : : {
1478 : 2316921 : int i;
1479 : :
1480 [ + + ]: 2329937 : for (i = locallock->numLockOwners - 1; i >= 0; i--)
1481 : : {
1482 [ + + ]: 13016 : if (locallock->lockOwners[i].owner != NULL)
1483 : 13008 : ResourceOwnerForgetLock(locallock->lockOwners[i].owner, locallock);
1484 : 13016 : }
1485 : 2316921 : locallock->numLockOwners = 0;
1486 [ - + ]: 2316921 : if (locallock->lockOwners != NULL)
1487 : 2316921 : pfree(locallock->lockOwners);
1488 : 2316921 : locallock->lockOwners = NULL;
1489 : :
1490 [ + + ]: 2316921 : if (locallock->holdsStrongLockCount)
1491 : : {
1492 : 33094 : uint32 fasthashcode;
1493 : :
1494 : 33094 : fasthashcode = FastPathStrongLockHashPartition(locallock->hashcode);
1495 : :
1496 [ + + ]: 33094 : SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
1497 [ + - ]: 33094 : Assert(FastPathStrongRelationLocks->count[fasthashcode] > 0);
1498 : 33094 : FastPathStrongRelationLocks->count[fasthashcode]--;
1499 : 33094 : locallock->holdsStrongLockCount = false;
1500 : 33094 : SpinLockRelease(&FastPathStrongRelationLocks->mutex);
1501 : 33094 : }
1502 : :
1503 [ + - + - ]: 4633842 : if (!hash_search(LockMethodLocalHash,
1504 : 2316921 : &(locallock->tag),
1505 : : HASH_REMOVE, NULL))
1506 [ # # # # ]: 0 : elog(WARNING, "locallock table corrupted");
1507 : :
1508 : : /*
1509 : : * Indicate that the lock is released for certain types of locks
1510 : : */
1511 : 2316921 : CheckAndSetLockHeld(locallock, false);
1512 : 2316921 : }
1513 : :
1514 : : /*
1515 : : * LockCheckConflicts -- test whether requested lock conflicts
1516 : : * with those already granted
1517 : : *
1518 : : * Returns true if conflict, false if no conflict.
1519 : : *
1520 : : * NOTES:
1521 : : * Here's what makes this complicated: one process's locks don't
1522 : : * conflict with one another, no matter what purpose they are held for
1523 : : * (eg, session and transaction locks do not conflict). Nor do the locks
1524 : : * of one process in a lock group conflict with those of another process in
1525 : : * the same group. So, we must subtract off these locks when determining
1526 : : * whether the requested new lock conflicts with those already held.
1527 : : */
1528 : : bool
1529 : 244163 : LockCheckConflicts(LockMethod lockMethodTable,
1530 : : LOCKMODE lockmode,
1531 : : LOCK *lock,
1532 : : PROCLOCK *proclock)
1533 : : {
1534 : 244163 : int numLockModes = lockMethodTable->numLockModes;
1535 : 244163 : LOCKMASK myLocks;
1536 : 244163 : int conflictMask = lockMethodTable->conflictTab[lockmode];
1537 : 244163 : int conflictsRemaining[MAX_LOCKMODES];
1538 : 244163 : int totalConflictsRemaining = 0;
1539 : 244163 : dlist_iter proclock_iter;
1540 : 244163 : int i;
1541 : :
1542 : : /*
1543 : : * first check for global conflicts: If no locks conflict with my request,
1544 : : * then I get the lock.
1545 : : *
1546 : : * Checking for conflict: lock->grantMask represents the types of
1547 : : * currently held locks. conflictTable[lockmode] has a bit set for each
1548 : : * type of lock that conflicts with request. Bitwise compare tells if
1549 : : * there is a conflict.
1550 : : */
1551 [ + + ]: 244163 : if (!(conflictMask & lock->grantMask))
1552 : : {
1553 : : PROCLOCK_PRINT("LockCheckConflicts: no conflict", proclock);
1554 : 231708 : return false;
1555 : : }
1556 : :
1557 : : /*
1558 : : * Rats. Something conflicts. But it could still be my own lock, or a
1559 : : * lock held by another member of my locking group. First, figure out how
1560 : : * many conflicts remain after subtracting out any locks I hold myself.
1561 : : */
1562 : 12455 : myLocks = proclock->holdMask;
1563 [ + + ]: 112095 : for (i = 1; i <= numLockModes; i++)
1564 : : {
1565 [ + + ]: 99640 : if ((conflictMask & LOCKBIT_ON(i)) == 0)
1566 : : {
1567 : 60376 : conflictsRemaining[i] = 0;
1568 : 60376 : continue;
1569 : : }
1570 : 39264 : conflictsRemaining[i] = lock->granted[i];
1571 [ + + ]: 39264 : if (myLocks & LOCKBIT_ON(i))
1572 : 12964 : --conflictsRemaining[i];
1573 : 39264 : totalConflictsRemaining += conflictsRemaining[i];
1574 : 39264 : }
1575 : :
1576 : : /* If no conflicts remain, we get the lock. */
1577 [ + + ]: 12455 : if (totalConflictsRemaining == 0)
1578 : : {
1579 : : PROCLOCK_PRINT("LockCheckConflicts: resolved (simple)", proclock);
1580 : 12201 : return false;
1581 : : }
1582 : :
1583 : : /* If no group locking, it's definitely a conflict. */
1584 [ + + + + ]: 254 : if (proclock->groupLeader == MyProc && MyProc->lockGroupLeader == NULL)
1585 : : {
1586 [ + - ]: 35 : Assert(proclock->tag.myProc == MyProc);
1587 : : PROCLOCK_PRINT("LockCheckConflicts: conflicting (simple)",
1588 : : proclock);
1589 : 35 : return true;
1590 : : }
1591 : :
1592 : : /*
1593 : : * The relation extension lock conflict even between the group members.
1594 : : */
1595 [ - + ]: 219 : if (LOCK_LOCKTAG(*lock) == LOCKTAG_RELATION_EXTEND)
1596 : : {
1597 : : PROCLOCK_PRINT("LockCheckConflicts: conflicting (group)",
1598 : : proclock);
1599 : 0 : return true;
1600 : : }
1601 : :
1602 : : /*
1603 : : * Locks held in conflicting modes by members of our own lock group are
1604 : : * not real conflicts; we can subtract those out and see if we still have
1605 : : * a conflict. This is O(N) in the number of processes holding or
1606 : : * awaiting locks on this object. We could improve that by making the
1607 : : * shared memory state more complex (and larger) but it doesn't seem worth
1608 : : * it.
1609 : : */
1610 [ + - + + ]: 462 : dlist_foreach(proclock_iter, &lock->procLocks)
1611 : : {
1612 : 866 : PROCLOCK *otherproclock =
1613 : 433 : dlist_container(PROCLOCK, lockLink, proclock_iter.cur);
1614 : :
1615 [ + + ]: 433 : if (proclock != otherproclock &&
1616 [ + + - + ]: 404 : proclock->groupLeader == otherproclock->groupLeader &&
1617 : 192 : (otherproclock->holdMask & conflictMask) != 0)
1618 : : {
1619 : 192 : int intersectMask = otherproclock->holdMask & conflictMask;
1620 : :
1621 [ + + ]: 1728 : for (i = 1; i <= numLockModes; i++)
1622 : : {
1623 [ + + ]: 1536 : if ((intersectMask & LOCKBIT_ON(i)) != 0)
1624 : : {
1625 [ + - ]: 195 : if (conflictsRemaining[i] <= 0)
1626 [ # # # # ]: 0 : elog(PANIC, "proclocks held do not match lock");
1627 : 195 : conflictsRemaining[i]--;
1628 : 195 : totalConflictsRemaining--;
1629 : 195 : }
1630 : 1536 : }
1631 : :
1632 [ + + ]: 192 : if (totalConflictsRemaining == 0)
1633 : : {
1634 : : PROCLOCK_PRINT("LockCheckConflicts: resolved (group)",
1635 : : proclock);
1636 : 190 : return false;
1637 : : }
1638 [ + + ]: 192 : }
1639 [ + + ]: 433 : }
1640 : :
1641 : : /* Nope, it's a real conflict. */
1642 : : PROCLOCK_PRINT("LockCheckConflicts: conflicting (group)", proclock);
1643 : 29 : return true;
1644 : 244163 : }
1645 : :
1646 : : /*
1647 : : * GrantLock -- update the lock and proclock data structures to show
1648 : : * the lock request has been granted.
1649 : : *
1650 : : * NOTE: if proc was blocked, it also needs to be removed from the wait list
1651 : : * and have its waitLock/waitProcLock fields cleared. That's not done here.
1652 : : *
1653 : : * NOTE: the lock grant also has to be recorded in the associated LOCALLOCK
1654 : : * table entry; but since we may be awaking some other process, we can't do
1655 : : * that here; it's done by GrantLockLocal, instead.
1656 : : */
1657 : : void
1658 : 244382 : GrantLock(LOCK *lock, PROCLOCK *proclock, LOCKMODE lockmode)
1659 : : {
1660 : 244382 : lock->nGranted++;
1661 : 244382 : lock->granted[lockmode]++;
1662 : 244382 : lock->grantMask |= LOCKBIT_ON(lockmode);
1663 [ + + ]: 244382 : if (lock->granted[lockmode] == lock->requested[lockmode])
1664 : 244322 : lock->waitMask &= LOCKBIT_OFF(lockmode);
1665 : 244382 : proclock->holdMask |= LOCKBIT_ON(lockmode);
1666 : : LOCK_PRINT("GrantLock", lock, lockmode);
1667 [ + - ]: 244382 : Assert((lock->nGranted > 0) && (lock->granted[lockmode] > 0));
1668 [ + - ]: 244382 : Assert(lock->nGranted <= lock->nRequested);
1669 : 244382 : }
1670 : :
1671 : : /*
1672 : : * UnGrantLock -- opposite of GrantLock.
1673 : : *
1674 : : * Updates the lock and proclock data structures to show that the lock
1675 : : * is no longer held nor requested by the current holder.
1676 : : *
1677 : : * Returns true if there were any waiters waiting on the lock that
1678 : : * should now be woken up with ProcLockWakeup.
1679 : : */
1680 : : static bool
1681 : 244382 : UnGrantLock(LOCK *lock, LOCKMODE lockmode,
1682 : : PROCLOCK *proclock, LockMethod lockMethodTable)
1683 : : {
1684 : 244382 : bool wakeupNeeded = false;
1685 : :
1686 [ + - ]: 244382 : Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
1687 [ + - ]: 244382 : Assert((lock->nGranted > 0) && (lock->granted[lockmode] > 0));
1688 [ + - ]: 244382 : Assert(lock->nGranted <= lock->nRequested);
1689 : :
1690 : : /*
1691 : : * fix the general lock stats
1692 : : */
1693 : 244382 : lock->nRequested--;
1694 : 244382 : lock->requested[lockmode]--;
1695 : 244382 : lock->nGranted--;
1696 : 244382 : lock->granted[lockmode]--;
1697 : :
1698 [ + + ]: 244382 : if (lock->granted[lockmode] == 0)
1699 : : {
1700 : : /* change the conflict mask. No more of this lock type. */
1701 : 238209 : lock->grantMask &= LOCKBIT_OFF(lockmode);
1702 : 238209 : }
1703 : :
1704 : : LOCK_PRINT("UnGrantLock: updated", lock, lockmode);
1705 : :
1706 : : /*
1707 : : * We need only run ProcLockWakeup if the released lock conflicts with at
1708 : : * least one of the lock types requested by waiter(s). Otherwise whatever
1709 : : * conflict made them wait must still exist. NOTE: before MVCC, we could
1710 : : * skip wakeup if lock->granted[lockmode] was still positive. But that's
1711 : : * not true anymore, because the remaining granted locks might belong to
1712 : : * some waiter, who could now be awakened because he doesn't conflict with
1713 : : * his own locks.
1714 : : */
1715 [ + + ]: 244382 : if (lockMethodTable->conflictTab[lockmode] & lock->waitMask)
1716 : 48 : wakeupNeeded = true;
1717 : :
1718 : : /*
1719 : : * Now fix the per-proclock state.
1720 : : */
1721 : 244382 : proclock->holdMask &= LOCKBIT_OFF(lockmode);
1722 : : PROCLOCK_PRINT("UnGrantLock: updated", proclock);
1723 : :
1724 : 488764 : return wakeupNeeded;
1725 : 244382 : }
1726 : :
1727 : : /*
1728 : : * CleanUpLock -- clean up after releasing a lock. We garbage-collect the
1729 : : * proclock and lock objects if possible, and call ProcLockWakeup if there
1730 : : * are remaining requests and the caller says it's OK. (Normally, this
1731 : : * should be called after UnGrantLock, and wakeupNeeded is the result from
1732 : : * UnGrantLock.)
1733 : : *
1734 : : * The appropriate partition lock must be held at entry, and will be
1735 : : * held at exit.
1736 : : */
1737 : : static void
1738 : 238202 : CleanUpLock(LOCK *lock, PROCLOCK *proclock,
1739 : : LockMethod lockMethodTable, uint32 hashcode,
1740 : : bool wakeupNeeded)
1741 : : {
1742 : : /*
1743 : : * If this was my last hold on this lock, delete my entry in the proclock
1744 : : * table.
1745 : : */
1746 [ + + ]: 238202 : if (proclock->holdMask == 0)
1747 : : {
1748 : 227043 : uint32 proclock_hashcode;
1749 : :
1750 : : PROCLOCK_PRINT("CleanUpLock: deleting", proclock);
1751 : 227043 : dlist_delete(&proclock->lockLink);
1752 : 227043 : dlist_delete(&proclock->procLink);
1753 : 227043 : proclock_hashcode = ProcLockHashCode(&proclock->tag, hashcode);
1754 [ + - + - ]: 454086 : if (!hash_search_with_hash_value(LockMethodProcLockHash,
1755 : 227043 : &(proclock->tag),
1756 : 227043 : proclock_hashcode,
1757 : : HASH_REMOVE,
1758 : : NULL))
1759 [ # # # # ]: 0 : elog(PANIC, "proclock table corrupted");
1760 : 227043 : }
1761 : :
1762 [ + + ]: 238202 : if (lock->nRequested == 0)
1763 : : {
1764 : : /*
1765 : : * The caller just released the last lock, so garbage-collect the lock
1766 : : * object.
1767 : : */
1768 : : LOCK_PRINT("CleanUpLock: deleting", lock, 0);
1769 [ + - ]: 219939 : Assert(dlist_is_empty(&lock->procLocks));
1770 [ + - + - ]: 439878 : if (!hash_search_with_hash_value(LockMethodLockHash,
1771 : 219939 : &(lock->tag),
1772 : 219939 : hashcode,
1773 : : HASH_REMOVE,
1774 : : NULL))
1775 [ # # # # ]: 0 : elog(PANIC, "lock table corrupted");
1776 : 219939 : }
1777 [ + + ]: 18263 : else if (wakeupNeeded)
1778 : : {
1779 : : /* There are waiters on this lock, so wake them up. */
1780 : 49 : ProcLockWakeup(lockMethodTable, lock);
1781 : 49 : }
1782 : 238202 : }
1783 : :
1784 : : /*
1785 : : * GrantLockLocal -- update the locallock data structures to show
1786 : : * the lock request has been granted.
1787 : : *
1788 : : * We expect that LockAcquire made sure there is room to add a new
1789 : : * ResourceOwner entry.
1790 : : */
1791 : : static void
1792 : 3804546 : GrantLockLocal(LOCALLOCK *locallock, ResourceOwner owner)
1793 : : {
1794 : 3804546 : LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
1795 : 3804546 : int i;
1796 : :
1797 [ + - ]: 3804546 : Assert(locallock->numLockOwners < locallock->maxLockOwners);
1798 : : /* Count the total */
1799 : 3804546 : locallock->nLocks++;
1800 : : /* Count the per-owner lock */
1801 [ + + ]: 3855623 : for (i = 0; i < locallock->numLockOwners; i++)
1802 : : {
1803 [ + + ]: 1498240 : if (lockOwners[i].owner == owner)
1804 : : {
1805 : 1447163 : lockOwners[i].nLocks++;
1806 : 1447163 : return;
1807 : : }
1808 : 51077 : }
1809 : 2357383 : lockOwners[i].owner = owner;
1810 : 2357383 : lockOwners[i].nLocks = 1;
1811 : 2357383 : locallock->numLockOwners++;
1812 [ + + ]: 2357383 : if (owner != NULL)
1813 : 2356519 : ResourceOwnerRememberLock(owner, locallock);
1814 : :
1815 : : /* Indicate that the lock is acquired for certain types of locks. */
1816 : 2357383 : CheckAndSetLockHeld(locallock, true);
1817 [ - + ]: 3804546 : }
1818 : :
1819 : : /*
1820 : : * BeginStrongLockAcquire - inhibit use of fastpath for a given LOCALLOCK,
1821 : : * and arrange for error cleanup if it fails
1822 : : */
1823 : : static void
1824 : 33094 : BeginStrongLockAcquire(LOCALLOCK *locallock, uint32 fasthashcode)
1825 : : {
1826 [ + - ]: 33094 : Assert(StrongLockInProgress == NULL);
1827 [ + - ]: 33094 : Assert(locallock->holdsStrongLockCount == false);
1828 : :
1829 : : /*
1830 : : * Adding to a memory location is not atomic, so we take a spinlock to
1831 : : * ensure we don't collide with someone else trying to bump the count at
1832 : : * the same time.
1833 : : *
1834 : : * XXX: It might be worth considering using an atomic fetch-and-add
1835 : : * instruction here, on architectures where that is supported.
1836 : : */
1837 : :
1838 [ + + ]: 33094 : SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
1839 : 33094 : FastPathStrongRelationLocks->count[fasthashcode]++;
1840 : 33094 : locallock->holdsStrongLockCount = true;
1841 : 33094 : StrongLockInProgress = locallock;
1842 : 33094 : SpinLockRelease(&FastPathStrongRelationLocks->mutex);
1843 : 33094 : }
1844 : :
1845 : : /*
1846 : : * FinishStrongLockAcquire - cancel pending cleanup for a strong lock
1847 : : * acquisition once it's no longer needed
1848 : : */
1849 : : static void
1850 : 244099 : FinishStrongLockAcquire(void)
1851 : : {
1852 : 244099 : StrongLockInProgress = NULL;
1853 : 244099 : }
1854 : :
1855 : : /*
1856 : : * AbortStrongLockAcquire - undo strong lock state changes performed by
1857 : : * BeginStrongLockAcquire.
1858 : : */
1859 : : void
1860 : 66115 : AbortStrongLockAcquire(void)
1861 : : {
1862 : 66115 : uint32 fasthashcode;
1863 : 66115 : LOCALLOCK *locallock = StrongLockInProgress;
1864 : :
1865 [ - + ]: 66115 : if (locallock == NULL)
1866 : 66115 : return;
1867 : :
1868 : 0 : fasthashcode = FastPathStrongLockHashPartition(locallock->hashcode);
1869 [ # # ]: 0 : Assert(locallock->holdsStrongLockCount == true);
1870 [ # # ]: 0 : SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
1871 [ # # ]: 0 : Assert(FastPathStrongRelationLocks->count[fasthashcode] > 0);
1872 : 0 : FastPathStrongRelationLocks->count[fasthashcode]--;
1873 : 0 : locallock->holdsStrongLockCount = false;
1874 : 0 : StrongLockInProgress = NULL;
1875 : 0 : SpinLockRelease(&FastPathStrongRelationLocks->mutex);
1876 [ - + ]: 66115 : }
1877 : :
1878 : : /*
1879 : : * GrantAwaitedLock -- call GrantLockLocal for the lock we are doing
1880 : : * WaitOnLock on.
1881 : : *
1882 : : * proc.c needs this for the case where we are booted off the lock by
1883 : : * timeout, but discover that someone granted us the lock anyway.
1884 : : *
1885 : : * We could just export GrantLockLocal, but that would require including
1886 : : * resowner.h in lock.h, which creates circularity.
1887 : : */
1888 : : void
1889 : 0 : GrantAwaitedLock(void)
1890 : : {
1891 : 0 : GrantLockLocal(awaitedLock, awaitedOwner);
1892 : 0 : }
1893 : :
1894 : : /*
1895 : : * GetAwaitedLock -- Return the lock we're currently doing WaitOnLock on.
1896 : : */
1897 : : LOCALLOCK *
1898 : 66158 : GetAwaitedLock(void)
1899 : : {
1900 : 66158 : return awaitedLock;
1901 : : }
1902 : :
1903 : : /*
1904 : : * ResetAwaitedLock -- Forget that we are waiting on a lock.
