Branch data Line data Source code
1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * walsender.c
4 : : *
5 : : * The WAL sender process (walsender) is new as of Postgres 9.0. It takes
6 : : * care of sending XLOG from the primary server to a single recipient.
7 : : * (Note that there can be more than one walsender process concurrently.)
8 : : * It is started by the postmaster when the walreceiver of a standby server
9 : : * connects to the primary server and requests XLOG streaming replication.
10 : : *
11 : : * A walsender is similar to a regular backend, ie. there is a one-to-one
12 : : * relationship between a connection and a walsender process, but instead
13 : : * of processing SQL queries, it understands a small set of special
14 : : * replication-mode commands. The START_REPLICATION command begins streaming
15 : : * WAL to the client. While streaming, the walsender keeps reading XLOG
16 : : * records from the disk and sends them to the standby server over the
17 : : * COPY protocol, until either side ends the replication by exiting COPY
18 : : * mode (or until the connection is closed).
19 : : *
20 : : * Normal termination is by SIGTERM, which instructs the walsender to
21 : : * close the connection and exit(0) at the next convenient moment. Emergency
22 : : * termination is by SIGQUIT; like any backend, the walsender will simply
23 : : * abort and exit on SIGQUIT. A close of the connection and a FATAL error
24 : : * are treated as not a crash but approximately normal termination;
25 : : * the walsender will exit quickly without sending any more XLOG records.
26 : : *
27 : : * If the server is shut down, checkpointer sends us
28 : : * PROCSIG_WALSND_INIT_STOPPING after all regular backends have exited. If
29 : : * the backend is idle or runs an SQL query this causes the backend to
30 : : * shutdown, if logical replication is in progress all existing WAL records
31 : : * are processed followed by a shutdown. Otherwise this causes the walsender
32 : : * to switch to the "stopping" state. In this state, the walsender will reject
33 : : * any further replication commands. The checkpointer begins the shutdown
34 : : * checkpoint once all walsenders are confirmed as stopping. When the shutdown
35 : : * checkpoint finishes, the postmaster sends us SIGUSR2. This instructs
36 : : * walsender to send any outstanding WAL, including the shutdown checkpoint
37 : : * record, wait for it to be replicated to the standby, and then exit.
38 : : *
39 : : *
40 : : * Portions Copyright (c) 2010-2026, PostgreSQL Global Development Group
41 : : *
42 : : * IDENTIFICATION
43 : : * src/backend/replication/walsender.c
44 : : *
45 : : *-------------------------------------------------------------------------
46 : : */
47 : : #include "postgres.h"
48 : :
49 : : #include <signal.h>
50 : : #include <unistd.h>
51 : :
52 : : #include "access/timeline.h"
53 : : #include "access/transam.h"
54 : : #include "access/twophase.h"
55 : : #include "access/xact.h"
56 : : #include "access/xlog_internal.h"
57 : : #include "access/xlogreader.h"
58 : : #include "access/xlogrecovery.h"
59 : : #include "access/xlogutils.h"
60 : : #include "backup/basebackup.h"
61 : : #include "backup/basebackup_incremental.h"
62 : : #include "catalog/pg_authid.h"
63 : : #include "catalog/pg_type.h"
64 : : #include "commands/defrem.h"
65 : : #include "funcapi.h"
66 : : #include "libpq/libpq.h"
67 : : #include "libpq/pqformat.h"
68 : : #include "libpq/protocol.h"
69 : : #include "miscadmin.h"
70 : : #include "nodes/replnodes.h"
71 : : #include "pgstat.h"
72 : : #include "postmaster/interrupt.h"
73 : : #include "replication/decode.h"
74 : : #include "replication/logical.h"
75 : : #include "replication/slotsync.h"
76 : : #include "replication/slot.h"
77 : : #include "replication/snapbuild.h"
78 : : #include "replication/syncrep.h"
79 : : #include "replication/walreceiver.h"
80 : : #include "replication/walsender.h"
81 : : #include "replication/walsender_private.h"
82 : : #include "storage/condition_variable.h"
83 : : #include "storage/aio_subsys.h"
84 : : #include "storage/fd.h"
85 : : #include "storage/ipc.h"
86 : : #include "storage/pmsignal.h"
87 : : #include "storage/proc.h"
88 : : #include "storage/procarray.h"
89 : : #include "tcop/dest.h"
90 : : #include "tcop/tcopprot.h"
91 : : #include "utils/acl.h"
92 : : #include "utils/builtins.h"
93 : : #include "utils/guc.h"
94 : : #include "utils/lsyscache.h"
95 : : #include "utils/memutils.h"
96 : : #include "utils/pg_lsn.h"
97 : : #include "utils/pgstat_internal.h"
98 : : #include "utils/ps_status.h"
99 : : #include "utils/timeout.h"
100 : : #include "utils/timestamp.h"
101 : :
102 : : /* Minimum interval used by walsender for stats flushes, in ms */
103 : : #define WALSENDER_STATS_FLUSH_INTERVAL 1000
104 : :
105 : : /*
106 : : * Maximum data payload in a WAL data message. Must be >= XLOG_BLCKSZ.