1905 : : */
1906 : : void
1907 : 1 : ResetAwaitedLock(void)
1908 : : {
1909 : 1 : awaitedLock = NULL;
1910 : 1 : }
1911 : :
1912 : : /*
1913 : : * MarkLockClear -- mark an acquired lock as "clear"
1914 : : *
1915 : : * This means that we know we have absorbed all sinval messages that other
1916 : : * sessions generated before we acquired this lock, and so we can confidently
1917 : : * assume we know about any catalog changes protected by this lock.
1918 : : */
1919 : : void
1920 : 2230721 : MarkLockClear(LOCALLOCK *locallock)
1921 : : {
1922 [ + - ]: 2230721 : Assert(locallock->nLocks > 0);
1923 : 2230721 : locallock->lockCleared = true;
1924 : 2230721 : }
1925 : :
1926 : : /*
1927 : : * WaitOnLock -- wait to acquire a lock
1928 : : *
1929 : : * This is a wrapper around ProcSleep, with extra tracing and bookkeeping.
1930 : : */
1931 : : static ProcWaitStatus
1932 : 42 : WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner)
1933 : : {
1934 : 42 : ProcWaitStatus result;
1935 : 42 : ErrorContextCallback waiterrcontext;
1936 : :
1937 : 42 : TRACE_POSTGRESQL_LOCK_WAIT_START(locallock->tag.lock.locktag_field1,
1938 : : locallock->tag.lock.locktag_field2,
1939 : : locallock->tag.lock.locktag_field3,
1940 : : locallock->tag.lock.locktag_field4,
1941 : : locallock->tag.lock.locktag_type,
1942 : : locallock->tag.mode);
1943 : :
1944 : : /* Setup error traceback support for ereport() */
1945 : 42 : waiterrcontext.callback = waitonlock_error_callback;
1946 : 42 : waiterrcontext.arg = locallock;
1947 : 42 : waiterrcontext.previous = error_context_stack;
1948 : 42 : error_context_stack = &waiterrcontext;
1949 : :
1950 : : /* adjust the process title to indicate that it's waiting */
1951 : 42 : set_ps_display_suffix("waiting");
1952 : :
1953 : : /*
1954 : : * Record the fact that we are waiting for a lock, so that
1955 : : * LockErrorCleanup will clean up if cancel/die happens.
1956 : : */
1957 : 42 : awaitedLock = locallock;
1958 : 42 : awaitedOwner = owner;
1959 : :
1960 : : /*
1961 : : * NOTE: Think not to put any shared-state cleanup after the call to
1962 : : * ProcSleep, in either the normal or failure path. The lock state must
1963 : : * be fully set by the lock grantor, or by CheckDeadLock if we give up
1964 : : * waiting for the lock. This is necessary because of the possibility
1965 : : * that a cancel/die interrupt will interrupt ProcSleep after someone else
1966 : : * grants us the lock, but before we've noticed it. Hence, after granting,
1967 : : * the locktable state must fully reflect the fact that we own the lock;
1968 : : * we can't do additional work on return.
1969 : : *
1970 : : * We can and do use a PG_TRY block to try to clean up after failure, but
1971 : : * this still has a major limitation: elog(FATAL) can occur while waiting
1972 : : * (eg, a "die" interrupt), and then control won't come back here. So all
1973 : : * cleanup of essential state should happen in LockErrorCleanup, not here.
1974 : : * We can use PG_TRY to clear the "waiting" status flags, since doing that
1975 : : * is unimportant if the process exits.
1976 : : */
1977 [ + - ]: 42 : PG_TRY();
1978 : : {
1979 : 42 : result = ProcSleep(locallock);
1980 : : }
1981 : 42 : PG_CATCH();
1982 : : {
1983 : : /* In this path, awaitedLock remains set until LockErrorCleanup */
1984 : :
1985 : : /* reset ps display to remove the suffix */
1986 : 0 : set_ps_display_remove_suffix();
1987 : :
1988 : : /* and propagate the error */
1989 : 0 : PG_RE_THROW();
1990 : : }
1991 [ + - ]: 42 : PG_END_TRY();
1992 : :
1993 : : /*
1994 : : * We no longer want LockErrorCleanup to do anything.
1995 : : */
1996 : 42 : awaitedLock = NULL;
1997 : :
1998 : : /* reset ps display to remove the suffix */
1999 : 42 : set_ps_display_remove_suffix();
2000 : :
2001 : 42 : error_context_stack = waiterrcontext.previous;
2002 : :
2003 : 42 : TRACE_POSTGRESQL_LOCK_WAIT_DONE(locallock->tag.lock.locktag_field1,
2004 : : locallock->tag.lock.locktag_field2,
2005 : : locallock->tag.lock.locktag_field3,
2006 : : locallock->tag.lock.locktag_field4,
2007 : : locallock->tag.lock.locktag_type,
2008 : : locallock->tag.mode);
2009 : :
2010 : 84 : return result;
2011 : 42 : }
2012 : :
2013 : : /*
2014 : : * error context callback for failures in WaitOnLock
2015 : : *
2016 : : * We report which lock was being waited on, in the same style used in
2017 : : * deadlock reports. This helps with lock timeout errors in particular.
2018 : : */
2019 : : static void
2020 : 5 : waitonlock_error_callback(void *arg)
2021 : : {
2022 : 5 : LOCALLOCK *locallock = (LOCALLOCK *) arg;
2023 : 5 : const LOCKTAG *tag = &locallock->tag.lock;
2024 : 5 : LOCKMODE mode = locallock->tag.mode;
2025 : 5 : StringInfoData locktagbuf;
2026 : :
2027 : 5 : initStringInfo(&locktagbuf);
2028 : 5 : DescribeLockTag(&locktagbuf, tag);
2029 : :
2030 : 10 : errcontext("waiting for %s on %s",
2031 : 5 : GetLockmodeName(tag->locktag_lockmethodid, mode),
2032 : 5 : locktagbuf.data);
2033 : 5 : }
2034 : :
2035 : : /*
2036 : : * Remove a proc from the wait-queue it is on (caller must know it is on one).
2037 : : * This is only used when the proc has failed to get the lock, so we set its
2038 : : * waitStatus to PROC_WAIT_STATUS_ERROR.
2039 : : *
2040 : : * Appropriate partition lock must be held by caller. Also, caller is
2041 : : * responsible for signaling the proc if needed.
2042 : : *
2043 : : * NB: this does not clean up any locallock object that may exist for the lock.
2044 : : */
2045 : : void
2046 : 1 : RemoveFromWaitQueue(PGPROC *proc, uint32 hashcode)
2047 : : {
2048 : 1 : LOCK *waitLock = proc->waitLock;
2049 : 1 : PROCLOCK *proclock = proc->waitProcLock;
2050 : 1 : LOCKMODE lockmode = proc->waitLockMode;
2051 : 1 : LOCKMETHODID lockmethodid = LOCK_LOCKMETHOD(*waitLock);
2052 : :
2053 : : /* Make sure proc is waiting */
2054 [ + - ]: 1 : Assert(proc->waitStatus == PROC_WAIT_STATUS_WAITING);
2055 [ + - ]: 1 : Assert(proc->links.next != NULL);
2056 [ + - ]: 1 : Assert(waitLock);
2057 [ + - ]: 1 : Assert(!dclist_is_empty(&waitLock->waitProcs));
2058 [ + - ]: 1 : Assert(0 < lockmethodid && lockmethodid < lengthof(LockMethods));
2059 : :
2060 : : /* Remove proc from lock's wait queue */
2061 : 1 : dclist_delete_from_thoroughly(&waitLock->waitProcs, &proc->links);
2062 : :
2063 : : /* Undo increments of request counts by waiting process */
2064 [ + - ]: 1 : Assert(waitLock->nRequested > 0);
2065 [ + - ]: 1 : Assert(waitLock->nRequested > proc->waitLock->nGranted);
2066 : 1 : waitLock->nRequested--;
2067 [ + - ]: 1 : Assert(waitLock->requested[lockmode] > 0);
2068 : 1 : waitLock->requested[lockmode]--;
2069 : : /* don't forget to clear waitMask bit if appropriate */
2070 [ - + ]: 1 : if (waitLock->granted[lockmode] == waitLock->requested[lockmode])
2071 : 1 : waitLock->waitMask &= LOCKBIT_OFF(lockmode);
2072 : :
2073 : : /* Clean up the proc's own state, and pass it the ok/fail signal */
2074 : 1 : proc->waitLock = NULL;
2075 : 1 : proc->waitProcLock = NULL;
2076 : 1 : proc->waitStatus = PROC_WAIT_STATUS_ERROR;
2077 : :
2078 : : /*
2079 : : * Delete the proclock immediately if it represents no already-held locks.
2080 : : * (This must happen now because if the owner of the lock decides to
2081 : : * release it, and the requested/granted counts then go to zero,
2082 : : * LockRelease expects there to be no remaining proclocks.) Then see if
2083 : : * any other waiters for the lock can be woken up now.
2084 : : */
2085 : 2 : CleanUpLock(waitLock, proclock,
2086 : 1 : LockMethods[lockmethodid], hashcode,
2087 : : true);
2088 : 1 : }
2089 : :
2090 : : /*
2091 : : * LockRelease -- look up 'locktag' and release one 'lockmode' lock on it.
2092 : : * Release a session lock if 'sessionLock' is true, else release a
2093 : : * regular transaction lock.
2094 : : *
2095 : : * Side Effects: find any waiting processes that are now wakable,
2096 : : * grant them their requested locks and awaken them.
2097 : : * (We have to grant the lock here to avoid a race between
2098 : : * the waking process and any new process to
2099 : : * come along and request the lock.)
2100 : : */
2101 : : bool
2102 : 2591592 : LockRelease(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock)
2103 : : {
2104 : 2591592 : LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
2105 : 2591592 : LockMethod lockMethodTable;
2106 : 2591592 : LOCALLOCKTAG localtag;
2107 : 2591592 : LOCALLOCK *locallock;
2108 : 2591592 : LOCK *lock;
2109 : 2591592 : PROCLOCK *proclock;
2110 : 2591592 : LWLock *partitionLock;
2111 : 2591592 : bool wakeupNeeded;
2112 : :
2113 [ + - ]: 2591592 : if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
2114 [ # # # # ]: 0 : elog(ERROR, "unrecognized lock method: %d", lockmethodid);
2115 : 2591592 : lockMethodTable = LockMethods[lockmethodid];
2116 [ + - ]: 2591592 : if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
2117 [ # # # # ]: 0 : elog(ERROR, "unrecognized lock mode: %d", lockmode);
2118 : :
2119 : : #ifdef LOCK_DEBUG
2120 : : if (LOCK_DEBUG_ENABLED(locktag))
2121 : : elog(LOG, "LockRelease: lock [%u,%u] %s",
2122 : : locktag->locktag_field1, locktag->locktag_field2,
2123 : : lockMethodTable->lockModeNames[lockmode]);
2124 : : #endif
2125 : :
2126 : : /*
2127 : : * Find the LOCALLOCK entry for this lock and lockmode
2128 : : */
2129 [ + - - + : 2591592 : MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
# # # # #
# ]
2130 : 2591592 : localtag.lock = *locktag;
2131 : 2591592 : localtag.mode = lockmode;
2132 : :
2133 : 2591592 : locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
2134 : : &localtag,
2135 : : HASH_FIND, NULL);
2136 : :
2137 : : /*
2138 : : * let the caller print its own error message, too. Do not ereport(ERROR).
2139 : : */
2140 [ + + - + ]: 2591592 : if (!locallock || locallock->nLocks <= 0)
2141 : : {
2142 [ - + + - ]: 4 : elog(WARNING, "you don't own a lock of type %s",
2143 : : lockMethodTable->lockModeNames[lockmode]);
2144 : 4 : return false;
2145 : : }
2146 : :
2147 : : /*
2148 : : * Decrease the count for the resource owner.
2149 : : */
2150 : : {
2151 : 2591588 : LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
2152 : 2591588 : ResourceOwner owner;
2153 : 2591588 : int i;
2154 : :
2155 : : /* Identify owner for lock */
2156 [ + + ]: 2591588 : if (sessionLock)
2157 : 864 : owner = NULL;
2158 : : else
2159 : 2590724 : owner = CurrentResourceOwner;
2160 : :
2161 [ + + ]: 2591866 : for (i = locallock->numLockOwners - 1; i >= 0; i--)
2162 : : {
2163 [ + + ]: 2591862 : if (lockOwners[i].owner == owner)
2164 : : {
2165 [ + - ]: 2591584 : Assert(lockOwners[i].nLocks > 0);
2166 [ + + ]: 2591584 : if (--lockOwners[i].nLocks == 0)
2167 : : {
2168 [ + + ]: 2146842 : if (owner != NULL)
2169 : 2145986 : ResourceOwnerForgetLock(owner, locallock);
2170 : : /* compact out unused slot */
2171 : 2146842 : locallock->numLockOwners--;
2172 [ + + ]: 2146842 : if (i < locallock->numLockOwners)
2173 : 7 : lockOwners[i] = lockOwners[locallock->numLockOwners];
2174 : 2146842 : }
2175 : 2591584 : break;
2176 : : }
2177 : 278 : }
2178 [ + + ]: 2591588 : if (i < 0)
2179 : : {
2180 : : /* don't release a lock belonging to another owner */
2181 [ - + + - ]: 4 : elog(WARNING, "you don't own a lock of type %s",
2182 : : lockMethodTable->lockModeNames[lockmode]);
2183 : 4 : return false;
2184 : : }
2185 [ + + ]: 2591588 : }
2186 : :
2187 : : /*
2188 : : * Decrease the total local count. If we're still holding the lock, we're
2189 : : * done.
2190 : : */
2191 : 2591584 : locallock->nLocks--;
2192 : :
2193 [ + + ]: 2591584 : if (locallock->nLocks > 0)
2194 : 470085 : return true;
2195 : :
2196 : : /*
2197 : : * At this point we can no longer suppose we are clear of invalidation
2198 : : * messages related to this lock. Although we'll delete the LOCALLOCK
2199 : : * object before any intentional return from this routine, it seems worth
2200 : : * the trouble to explicitly reset lockCleared right now, just in case
2201 : : * some error prevents us from deleting the LOCALLOCK.
2202 : : */
2203 : 2121499 : locallock->lockCleared = false;
2204 : :
2205 : : /* Attempt fast release of any lock eligible for the fast path. */
2206 [ + + + + : 2121499 : if (EligibleForRelationFastPath(locktag, lockmode) &&
+ + + + +
+ + + ]
2207 : 1993225 : FastPathLocalUseCounts[FAST_PATH_REL_GROUP(locktag->locktag_field2)] > 0)
2208 : : {
2209 : 1974922 : bool released;
2210 : :
2211 : : /*
2212 : : * We might not find the lock here, even if we originally entered it
2213 : : * here. Another backend may have moved it to the main table.
2214 : : */
2215 : 1974922 : LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
2216 : 3949844 : released = FastPathUnGrantRelationLock(locktag->locktag_field2,
2217 : 1974922 : lockmode);
2218 : 1974922 : LWLockRelease(&MyProc->fpInfoLock);
2219 [ + + ]: 1974922 : if (released)
2220 : : {
2221 : 1967675 : RemoveLocalLock(locallock);
2222 : 1967675 : return true;
2223 : : }
2224 [ + + ]: 1974922 : }
2225 : :
2226 : : /*
2227 : : * Otherwise we've got to mess with the shared lock table.
2228 : : */
2229 : 153824 : partitionLock = LockHashPartitionLock(locallock->hashcode);
2230 : :
2231 : 153824 : LWLockAcquire(partitionLock, LW_EXCLUSIVE);
2232 : :
2233 : : /*
2234 : : * Normally, we don't need to re-find the lock or proclock, since we kept
2235 : : * their addresses in the locallock table, and they couldn't have been
2236 : : * removed while we were holding a lock on them. But it's possible that
2237 : : * the lock was taken fast-path and has since been moved to the main hash
2238 : : * table by another backend, in which case we will need to look up the
2239 : : * objects here. We assume the lock field is NULL if so.
2240 : : */
2241 : 153824 : lock = locallock->lock;
2242 [ + - ]: 153824 : if (!lock)
2243 : : {
2244 : 0 : PROCLOCKTAG proclocktag;
2245 : :
2246 [ # # ]: 0 : Assert(EligibleForRelationFastPath(locktag, lockmode));
2247 : 0 : lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
2248 : 0 : locktag,
2249 : 0 : locallock->hashcode,
2250 : : HASH_FIND,
2251 : : NULL);
2252 [ # # ]: 0 : if (!lock)
2253 [ # # # # ]: 0 : elog(ERROR, "failed to re-find shared lock object");
2254 : 0 : locallock->lock = lock;
2255 : :
2256 : 0 : proclocktag.myLock = lock;
2257 : 0 : proclocktag.myProc = MyProc;
2258 : 0 : locallock->proclock = (PROCLOCK *) hash_search(LockMethodProcLockHash,
2259 : : &proclocktag,
2260 : : HASH_FIND,
2261 : : NULL);
2262 [ # # ]: 0 : if (!locallock->proclock)
2263 [ # # # # ]: 0 : elog(ERROR, "failed to re-find shared proclock object");
2264 : 0 : }
2265 : : LOCK_PRINT("LockRelease: found", lock, lockmode);
2266 : 153824 : proclock = locallock->proclock;
2267 : : PROCLOCK_PRINT("LockRelease: found", proclock);
2268 : :
2269 : : /*
2270 : : * Double-check that we are actually holding a lock of the type we want to
2271 : : * release.
2272 : : */
2273 [ + - ]: 153824 : if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
2274 : : {
2275 : : PROCLOCK_PRINT("LockRelease: WRONGTYPE", proclock);
2276 : 0 : LWLockRelease(partitionLock);
2277 [ # # # # ]: 0 : elog(WARNING, "you don't own a lock of type %s",
2278 : : lockMethodTable->lockModeNames[lockmode]);
2279 : 0 : RemoveLocalLock(locallock);
2280 : 0 : return false;
2281 : : }
2282 : :
2283 : : /*
2284 : : * Do the releasing. CleanUpLock will waken any now-wakable waiters.
2285 : : */
2286 : 153824 : wakeupNeeded = UnGrantLock(lock, lockmode, proclock, lockMethodTable);
2287 : :
2288 : 307648 : CleanUpLock(lock, proclock,
2289 : 153824 : lockMethodTable, locallock->hashcode,
2290 : 153824 : wakeupNeeded);
2291 : :
2292 : 153824 : LWLockRelease(partitionLock);
2293 : :
2294 : 153824 : RemoveLocalLock(locallock);
2295 : 153824 : return true;
2296 : 2591592 : }
2297 : :
2298 : : /*
2299 : : * LockReleaseAll -- Release all locks of the specified lock method that
2300 : : * are held by the current process.
2301 : : *
2302 : : * Well, not necessarily *all* locks. The available behaviors are:
2303 : : * allLocks == true: release all locks including session locks.
2304 : : * allLocks == false: release all non-session locks.
2305 : : */
2306 : : void
2307 : 116627 : LockReleaseAll(LOCKMETHODID lockmethodid, bool allLocks)
2308 : : {
2309 : 116627 : HASH_SEQ_STATUS status;
2310 : 116627 : LockMethod lockMethodTable;
2311 : 116627 : int i,
2312 : : numLockModes;
2313 : 116627 : LOCALLOCK *locallock;
2314 : 116627 : LOCK *lock;
2315 : 116627 : int partition;
2316 : 116627 : bool have_fast_path_lwlock = false;
2317 : :
2318 [ + - ]: 116627 : if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
2319 [ # # # # ]: 0 : elog(ERROR, "unrecognized lock method: %d", lockmethodid);
2320 : 116627 : lockMethodTable = LockMethods[lockmethodid];
2321 : :
2322 : : #ifdef LOCK_DEBUG
2323 : : if (*(lockMethodTable->trace_flag))
2324 : : elog(LOG, "LockReleaseAll: lockmethod=%d", lockmethodid);
2325 : : #endif
2326 : :
2327 : : /*
2328 : : * Get rid of our fast-path VXID lock, if appropriate. Note that this is
2329 : : * the only way that the lock we hold on our own VXID can ever get
2330 : : * released: it is always and only released when a toplevel transaction
2331 : : * ends.
2332 : : */
2333 [ + + ]: 116627 : if (lockmethodid == DEFAULT_LOCKMETHOD)
2334 : 57914 : VirtualXactLockTableCleanup();
2335 : :
2336 : 116627 : numLockModes = lockMethodTable->numLockModes;
2337 : :
2338 : : /*
2339 : : * First we run through the locallock table and get rid of unwanted
2340 : : * entries, then we scan the process's proclocks and get rid of those. We
2341 : : * do this separately because we may have multiple locallock entries
2342 : : * pointing to the same proclock, and we daren't end up with any dangling
2343 : : * pointers. Fast-path locks are cleaned up during the locallock table
2344 : : * scan, though.
2345 : : */
2346 : 116627 : hash_seq_init(&status, LockMethodLocalHash);
2347 : :
2348 [ + + ]: 317168 : while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
2349 : : {
2350 : : /*
2351 : : * If the LOCALLOCK entry is unused, something must've gone wrong
2352 : : * while trying to acquire this lock. Just forget the local entry.
2353 : : */
2354 [ + + ]: 200541 : if (locallock->nLocks == 0)
2355 : : {
2356 : 1 : RemoveLocalLock(locallock);
2357 : 1 : continue;
2358 : : }
2359 : :
2360 : : /* Ignore items that are not of the lockmethod to be removed */
2361 [ + + ]: 200540 : if (LOCALLOCK_LOCKMETHOD(*locallock) != lockmethodid)
2362 : 2564 : continue;
2363 : :
2364 : : /*
2365 : : * If we are asked to release all locks, we can just zap the entry.
2366 : : * Otherwise, must scan to see if there are session locks. We assume
2367 : : * there is at most one lockOwners entry for session locks.
2368 : : */
2369 [ + + ]: 197976 : if (!allLocks)
2370 : : {
2371 : 185157 : LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
2372 : :
2373 : : /* If session lock is above array position 0, move it down to 0 */
2374 [ + + ]: 371583 : for (i = 0; i < locallock->numLockOwners; i++)
2375 : : {
2376 [ + + ]: 186426 : if (lockOwners[i].owner == NULL)
2377 : 2555 : lockOwners[0] = lockOwners[i];
2378 : : else
2379 : 183871 : ResourceOwnerForgetLock(lockOwners[i].owner, locallock);
2380 : 186426 : }
2381 : :
2382 [ + - ]: 185157 : if (locallock->numLockOwners > 0 &&
2383 [ + + + - ]: 185157 : lockOwners[0].owner == NULL &&
2384 : 2555 : lockOwners[0].nLocks > 0)
2385 : : {
2386 : : /* Fix the locallock to show just the session locks */
2387 : 2555 : locallock->nLocks = lockOwners[0].nLocks;
2388 : 2555 : locallock->numLockOwners = 1;
2389 : : /* We aren't deleting this locallock, so done */
2390 : 2555 : continue;
2391 : : }
2392 : : else
2393 : 182602 : locallock->numLockOwners = 0;
2394 [ + + ]: 185157 : }
2395 : :
2396 : : #ifdef USE_ASSERT_CHECKING
2397 : :
2398 : : /*
2399 : : * Tuple locks are currently held only for short durations within a
2400 : : * transaction. Check that we didn't forget to release one.
2401 : : */
2402 [ + + + - ]: 195421 : if (LOCALLOCK_LOCKTAG(*locallock) == LOCKTAG_TUPLE && !allLocks)
2403 [ # # # # ]: 0 : elog(WARNING, "tuple lock held at commit");
2404 : : #endif
2405 : :
2406 : : /*
2407 : : * If the lock or proclock pointers are NULL, this lock was taken via
2408 : : * the relation fast-path (and is not known to have been transferred).
2409 : : */
2410 [ + + - + ]: 195421 : if (locallock->proclock == NULL || locallock->lock == NULL)
2411 : : {
2412 : 105146 : LOCKMODE lockmode = locallock->tag.mode;
2413 : 105146 : Oid relid;
2414 : :
2415 : : /* Verify that a fast-path lock is what we've got. */
2416 [ + - ]: 105146 : if (!EligibleForRelationFastPath(&locallock->tag.lock, lockmode))
2417 [ # # # # ]: 0 : elog(PANIC, "locallock table corrupted");
2418 : :
2419 : : /*
2420 : : * If we don't currently hold the LWLock that protects our
2421 : : * fast-path data structures, we must acquire it before attempting
2422 : : * to release the lock via the fast-path. We will continue to
2423 : : * hold the LWLock until we're done scanning the locallock table,
2424 : : * unless we hit a transferred fast-path lock. (XXX is this
2425 : : * really such a good idea? There could be a lot of entries ...)
2426 : : */
2427 [ + + ]: 105146 : if (!have_fast_path_lwlock)
2428 : : {
2429 : 27141 : LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
2430 : 27141 : have_fast_path_lwlock = true;
2431 : 27141 : }
2432 : :
2433 : : /* Attempt fast-path release. */
2434 : 105146 : relid = locallock->tag.lock.locktag_field2;
2435 [ + + ]: 105146 : if (FastPathUnGrantRelationLock(relid, lockmode))
2436 : : {
2437 : 104886 : RemoveLocalLock(locallock);
2438 : 104886 : continue;
2439 : : }
2440 : :
2441 : : /*
2442 : : * Our lock, originally taken via the fast path, has been
2443 : : * transferred to the main lock table. That's going to require
2444 : : * some extra work, so release our fast-path lock before starting.
2445 : : */
2446 : 260 : LWLockRelease(&MyProc->fpInfoLock);
2447 : 260 : have_fast_path_lwlock = false;
2448 : :
2449 : : /*
2450 : : * Now dump the lock. We haven't got a pointer to the LOCK or
2451 : : * PROCLOCK in this case, so we have to handle this a bit
2452 : : * differently than a normal lock release. Unfortunately, this
2453 : : * requires an extra LWLock acquire-and-release cycle on the
2454 : : * partitionLock, but hopefully it shouldn't happen often.
2455 : : */
2456 : 520 : LockRefindAndRelease(lockMethodTable, MyProc,
2457 : 260 : &locallock->tag.lock, lockmode, false);
2458 : 260 : RemoveLocalLock(locallock);
2459 : 260 : continue;
2460 : 105146 : }
2461 : :
2462 : : /* Mark the proclock to show we need to release this lockmode */
2463 [ - + ]: 90275 : if (locallock->nLocks > 0)
2464 : 90275 : locallock->proclock->releaseMask |= LOCKBIT_ON(locallock->tag.mode);
2465 : :
2466 : : /* And remove the locallock hashtable entry */
2467 : 90275 : RemoveLocalLock(locallock);
2468 : : }
2469 : :
2470 : : /* Done with the fast-path data structures */
2471 [ + + ]: 116627 : if (have_fast_path_lwlock)
2472 : 26881 : LWLockRelease(&MyProc->fpInfoLock);
2473 : :
2474 : : /*
2475 : : * Now, scan each lock partition separately.
2476 : : */
2477 [ + + ]: 1982659 : for (partition = 0; partition < NUM_LOCK_PARTITIONS; partition++)
2478 : : {
2479 : 1866032 : LWLock *partitionLock;
2480 : 1866032 : dlist_head *procLocks = &MyProc->myProcLocks[partition];
2481 : 1866032 : dlist_mutable_iter proclock_iter;
2482 : :
2483 : 1866032 : partitionLock = LockHashPartitionLockByIndex(partition);
2484 : :
2485 : : /*
2486 : : * If the proclock list for this partition is empty, we can skip
2487 : : * acquiring the partition lock. This optimization is trickier than
2488 : : * it looks, because another backend could be in process of adding
2489 : : * something to our proclock list due to promoting one of our
2490 : : * fast-path locks. However, any such lock must be one that we
2491 : : * decided not to delete above, so it's okay to skip it again now;
2492 : : * we'd just decide not to delete it again. We must, however, be
2493 : : * careful to re-fetch the list header once we've acquired the
2494 : : * partition lock, to be sure we have a valid, up-to-date pointer.
2495 : : * (There is probably no significant risk if pointer fetch/store is
2496 : : * atomic, but we don't wish to assume that.)
2497 : : *
2498 : : * XXX This argument assumes that the locallock table correctly
2499 : : * represents all of our fast-path locks. While allLocks mode
2500 : : * guarantees to clean up all of our normal locks regardless of the
2501 : : * locallock situation, we lose that guarantee for fast-path locks.
2502 : : * This is not ideal.
2503 : : */
2504 [ + + ]: 1866032 : if (dlist_is_empty(procLocks))
2505 : 1792853 : continue; /* needn't examine this partition */
2506 : :
2507 : 73179 : LWLockAcquire(partitionLock, LW_EXCLUSIVE);
2508 : :
2509 [ + - + + ]: 162267 : dlist_foreach_modify(proclock_iter, procLocks)
2510 : : {
2511 : 89088 : PROCLOCK *proclock = dlist_container(PROCLOCK, procLink, proclock_iter.cur);
2512 : 89088 : bool wakeupNeeded = false;
2513 : :
2514 [ - + ]: 89088 : Assert(proclock->tag.myProc == MyProc);
2515 : :
2516 : 89088 : lock = proclock->tag.myLock;
2517 : :
2518 : : /* Ignore items that are not of the lockmethod to be removed */
2519 [ + + ]: 89088 : if (LOCK_LOCKMETHOD(*lock) != lockmethodid)
2520 : 2563 : continue;
2521 : :
2522 : : /*
2523 : : * In allLocks mode, force release of all locks even if locallock
2524 : : * table had problems
2525 : : */
2526 [ + + ]: 86525 : if (allLocks)
2527 : 5792 : proclock->releaseMask = proclock->holdMask;
2528 : : else
2529 [ - + ]: 80733 : Assert((proclock->releaseMask & ~proclock->holdMask) == 0);
2530 : :
2531 : : /*
2532 : : * Ignore items that have nothing to be released, unless they have
2533 : : * holdMask == 0 and are therefore recyclable
2534 : : */
2535 [ + + - + ]: 86525 : if (proclock->releaseMask == 0 && proclock->holdMask != 0)
2536 : 2431 : continue;
2537 : :
2538 : : PROCLOCK_PRINT("LockReleaseAll", proclock);
2539 : : LOCK_PRINT("LockReleaseAll", lock, 0);
2540 [ - + ]: 84094 : Assert(lock->nRequested >= 0);
2541 [ - + ]: 84094 : Assert(lock->nGranted >= 0);
2542 [ - + ]: 84094 : Assert(lock->nGranted <= lock->nRequested);
2543 [ - + ]: 84094 : Assert((proclock->holdMask & ~lock->grantMask) == 0);
2544 : :
2545 : : /*
2546 : : * Release the previously-marked lock modes
2547 : : */
2548 [ + + ]: 756846 : for (i = 1; i <= numLockModes; i++)
2549 : : {
2550 [ + + ]: 672752 : if (proclock->releaseMask & LOCKBIT_ON(i))
2551 : 180550 : wakeupNeeded |= UnGrantLock(lock, i, proclock,
2552 : 90275 : lockMethodTable);
2553 : 672752 : }
2554 [ + - ]: 84094 : Assert((lock->nRequested >= 0) && (lock->nGranted >= 0));
2555 [ - + ]: 84094 : Assert(lock->nGranted <= lock->nRequested);
2556 : : LOCK_PRINT("LockReleaseAll: updated", lock, 0);
2557 : :
2558 : 84094 : proclock->releaseMask = 0;
2559 : :
2560 : : /* CleanUpLock will wake up waiters if needed. */
2561 : 168188 : CleanUpLock(lock, proclock,
2562 : 84094 : lockMethodTable,
2563 : 84094 : LockTagHashCode(&lock->tag),
2564 : 84094 : wakeupNeeded);
2565 [ + + ]: 89088 : } /* loop over PROCLOCKs within this partition */
2566 : :
2567 : 73179 : LWLockRelease(partitionLock);
2568 [ + + ]: 1866032 : } /* loop over partitions */
2569 : :
2570 : : #ifdef LOCK_DEBUG
2571 : : if (*(lockMethodTable->trace_flag))
2572 : : elog(LOG, "LockReleaseAll done");
2573 : : #endif
2574 : 116627 : }
2575 : :
2576 : : /*
2577 : : * LockReleaseSession -- Release all session locks of the specified lock method
2578 : : * that are held by the current process.
2579 : : */
2580 : : void
2581 : 3 : LockReleaseSession(LOCKMETHODID lockmethodid)
2582 : : {
2583 : 3 : HASH_SEQ_STATUS status;
2584 : 3 : LOCALLOCK *locallock;
2585 : :
2586 [ + - ]: 3 : if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
2587 [ # # # # ]: 0 : elog(ERROR, "unrecognized lock method: %d", lockmethodid);
2588 : :
2589 : 3 : hash_seq_init(&status, LockMethodLocalHash);
2590 : :
2591 [ + + ]: 16 : while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
2592 : : {
2593 : : /* Ignore items that are not of the specified lock method */
2594 [ + + ]: 13 : if (LOCALLOCK_LOCKMETHOD(*locallock) != lockmethodid)
2595 : 1 : continue;
2596 : :
2597 : 12 : ReleaseLockIfHeld(locallock, true);
2598 : : }
2599 : 3 : }
2600 : :
2601 : : /*
2602 : : * LockReleaseCurrentOwner
2603 : : * Release all locks belonging to CurrentResourceOwner
2604 : : *
2605 : : * If the caller knows what those locks are, it can pass them as an array.
2606 : : * That speeds up the call significantly, when a lot of locks are held.
2607 : : * Otherwise, pass NULL for locallocks, and we'll traverse through our hash
2608 : : * table to find them.
2609 : : */
2610 : : void
2611 : 1396 : LockReleaseCurrentOwner(LOCALLOCK **locallocks, int nlocks)
2612 : : {
2613 [ + + ]: 1396 : if (locallocks == NULL)
2614 : : {
2615 : 1 : HASH_SEQ_STATUS status;
2616 : 1 : LOCALLOCK *locallock;
2617 : :
2618 : 1 : hash_seq_init(&status, LockMethodLocalHash);
2619 : :
2620 [ + + ]: 85 : while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
2621 : 84 : ReleaseLockIfHeld(locallock, false);
2622 : 1 : }
2623 : : else
2624 : : {
2625 : 1395 : int i;
2626 : :
2627 [ + + ]: 2154 : for (i = nlocks - 1; i >= 0; i--)
2628 : 759 : ReleaseLockIfHeld(locallocks[i], false);
2629 : 1395 : }
2630 : 1396 : }
2631 : :
2632 : : /*
2633 : : * ReleaseLockIfHeld
2634 : : * Release any session-level locks on this lockable object if sessionLock
2635 : : * is true; else, release any locks held by CurrentResourceOwner.
2636 : : *
2637 : : * It is tempting to pass this a ResourceOwner pointer (or NULL for session
2638 : : * locks), but without refactoring LockRelease() we cannot support releasing
2639 : : * locks belonging to resource owners other than CurrentResourceOwner.
2640 : : * If we were to refactor, it'd be a good idea to fix it so we don't have to
2641 : : * do a hashtable lookup of the locallock, too. However, currently this
2642 : : * function isn't used heavily enough to justify refactoring for its
2643 : : * convenience.
2644 : : */
2645 : : static void
2646 : 855 : ReleaseLockIfHeld(LOCALLOCK *locallock, bool sessionLock)
2647 : : {
2648 : 855 : ResourceOwner owner;
2649 : 855 : LOCALLOCKOWNER *lockOwners;
2650 : 855 : int i;
2651 : :
2652 : : /* Identify owner for lock (must match LockRelease!) */
2653 [ + + ]: 855 : if (sessionLock)
2654 : 12 : owner = NULL;
2655 : : else
2656 : 843 : owner = CurrentResourceOwner;
2657 : :
2658 : : /* Scan to see if there are any locks belonging to the target owner */
2659 : 855 : lockOwners = locallock->lockOwners;
2660 [ + + ]: 919 : for (i = locallock->numLockOwners - 1; i >= 0; i--)
2661 : : {
2662 [ + + ]: 855 : if (lockOwners[i].owner == owner)
2663 : : {
2664 [ + - ]: 791 : Assert(lockOwners[i].nLocks > 0);
2665 [ + + ]: 791 : if (lockOwners[i].nLocks < locallock->nLocks)
2666 : : {
2667 : : /*
2668 : : * We will still hold this lock after forgetting this
2669 : : * ResourceOwner.
2670 : : */
2671 : 214 : locallock->nLocks -= lockOwners[i].nLocks;
2672 : : /* compact out unused slot */
2673 : 214 : locallock->numLockOwners--;
2674 [ - + ]: 214 : if (owner != NULL)
2675 : 214 : ResourceOwnerForgetLock(owner, locallock);
2676 [ + - ]: 214 : if (i < locallock->numLockOwners)
2677 : 0 : lockOwners[i] = lockOwners[locallock->numLockOwners];
2678 : 214 : }
2679 : : else
2680 : : {
2681 [ + - ]: 577 : Assert(lockOwners[i].nLocks == locallock->nLocks);
2682 : : /* We want to call LockRelease just once */
2683 : 577 : lockOwners[i].nLocks = 1;
2684 : 577 : locallock->nLocks = 1;
2685 [ + - + - ]: 1154 : if (!LockRelease(&locallock->tag.lock,
2686 : 577 : locallock->tag.mode,
2687 : 577 : sessionLock))
2688 [ # # # # ]: 0 : elog(WARNING, "ReleaseLockIfHeld: failed??");
2689 : : }
2690 : 791 : break;
2691 : : }
2692 : 64 : }
2693 : 855 : }
2694 : :
2695 : : /*
2696 : : * LockReassignCurrentOwner
2697 : : * Reassign all locks belonging to CurrentResourceOwner to belong
2698 : : * to its parent resource owner.
2699 : : *
2700 : : * If the caller knows what those locks are, it can pass them as an array.
2701 : : * That speeds up the call significantly, when a lot of locks are held
2702 : : * (e.g pg_dump with a large schema). Otherwise, pass NULL for locallocks,
2703 : : * and we'll traverse through our hash table to find them.
2704 : : */
2705 : : void
2706 : 54506 : LockReassignCurrentOwner(LOCALLOCK **locallocks, int nlocks)
2707 : : {
2708 : 54506 : ResourceOwner parent = ResourceOwnerGetParent(CurrentResourceOwner);
2709 : :
2710 [ + - ]: 54506 : Assert(parent != NULL);
2711 : :
2712 [ + + ]: 54506 : if (locallocks == NULL)
2713 : : {
2714 : 833 : HASH_SEQ_STATUS status;
2715 : 833 : LOCALLOCK *locallock;
2716 : :
2717 : 833 : hash_seq_init(&status, LockMethodLocalHash);
2718 : :
2719 [ + + ]: 20600 : while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
2720 : 19767 : LockReassignOwner(locallock, parent);
2721 : 833 : }
2722 : : else
2723 : : {
2724 : 53673 : int i;
2725 : :
2726 [ + + ]: 120370 : for (i = nlocks - 1; i >= 0; i--)
2727 : 66697 : LockReassignOwner(locallocks[i], parent);
2728 : 53673 : }
2729 : 54506 : }
2730 : :
2731 : : /*
2732 : : * Subroutine of LockReassignCurrentOwner. Reassigns a given lock belonging to
2733 : : * CurrentResourceOwner to its parent.
2734 : : */
2735 : : static void
2736 : 86464 : LockReassignOwner(LOCALLOCK *locallock, ResourceOwner parent)
2737 : : {
2738 : 86464 : LOCALLOCKOWNER *lockOwners;
2739 : 86464 : int i;
2740 : 86464 : int ic = -1;
2741 : 86464 : int ip = -1;
2742 : :
2743 : : /*
2744 : : * Scan to see if there are any locks belonging to current owner or its
2745 : : * parent
2746 : : */
2747 : 86464 : lockOwners = locallock->lockOwners;
2748 [ + + ]: 187756 : for (i = locallock->numLockOwners - 1; i >= 0; i--)
2749 : : {
2750 [ + + ]: 101292 : if (lockOwners[i].owner == CurrentResourceOwner)
2751 : 85455 : ic = i;
2752 [ + + ]: 15837 : else if (lockOwners[i].owner == parent)
2753 : 14440 : ip = i;
2754 : 101292 : }
2755 : :
2756 [ + + ]: 86464 : if (ic < 0)
2757 : 1009 : return; /* no current locks */
2758 : :
2759 [ + + ]: 85455 : if (ip < 0)
2760 : : {
2761 : : /* Parent has no slot, so just give it the child's slot */
2762 : 72015 : lockOwners[ic].owner = parent;
2763 : 72015 : ResourceOwnerRememberLock(parent, locallock);
2764 : 72015 : }
2765 : : else
2766 : : {
2767 : : /* Merge child's count with parent's */
2768 : 13440 : lockOwners[ip].nLocks += lockOwners[ic].nLocks;
2769 : : /* compact out unused slot */
2770 : 13440 : locallock->numLockOwners--;
2771 [ + + ]: 13440 : if (ic < locallock->numLockOwners)
2772 : 76 : lockOwners[ic] = lockOwners[locallock->numLockOwners];
2773 : : }
2774 : 85455 : ResourceOwnerForgetLock(CurrentResourceOwner, locallock);
2775 [ - + ]: 86464 : }
2776 : :
2777 : : /*
2778 : : * FastPathGrantRelationLock
2779 : : * Grant lock using per-backend fast-path array, if there is space.