107 : : *
108 : : * We don't have a good idea of what a good value would be; there's some
109 : : * overhead per message in both walsender and walreceiver, but on the other
110 : : * hand sending large batches makes walsender less responsive to signals
111 : : * because signals are checked only between messages. 128kB (with
112 : : * default 8k blocks) seems like a reasonable guess for now.
113 : : */
114 : : #define MAX_SEND_SIZE (XLOG_BLCKSZ * 16)
115 : :
116 : : /* Array of WalSnds in shared memory */
117 : : WalSndCtlData *WalSndCtl = NULL;
118 : :
119 : : /* My slot in the shared memory array */
120 : : WalSnd *MyWalSnd = NULL;
121 : :
122 : : /* Global state */
123 : : bool am_walsender = false; /* Am I a walsender process? */
124 : : bool am_cascading_walsender = false; /* Am I cascading WAL to another
125 : : * standby? */
126 : : bool am_db_walsender = false; /* Connected to a database? */
127 : :
128 : : /* GUC variables */
129 : : int max_wal_senders = 10; /* the maximum number of concurrent
130 : : * walsenders */
131 : : int wal_sender_timeout = 60 * 1000; /* maximum time to send one WAL
132 : : * data message */
133 : : bool log_replication_commands = false;
134 : :
135 : : /*
136 : : * State for WalSndWakeupRequest
137 : : */
138 : : bool wake_wal_senders = false;
139 : :
140 : : /*
141 : : * xlogreader used for replication. Note that a WAL sender doing physical
142 : : * replication does not need xlogreader to read WAL, but it needs one to
143 : : * keep a state of its work.
144 : : */
145 : : static XLogReaderState *xlogreader = NULL;
146 : :
147 : : /*
148 : : * If the UPLOAD_MANIFEST command is used to provide a backup manifest in
149 : : * preparation for an incremental backup, uploaded_manifest will be point
150 : : * to an object containing information about its contexts, and
151 : : * uploaded_manifest_mcxt will point to the memory context that contains
152 : : * that object and all of its subordinate data. Otherwise, both values will
153 : : * be NULL.
154 : : */
155 : : static IncrementalBackupInfo *uploaded_manifest = NULL;
156 : : static MemoryContext uploaded_manifest_mcxt = NULL;
157 : :
158 : : /*
159 : : * These variables keep track of the state of the timeline we're currently
160 : : * sending. sendTimeLine identifies the timeline. If sendTimeLineIsHistoric,
161 : : * the timeline is not the latest timeline on this server, and the server's
162 : : * history forked off from that timeline at sendTimeLineValidUpto.
163 : : */
164 : : static TimeLineID sendTimeLine = 0;
165 : : static TimeLineID sendTimeLineNextTLI = 0;
166 : : static bool sendTimeLineIsHistoric = false;
167 : : static XLogRecPtr sendTimeLineValidUpto = InvalidXLogRecPtr;
168 : :
169 : : /*
170 : : * How far have we sent WAL already? This is also advertised in
171 : : * MyWalSnd->sentPtr. (Actually, this is the next WAL location to send.)
172 : : */
173 : : static XLogRecPtr sentPtr = InvalidXLogRecPtr;
174 : :
175 : : /* Buffers for constructing outgoing messages and processing reply messages. */
176 : : static StringInfoData output_message;
177 : : static StringInfoData reply_message;
178 : : static StringInfoData tmpbuf;
179 : :
180 : : /* Timestamp of last ProcessRepliesIfAny(). */
181 : : static TimestampTz last_processing = 0;
182 : :
183 : : /*
184 : : * Timestamp of last ProcessRepliesIfAny() that saw a reply from the
185 : : * standby. Set to 0 if wal_sender_timeout doesn't need to be active.