2780 : : */
2781 : : static bool
2782 : 2072821 : FastPathGrantRelationLock(Oid relid, LOCKMODE lockmode)
2783 : : {
2784 : 2072821 : uint32 i;
2785 : 2072821 : uint32 unused_slot = FastPathLockSlotsPerBackend();
2786 : :
2787 : : /* fast-path group the lock belongs to */
2788 : 2072821 : uint32 group = FAST_PATH_REL_GROUP(relid);
2789 : :
2790 : : /* Scan for existing entry for this relid, remembering empty slot. */
2791 [ + + ]: 35180967 : for (i = 0; i < FP_LOCK_SLOTS_PER_GROUP; i++)
2792 : : {
2793 : : /* index into the whole per-backend array */
2794 [ - + - + ]: 33156609 : uint32 f = FAST_PATH_SLOT(group, i);
2795 : :
2796 [ - + - + : 33156609 : if (FAST_PATH_GET_BITS(MyProc, f) == 0)
+ + ]
2797 : 32184862 : unused_slot = f;
2798 [ + + ]: 971747 : else if (MyProc->fpRelId[f] == relid)
2799 : : {
2800 [ - + + - : 48463 : Assert(!FAST_PATH_CHECK_LOCKMODE(MyProc, f, lockmode));
+ - - + -
+ - + ]
2801 [ - + - + : 48463 : FAST_PATH_SET_LOCKMODE(MyProc, f, lockmode);
+ - - + -
+ ]
2802 : 48463 : return true;
2803 : : }
2804 [ + + ]: 33156609 : }
2805 : :
2806 : : /* If no existing entry, use any empty slot. */
2807 [ + - ]: 2024358 : if (unused_slot < FastPathLockSlotsPerBackend())
2808 : : {
2809 : 2024358 : MyProc->fpRelId[unused_slot] = relid;
2810 [ + - + - : 2024358 : FAST_PATH_SET_LOCKMODE(MyProc, unused_slot, lockmode);
+ - + - +
- ]
2811 : 2024358 : ++FastPathLocalUseCounts[group];
2812 : 2024358 : return true;
2813 : : }
2814 : :
2815 : : /* No existing entry, and no empty slot. */
2816 : 0 : return false;
2817 : 2072821 : }
2818 : :
2819 : : /*
2820 : : * FastPathUnGrantRelationLock
2821 : : * Release fast-path lock, if present. Update backend-private local
2822 : : * use count, while we're at it.
2823 : : */
2824 : : static bool
2825 : 2080068 : FastPathUnGrantRelationLock(Oid relid, LOCKMODE lockmode)
2826 : : {
2827 : 2080068 : uint32 i;
2828 : 2080068 : bool result = false;
2829 : :
2830 : : /* fast-path group the lock belongs to */
2831 : 2080068 : uint32 group = FAST_PATH_REL_GROUP(relid);
2832 : :
2833 : 2080068 : FastPathLocalUseCounts[group] = 0;
2834 [ + + ]: 35361156 : for (i = 0; i < FP_LOCK_SLOTS_PER_GROUP; i++)
2835 : : {
2836 : : /* index into the whole per-backend array */
2837 [ + - - + ]: 33281088 : uint32 f = FAST_PATH_SLOT(group, i);
2838 : :
2839 : 33281088 : if (MyProc->fpRelId[f] == relid
2840 [ + + - + : 33281088 : && FAST_PATH_CHECK_LOCKMODE(MyProc, f, lockmode))
- + - + -
+ - + +
+ ]
2841 : : {
2842 [ - + ]: 2072561 : Assert(!result);
2843 [ - + - + : 2072561 : FAST_PATH_CLEAR_LOCKMODE(MyProc, f, lockmode);
- + - + -
+ ]
2844 : 2072561 : result = true;
2845 : : /* we continue iterating so as to update FastPathLocalUseCount */
2846 : 2072561 : }
2847 [ - + - + : 33281088 : if (FAST_PATH_GET_BITS(MyProc, f) != 0)
+ + ]
2848 : 989774 : ++FastPathLocalUseCounts[group];
2849 : 33281088 : }
2850 : 4160136 : return result;
2851 : 2080068 : }
2852 : :
2853 : : /*
2854 : : * FastPathTransferRelationLocks
2855 : : * Transfer locks matching the given lock tag from per-backend fast-path
2856 : : * arrays to the shared hash table.
2857 : : *
2858 : : * Returns true if successful, false if ran out of shared memory.
2859 : : */
2860 : : static bool
2861 : 33094 : FastPathTransferRelationLocks(LockMethod lockMethodTable, const LOCKTAG *locktag,
2862 : : uint32 hashcode)
2863 : : {
2864 : 33094 : LWLock *partitionLock = LockHashPartitionLock(hashcode);
2865 : 33094 : Oid relid = locktag->locktag_field2;
2866 : 33094 : uint32 i;
2867 : :
2868 : : /* fast-path group the lock belongs to */
2869 : 33094 : uint32 group = FAST_PATH_REL_GROUP(relid);
2870 : :
2871 : : /*
2872 : : * Every PGPROC that can potentially hold a fast-path lock is present in
2873 : : * ProcGlobal->allProcs. Prepared transactions are not, but any
2874 : : * outstanding fast-path locks held by prepared transactions are
2875 : : * transferred to the main lock table.
2876 : : */
2877 [ + + ]: 5467650 : for (i = 0; i < ProcGlobal->allProcCount; i++)
2878 : : {
2879 : 5434556 : PGPROC *proc = GetPGProcByNumber(i);
2880 : 5434556 : uint32 j;
2881 : :
2882 : 5434556 : LWLockAcquire(&proc->fpInfoLock, LW_EXCLUSIVE);
2883 : :
2884 : : /*
2885 : : * If the target backend isn't referencing the same database as the
2886 : : * lock, then we needn't examine the individual relation IDs at all;
2887 : : * none of them can be relevant.
2888 : : *
2889 : : * proc->databaseId is set at backend startup time and never changes
2890 : : * thereafter, so it might be safe to perform this test before
2891 : : * acquiring &proc->fpInfoLock. In particular, it's certainly safe to
2892 : : * assume that if the target backend holds any fast-path locks, it
2893 : : * must have performed a memory-fencing operation (in particular, an
2894 : : * LWLock acquisition) since setting proc->databaseId. However, it's
2895 : : * less clear that our backend is certain to have performed a memory
2896 : : * fencing operation since the other backend set proc->databaseId. So
2897 : : * for now, we test it after acquiring the LWLock just to be safe.
2898 : : *
2899 : : * Also skip groups without any registered fast-path locks.
2900 : : */
2901 [ + + + + ]: 5434556 : if (proc->databaseId != locktag->locktag_field1 ||
2902 : 3281385 : proc->fpLockBits[group] == 0)
2903 : : {
2904 : 5385897 : LWLockRelease(&proc->fpInfoLock);
2905 : 5385897 : continue;
2906 : : }
2907 : :
2908 [ + + ]: 826913 : for (j = 0; j < FP_LOCK_SLOTS_PER_GROUP; j++)
2909 : : {
2910 : 778507 : uint32 lockmode;
2911 : :
2912 : : /* index into the whole per-backend array */
2913 [ + - - + ]: 778507 : uint32 f = FAST_PATH_SLOT(group, j);
2914 : :
2915 : : /* Look for an allocated slot matching the given relid. */
2916 [ + + - + : 778507 : if (relid != proc->fpRelId[f] || FAST_PATH_GET_BITS(proc, f) == 0)
+ - + + ]
2917 : 778254 : continue;
2918 : :
2919 : : /* Find or create lock object. */
2920 : 253 : LWLockAcquire(partitionLock, LW_EXCLUSIVE);
2921 [ + + ]: 1012 : for (lockmode = FAST_PATH_LOCKNUMBER_OFFSET;
2922 : 1012 : lockmode < FAST_PATH_LOCKNUMBER_OFFSET + FAST_PATH_BITS_PER_SLOT;
2923 : 759 : ++lockmode)
2924 : : {
2925 : 759 : PROCLOCK *proclock;
2926 : :
2927 [ - + - + : 759 : if (!FAST_PATH_CHECK_LOCKMODE(proc, f, lockmode))
+ - + - -
+ + + ]
2928 : 499 : continue;
2929 : 520 : proclock = SetupLockInTable(lockMethodTable, proc, locktag,
2930 : 260 : hashcode, lockmode);
2931 [ + - ]: 260 : if (!proclock)
2932 : : {
2933 : 0 : LWLockRelease(partitionLock);
2934 : 0 : LWLockRelease(&proc->fpInfoLock);
2935 : 0 : return false;
2936 : : }
2937 : 260 : GrantLock(proclock->tag.myLock, proclock, lockmode);
2938 [ + - - + : 260 : FAST_PATH_CLEAR_LOCKMODE(proc, f, lockmode);
+ - - + -
+ ]
2939 [ + - + ]: 759 : }
2940 : 253 : LWLockRelease(partitionLock);
2941 : :
2942 : : /* No need to examine remaining slots. */
2943 : 253 : break;
2944 [ - + + ]: 778507 : }
2945 : 48659 : LWLockRelease(&proc->fpInfoLock);
2946 [ + + - ]: 5434556 : }
2947 : 33094 : return true;
2948 : 33094 : }
2949 : :
2950 : : /*
2951 : : * FastPathGetRelationLockEntry
2952 : : * Return the PROCLOCK for a lock originally taken via the fast-path,
2953 : : * transferring it to the primary lock table if necessary.
2954 : : *
2955 : : * Note: caller takes care of updating the locallock object.
2956 : : */
2957 : : static PROCLOCK *
2958 : 0 : FastPathGetRelationLockEntry(LOCALLOCK *locallock)
2959 : : {
2960 : 0 : LockMethod lockMethodTable = LockMethods[DEFAULT_LOCKMETHOD];
2961 : 0 : LOCKTAG *locktag = &locallock->tag.lock;
2962 : 0 : PROCLOCK *proclock = NULL;
2963 : 0 : LWLock *partitionLock = LockHashPartitionLock(locallock->hashcode);
2964 : 0 : Oid relid = locktag->locktag_field2;
2965 : 0 : uint32 i,
2966 : : group;
2967 : :
2968 : : /* fast-path group the lock belongs to */
2969 : 0 : group = FAST_PATH_REL_GROUP(relid);
2970 : :
2971 : 0 : LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
2972 : :
2973 [ # # ]: 0 : for (i = 0; i < FP_LOCK_SLOTS_PER_GROUP; i++)
2974 : : {
2975 : 0 : uint32 lockmode;
2976 : :
2977 : : /* index into the whole per-backend array */
2978 [ # # # # ]: 0 : uint32 f = FAST_PATH_SLOT(group, i);
2979 : :
2980 : : /* Look for an allocated slot matching the given relid. */
2981 [ # # # # : 0 : if (relid != MyProc->fpRelId[f] || FAST_PATH_GET_BITS(MyProc, f) == 0)
# # # # ]
2982 : 0 : continue;
2983 : :
2984 : : /* If we don't have a lock of the given mode, forget it! */
2985 : 0 : lockmode = locallock->tag.mode;
2986 [ # # # # : 0 : if (!FAST_PATH_CHECK_LOCKMODE(MyProc, f, lockmode))
# # # # #
# # # ]
2987 : 0 : break;
2988 : :
2989 : : /* Find or create lock object. */
2990 : 0 : LWLockAcquire(partitionLock, LW_EXCLUSIVE);
2991 : :
2992 : 0 : proclock = SetupLockInTable(lockMethodTable, MyProc, locktag,
2993 : 0 : locallock->hashcode, lockmode);
2994 [ # # ]: 0 : if (!proclock)
2995 : : {
2996 : 0 : LWLockRelease(partitionLock);
2997 : 0 : LWLockRelease(&MyProc->fpInfoLock);
2998 [ # # # # ]: 0 : ereport(ERROR,
2999 : : (errcode(ERRCODE_OUT_OF_MEMORY),
3000 : : errmsg("out of shared memory"),
3001 : : errhint("You might need to increase \"%s\".", "max_locks_per_transaction")));
3002 : 0 : }
3003 : 0 : GrantLock(proclock->tag.myLock, proclock, lockmode);
3004 [ # # # # : 0 : FAST_PATH_CLEAR_LOCKMODE(MyProc, f, lockmode);
# # # # #
# ]
3005 : :
3006 : 0 : LWLockRelease(partitionLock);
3007 : :
3008 : : /* No need to examine remaining slots. */
3009 : 0 : break;
3010 [ # # # ]: 0 : }
3011 : :
3012 : 0 : LWLockRelease(&MyProc->fpInfoLock);
3013 : :
3014 : : /* Lock may have already been transferred by some other backend. */
3015 [ # # ]: 0 : if (proclock == NULL)
3016 : : {
3017 : 0 : LOCK *lock;
3018 : 0 : PROCLOCKTAG proclocktag;
3019 : 0 : uint32 proclock_hashcode;
3020 : :
3021 : 0 : LWLockAcquire(partitionLock, LW_SHARED);
3022 : :
3023 : 0 : lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
3024 : 0 : locktag,
3025 : 0 : locallock->hashcode,
3026 : : HASH_FIND,
3027 : : NULL);
3028 [ # # ]: 0 : if (!lock)
3029 [ # # # # ]: 0 : elog(ERROR, "failed to re-find shared lock object");
3030 : :
3031 : 0 : proclocktag.myLock = lock;
3032 : 0 : proclocktag.myProc = MyProc;
3033 : :
3034 : 0 : proclock_hashcode = ProcLockHashCode(&proclocktag, locallock->hashcode);
3035 : 0 : proclock = (PROCLOCK *)
3036 : 0 : hash_search_with_hash_value(LockMethodProcLockHash,
3037 : : &proclocktag,
3038 : 0 : proclock_hashcode,
3039 : : HASH_FIND,
3040 : : NULL);
3041 [ # # ]: 0 : if (!proclock)
3042 [ # # # # ]: 0 : elog(ERROR, "failed to re-find shared proclock object");
3043 : 0 : LWLockRelease(partitionLock);
3044 : 0 : }
3045 : :
3046 : 0 : return proclock;
3047 : 0 : }
3048 : :
3049 : : /*
3050 : : * GetLockConflicts
3051 : : * Get an array of VirtualTransactionIds of xacts currently holding locks
3052 : : * that would conflict with the specified lock/lockmode.
3053 : : * xacts merely awaiting such a lock are NOT reported.
3054 : : *
3055 : : * The result array is palloc'd and is terminated with an invalid VXID.
3056 : : * *countp, if not null, is updated to the number of items set.
3057 : : *
3058 : : * Of course, the result could be out of date by the time it's returned, so
3059 : : * use of this function has to be thought about carefully. Similarly, a
3060 : : * PGPROC with no "lxid" will be considered non-conflicting regardless of any
3061 : : * lock it holds. Existing callers don't care about a locker after that
3062 : : * locker's pg_xact updates complete. CommitTransaction() clears "lxid" after
3063 : : * pg_xact updates and before releasing locks.
3064 : : *
3065 : : * Note we never include the current xact's vxid in the result array,
3066 : : * since an xact never blocks itself.
3067 : : */
3068 : : VirtualTransactionId *
3069 : 214 : GetLockConflicts(const LOCKTAG *locktag, LOCKMODE lockmode, int *countp)
3070 : : {
3071 : : static VirtualTransactionId *vxids;
3072 : 214 : LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
3073 : 214 : LockMethod lockMethodTable;
3074 : 214 : LOCK *lock;
3075 : 214 : LOCKMASK conflictMask;
3076 : 214 : dlist_iter proclock_iter;
3077 : 214 : PROCLOCK *proclock;
3078 : 214 : uint32 hashcode;
3079 : 214 : LWLock *partitionLock;
3080 : 214 : int count = 0;
3081 : 214 : int fast_count = 0;
3082 : :
3083 [ + - ]: 214 : if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
3084 [ # # # # ]: 0 : elog(ERROR, "unrecognized lock method: %d", lockmethodid);
3085 : 214 : lockMethodTable = LockMethods[lockmethodid];
3086 [ + - ]: 214 : if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
3087 [ # # # # ]: 0 : elog(ERROR, "unrecognized lock mode: %d", lockmode);
3088 : :
3089 : : /*
3090 : : * Allocate memory to store results, and fill with InvalidVXID. We only
3091 : : * need enough space for MaxBackends + max_prepared_xacts + a terminator.
3092 : : * InHotStandby allocate once in TopMemoryContext.
3093 : : */
3094 [ - + ]: 214 : if (InHotStandby)
3095 : : {
3096 [ # # ]: 0 : if (vxids == NULL)
3097 : 0 : vxids = (VirtualTransactionId *)
3098 : 0 : MemoryContextAlloc(TopMemoryContext,
3099 : 0 : sizeof(VirtualTransactionId) *
3100 : 0 : (MaxBackends + max_prepared_xacts + 1));
3101 : 0 : }
3102 : : else
3103 : 214 : vxids = palloc0_array(VirtualTransactionId, (MaxBackends + max_prepared_xacts + 1));
3104 : :
3105 : : /* Compute hash code and partition lock, and look up conflicting modes. */
3106 : 214 : hashcode = LockTagHashCode(locktag);
3107 : 214 : partitionLock = LockHashPartitionLock(hashcode);
3108 : 214 : conflictMask = lockMethodTable->conflictTab[lockmode];
3109 : :
3110 : : /*
3111 : : * Fast path locks might not have been entered in the primary lock table.
3112 : : * If the lock we're dealing with could conflict with such a lock, we must
3113 : : * examine each backend's fast-path array for conflicts.
3114 : : */
3115 [ + - + - : 214 : if (ConflictsWithRelationFastPath(locktag, lockmode))
+ - - + ]
3116 : : {
3117 : 214 : int i;
3118 : 214 : Oid relid = locktag->locktag_field2;
3119 : 214 : VirtualTransactionId vxid;
3120 : :
3121 : : /* fast-path group the lock belongs to */
3122 : 214 : uint32 group = FAST_PATH_REL_GROUP(relid);
3123 : :
3124 : : /*
3125 : : * Iterate over relevant PGPROCs. Anything held by a prepared
3126 : : * transaction will have been transferred to the primary lock table,
3127 : : * so we need not worry about those. This is all a bit fuzzy, because
3128 : : * new locks could be taken after we've visited a particular
3129 : : * partition, but the callers had better be prepared to deal with that
3130 : : * anyway, since the locks could equally well be taken between the
3131 : : * time we return the value and the time the caller does something
3132 : : * with it.
3133 : : */
3134 [ + + ]: 35310 : for (i = 0; i < ProcGlobal->allProcCount; i++)
3135 : : {
3136 : 35096 : PGPROC *proc = GetPGProcByNumber(i);
3137 : 35096 : uint32 j;
3138 : :
3139 : : /* A backend never blocks itself */
3140 [ + + ]: 35096 : if (proc == MyProc)
3141 : 214 : continue;
3142 : :
3143 : 34882 : LWLockAcquire(&proc->fpInfoLock, LW_SHARED);
3144 : :
3145 : : /*
3146 : : * If the target backend isn't referencing the same database as
3147 : : * the lock, then we needn't examine the individual relation IDs
3148 : : * at all; none of them can be relevant.
3149 : : *
3150 : : * See FastPathTransferRelationLocks() for discussion of why we do
3151 : : * this test after acquiring the lock.
3152 : : *
3153 : : * Also skip groups without any registered fast-path locks.
3154 : : */
3155 [ + + + + ]: 34882 : if (proc->databaseId != locktag->locktag_field1 ||
3156 : 19443 : proc->fpLockBits[group] == 0)
3157 : : {
3158 : 34832 : LWLockRelease(&proc->fpInfoLock);
3159 : 34832 : continue;
3160 : : }
3161 : :
3162 [ + + ]: 850 : for (j = 0; j < FP_LOCK_SLOTS_PER_GROUP; j++)
3163 : : {
3164 : 800 : uint32 lockmask;
3165 : :
3166 : : /* index into the whole per-backend array */
3167 [ + - + - ]: 800 : uint32 f = FAST_PATH_SLOT(group, j);
3168 : :
3169 : : /* Look for an allocated slot matching the given relid. */
3170 [ + - ]: 800 : if (relid != proc->fpRelId[f])
3171 : 800 : continue;
3172 [ # # # # ]: 0 : lockmask = FAST_PATH_GET_BITS(proc, f);
3173 [ # # ]: 0 : if (!lockmask)
3174 : 0 : continue;
3175 : 0 : lockmask <<= FAST_PATH_LOCKNUMBER_OFFSET;
3176 : :
3177 : : /*
3178 : : * There can only be one entry per relation, so if we found it
3179 : : * and it doesn't conflict, we can skip the rest of the slots.
3180 : : */
3181 [ # # ]: 0 : if ((lockmask & conflictMask) == 0)
3182 : 0 : break;
3183 : :
3184 : : /* Conflict! */
3185 : 0 : GET_VXID_FROM_PGPROC(vxid, *proc);
3186 : :
3187 [ # # ]: 0 : if (VirtualTransactionIdIsValid(vxid))
3188 : 0 : vxids[count++] = vxid;
3189 : : /* else, xact already committed or aborted */
3190 : :
3191 : : /* No need to examine remaining slots. */
3192 : 0 : break;
3193 [ - + ]: 800 : }
3194 : :
3195 : 50 : LWLockRelease(&proc->fpInfoLock);
3196 [ + + ]: 35096 : }
3197 : 214 : }
3198 : :
3199 : : /* Remember how many fast-path conflicts we found. */
3200 : 214 : fast_count = count;
3201 : :
3202 : : /*
3203 : : * Look up the lock object matching the tag.
3204 : : */
3205 : 214 : LWLockAcquire(partitionLock, LW_SHARED);
3206 : :
3207 : 428 : lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
3208 : 214 : locktag,
3209 : 214 : hashcode,
3210 : : HASH_FIND,
3211 : : NULL);
3212 [ + + ]: 214 : if (!lock)
3213 : : {
3214 : : /*
3215 : : * If the lock object doesn't exist, there is nothing holding a lock
3216 : : * on this lockable object.
3217 : : */
3218 : 2 : LWLockRelease(partitionLock);
3219 : 2 : vxids[count].procNumber = INVALID_PROC_NUMBER;
3220 : 2 : vxids[count].localTransactionId = InvalidLocalTransactionId;
3221 [ + - ]: 2 : if (countp)
3222 : 0 : *countp = count;
3223 : 2 : return vxids;
3224 : : }
3225 : :
3226 : : /*
3227 : : * Examine each existing holder (or awaiter) of the lock.
3228 : : */
3229 [ + - + + ]: 424 : dlist_foreach(proclock_iter, &lock->procLocks)
3230 : : {
3231 : 212 : proclock = dlist_container(PROCLOCK, lockLink, proclock_iter.cur);
3232 : :
3233 [ - + ]: 212 : if (conflictMask & proclock->holdMask)
3234 : : {
3235 : 212 : PGPROC *proc = proclock->tag.myProc;
3236 : :
3237 : : /* A backend never blocks itself */
3238 [ - + ]: 212 : if (proc != MyProc)
3239 : : {
3240 : 0 : VirtualTransactionId vxid;
3241 : :
3242 : 0 : GET_VXID_FROM_PGPROC(vxid, *proc);
3243 : :
3244 [ # # ]: 0 : if (VirtualTransactionIdIsValid(vxid))
3245 : : {
3246 : 0 : int i;
3247 : :
3248 : : /* Avoid duplicate entries. */
3249 [ # # ]: 0 : for (i = 0; i < fast_count; ++i)
3250 [ # # # # ]: 0 : if (VirtualTransactionIdEquals(vxids[i], vxid))
3251 : 0 : break;
3252 [ # # ]: 0 : if (i >= fast_count)
3253 : 0 : vxids[count++] = vxid;
3254 : 0 : }
3255 : : /* else, xact already committed or aborted */
3256 : 0 : }
3257 : 212 : }
3258 : 212 : }
3259 : :
3260 : 212 : LWLockRelease(partitionLock);
3261 : :
3262 [ + - ]: 212 : if (count > MaxBackends + max_prepared_xacts) /* should never happen */
3263 [ # # # # ]: 0 : elog(PANIC, "too many conflicting locks found");
3264 : :
3265 : 212 : vxids[count].procNumber = INVALID_PROC_NUMBER;
3266 : 212 : vxids[count].localTransactionId = InvalidLocalTransactionId;
3267 [ - + ]: 212 : if (countp)
3268 : 212 : *countp = count;
3269 : 212 : return vxids;
3270 : 214 : }
3271 : :
3272 : : /*
3273 : : * Find a lock in the shared lock table and release it. It is the caller's
3274 : : * responsibility to verify that this is a sane thing to do. (For example, it
3275 : : * would be bad to release a lock here if there might still be a LOCALLOCK
3276 : : * object with pointers to it.)
3277 : : *
3278 : : * We currently use this in two situations: first, to release locks held by
3279 : : * prepared transactions on commit (see lock_twophase_postcommit); and second,
3280 : : * to release locks taken via the fast-path, transferred to the main hash
3281 : : * table, and then released (see LockReleaseAll).
3282 : : */
3283 : : static void
3284 : 283 : LockRefindAndRelease(LockMethod lockMethodTable, PGPROC *proc,
3285 : : LOCKTAG *locktag, LOCKMODE lockmode,
3286 : : bool decrement_strong_lock_count)
3287 : : {
3288 : 283 : LOCK *lock;
3289 : 283 : PROCLOCK *proclock;
3290 : 283 : PROCLOCKTAG proclocktag;
3291 : 283 : uint32 hashcode;
3292 : 283 : uint32 proclock_hashcode;
3293 : 283 : LWLock *partitionLock;
3294 : 283 : bool wakeupNeeded;
3295 : :
3296 : 283 : hashcode = LockTagHashCode(locktag);
3297 : 283 : partitionLock = LockHashPartitionLock(hashcode);
3298 : :
3299 : 283 : LWLockAcquire(partitionLock, LW_EXCLUSIVE);
3300 : :
3301 : : /*
3302 : : * Re-find the lock object (it had better be there).
3303 : : */
3304 : 566 : lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
3305 : 283 : locktag,
3306 : 283 : hashcode,
3307 : : HASH_FIND,
3308 : : NULL);
3309 [ + - ]: 283 : if (!lock)
3310 [ # # # # ]: 0 : elog(PANIC, "failed to re-find shared lock object");
3311 : :
3312 : : /*
3313 : : * Re-find the proclock object (ditto).
3314 : : */
3315 : 283 : proclocktag.myLock = lock;
3316 : 283 : proclocktag.myProc = proc;
3317 : :
3318 : 283 : proclock_hashcode = ProcLockHashCode(&proclocktag, hashcode);
3319 : :
3320 : 566 : proclock = (PROCLOCK *) hash_search_with_hash_value(LockMethodProcLockHash,
3321 : : &proclocktag,
3322 : 283 : proclock_hashcode,
3323 : : HASH_FIND,
3324 : : NULL);
3325 [ + - ]: 283 : if (!proclock)
3326 [ # # # # ]: 0 : elog(PANIC, "failed to re-find shared proclock object");
3327 : :
3328 : : /*
3329 : : * Double-check that we are actually holding a lock of the type we want to
3330 : : * release.
3331 : : */
3332 [ + - ]: 283 : if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
3333 : : {
3334 : : PROCLOCK_PRINT("lock_twophase_postcommit: WRONGTYPE", proclock);
3335 : 0 : LWLockRelease(partitionLock);
3336 [ # # # # ]: 0 : elog(WARNING, "you don't own a lock of type %s",
3337 : : lockMethodTable->lockModeNames[lockmode]);
3338 : 0 : return;
3339 : : }
3340 : :
3341 : : /*
3342 : : * Do the releasing. CleanUpLock will waken any now-wakable waiters.
3343 : : */
3344 : 283 : wakeupNeeded = UnGrantLock(lock, lockmode, proclock, lockMethodTable);
3345 : :
3346 : 566 : CleanUpLock(lock, proclock,
3347 : 283 : lockMethodTable, hashcode,
3348 : 283 : wakeupNeeded);
3349 : :
3350 : 283 : LWLockRelease(partitionLock);
3351 : :
3352 : : /*
3353 : : * Decrement strong lock count. This logic is needed only for 2PC.
3354 : : */
3355 : 283 : if (decrement_strong_lock_count
3356 [ - + # # : 283 : && ConflictsWithRelationFastPath(locktag, lockmode))
# # # # #
# ]
3357 : : {
3358 : 0 : uint32 fasthashcode = FastPathStrongLockHashPartition(hashcode);
3359 : :
3360 [ # # ]: 0 : SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
3361 [ # # ]: 0 : Assert(FastPathStrongRelationLocks->count[fasthashcode] > 0);
3362 : 0 : FastPathStrongRelationLocks->count[fasthashcode]--;
3363 : 0 : SpinLockRelease(&FastPathStrongRelationLocks->mutex);
3364 : 0 : }
3365 [ - + ]: 283 : }
3366 : :
3367 : : /*
3368 : : * CheckForSessionAndXactLocks
3369 : : * Check to see if transaction holds both session-level and xact-level
3370 : : * locks on the same object; if so, throw an error.
3371 : : *
3372 : : * If we have both session- and transaction-level locks on the same object,
3373 : : * PREPARE TRANSACTION must fail. This should never happen with regular
3374 : : * locks, since we only take those at session level in some special operations
3375 : : * like VACUUM. It's possible to hit this with advisory locks, though.
3376 : : *
3377 : : * It would be nice if we could keep the session hold and give away the
3378 : : * transactional hold to the prepared xact. However, that would require two
3379 : : * PROCLOCK objects, and we cannot be sure that another PROCLOCK will be
3380 : : * available when it comes time for PostPrepare_Locks to do the deed.
3381 : : * So for now, we error out while we can still do so safely.
3382 : : *
3383 : : * Since the LOCALLOCK table stores a separate entry for each lockmode,
3384 : : * we can't implement this check by examining LOCALLOCK entries in isolation.
3385 : : * We must build a transient hashtable that is indexed by locktag only.
3386 : : */
3387 : : static void
3388 : 0 : CheckForSessionAndXactLocks(void)
3389 : : {
3390 : : typedef struct
3391 : : {
3392 : : LOCKTAG lock; /* identifies the lockable object */
3393 : : bool sessLock; /* is any lockmode held at session level? */
3394 : : bool xactLock; /* is any lockmode held at xact level? */
3395 : : } PerLockTagEntry;
3396 : :
3397 : 0 : HASHCTL hash_ctl;
3398 : 0 : HTAB *lockhtab;
3399 : 0 : HASH_SEQ_STATUS status;
3400 : 0 : LOCALLOCK *locallock;
3401 : :
3402 : : /* Create a local hash table keyed by LOCKTAG only */
3403 : 0 : hash_ctl.keysize = sizeof(LOCKTAG);
3404 : 0 : hash_ctl.entrysize = sizeof(PerLockTagEntry);
3405 : 0 : hash_ctl.hcxt = CurrentMemoryContext;
3406 : :
3407 : 0 : lockhtab = hash_create("CheckForSessionAndXactLocks table",
3408 : : 256, /* arbitrary initial size */
3409 : : &hash_ctl,
3410 : : HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
3411 : :
3412 : : /* Scan local lock table to find entries for each LOCKTAG */
3413 : 0 : hash_seq_init(&status, LockMethodLocalHash);
3414 : :
3415 [ # # ]: 0 : while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
3416 : : {
3417 : 0 : LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
3418 : 0 : PerLockTagEntry *hentry;
3419 : 0 : bool found;
3420 : 0 : int i;
3421 : :
3422 : : /*
3423 : : * Ignore VXID locks. We don't want those to be held by prepared
3424 : : * transactions, since they aren't meaningful after a restart.
3425 : : */
3426 [ # # ]: 0 : if (locallock->tag.lock.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
3427 : 0 : continue;
3428 : :
3429 : : /* Ignore it if we don't actually hold the lock */
3430 [ # # ]: 0 : if (locallock->nLocks <= 0)
3431 : 0 : continue;
3432 : :
3433 : : /* Otherwise, find or make an entry in lockhtab */
3434 : 0 : hentry = (PerLockTagEntry *) hash_search(lockhtab,
3435 : 0 : &locallock->tag.lock,
3436 : : HASH_ENTER, &found);
3437 [ # # ]: 0 : if (!found) /* initialize, if newly created */
3438 : 0 : hentry->sessLock = hentry->xactLock = false;
3439 : :
3440 : : /* Scan to see if we hold lock at session or xact level or both */
3441 [ # # ]: 0 : for (i = locallock->numLockOwners - 1; i >= 0; i--)
3442 : : {
3443 [ # # ]: 0 : if (lockOwners[i].owner == NULL)
3444 : 0 : hentry->sessLock = true;
3445 : : else
3446 : 0 : hentry->xactLock = true;
3447 : 0 : }
3448 : :
3449 : : /*
3450 : : * We can throw error immediately when we see both types of locks; no
3451 : : * need to wait around to see if there are more violations.
3452 : : */
3453 [ # # # # ]: 0 : if (hentry->sessLock && hentry->xactLock)
3454 [ # # # # ]: 0 : ereport(ERROR,
3455 : : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
3456 : : errmsg("cannot PREPARE while holding both session-level and transaction-level locks on the same object")));
3457 [ # # # ]: 0 : }
3458 : :
3459 : : /* Success, so clean up */
3460 : 0 : hash_destroy(lockhtab);
3461 : 0 : }
3462 : :
3463 : : /*
3464 : : * AtPrepare_Locks
3465 : : * Do the preparatory work for a PREPARE: make 2PC state file records
3466 : : * for all locks currently held.
3467 : : *
3468 : : * Session-level locks are ignored, as are VXID locks.
3469 : : *
3470 : : * For the most part, we don't need to touch shared memory for this ---
3471 : : * all the necessary state information is in the locallock table.
3472 : : * Fast-path locks are an exception, however: we move any such locks to
3473 : : * the main table before allowing PREPARE TRANSACTION to succeed.
3474 : : */
3475 : : void
3476 : 0 : AtPrepare_Locks(void)
3477 : : {
3478 : 0 : HASH_SEQ_STATUS status;
3479 : 0 : LOCALLOCK *locallock;
3480 : :
3481 : : /* First, verify there aren't locks of both xact and session level */
3482 : 0 : CheckForSessionAndXactLocks();
3483 : :
3484 : : /* Now do the per-locallock cleanup work */
3485 : 0 : hash_seq_init(&status, LockMethodLocalHash);
3486 : :
3487 [ # # ]: 0 : while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
3488 : : {
3489 : 0 : TwoPhaseLockRecord record;
3490 : 0 : LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
3491 : 0 : bool haveSessionLock;
3492 : 0 : bool haveXactLock;
3493 : 0 : int i;
3494 : :
3495 : : /*
3496 : : * Ignore VXID locks. We don't want those to be held by prepared
3497 : : * transactions, since they aren't meaningful after a restart.
3498 : : */
3499 [ # # ]: 0 : if (locallock->tag.lock.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
3500 : 0 : continue;
3501 : :
3502 : : /* Ignore it if we don't actually hold the lock */
3503 [ # # ]: 0 : if (locallock->nLocks <= 0)
3504 : 0 : continue;
3505 : :
3506 : : /* Scan to see whether we hold it at session or transaction level */
3507 : 0 : haveSessionLock = haveXactLock = false;
3508 [ # # ]: 0 : for (i = locallock->numLockOwners - 1; i >= 0; i--)
3509 : : {
3510 [ # # ]: 0 : if (lockOwners[i].owner == NULL)
3511 : 0 : haveSessionLock = true;
3512 : : else
3513 : 0 : haveXactLock = true;
3514 : 0 : }
3515 : :
3516 : : /* Ignore it if we have only session lock */
3517 [ # # ]: 0 : if (!haveXactLock)
3518 : 0 : continue;
3519 : :
3520 : : /* This can't happen, because we already checked it */
3521 [ # # ]: 0 : if (haveSessionLock)
3522 [ # # # # ]: 0 : ereport(ERROR,
3523 : : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
3524 : : errmsg("cannot PREPARE while holding both session-level and transaction-level locks on the same object")));
3525 : :
3526 : : /*
3527 : : * If the local lock was taken via the fast-path, we need to move it
3528 : : * to the primary lock table, or just get a pointer to the existing
3529 : : * primary lock table entry if by chance it's already been
3530 : : * transferred.
3531 : : */
3532 [ # # ]: 0 : if (locallock->proclock == NULL)
3533 : : {
3534 : 0 : locallock->proclock = FastPathGetRelationLockEntry(locallock);
3535 : 0 : locallock->lock = locallock->proclock->tag.myLock;
3536 : 0 : }
3537 : :
3538 : : /*
3539 : : * Arrange to not release any strong lock count held by this lock
3540 : : * entry. We must retain the count until the prepared transaction is
3541 : : * committed or rolled back.
3542 : : */
3543 : 0 : locallock->holdsStrongLockCount = false;
3544 : :
3545 : : /*
3546 : : * Create a 2PC record.
3547 : : */
3548 : 0 : memcpy(&(record.locktag), &(locallock->tag.lock), sizeof(LOCKTAG));
3549 : 0 : record.lockmode = locallock->tag.mode;
3550 : :
3551 : 0 : RegisterTwoPhaseRecord(TWOPHASE_RM_LOCK_ID, 0,
3552 : : &record, sizeof(TwoPhaseLockRecord));
3553 [ # # # ]: 0 : }
3554 : 0 : }
3555 : :
3556 : : /*
3557 : : * PostPrepare_Locks
3558 : : * Clean up after successful PREPARE
3559 : : *
3560 : : * Here, we want to transfer ownership of our locks to a dummy PGPROC
3561 : : * that's now associated with the prepared transaction, and we want to
3562 : : * clean out the corresponding entries in the LOCALLOCK table.
3563 : : *
3564 : : * Note: by removing the LOCALLOCK entries, we are leaving dangling
3565 : : * pointers in the transaction's resource owner. This is OK at the
3566 : : * moment since resowner.c doesn't try to free locks retail at a toplevel
3567 : : * transaction commit or abort. We could alternatively zero out nLocks
3568 : : * and leave the LOCALLOCK entries to be garbage-collected by LockReleaseAll,
3569 : : * but that probably costs more cycles.
3570 : : */
3571 : : void
3572 : 0 : PostPrepare_Locks(FullTransactionId fxid)
3573 : : {
3574 : 0 : PGPROC *newproc = TwoPhaseGetDummyProc(fxid, false);
3575 : 0 : HASH_SEQ_STATUS status;
3576 : 0 : LOCALLOCK *locallock;
3577 : 0 : LOCK *lock;
3578 : 0 : PROCLOCK *proclock;
3579 : 0 : PROCLOCKTAG proclocktag;
3580 : 0 : int partition;
3581 : :
3582 : : /* Can't prepare a lock group follower. */
3583 [ # # # # ]: 0 : Assert(MyProc->lockGroupLeader == NULL ||
3584 : : MyProc->lockGroupLeader == MyProc);
3585 : :
3586 : : /* This is a critical section: any error means big trouble */
3587 : 0 : START_CRIT_SECTION();
3588 : :
3589 : : /*
3590 : : * First we run through the locallock table and get rid of unwanted
3591 : : * entries, then we scan the process's proclocks and transfer them to the
3592 : : * target proc.
3593 : : *
3594 : : * We do this separately because we may have multiple locallock entries
3595 : : * pointing to the same proclock, and we daren't end up with any dangling
3596 : : * pointers.
3597 : : */
3598 : 0 : hash_seq_init(&status, LockMethodLocalHash);
3599 : :
3600 [ # # ]: 0 : while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
3601 : : {
3602 : 0 : LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
3603 : 0 : bool haveSessionLock;
3604 : 0 : bool haveXactLock;
3605 : 0 : int i;
3606 : :
3607 [ # # # # ]: 0 : if (locallock->proclock == NULL || locallock->lock == NULL)
3608 : : {
3609 : : /*
3610 : : * We must've run out of shared memory while trying to set up this
3611 : : * lock. Just forget the local entry.