186 : : */
187 : : static TimestampTz last_reply_timestamp = 0;
188 : :
189 : : /* Have we sent a heartbeat message asking for reply, since last reply? */
190 : : static bool waiting_for_ping_response = false;
191 : :
192 : : /*
193 : : * While streaming WAL in Copy mode, streamingDoneSending is set to true
194 : : * after we have sent CopyDone. We should not send any more CopyData messages
195 : : * after that. streamingDoneReceiving is set to true when we receive CopyDone
196 : : * from the other end. When both become true, it's time to exit Copy mode.
197 : : */
198 : : static bool streamingDoneSending;
199 : : static bool streamingDoneReceiving;
200 : :
201 : : /* Are we there yet? */
202 : : static bool WalSndCaughtUp = false;
203 : :
204 : : /* Flags set by signal handlers for later service in main loop */
205 : : static volatile sig_atomic_t got_SIGUSR2 = false;
206 : : static volatile sig_atomic_t got_STOPPING = false;
207 : :
208 : : /*
209 : : * This is set while we are streaming. When not set
210 : : * PROCSIG_WALSND_INIT_STOPPING signal will be handled like SIGTERM. When set,
211 : : * the main loop is responsible for checking got_STOPPING and terminating when
212 : : * it's set (after streaming any remaining WAL).
213 : : */
214 : : static volatile sig_atomic_t replication_active = false;
215 : :
216 : : static LogicalDecodingContext *logical_decoding_ctx = NULL;
217 : :
218 : : /* A sample associating a WAL location with the time it was written. */
219 : : typedef struct
220 : : {
221 : : XLogRecPtr lsn;
222 : : TimestampTz time;
223 : : } WalTimeSample;
224 : :
225 : : /* The size of our buffer of time samples. */
226 : : #define LAG_TRACKER_BUFFER_SIZE 8192
227 : :
228 : : /* A mechanism for tracking replication lag. */
229 : : typedef struct
230 : : {
231 : : XLogRecPtr last_lsn;
232 : : WalTimeSample buffer[LAG_TRACKER_BUFFER_SIZE];
233 : : int write_head;
234 : : int read_heads[NUM_SYNC_REP_WAIT_MODE];
235 : : WalTimeSample last_read[NUM_SYNC_REP_WAIT_MODE];
236 : :
237 : : /*
238 : : * Overflow entries for read heads that collide with the write head.
239 : : *
240 : : * When the cyclic buffer fills (write head is about to collide with a
241 : : * read head), we save that read head's current sample here and mark it as
242 : : * using overflow (read_heads[i] = -1). This allows the write head to
243 : : * continue advancing while the overflowed mode continues lag computation
244 : : * using the saved sample.
245 : : *
246 : : * Once the standby's reported LSN advances past the overflow entry's LSN,
247 : : * we transition back to normal buffer-based tracking.
248 : : */
249 : : WalTimeSample overflowed[NUM_SYNC_REP_WAIT_MODE];
250 : : } LagTracker;
251 : :
252 : : static LagTracker *lag_tracker;
253 : :
254 : : /* Signal handlers */
255 : : static void WalSndLastCycleHandler(SIGNAL_ARGS);
256 : :
257 : : /* Prototypes for private functions */
258 : : typedef void (*WalSndSendDataCallback) (void);
259 : : static void WalSndLoop(WalSndSendDataCallback send_data);
260 : : static void InitWalSenderSlot(void);
261 : : static void WalSndKill(int code, Datum arg);
262 : : pg_noreturn static void WalSndShutdown(void);
263 : : static void XLogSendPhysical(void);
264 : : static void XLogSendLogical(void);
265 : : static void WalSndDone(WalSndSendDataCallback send_data);
266 : : static void IdentifySystem(void);
267 : : static void UploadManifest(void);
268 : : static bool HandleUploadManifestPacket(StringInfo buf, off_t *offset,
269 : : IncrementalBackupInfo *ib);
270 : : static void ReadReplicationSlot(ReadReplicationSlotCmd *cmd);
271 : : static void CreateReplicationSlot(CreateReplicationSlotCmd *cmd);
272 : : static void DropReplicationSlot(DropReplicationSlotCmd *cmd);
273 : : static void StartReplication(StartReplicationCmd *cmd);
274 : : static void StartLogicalReplication(StartReplicationCmd *cmd);
275 : : static void ProcessStandbyMessage(void);
276 : : static void ProcessStandbyReplyMessage(void);
277 : : static void ProcessStandbyHSFeedbackMessage(void);
278 : : static void ProcessStandbyPSRequestMessage(void);