3612 : : */
3613 [ # # ]: 0 : Assert(locallock->nLocks == 0);
3614 : 0 : RemoveLocalLock(locallock);
3615 : 0 : continue;
3616 : : }
3617 : :
3618 : : /* Ignore VXID locks */
3619 [ # # ]: 0 : if (locallock->tag.lock.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
3620 : 0 : continue;
3621 : :
3622 : : /* Scan to see whether we hold it at session or transaction level */
3623 : 0 : haveSessionLock = haveXactLock = false;
3624 [ # # ]: 0 : for (i = locallock->numLockOwners - 1; i >= 0; i--)
3625 : : {
3626 [ # # ]: 0 : if (lockOwners[i].owner == NULL)
3627 : 0 : haveSessionLock = true;
3628 : : else
3629 : 0 : haveXactLock = true;
3630 : 0 : }
3631 : :
3632 : : /* Ignore it if we have only session lock */
3633 [ # # ]: 0 : if (!haveXactLock)
3634 : 0 : continue;
3635 : :
3636 : : /* This can't happen, because we already checked it */
3637 [ # # ]: 0 : if (haveSessionLock)
3638 [ # # # # ]: 0 : ereport(PANIC,
3639 : : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
3640 : : errmsg("cannot PREPARE while holding both session-level and transaction-level locks on the same object")));
3641 : :
3642 : : /* Mark the proclock to show we need to release this lockmode */
3643 [ # # ]: 0 : if (locallock->nLocks > 0)
3644 : 0 : locallock->proclock->releaseMask |= LOCKBIT_ON(locallock->tag.mode);
3645 : :
3646 : : /* And remove the locallock hashtable entry */
3647 : 0 : RemoveLocalLock(locallock);
3648 [ # # ]: 0 : }
3649 : :
3650 : : /*
3651 : : * Now, scan each lock partition separately.
3652 : : */
3653 [ # # ]: 0 : for (partition = 0; partition < NUM_LOCK_PARTITIONS; partition++)
3654 : : {
3655 : 0 : LWLock *partitionLock;
3656 : 0 : dlist_head *procLocks = &(MyProc->myProcLocks[partition]);
3657 : 0 : dlist_mutable_iter proclock_iter;
3658 : :
3659 : 0 : partitionLock = LockHashPartitionLockByIndex(partition);
3660 : :
3661 : : /*
3662 : : * If the proclock list for this partition is empty, we can skip
3663 : : * acquiring the partition lock. This optimization is safer than the
3664 : : * situation in LockReleaseAll, because we got rid of any fast-path
3665 : : * locks during AtPrepare_Locks, so there cannot be any case where
3666 : : * another backend is adding something to our lists now. For safety,
3667 : : * though, we code this the same way as in LockReleaseAll.
3668 : : */
3669 [ # # ]: 0 : if (dlist_is_empty(procLocks))
3670 : 0 : continue; /* needn't examine this partition */
3671 : :
3672 : 0 : LWLockAcquire(partitionLock, LW_EXCLUSIVE);
3673 : :
3674 [ # # # # ]: 0 : dlist_foreach_modify(proclock_iter, procLocks)
3675 : : {
3676 : 0 : proclock = dlist_container(PROCLOCK, procLink, proclock_iter.cur);
3677 : :
3678 [ # # ]: 0 : Assert(proclock->tag.myProc == MyProc);
3679 : :
3680 : 0 : lock = proclock->tag.myLock;
3681 : :
3682 : : /* Ignore VXID locks */
3683 [ # # ]: 0 : if (lock->tag.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
3684 : 0 : continue;
3685 : :
3686 : : PROCLOCK_PRINT("PostPrepare_Locks", proclock);
3687 : : LOCK_PRINT("PostPrepare_Locks", lock, 0);
3688 [ # # ]: 0 : Assert(lock->nRequested >= 0);
3689 [ # # ]: 0 : Assert(lock->nGranted >= 0);
3690 [ # # ]: 0 : Assert(lock->nGranted <= lock->nRequested);
3691 [ # # ]: 0 : Assert((proclock->holdMask & ~lock->grantMask) == 0);
3692 : :
3693 : : /* Ignore it if nothing to release (must be a session lock) */
3694 [ # # ]: 0 : if (proclock->releaseMask == 0)
3695 : 0 : continue;
3696 : :
3697 : : /* Else we should be releasing all locks */
3698 [ # # ]: 0 : if (proclock->releaseMask != proclock->holdMask)
3699 [ # # # # ]: 0 : elog(PANIC, "we seem to have dropped a bit somewhere");
3700 : :
3701 : : /*
3702 : : * We cannot simply modify proclock->tag.myProc to reassign
3703 : : * ownership of the lock, because that's part of the hash key and
3704 : : * the proclock would then be in the wrong hash chain. Instead
3705 : : * use hash_update_hash_key. (We used to create a new hash entry,
3706 : : * but that risks out-of-memory failure if other processes are
3707 : : * busy making proclocks too.) We must unlink the proclock from
3708 : : * our procLink chain and put it into the new proc's chain, too.
3709 : : *
3710 : : * Note: the updated proclock hash key will still belong to the
3711 : : * same hash partition, cf proclock_hash(). So the partition lock
3712 : : * we already hold is sufficient for this.
3713 : : */
3714 : 0 : dlist_delete(&proclock->procLink);
3715 : :
3716 : : /*
3717 : : * Create the new hash key for the proclock.
3718 : : */
3719 : 0 : proclocktag.myLock = lock;
3720 : 0 : proclocktag.myProc = newproc;
3721 : :
3722 : : /*
3723 : : * Update groupLeader pointer to point to the new proc. (We'd
3724 : : * better not be a member of somebody else's lock group!)
3725 : : */
3726 [ # # ]: 0 : Assert(proclock->groupLeader == proclock->tag.myProc);
3727 : 0 : proclock->groupLeader = newproc;
3728 : :
3729 : : /*
3730 : : * Update the proclock. We should not find any existing entry for
3731 : : * the same hash key, since there can be only one entry for any
3732 : : * given lock with my own proc.
3733 : : */
3734 [ # # # # ]: 0 : if (!hash_update_hash_key(LockMethodProcLockHash,
3735 : 0 : proclock,
3736 : : &proclocktag))
3737 [ # # # # ]: 0 : elog(PANIC, "duplicate entry found while reassigning a prepared transaction's locks");
3738 : :
3739 : : /* Re-link into the new proc's proclock list */
3740 : 0 : dlist_push_tail(&newproc->myProcLocks[partition], &proclock->procLink);
3741 : :
3742 : : PROCLOCK_PRINT("PostPrepare_Locks: updated", proclock);
3743 : 0 : } /* loop over PROCLOCKs within this partition */
3744 : :
3745 : 0 : LWLockRelease(partitionLock);
3746 [ # # ]: 0 : } /* loop over partitions */
3747 : :
3748 [ # # ]: 0 : END_CRIT_SECTION();
3749 : 0 : }
3750 : :
3751 : :
3752 : : /*
3753 : : * Estimate shared-memory space used for lock tables
3754 : : */
3755 : : Size
3756 : 9 : LockManagerShmemSize(void)
3757 : : {
3758 : 9 : Size size = 0;
3759 : 9 : long max_table_size;
3760 : :
3761 : : /* lock hash table */
3762 : 9 : max_table_size = NLOCKENTS();
3763 : 9 : size = add_size(size, hash_estimate_size(max_table_size, sizeof(LOCK)));
3764 : :
3765 : : /* proclock hash table */
3766 : 9 : max_table_size *= 2;
3767 : 9 : size = add_size(size, hash_estimate_size(max_table_size, sizeof(PROCLOCK)));
3768 : :
3769 : : /*
3770 : : * Since NLOCKENTS is only an estimate, add 10% safety margin.
3771 : : */
3772 : 9 : size = add_size(size, size / 10);
3773 : :
3774 : 18 : return size;
3775 : 9 : }
3776 : :
3777 : : /*
3778 : : * GetLockStatusData - Return a summary of the lock manager's internal
3779 : : * status, for use in a user-level reporting function.
3780 : : *
3781 : : * The return data consists of an array of LockInstanceData objects,
3782 : : * which are a lightly abstracted version of the PROCLOCK data structures,
3783 : : * i.e. there is one entry for each unique lock and interested PGPROC.
3784 : : * It is the caller's responsibility to match up related items (such as
3785 : : * references to the same lockable object or PGPROC) if wanted.
3786 : : *
3787 : : * The design goal is to hold the LWLocks for as short a time as possible;
3788 : : * thus, this function simply makes a copy of the necessary data and releases
3789 : : * the locks, allowing the caller to contemplate and format the data for as
3790 : : * long as it pleases.
3791 : : */
3792 : : LockData *
3793 : 70 : GetLockStatusData(void)
3794 : : {
3795 : 70 : LockData *data;
3796 : 70 : PROCLOCK *proclock;
3797 : 70 : HASH_SEQ_STATUS seqstat;
3798 : 70 : int els;
3799 : 70 : int el;
3800 : 70 : int i;
3801 : :
3802 : 70 : data = palloc_object(LockData);
3803 : :
3804 : : /* Guess how much space we'll need. */
3805 : 70 : els = MaxBackends;
3806 : 70 : el = 0;
3807 : 70 : data->locks = palloc_array(LockInstanceData, els);
3808 : :
3809 : : /*
3810 : : * First, we iterate through the per-backend fast-path arrays, locking
3811 : : * them one at a time. This might produce an inconsistent picture of the
3812 : : * system state, but taking all of those LWLocks at the same time seems
3813 : : * impractical (in particular, note MAX_SIMUL_LWLOCKS). It shouldn't
3814 : : * matter too much, because none of these locks can be involved in lock
3815 : : * conflicts anyway - anything that might must be present in the main lock
3816 : : * table. (For the same reason, we don't sweat about making leaderPid
3817 : : * completely valid. We cannot safely dereference another backend's
3818 : : * lockGroupLeader field without holding all lock partition locks, and
3819 : : * it's not worth that.)
3820 : : */
3821 [ + + ]: 11550 : for (i = 0; i < ProcGlobal->allProcCount; ++i)
3822 : : {
3823 : 11480 : PGPROC *proc = GetPGProcByNumber(i);
3824 : :
3825 : : /* Skip backends with pid=0, as they don't hold fast-path locks */
3826 [ + + ]: 11480 : if (proc->pid == 0)
3827 : 10346 : continue;
3828 : :
3829 : 1134 : LWLockAcquire(&proc->fpInfoLock, LW_SHARED);
3830 : :
3831 [ + + ]: 5670 : for (uint32 g = 0; g < FastPathLockGroupsPerBackend; g++)
3832 : : {
3833 : : /* Skip groups without registered fast-path locks */
3834 [ + + ]: 4536 : if (proc->fpLockBits[g] == 0)
3835 : 3958 : continue;
3836 : :
3837 [ + + ]: 9826 : for (int j = 0; j < FP_LOCK_SLOTS_PER_GROUP; j++)
3838 : : {
3839 : 9248 : LockInstanceData *instance;
3840 [ + - - + ]: 9248 : uint32 f = FAST_PATH_SLOT(g, j);
3841 [ - + - + ]: 9248 : uint32 lockbits = FAST_PATH_GET_BITS(proc, f);
3842 : :
3843 : : /* Skip unallocated slots */
3844 [ + + ]: 9248 : if (!lockbits)
3845 : 8258 : continue;
3846 : :
3847 [ + - ]: 990 : if (el >= els)
3848 : : {
3849 : 0 : els += MaxBackends;
3850 : 0 : data->locks = (LockInstanceData *)
3851 : 0 : repalloc(data->locks, sizeof(LockInstanceData) * els);
3852 : 0 : }
3853 : :
3854 : 990 : instance = &data->locks[el];
3855 : 990 : SET_LOCKTAG_RELATION(instance->locktag, proc->databaseId,
3856 : : proc->fpRelId[f]);
3857 : 990 : instance->holdMask = lockbits << FAST_PATH_LOCKNUMBER_OFFSET;
3858 : 990 : instance->waitLockMode = NoLock;
3859 : 990 : instance->vxid.procNumber = proc->vxid.procNumber;
3860 : 990 : instance->vxid.localTransactionId = proc->vxid.lxid;
3861 : 990 : instance->pid = proc->pid;
3862 : 990 : instance->leaderPid = proc->pid;
3863 : 990 : instance->fastpath = true;
3864 : :
3865 : : /*
3866 : : * Successfully taking fast path lock means there were no
3867 : : * conflicting locks.
3868 : : */
3869 : 990 : instance->waitStart = 0;
3870 : :
3871 : 990 : el++;
3872 [ + + ]: 9248 : }
3873 : 578 : }
3874 : :
3875 [ + + ]: 1134 : if (proc->fpVXIDLock)
3876 : : {
3877 : 336 : VirtualTransactionId vxid;
3878 : 336 : LockInstanceData *instance;
3879 : :
3880 [ + - ]: 336 : if (el >= els)
3881 : : {
3882 : 0 : els += MaxBackends;
3883 : 0 : data->locks = (LockInstanceData *)
3884 : 0 : repalloc(data->locks, sizeof(LockInstanceData) * els);
3885 : 0 : }
3886 : :
3887 : 336 : vxid.procNumber = proc->vxid.procNumber;
3888 : 336 : vxid.localTransactionId = proc->fpLocalTransactionId;
3889 : :
3890 : 336 : instance = &data->locks[el];
3891 : 336 : SET_LOCKTAG_VIRTUALTRANSACTION(instance->locktag, vxid);
3892 : 336 : instance->holdMask = LOCKBIT_ON(ExclusiveLock);
3893 : 336 : instance->waitLockMode = NoLock;
3894 : 336 : instance->vxid.procNumber = proc->vxid.procNumber;
3895 : 336 : instance->vxid.localTransactionId = proc->vxid.lxid;
3896 : 336 : instance->pid = proc->pid;
3897 : 336 : instance->leaderPid = proc->pid;
3898 : 336 : instance->fastpath = true;
3899 : 336 : instance->waitStart = 0;
3900 : :
3901 : 336 : el++;
3902 : 336 : }
3903 : :
3904 : 1134 : LWLockRelease(&proc->fpInfoLock);
3905 [ + + ]: 11480 : }
3906 : :
3907 : : /*
3908 : : * Next, acquire lock on the entire shared lock data structure. We do
3909 : : * this so that, at least for locks in the primary lock table, the state
3910 : : * will be self-consistent.
3911 : : *
3912 : : * Since this is a read-only operation, we take shared instead of
3913 : : * exclusive lock. There's not a whole lot of point to this, because all
3914 : : * the normal operations require exclusive lock, but it doesn't hurt
3915 : : * anything either. It will at least allow two backends to do
3916 : : * GetLockStatusData in parallel.
3917 : : *
3918 : : * Must grab LWLocks in partition-number order to avoid LWLock deadlock.
3919 : : */
3920 [ + + ]: 1190 : for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
3921 : 1120 : LWLockAcquire(LockHashPartitionLockByIndex(i), LW_SHARED);
3922 : :
3923 : : /* Now we can safely count the number of proclocks */
3924 : 70 : data->nelements = el + hash_get_num_entries(LockMethodProcLockHash);
3925 [ + - ]: 70 : if (data->nelements > els)
3926 : : {
3927 : 0 : els = data->nelements;
3928 : 0 : data->locks = (LockInstanceData *)
3929 : 0 : repalloc(data->locks, sizeof(LockInstanceData) * els);
3930 : 0 : }
3931 : :
3932 : : /* Now scan the tables to copy the data */
3933 : 70 : hash_seq_init(&seqstat, LockMethodProcLockHash);
3934 : :
3935 [ + + ]: 672 : while ((proclock = (PROCLOCK *) hash_seq_search(&seqstat)))
3936 : : {
3937 : 602 : PGPROC *proc = proclock->tag.myProc;
3938 : 602 : LOCK *lock = proclock->tag.myLock;
3939 : 602 : LockInstanceData *instance = &data->locks[el];
3940 : :
3941 : 602 : memcpy(&instance->locktag, &lock->tag, sizeof(LOCKTAG));
3942 : 602 : instance->holdMask = proclock->holdMask;
3943 [ + + ]: 602 : if (proc->waitLock == proclock->tag.myLock)
3944 : 2 : instance->waitLockMode = proc->waitLockMode;
3945 : : else
3946 : 600 : instance->waitLockMode = NoLock;
3947 : 602 : instance->vxid.procNumber = proc->vxid.procNumber;
3948 : 602 : instance->vxid.localTransactionId = proc->vxid.lxid;
3949 : 602 : instance->pid = proc->pid;
3950 : 602 : instance->leaderPid = proclock->groupLeader->pid;
3951 : 602 : instance->fastpath = false;
3952 : 602 : instance->waitStart = (TimestampTz) pg_atomic_read_u64(&proc->waitStart);
3953 : :
3954 : 602 : el++;
3955 : 602 : }
3956 : :
3957 : : /*
3958 : : * And release locks. We do this in reverse order for two reasons: (1)
3959 : : * Anyone else who needs more than one of the locks will be trying to lock
3960 : : * them in increasing order; we don't want to release the other process
3961 : : * until it can get all the locks it needs. (2) This avoids O(N^2)
3962 : : * behavior inside LWLockRelease.
3963 : : */
3964 [ + + ]: 1190 : for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
3965 : 1120 : LWLockRelease(LockHashPartitionLockByIndex(i));
3966 : :
3967 [ + - ]: 70 : Assert(el == data->nelements);
3968 : :
3969 : 140 : return data;
3970 : 70 : }
3971 : :
3972 : : /*
3973 : : * GetBlockerStatusData - Return a summary of the lock manager's state
3974 : : * concerning locks that are blocking the specified PID or any member of
3975 : : * the PID's lock group, for use in a user-level reporting function.
3976 : : *
3977 : : * For each PID within the lock group that is awaiting some heavyweight lock,
3978 : : * the return data includes an array of LockInstanceData objects, which are
3979 : : * the same data structure used by GetLockStatusData; but unlike that function,
3980 : : * this one reports only the PROCLOCKs associated with the lock that that PID
3981 : : * is blocked on. (Hence, all the locktags should be the same for any one
3982 : : * blocked PID.) In addition, we return an array of the PIDs of those backends
3983 : : * that are ahead of the blocked PID in the lock's wait queue. These can be
3984 : : * compared with the PIDs in the LockInstanceData objects to determine which
3985 : : * waiters are ahead of or behind the blocked PID in the queue.
3986 : : *
3987 : : * If blocked_pid isn't a valid backend PID or nothing in its lock group is
3988 : : * waiting on any heavyweight lock, return empty arrays.
3989 : : *
3990 : : * The design goal is to hold the LWLocks for as short a time as possible;
3991 : : * thus, this function simply makes a copy of the necessary data and releases
3992 : : * the locks, allowing the caller to contemplate and format the data for as
3993 : : * long as it pleases.
3994 : : */
3995 : : BlockedProcsData *
3996 : 0 : GetBlockerStatusData(int blocked_pid)
3997 : : {
3998 : 0 : BlockedProcsData *data;
3999 : 0 : PGPROC *proc;
4000 : 0 : int i;
4001 : :
4002 : 0 : data = palloc_object(BlockedProcsData);
4003 : :
4004 : : /*
4005 : : * Guess how much space we'll need, and preallocate. Most of the time
4006 : : * this will avoid needing to do repalloc while holding the LWLocks. (We
4007 : : * assume, but check with an Assert, that MaxBackends is enough entries
4008 : : * for the procs[] array; the other two could need enlargement, though.)
4009 : : */
4010 : 0 : data->nprocs = data->nlocks = data->npids = 0;
4011 : 0 : data->maxprocs = data->maxlocks = data->maxpids = MaxBackends;
4012 : 0 : data->procs = palloc_array(BlockedProcData, data->maxprocs);
4013 : 0 : data->locks = palloc_array(LockInstanceData, data->maxlocks);
4014 : 0 : data->waiter_pids = palloc_array(int, data->maxpids);
4015 : :
4016 : : /*
4017 : : * In order to search the ProcArray for blocked_pid and assume that that
4018 : : * entry won't immediately disappear under us, we must hold ProcArrayLock.
4019 : : * In addition, to examine the lock grouping fields of any other backend,
4020 : : * we must hold all the hash partition locks. (Only one of those locks is
4021 : : * actually relevant for any one lock group, but we can't know which one
4022 : : * ahead of time.) It's fairly annoying to hold all those locks
4023 : : * throughout this, but it's no worse than GetLockStatusData(), and it
4024 : : * does have the advantage that we're guaranteed to return a
4025 : : * self-consistent instantaneous state.