279 : : static void ProcessRepliesIfAny(void);
280 : : static void ProcessPendingWrites(void);
281 : : static void WalSndKeepalive(bool requestReply, XLogRecPtr writePtr);
282 : : static void WalSndKeepaliveIfNecessary(void);
283 : : static void WalSndCheckTimeOut(void);
284 : : static long WalSndComputeSleeptime(TimestampTz now);
285 : : static void WalSndWait(uint32 socket_events, long timeout, uint32 wait_event);
286 : : static void WalSndPrepareWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid, bool last_write);
287 : : static void WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid, bool last_write);
288 : : static void WalSndUpdateProgress(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
289 : : bool skipped_xact);
290 : : static XLogRecPtr WalSndWaitForWal(XLogRecPtr loc);
291 : : static void LagTrackerWrite(XLogRecPtr lsn, TimestampTz local_flush_time);
292 : : static TimeOffset LagTrackerRead(int head, XLogRecPtr lsn, TimestampTz now);
293 : : static bool TransactionIdInRecentPast(TransactionId xid, uint32 epoch);
294 : :
295 : : static void WalSndSegmentOpen(XLogReaderState *state, XLogSegNo nextSegNo,
296 : : TimeLineID *tli_p);
297 : :
298 : :
299 : : /* Initialize walsender process before entering the main command loop */
300 : : void
301 : 0 : InitWalSender(void)
302 : : {
303 : 0 : am_cascading_walsender = RecoveryInProgress();
304 : :
305 : : /* Create a per-walsender data structure in shared memory */
306 : 0 : InitWalSenderSlot();
307 : :
308 : : /* need resource owner for e.g. basebackups */
309 : 0 : CreateAuxProcessResourceOwner();
310 : :
311 : : /*
312 : : * Let postmaster know that we're a WAL sender. Once we've declared us as
313 : : * a WAL sender process, postmaster will let us outlive the bgwriter and
314 : : * kill us last in the shutdown sequence, so we get a chance to stream all
315 : : * remaining WAL at shutdown, including the shutdown checkpoint. Note that
316 : : * there's no going back, and we mustn't write any WAL records after this.
317 : : */
318 : 0 : MarkPostmasterChildWalSender();
319 : 0 : SendPostmasterSignal(PMSIGNAL_ADVANCE_STATE_MACHINE);
320 : :
321 : : /*
322 : : * If the client didn't specify a database to connect to, show in PGPROC
323 : : * that our advertised xmin should affect vacuum horizons in all
324 : : * databases. This allows physical replication clients to send hot
325 : : * standby feedback that will delay vacuum cleanup in all databases.
326 : : */
327 [ # # ]: 0 : if (MyDatabaseId == InvalidOid)
328 : : {
329 [ # # ]: 0 : Assert(MyProc->xmin == InvalidTransactionId);
330 : 0 : LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
331 : 0 : MyProc->statusFlags |= PROC_AFFECTS_ALL_HORIZONS;
332 : 0 : ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags;
333 : 0 : LWLockRelease(ProcArrayLock);
334 : 0 : }
335 : :
336 : : /* Initialize empty timestamp buffer for lag tracking. */
337 : 0 : lag_tracker = MemoryContextAllocZero(TopMemoryContext, sizeof(LagTracker));
338 : 0 : }
339 : :
340 : : /*
341 : : * Clean up after an error.
342 : : *
343 : : * WAL sender processes don't use transactions like regular backends do.
344 : : * This function does any cleanup required after an error in a WAL sender
345 : : * process, similar to what transaction abort does in a regular backend.
346 : : */
347 : : void
348 : 0 : WalSndErrorCleanup(void)
349 : : {
350 : 0 : LWLockReleaseAll();
351 : 0 : ConditionVariableCancelSleep();
352 : 0 : pgstat_report_wait_end();
353 : 0 : pgaio_error_cleanup();
354 : :
355 [ # # # # ]: 0 : if (xlogreader != NULL && xlogreader->seg.ws_file >= 0)
356 : 0 : wal_segment_close(xlogreader);
357 : :
358 [ # # ]: 0 : if (MyReplicationSlot != NULL)
359 : 0 : ReplicationSlotRelease();
360 : :
361 : 0 : ReplicationSlotCleanup(false);
362 : :
363 : 0 : replication_active = false;
364 : :
365 : : /*
366 : : * If there is a transaction in progress, it will clean up our
367 : : * ResourceOwner, but if a replication command set up a resource owner
368 : : * without a transaction, we've got to clean that up now.