4026 : : */
4027 : 0 : LWLockAcquire(ProcArrayLock, LW_SHARED);
4028 : :
4029 : 0 : proc = BackendPidGetProcWithLock(blocked_pid);
4030 : :
4031 : : /* Nothing to do if it's gone */
4032 [ # # ]: 0 : if (proc != NULL)
4033 : : {
4034 : : /*
4035 : : * Acquire lock on the entire shared lock data structure. See notes
4036 : : * in GetLockStatusData().
4037 : : */
4038 [ # # ]: 0 : for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
4039 : 0 : LWLockAcquire(LockHashPartitionLockByIndex(i), LW_SHARED);
4040 : :
4041 [ # # ]: 0 : if (proc->lockGroupLeader == NULL)
4042 : : {
4043 : : /* Easy case, proc is not a lock group member */
4044 : 0 : GetSingleProcBlockerStatusData(proc, data);
4045 : 0 : }
4046 : : else
4047 : : {
4048 : : /* Examine all procs in proc's lock group */
4049 : 0 : dlist_iter iter;
4050 : :
4051 [ # # # # ]: 0 : dlist_foreach(iter, &proc->lockGroupLeader->lockGroupMembers)
4052 : : {
4053 : 0 : PGPROC *memberProc;
4054 : :
4055 : 0 : memberProc = dlist_container(PGPROC, lockGroupLink, iter.cur);
4056 : 0 : GetSingleProcBlockerStatusData(memberProc, data);
4057 : 0 : }
4058 : 0 : }
4059 : :
4060 : : /*
4061 : : * And release locks. See notes in GetLockStatusData().
4062 : : */
4063 [ # # ]: 0 : for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
4064 : 0 : LWLockRelease(LockHashPartitionLockByIndex(i));
4065 : :
4066 [ # # ]: 0 : Assert(data->nprocs <= data->maxprocs);
4067 : 0 : }
4068 : :
4069 : 0 : LWLockRelease(ProcArrayLock);
4070 : :
4071 : 0 : return data;
4072 : 0 : }
4073 : :
4074 : : /* Accumulate data about one possibly-blocked proc for GetBlockerStatusData */
4075 : : static void
4076 : 0 : GetSingleProcBlockerStatusData(PGPROC *blocked_proc, BlockedProcsData *data)
4077 : : {
4078 : 0 : LOCK *theLock = blocked_proc->waitLock;
4079 : 0 : BlockedProcData *bproc;
4080 : 0 : dlist_iter proclock_iter;
4081 : 0 : dlist_iter proc_iter;
4082 : 0 : dclist_head *waitQueue;
4083 : 0 : int queue_size;
4084 : :
4085 : : /* Nothing to do if this proc is not blocked */
4086 [ # # ]: 0 : if (theLock == NULL)
4087 : 0 : return;
4088 : :
4089 : : /* Set up a procs[] element */
4090 : 0 : bproc = &data->procs[data->nprocs++];
4091 : 0 : bproc->pid = blocked_proc->pid;
4092 : 0 : bproc->first_lock = data->nlocks;
4093 : 0 : bproc->first_waiter = data->npids;
4094 : :
4095 : : /*
4096 : : * We may ignore the proc's fast-path arrays, since nothing in those could
4097 : : * be related to a contended lock.
4098 : : */
4099 : :
4100 : : /* Collect all PROCLOCKs associated with theLock */
4101 [ # # # # ]: 0 : dlist_foreach(proclock_iter, &theLock->procLocks)
4102 : : {
4103 : 0 : PROCLOCK *proclock =
4104 : 0 : dlist_container(PROCLOCK, lockLink, proclock_iter.cur);
4105 : 0 : PGPROC *proc = proclock->tag.myProc;
4106 : 0 : LOCK *lock = proclock->tag.myLock;
4107 : 0 : LockInstanceData *instance;
4108 : :
4109 [ # # ]: 0 : if (data->nlocks >= data->maxlocks)
4110 : : {
4111 : 0 : data->maxlocks += MaxBackends;
4112 : 0 : data->locks = (LockInstanceData *)
4113 : 0 : repalloc(data->locks, sizeof(LockInstanceData) * data->maxlocks);
4114 : 0 : }
4115 : :
4116 : 0 : instance = &data->locks[data->nlocks];
4117 : 0 : memcpy(&instance->locktag, &lock->tag, sizeof(LOCKTAG));
4118 : 0 : instance->holdMask = proclock->holdMask;
4119 [ # # ]: 0 : if (proc->waitLock == lock)
4120 : 0 : instance->waitLockMode = proc->waitLockMode;
4121 : : else
4122 : 0 : instance->waitLockMode = NoLock;
4123 : 0 : instance->vxid.procNumber = proc->vxid.procNumber;
4124 : 0 : instance->vxid.localTransactionId = proc->vxid.lxid;
4125 : 0 : instance->pid = proc->pid;
4126 : 0 : instance->leaderPid = proclock->groupLeader->pid;
4127 : 0 : instance->fastpath = false;
4128 : 0 : data->nlocks++;
4129 : 0 : }
4130 : :
4131 : : /* Enlarge waiter_pids[] if it's too small to hold all wait queue PIDs */
4132 : 0 : waitQueue = &(theLock->waitProcs);
4133 : 0 : queue_size = dclist_count(waitQueue);
4134 : :
4135 [ # # ]: 0 : if (queue_size > data->maxpids - data->npids)
4136 : : {
4137 [ # # ]: 0 : data->maxpids = Max(data->maxpids + MaxBackends,
4138 : : data->npids + queue_size);
4139 : 0 : data->waiter_pids = (int *) repalloc(data->waiter_pids,
4140 : 0 : sizeof(int) * data->maxpids);
4141 : 0 : }
4142 : :
4143 : : /* Collect PIDs from the lock's wait queue, stopping at blocked_proc */
4144 [ # # # # ]: 0 : dclist_foreach(proc_iter, waitQueue)
4145 : : {
4146 : 0 : PGPROC *queued_proc = dlist_container(PGPROC, links, proc_iter.cur);
4147 : :
4148 [ # # ]: 0 : if (queued_proc == blocked_proc)
4149 : 0 : break;
4150 : 0 : data->waiter_pids[data->npids++] = queued_proc->pid;
4151 : 0 : queued_proc = (PGPROC *) queued_proc->links.next;
4152 [ # # ]: 0 : }
4153 : :
4154 : 0 : bproc->num_locks = data->nlocks - bproc->first_lock;
4155 : 0 : bproc->num_waiters = data->npids - bproc->first_waiter;
4156 : 0 : }
4157 : :
4158 : : /*
4159 : : * Returns a list of currently held AccessExclusiveLocks, for use by
4160 : : * LogStandbySnapshot(). The result is a palloc'd array,
4161 : : * with the number of elements returned into *nlocks.
4162 : : *
4163 : : * XXX This currently takes a lock on all partitions of the lock table,
4164 : : * but it's possible to do better. By reference counting locks and storing
4165 : : * the value in the ProcArray entry for each backend we could tell if any
4166 : : * locks need recording without having to acquire the partition locks and
4167 : : * scan the lock table. Whether that's worth the additional overhead
4168 : : * is pretty dubious though.
4169 : : */
4170 : : xl_standby_lock *
4171 : 4 : GetRunningTransactionLocks(int *nlocks)
4172 : : {
4173 : 4 : xl_standby_lock *accessExclusiveLocks;
4174 : 4 : PROCLOCK *proclock;
4175 : 4 : HASH_SEQ_STATUS seqstat;
4176 : 4 : int i;
4177 : 4 : int index;
4178 : 4 : int els;
4179 : :
4180 : : /*
4181 : : * Acquire lock on the entire shared lock data structure.
4182 : : *
4183 : : * Must grab LWLocks in partition-number order to avoid LWLock deadlock.
4184 : : */
4185 [ + + ]: 68 : for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
4186 : 64 : LWLockAcquire(LockHashPartitionLockByIndex(i), LW_SHARED);
4187 : :
4188 : : /* Now we can safely count the number of proclocks */
4189 : 4 : els = hash_get_num_entries(LockMethodProcLockHash);
4190 : :
4191 : : /*
4192 : : * Allocating enough space for all locks in the lock table is overkill,
4193 : : * but it's more convenient and faster than having to enlarge the array.
4194 : : */
4195 : 4 : accessExclusiveLocks = palloc(els * sizeof(xl_standby_lock));
4196 : :
4197 : : /* Now scan the tables to copy the data */
4198 : 4 : hash_seq_init(&seqstat, LockMethodProcLockHash);
4199 : :
4200 : : /*
4201 : : * If lock is a currently granted AccessExclusiveLock then it will have
4202 : : * just one proclock holder, so locks are never accessed twice in this
4203 : : * particular case. Don't copy this code for use elsewhere because in the
4204 : : * general case this will give you duplicate locks when looking at
4205 : : * non-exclusive lock types.
4206 : : */
4207 : 4 : index = 0;
4208 [ + + ]: 16 : while ((proclock = (PROCLOCK *) hash_seq_search(&seqstat)))
4209 : : {
4210 : : /* make sure this definition matches the one used in LockAcquire */
4211 [ - + # # ]: 12 : if ((proclock->holdMask & LOCKBIT_ON(AccessExclusiveLock)) &&
4212 : 0 : proclock->tag.myLock->tag.locktag_type == LOCKTAG_RELATION)
4213 : : {
4214 : 0 : PGPROC *proc = proclock->tag.myProc;
4215 : 0 : LOCK *lock = proclock->tag.myLock;
4216 : 0 : TransactionId xid = proc->xid;
4217 : :
4218 : : /*
4219 : : * Don't record locks for transactions if we know they have
4220 : : * already issued their WAL record for commit but not yet released
4221 : : * lock. It is still possible that we see locks held by already
4222 : : * complete transactions, if they haven't yet zeroed their xids.
4223 : : */
4224 [ # # ]: 0 : if (!TransactionIdIsValid(xid))
4225 : 0 : continue;
4226 : :
4227 : 0 : accessExclusiveLocks[index].xid = xid;
4228 : 0 : accessExclusiveLocks[index].dbOid = lock->tag.locktag_field1;
4229 : 0 : accessExclusiveLocks[index].relOid = lock->tag.locktag_field2;
4230 : :
4231 : 0 : index++;
4232 [ # # # ]: 0 : }
4233 : : }
4234 : :
4235 [ + - ]: 4 : Assert(index <= els);
4236 : :
4237 : : /*
4238 : : * And release locks. We do this in reverse order for two reasons: (1)
4239 : : * Anyone else who needs more than one of the locks will be trying to lock
4240 : : * them in increasing order; we don't want to release the other process
4241 : : * until it can get all the locks it needs. (2) This avoids O(N^2)
4242 : : * behavior inside LWLockRelease.
4243 : : */
4244 [ + + ]: 68 : for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
4245 : 64 : LWLockRelease(LockHashPartitionLockByIndex(i));
4246 : :
4247 : 4 : *nlocks = index;
4248 : 8 : return accessExclusiveLocks;
4249 : 4 : }
4250 : :
4251 : : /* Provide the textual name of any lock mode */
4252 : : const char *
4253 : 2031 : GetLockmodeName(LOCKMETHODID lockmethodid, LOCKMODE mode)
4254 : : {
4255 [ + - ]: 2031 : Assert(lockmethodid > 0 && lockmethodid < lengthof(LockMethods));
4256 [ + - ]: 2031 : Assert(mode > 0 && mode <= LockMethods[lockmethodid]->numLockModes);
4257 : 2031 : return LockMethods[lockmethodid]->lockModeNames[mode];
4258 : : }
4259 : :
4260 : : #ifdef LOCK_DEBUG
4261 : : /*
4262 : : * Dump all locks in the given proc's myProcLocks lists.
4263 : : *
4264 : : * Caller is responsible for having acquired appropriate LWLocks.
4265 : : */
4266 : : void
4267 : : DumpLocks(PGPROC *proc)
4268 : : {
4269 : : int i;
4270 : :
4271 : : if (proc == NULL)
4272 : : return;
4273 : :
4274 : : if (proc->waitLock)
4275 : : LOCK_PRINT("DumpLocks: waiting on", proc->waitLock, 0);
4276 : :
4277 : : for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
4278 : : {
4279 : : dlist_head *procLocks = &proc->myProcLocks[i];
4280 : : dlist_iter iter;
4281 : :
4282 : : dlist_foreach(iter, procLocks)
4283 : : {
4284 : : PROCLOCK *proclock = dlist_container(PROCLOCK, procLink, iter.cur);
4285 : : LOCK *lock = proclock->tag.myLock;
4286 : :
4287 : : Assert(proclock->tag.myProc == proc);
4288 : : PROCLOCK_PRINT("DumpLocks", proclock);
4289 : : LOCK_PRINT("DumpLocks", lock, 0);
4290 : : }
4291 : : }
4292 : : }
4293 : :
4294 : : /*
4295 : : * Dump all lmgr locks.
4296 : : *
4297 : : * Caller is responsible for having acquired appropriate LWLocks.
4298 : : */
4299 : : void
4300 : : DumpAllLocks(void)
4301 : : {
4302 : : PGPROC *proc;
4303 : : PROCLOCK *proclock;
4304 : : LOCK *lock;
4305 : : HASH_SEQ_STATUS status;
4306 : :
4307 : : proc = MyProc;
4308 : :
4309 : : if (proc && proc->waitLock)
4310 : : LOCK_PRINT("DumpAllLocks: waiting on", proc->waitLock, 0);
4311 : :
4312 : : hash_seq_init(&status, LockMethodProcLockHash);
4313 : :
4314 : : while ((proclock = (PROCLOCK *) hash_seq_search(&status)) != NULL)
4315 : : {
4316 : : PROCLOCK_PRINT("DumpAllLocks", proclock);
4317 : :
4318 : : lock = proclock->tag.myLock;
4319 : : if (lock)
4320 : : LOCK_PRINT("DumpAllLocks", lock, 0);
4321 : : else
4322 : : elog(LOG, "DumpAllLocks: proclock->tag.myLock = NULL");
4323 : : }
4324 : : }
4325 : : #endif /* LOCK_DEBUG */
4326 : :
4327 : : /*
4328 : : * LOCK 2PC resource manager's routines
4329 : : */
4330 : :
4331 : : /*
4332 : : * Re-acquire a lock belonging to a transaction that was prepared.
4333 : : *
4334 : : * Because this function is run at db startup, re-acquiring the locks should
4335 : : * never conflict with running transactions because there are none. We
4336 : : * assume that the lock state represented by the stored 2PC files is legal.
4337 : : *
4338 : : * When switching from Hot Standby mode to normal operation, the locks will
4339 : : * be already held by the startup process. The locks are acquired for the new
4340 : : * procs without checking for conflicts, so we don't get a conflict between the
4341 : : * startup process and the dummy procs, even though we will momentarily have
4342 : : * a situation where two procs are holding the same AccessExclusiveLock,
4343 : : * which isn't normally possible because the conflict. If we're in standby
4344 : : * mode, but a recovery snapshot hasn't been established yet, it's possible
4345 : : * that some but not all of the locks are already held by the startup process.
4346 : : *
4347 : : * This approach is simple, but also a bit dangerous, because if there isn't
4348 : : * enough shared memory to acquire the locks, an error will be thrown, which
4349 : : * is promoted to FATAL and recovery will abort, bringing down postmaster.
4350 : : * A safer approach would be to transfer the locks like we do in
4351 : : * AtPrepare_Locks, but then again, in hot standby mode it's possible for
4352 : : * read-only backends to use up all the shared lock memory anyway, so that
4353 : : * replaying the WAL record that needs to acquire a lock will throw an error
4354 : : * and PANIC anyway.
4355 : : */
4356 : : void
4357 : 0 : lock_twophase_recover(FullTransactionId fxid, uint16 info,
4358 : : void *recdata, uint32 len)
4359 : : {
4360 : 0 : TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
4361 : 0 : PGPROC *proc = TwoPhaseGetDummyProc(fxid, false);
4362 : 0 : LOCKTAG *locktag;
4363 : 0 : LOCKMODE lockmode;
4364 : 0 : LOCKMETHODID lockmethodid;
4365 : 0 : LOCK *lock;
4366 : 0 : PROCLOCK *proclock;
4367 : 0 : PROCLOCKTAG proclocktag;
4368 : 0 : bool found;
4369 : 0 : uint32 hashcode;
4370 : 0 : uint32 proclock_hashcode;
4371 : 0 : int partition;
4372 : 0 : LWLock *partitionLock;
4373 : 0 : LockMethod lockMethodTable;
4374 : :
4375 [ # # ]: 0 : Assert(len == sizeof(TwoPhaseLockRecord));
4376 : 0 : locktag = &rec->locktag;
4377 : 0 : lockmode = rec->lockmode;
4378 : 0 : lockmethodid = locktag->locktag_lockmethodid;
4379 : :
4380 [ # # ]: 0 : if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
4381 [ # # # # ]: 0 : elog(ERROR, "unrecognized lock method: %d", lockmethodid);
4382 : 0 : lockMethodTable = LockMethods[lockmethodid];
4383 : :
4384 : 0 : hashcode = LockTagHashCode(locktag);
4385 : 0 : partition = LockHashPartition(hashcode);
4386 : 0 : partitionLock = LockHashPartitionLock(hashcode);
4387 : :
4388 : 0 : LWLockAcquire(partitionLock, LW_EXCLUSIVE);
4389 : :
4390 : : /*
4391 : : * Find or create a lock with this tag.
4392 : : */
4393 : 0 : lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
4394 : 0 : locktag,
4395 : 0 : hashcode,
4396 : : HASH_ENTER_NULL,
4397 : : &found);
4398 [ # # ]: 0 : if (!lock)
4399 : : {
4400 : 0 : LWLockRelease(partitionLock);
4401 [ # # # # ]: 0 : ereport(ERROR,
4402 : : (errcode(ERRCODE_OUT_OF_MEMORY),
4403 : : errmsg("out of shared memory"),
4404 : : errhint("You might need to increase \"%s\".", "max_locks_per_transaction")));
4405 : 0 : }
4406 : :
4407 : : /*
4408 : : * if it's a new lock object, initialize it
4409 : : */
4410 [ # # ]: 0 : if (!found)
4411 : : {
4412 : 0 : lock->grantMask = 0;
4413 : 0 : lock->waitMask = 0;
4414 : 0 : dlist_init(&lock->procLocks);
4415 : 0 : dclist_init(&lock->waitProcs);
4416 : 0 : lock->nRequested = 0;
4417 : 0 : lock->nGranted = 0;
4418 [ # # # # : 0 : MemSet(lock->requested, 0, sizeof(int) * MAX_LOCKMODES);
# # # # #
# ]
4419 [ # # # # : 0 : MemSet(lock->granted, 0, sizeof(int) * MAX_LOCKMODES);
# # # # #
# ]
4420 : : LOCK_PRINT("lock_twophase_recover: new", lock, lockmode);
4421 : 0 : }
4422 : : else
4423 : : {
4424 : : LOCK_PRINT("lock_twophase_recover: found", lock, lockmode);
4425 [ # # ]: 0 : Assert((lock->nRequested >= 0) && (lock->requested[lockmode] >= 0));
4426 [ # # ]: 0 : Assert((lock->nGranted >= 0) && (lock->granted[lockmode] >= 0));
4427 [ # # ]: 0 : Assert(lock->nGranted <= lock->nRequested);
4428 : : }
4429 : :
4430 : : /*
4431 : : * Create the hash key for the proclock table.
4432 : : */
4433 : 0 : proclocktag.myLock = lock;
4434 : 0 : proclocktag.myProc = proc;
4435 : :
4436 : 0 : proclock_hashcode = ProcLockHashCode(&proclocktag, hashcode);
4437 : :
4438 : : /*
4439 : : * Find or create a proclock entry with this tag
4440 : : */
4441 : 0 : proclock = (PROCLOCK *) hash_search_with_hash_value(LockMethodProcLockHash,
4442 : : &proclocktag,
4443 : 0 : proclock_hashcode,
4444 : : HASH_ENTER_NULL,
4445 : : &found);
4446 [ # # ]: 0 : if (!proclock)
4447 : : {
4448 : : /* Oops, not enough shmem for the proclock */
4449 [ # # ]: 0 : if (lock->nRequested == 0)
4450 : : {
4451 : : /*
4452 : : * There are no other requestors of this lock, so garbage-collect
4453 : : * the lock object. We *must* do this to avoid a permanent leak
4454 : : * of shared memory, because there won't be anything to cause
4455 : : * anyone to release the lock object later.