369 : : */
370 [ # # ]: 0 : if (!IsTransactionOrTransactionBlock())
371 : 0 : ReleaseAuxProcessResources(false);
372 : :
373 [ # # ]: 0 : if (got_STOPPING || got_SIGUSR2)
374 : 0 : proc_exit(0);
375 : :
376 : : /* Revert back to startup state */
377 : 0 : WalSndSetState(WALSNDSTATE_STARTUP);
378 : 0 : }
379 : :
380 : : /*
381 : : * Handle a client's connection abort in an orderly manner.
382 : : */
383 : : static void
384 : 0 : WalSndShutdown(void)
385 : : {
386 : : /*
387 : : * Reset whereToSendOutput to prevent ereport from attempting to send any
388 : : * more messages to the standby.
389 : : */
390 [ # # ]: 0 : if (whereToSendOutput == DestRemote)
391 : 0 : whereToSendOutput = DestNone;
392 : :
393 : 0 : proc_exit(0);
394 : : abort(); /* keep the compiler quiet */
395 : : }
396 : :
397 : : /*
398 : : * Handle the IDENTIFY_SYSTEM command.
399 : : */
400 : : static void
401 : 0 : IdentifySystem(void)
402 : : {
403 : 0 : char sysid[32];
404 : 0 : char xloc[MAXFNAMELEN];
405 : 0 : XLogRecPtr logptr;
406 : 0 : char *dbname = NULL;
407 : 0 : DestReceiver *dest;
408 : 0 : TupOutputState *tstate;
409 : 0 : TupleDesc tupdesc;
410 : 0 : Datum values[4];
411 : 0 : bool nulls[4] = {0};
412 : 0 : TimeLineID currTLI;
413 : :
414 : : /*
415 : : * Reply with a result set with one row, four columns. First col is system
416 : : * ID, second is timeline ID, third is current xlog location and the
417 : : * fourth contains the database name if we are connected to one.
418 : : */
419 : :
420 : 0 : snprintf(sysid, sizeof(sysid), UINT64_FORMAT,
421 : 0 : GetSystemIdentifier());
422 : :
423 : 0 : am_cascading_walsender = RecoveryInProgress();
424 [ # # ]: 0 : if (am_cascading_walsender)
425 : 0 : logptr = GetStandbyFlushRecPtr(&currTLI);
426 : : else
427 : 0 : logptr = GetFlushRecPtr(&currTLI);
428 : :
429 : 0 : snprintf(xloc, sizeof(xloc), "%X/%08X", LSN_FORMAT_ARGS(logptr));
430 : :
431 [ # # ]: 0 : if (MyDatabaseId != InvalidOid)
432 : : {
433 : 0 : MemoryContext cur = CurrentMemoryContext;
434 : :
435 : : /* syscache access needs a transaction env. */
436 : 0 : StartTransactionCommand();
437 : 0 : dbname = get_database_name(MyDatabaseId);
438 : : /* copy dbname out of TX context */
439 : 0 : dbname = MemoryContextStrdup(cur, dbname);
440 : 0 : CommitTransactionCommand();
441 : 0 : }
442 : :
443 : 0 : dest = CreateDestReceiver(DestRemoteSimple);
444 : :
445 : : /* need a tuple descriptor representing four columns */
446 : 0 : tupdesc = CreateTemplateTupleDesc(4);
447 : 0 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, "systemid",
448 : : TEXTOID, -1, 0);
449 : 0 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 2, "timeline",
450 : : INT8OID, -1, 0);
451 : 0 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 3, "xlogpos",
452 : : TEXTOID, -1, 0);
453 : 0 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 4, "dbname",
454 : : TEXTOID, -1, 0);
455 : :
456 : : /* prepare for projection of tuples */
457 : 0 : tstate = begin_tup_output_tupdesc(dest, tupdesc, &TTSOpsVirtual);
458 : :
459 : : /* column 1: system identifier */
460 : 0 : values[0] = CStringGetTextDatum(sysid);
461 : :
462 : : /* column 2: timeline */
463 : 0 : values[1] = Int64GetDatum(currTLI);
464 : :
465 : : /* column 3: wal location */