4456 : : */
4457 [ # # ]: 0 : Assert(dlist_is_empty(&lock->procLocks));
4458 [ # # # # ]: 0 : if (!hash_search_with_hash_value(LockMethodLockHash,
4459 : 0 : &(lock->tag),
4460 : 0 : hashcode,
4461 : : HASH_REMOVE,
4462 : : NULL))
4463 [ # # # # ]: 0 : elog(PANIC, "lock table corrupted");
4464 : 0 : }
4465 : 0 : LWLockRelease(partitionLock);
4466 [ # # # # ]: 0 : ereport(ERROR,
4467 : : (errcode(ERRCODE_OUT_OF_MEMORY),
4468 : : errmsg("out of shared memory"),
4469 : : errhint("You might need to increase \"%s\".", "max_locks_per_transaction")));
4470 : 0 : }
4471 : :
4472 : : /*
4473 : : * If new, initialize the new entry
4474 : : */
4475 [ # # ]: 0 : if (!found)
4476 : : {
4477 [ # # ]: 0 : Assert(proc->lockGroupLeader == NULL);
4478 : 0 : proclock->groupLeader = proc;
4479 : 0 : proclock->holdMask = 0;
4480 : 0 : proclock->releaseMask = 0;
4481 : : /* Add proclock to appropriate lists */
4482 : 0 : dlist_push_tail(&lock->procLocks, &proclock->lockLink);
4483 : 0 : dlist_push_tail(&proc->myProcLocks[partition],
4484 : 0 : &proclock->procLink);
4485 : : PROCLOCK_PRINT("lock_twophase_recover: new", proclock);
4486 : 0 : }
4487 : : else
4488 : : {
4489 : : PROCLOCK_PRINT("lock_twophase_recover: found", proclock);
4490 [ # # ]: 0 : Assert((proclock->holdMask & ~lock->grantMask) == 0);
4491 : : }
4492 : :
4493 : : /*
4494 : : * lock->nRequested and lock->requested[] count the total number of
4495 : : * requests, whether granted or waiting, so increment those immediately.
4496 : : */
4497 : 0 : lock->nRequested++;
4498 : 0 : lock->requested[lockmode]++;
4499 [ # # ]: 0 : Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
4500 : :
4501 : : /*
4502 : : * We shouldn't already hold the desired lock.
4503 : : */
4504 [ # # ]: 0 : if (proclock->holdMask & LOCKBIT_ON(lockmode))
4505 [ # # # # ]: 0 : elog(ERROR, "lock %s on object %u/%u/%u is already held",
4506 : : lockMethodTable->lockModeNames[lockmode],
4507 : : lock->tag.locktag_field1, lock->tag.locktag_field2,
4508 : : lock->tag.locktag_field3);
4509 : :
4510 : : /*
4511 : : * We ignore any possible conflicts and just grant ourselves the lock. Not
4512 : : * only because we don't bother, but also to avoid deadlocks when
4513 : : * switching from standby to normal mode. See function comment.
4514 : : */
4515 : 0 : GrantLock(lock, proclock, lockmode);
4516 : :
4517 : : /*
4518 : : * Bump strong lock count, to make sure any fast-path lock requests won't
4519 : : * be granted without consulting the primary lock table.
4520 : : */
4521 [ # # # # : 0 : if (ConflictsWithRelationFastPath(&lock->tag, lockmode))
# # # # ]
4522 : : {
4523 : 0 : uint32 fasthashcode = FastPathStrongLockHashPartition(hashcode);
4524 : :
4525 [ # # ]: 0 : SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
4526 : 0 : FastPathStrongRelationLocks->count[fasthashcode]++;
4527 : 0 : SpinLockRelease(&FastPathStrongRelationLocks->mutex);
4528 : 0 : }
4529 : :
4530 : 0 : LWLockRelease(partitionLock);
4531 : 0 : }
4532 : :
4533 : : /*
4534 : : * Re-acquire a lock belonging to a transaction that was prepared, when
4535 : : * starting up into hot standby mode.
4536 : : */
4537 : : void
4538 : 0 : lock_twophase_standby_recover(FullTransactionId fxid, uint16 info,
4539 : : void *recdata, uint32 len)
4540 : : {
4541 : 0 : TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
4542 : 0 : LOCKTAG *locktag;
4543 : 0 : LOCKMODE lockmode;
4544 : 0 : LOCKMETHODID lockmethodid;
4545 : :
4546 [ # # ]: 0 : Assert(len == sizeof(TwoPhaseLockRecord));
4547 : 0 : locktag = &rec->locktag;
4548 : 0 : lockmode = rec->lockmode;
4549 : 0 : lockmethodid = locktag->locktag_lockmethodid;
4550 : :
4551 [ # # ]: 0 : if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
4552 [ # # # # ]: 0 : elog(ERROR, "unrecognized lock method: %d", lockmethodid);
4553 : :
4554 [ # # # # ]: 0 : if (lockmode == AccessExclusiveLock &&
4555 : 0 : locktag->locktag_type == LOCKTAG_RELATION)
4556 : : {
4557 : 0 : StandbyAcquireAccessExclusiveLock(XidFromFullTransactionId(fxid),
4558 : 0 : locktag->locktag_field1 /* dboid */ ,
4559 : 0 : locktag->locktag_field2 /* reloid */ );
4560 : 0 : }
4561 : 0 : }
4562 : :
4563 : :
4564 : : /*
4565 : : * 2PC processing routine for COMMIT PREPARED case.
4566 : : *
4567 : : * Find and release the lock indicated by the 2PC record.
4568 : : */
4569 : : void
4570 : 0 : lock_twophase_postcommit(FullTransactionId fxid, uint16 info,
4571 : : void *recdata, uint32 len)
4572 : : {
4573 : 0 : TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
4574 : 0 : PGPROC *proc = TwoPhaseGetDummyProc(fxid, true);
4575 : 0 : LOCKTAG *locktag;
4576 : 0 : LOCKMETHODID lockmethodid;
4577 : 0 : LockMethod lockMethodTable;
4578 : :
4579 [ # # ]: 0 : Assert(len == sizeof(TwoPhaseLockRecord));
4580 : 0 : locktag = &rec->locktag;
4581 : 0 : lockmethodid = locktag->locktag_lockmethodid;
4582 : :
4583 [ # # ]: 0 : if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
4584 [ # # # # ]: 0 : elog(ERROR, "unrecognized lock method: %d", lockmethodid);
4585 : 0 : lockMethodTable = LockMethods[lockmethodid];
4586 : :
4587 : 0 : LockRefindAndRelease(lockMethodTable, proc, locktag, rec->lockmode, true);
4588 : 0 : }
4589 : :
4590 : : /*
4591 : : * 2PC processing routine for ROLLBACK PREPARED case.
4592 : : *
4593 : : * This is actually just the same as the COMMIT case.
4594 : : */
4595 : : void
4596 : 0 : lock_twophase_postabort(FullTransactionId fxid, uint16 info,
4597 : : void *recdata, uint32 len)
4598 : : {
4599 : 0 : lock_twophase_postcommit(fxid, info, recdata, len);
4600 : 0 : }
4601 : :
4602 : : /*
4603 : : * VirtualXactLockTableInsert
4604 : : *
4605 : : * Take vxid lock via the fast-path. There can't be any pre-existing
4606 : : * lockers, as we haven't advertised this vxid via the ProcArray yet.
4607 : : *
4608 : : * Since MyProc->fpLocalTransactionId will normally contain the same data
4609 : : * as MyProc->vxid.lxid, you might wonder if we really need both. The
4610 : : * difference is that MyProc->vxid.lxid is set and cleared unlocked, and
4611 : : * examined by procarray.c, while fpLocalTransactionId is protected by
4612 : : * fpInfoLock and is used only by the locking subsystem. Doing it this
4613 : : * way makes it easier to verify that there are no funny race conditions.
4614 : : *
4615 : : * We don't bother recording this lock in the local lock table, since it's
4616 : : * only ever released at the end of a transaction. Instead,
4617 : : * LockReleaseAll() calls VirtualXactLockTableCleanup().
4618 : : */
4619 : : void
4620 : 57914 : VirtualXactLockTableInsert(VirtualTransactionId vxid)
4621 : : {
4622 [ + - ]: 57914 : Assert(VirtualTransactionIdIsValid(vxid));
4623 : :
4624 : 57914 : LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
4625 : :
4626 [ + - ]: 57914 : Assert(MyProc->vxid.procNumber == vxid.procNumber);
4627 [ + - ]: 57914 : Assert(MyProc->fpLocalTransactionId == InvalidLocalTransactionId);
4628 [ + - ]: 57914 : Assert(MyProc->fpVXIDLock == false);
4629 : :
4630 : 57914 : MyProc->fpVXIDLock = true;
4631 : 57914 : MyProc->fpLocalTransactionId = vxid.localTransactionId;
4632 : :
4633 : 57914 : LWLockRelease(&MyProc->fpInfoLock);
4634 : 57914 : }
4635 : :
4636 : : /*
4637 : : * VirtualXactLockTableCleanup
4638 : : *
4639 : : * Check whether a VXID lock has been materialized; if so, release it,
4640 : : * unblocking waiters.
4641 : : */
4642 : : void
4643 : 57914 : VirtualXactLockTableCleanup(void)
4644 : : {
4645 : 57914 : bool fastpath;
4646 : 57914 : LocalTransactionId lxid;
4647 : :
4648 [ + - ]: 57914 : Assert(MyProc->vxid.procNumber != INVALID_PROC_NUMBER);
4649 : :
4650 : : /*
4651 : : * Clean up shared memory state.
4652 : : */
4653 : 57914 : LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
4654 : :
4655 : 57914 : fastpath = MyProc->fpVXIDLock;
4656 : 57914 : lxid = MyProc->fpLocalTransactionId;
4657 : 57914 : MyProc->fpVXIDLock = false;
4658 : 57914 : MyProc->fpLocalTransactionId = InvalidLocalTransactionId;
4659 : :
4660 : 57914 : LWLockRelease(&MyProc->fpInfoLock);
4661 : :
4662 : : /*
4663 : : * If fpVXIDLock has been cleared without touching fpLocalTransactionId,
4664 : : * that means someone transferred the lock to the main lock table.
4665 : : */
4666 [ + + - + ]: 57914 : if (!fastpath && LocalTransactionIdIsValid(lxid))
4667 : : {
4668 : 23 : VirtualTransactionId vxid;
4669 : 23 : LOCKTAG locktag;
4670 : :
4671 : 23 : vxid.procNumber = MyProcNumber;
4672 : 23 : vxid.localTransactionId = lxid;
4673 : 23 : SET_LOCKTAG_VIRTUALTRANSACTION(locktag, vxid);
4674 : :
4675 : 23 : LockRefindAndRelease(LockMethods[DEFAULT_LOCKMETHOD], MyProc,
4676 : : &locktag, ExclusiveLock, false);
4677 : 23 : }
4678 : 57914 : }
4679 : :
4680 : : /*
4681 : : * XactLockForVirtualXact
4682 : : *
4683 : : * If TransactionIdIsValid(xid), this is essentially XactLockTableWait(xid,
4684 : : * NULL, NULL, XLTW_None) or ConditionalXactLockTableWait(xid). Unlike those
4685 : : * functions, it assumes "xid" is never a subtransaction and that "xid" is
4686 : : * prepared, committed, or aborted.
4687 : : *
4688 : : * If !TransactionIdIsValid(xid), this locks every prepared XID having been
4689 : : * known as "vxid" before its PREPARE TRANSACTION.
4690 : : */
4691 : : static bool
4692 : 24 : XactLockForVirtualXact(VirtualTransactionId vxid,
4693 : : TransactionId xid, bool wait)
4694 : : {
4695 : 24 : bool more = false;
4696 : :
4697 : : /* There is no point to wait for 2PCs if you have no 2PCs. */
4698 [ - + ]: 24 : if (max_prepared_xacts == 0)
4699 : 24 : return true;
4700 : :
4701 : 0 : do
4702 : : {
4703 : 0 : LockAcquireResult lar;
4704 : 0 : LOCKTAG tag;
4705 : :
4706 : : /* Clear state from previous iterations. */
4707 [ # # ]: 0 : if (more)
4708 : : {
4709 : 0 : xid = InvalidTransactionId;
4710 : 0 : more = false;
4711 : 0 : }
4712 : :
4713 : : /* If we have no xid, try to find one. */
4714 [ # # ]: 0 : if (!TransactionIdIsValid(xid))
4715 : 0 : xid = TwoPhaseGetXidByVirtualXID(vxid, &more);
4716 [ # # ]: 0 : if (!TransactionIdIsValid(xid))
4717 : : {
4718 [ # # ]: 0 : Assert(!more);
4719 : 0 : return true;
4720 : : }
4721 : :
4722 : : /* Check or wait for XID completion. */
4723 : 0 : SET_LOCKTAG_TRANSACTION(tag, xid);
4724 : 0 : lar = LockAcquire(&tag, ShareLock, false, !wait);
4725 [ # # ]: 0 : if (lar == LOCKACQUIRE_NOT_AVAIL)
4726 : 0 : return false;
4727 : 0 : LockRelease(&tag, ShareLock, false);
4728 [ # # # # ]: 0 : } while (more);
4729 : :
4730 : 0 : return true;
4731 : 24 : }
4732 : :
4733 : : /*
4734 : : * VirtualXactLock
4735 : : *
4736 : : * If wait = true, wait as long as the given VXID or any XID acquired by the
4737 : : * same transaction is still running. Then, return true.
4738 : : *
4739 : : * If wait = false, just check whether that VXID or one of those XIDs is still
4740 : : * running, and return true or false.
4741 : : */
4742 : : bool
4743 : 24 : VirtualXactLock(VirtualTransactionId vxid, bool wait)
4744 : : {
4745 : 24 : LOCKTAG tag;
4746 : 24 : PGPROC *proc;
4747 : 24 : TransactionId xid = InvalidTransactionId;
4748 : :
4749 [ + - ]: 24 : Assert(VirtualTransactionIdIsValid(vxid));
4750 : :
4751 [ + - ]: 24 : if (VirtualTransactionIdIsRecoveredPreparedXact(vxid))
4752 : : /* no vxid lock; localTransactionId is a normal, locked XID */
4753 : 0 : return XactLockForVirtualXact(vxid, vxid.localTransactionId, wait);
4754 : :
4755 : 24 : SET_LOCKTAG_VIRTUALTRANSACTION(tag, vxid);
4756 : :
4757 : : /*
4758 : : * If a lock table entry must be made, this is the PGPROC on whose behalf
4759 : : * it must be done. Note that the transaction might end or the PGPROC
4760 : : * might be reassigned to a new backend before we get around to examining
4761 : : * it, but it doesn't matter. If we find upon examination that the
4762 : : * relevant lxid is no longer running here, that's enough to prove that
4763 : : * it's no longer running anywhere.
4764 : : */
4765 : 24 : proc = ProcNumberGetProc(vxid.procNumber);
4766 [ + - ]: 24 : if (proc == NULL)
4767 : 0 : return XactLockForVirtualXact(vxid, InvalidTransactionId, wait);
4768 : :
4769 : : /*
4770 : : * We must acquire this lock before checking the procNumber and lxid
4771 : : * against the ones we're waiting for. The target backend will only set
4772 : : * or clear lxid while holding this lock.
4773 : : */
4774 : 24 : LWLockAcquire(&proc->fpInfoLock, LW_EXCLUSIVE);
4775 : :
4776 : 24 : if (proc->vxid.procNumber != vxid.procNumber
4777 [ + - - + ]: 24 : || proc->fpLocalTransactionId != vxid.localTransactionId)
4778 : : {
4779 : : /* VXID ended */
4780 : 0 : LWLockRelease(&proc->fpInfoLock);
4781 : 0 : return XactLockForVirtualXact(vxid, InvalidTransactionId, wait);
4782 : : }
4783 : :
4784 : : /*
4785 : : * If we aren't asked to wait, there's no need to set up a lock table
4786 : : * entry. The transaction is still in progress, so just return false.
4787 : : */
4788 [ + - ]: 24 : if (!wait)
4789 : : {
4790 : 0 : LWLockRelease(&proc->fpInfoLock);
4791 : 0 : return false;
4792 : : }
4793 : :
4794 : : /*
4795 : : * OK, we're going to need to sleep on the VXID. But first, we must set
4796 : : * up the primary lock table entry, if needed (ie, convert the proc's
4797 : : * fast-path lock on its VXID to a regular lock).
4798 : : */
4799 [ + + ]: 24 : if (proc->fpVXIDLock)
4800 : : {
4801 : 23 : PROCLOCK *proclock;
4802 : 23 : uint32 hashcode;
4803 : 23 : LWLock *partitionLock;
4804 : :
4805 : 23 : hashcode = LockTagHashCode(&tag);
4806 : :
4807 : 23 : partitionLock = LockHashPartitionLock(hashcode);
4808 : 23 : LWLockAcquire(partitionLock, LW_EXCLUSIVE);
4809 : :
4810 : 46 : proclock = SetupLockInTable(LockMethods[DEFAULT_LOCKMETHOD], proc,
4811 : 23 : &tag, hashcode, ExclusiveLock);
4812 [ + - ]: 23 : if (!proclock)
4813 : : {
4814 : 0 : LWLockRelease(partitionLock);
4815 : 0 : LWLockRelease(&proc->fpInfoLock);
4816 [ # # # # ]: 0 : ereport(ERROR,
4817 : : (errcode(ERRCODE_OUT_OF_MEMORY),
4818 : : errmsg("out of shared memory"),
4819 : : errhint("You might need to increase \"%s\".", "max_locks_per_transaction")));
4820 : 0 : }
4821 : 23 : GrantLock(proclock->tag.myLock, proclock, ExclusiveLock);
4822 : :
4823 : 23 : LWLockRelease(partitionLock);
4824 : :
4825 : 23 : proc->fpVXIDLock = false;
4826 : 23 : }
4827 : :
4828 : : /*
4829 : : * If the proc has an XID now, we'll avoid a TwoPhaseGetXidByVirtualXID()
4830 : : * search. The proc might have assigned this XID but not yet locked it,
4831 : : * in which case the proc will lock this XID before releasing the VXID.
4832 : : * The fpInfoLock critical section excludes VirtualXactLockTableCleanup(),
4833 : : * so we won't save an XID of a different VXID. It doesn't matter whether
4834 : : * we save this before or after setting up the primary lock table entry.
4835 : : */
4836 : 24 : xid = proc->xid;
4837 : :
4838 : : /* Done with proc->fpLockBits */
4839 : 24 : LWLockRelease(&proc->fpInfoLock);
4840 : :
4841 : : /* Time to wait. */
4842 : 24 : (void) LockAcquire(&tag, ShareLock, false, false);
4843 : :
4844 : 24 : LockRelease(&tag, ShareLock, false);
4845 : 24 : return XactLockForVirtualXact(vxid, xid, wait);
4846 : 24 : }
4847 : :
4848 : : /*
4849 : : * LockWaiterCount
4850 : : *
4851 : : * Find the number of lock requester on this locktag
4852 : : */
4853 : : int
4854 : 13530 : LockWaiterCount(const LOCKTAG *locktag)
4855 : : {
4856 : 13530 : LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
4857 : 13530 : LOCK *lock;
4858 : 13530 : bool found;
4859 : 13530 : uint32 hashcode;
4860 : 13530 : LWLock *partitionLock;
4861 : 13530 : int waiters = 0;
4862 : :
4863 [ + - ]: 13530 : if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
4864 [ # # # # ]: 0 : elog(ERROR, "unrecognized lock method: %d", lockmethodid);
4865 : :
4866 : 13530 : hashcode = LockTagHashCode(locktag);
4867 : 13530 : partitionLock = LockHashPartitionLock(hashcode);
4868 : 13530 : LWLockAcquire(partitionLock, LW_EXCLUSIVE);
4869 : :
4870 : 27060 : lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
4871 : 13530 : locktag,
4872 : 13530 : hashcode,
4873 : : HASH_FIND,
4874 : : &found);
4875 [ + + ]: 13530 : if (found)
4876 : : {
4877 [ + - ]: 9 : Assert(lock != NULL);
4878 : 9 : waiters = lock->nRequested;
4879 : 9 : }
4880 : 13530 : LWLockRelease(partitionLock);
4881 : :
4882 : 27060 : return waiters;
4883 : 13530 : }
|