466 : 0 : values[2] = CStringGetTextDatum(xloc);
467 : :
468 : : /* column 4: database name, or NULL if none */
469 [ # # ]: 0 : if (dbname)
470 : 0 : values[3] = CStringGetTextDatum(dbname);
471 : : else
472 : 0 : nulls[3] = true;
473 : :
474 : : /* send it to dest */
475 : 0 : do_tup_output(tstate, values, nulls);
476 : :
477 : 0 : end_tup_output(tstate);
478 : 0 : }
479 : :
480 : : /* Handle READ_REPLICATION_SLOT command */
481 : : static void
482 : 0 : ReadReplicationSlot(ReadReplicationSlotCmd *cmd)
483 : : {
484 : : #define READ_REPLICATION_SLOT_COLS 3
485 : 0 : ReplicationSlot *slot;
486 : 0 : DestReceiver *dest;
487 : 0 : TupOutputState *tstate;
488 : 0 : TupleDesc tupdesc;
489 : 0 : Datum values[READ_REPLICATION_SLOT_COLS] = {0};
490 : 0 : bool nulls[READ_REPLICATION_SLOT_COLS];
491 : :
492 : 0 : tupdesc = CreateTemplateTupleDesc(READ_REPLICATION_SLOT_COLS);
493 : 0 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, "slot_type",
494 : : TEXTOID, -1, 0);
495 : 0 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 2, "restart_lsn",
496 : : TEXTOID, -1, 0);
497 : : /* TimeLineID is unsigned, so int4 is not wide enough. */
498 : 0 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 3, "restart_tli",
499 : : INT8OID, -1, 0);
500 : :
501 : 0 : memset(nulls, true, READ_REPLICATION_SLOT_COLS * sizeof(bool));
502 : :
503 : 0 : LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
504 : 0 : slot = SearchNamedReplicationSlot(cmd->slotname, false);
505 [ # # # # ]: 0 : if (slot == NULL || !slot->in_use)
506 : : {
507 : 0 : LWLockRelease(ReplicationSlotControlLock);
508 : 0 : }
509 : : else
510 : : {
511 : 0 : ReplicationSlot slot_contents;
512 : 0 : int i = 0;
513 : :
514 : : /* Copy slot contents while holding spinlock */
515 [ # # ]: 0 : SpinLockAcquire(&slot->mutex);
516 : 0 : slot_contents = *slot;
517 : 0 : SpinLockRelease(&slot->mutex);
518 : 0 : LWLockRelease(ReplicationSlotControlLock);
519 : :
520 [ # # ]: 0 : if (OidIsValid(slot_contents.data.database))
521 [ # # # # ]: 0 : ereport(ERROR,
522 : : errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
523 : : errmsg("cannot use %s with a logical replication slot",
524 : : "READ_REPLICATION_SLOT"));
525 : :
526 : : /* slot type */
527 : 0 : values[i] = CStringGetTextDatum("physical");
528 : 0 : nulls[i] = false;
529 : 0 : i++;
530 : :
531 : : /* start LSN */
532 [ # # ]: 0 : if (XLogRecPtrIsValid(slot_contents.data.restart_lsn))
533 : : {
534 : 0 : char xloc[64];
535 : :
536 : 0 : snprintf(xloc, sizeof(xloc), "%X/%08X",
537 : 0 : LSN_FORMAT_ARGS(slot_contents.data.restart_lsn));
538 : 0 : values[i] = CStringGetTextDatum(xloc);
539 : 0 : nulls[i] = false;
540 : 0 : }
541 : 0 : i++;
542 : :
543 : : /* timeline this WAL was produced on */
544 [ # # ]: 0 : if (XLogRecPtrIsValid(slot_contents.data.restart_lsn))
545 : : {
546 : 0 : TimeLineID slots_position_timeline;
547 : 0 : TimeLineID current_timeline;
548 : 0 : List *timeline_history = NIL;
549 : :
550 : : /*
551 : : * While in recovery, use as timeline the currently-replaying one
552 : : * to get the LSN position's history.
553 : : */
554 [ # # ]: 0 : if (RecoveryInProgress())
555 : 0 : (void) GetXLogReplayRecPtr(¤t_timeline);
556 : : else
557 : 0 : current_timeline = GetWALInsertionTimeLine();
558 : :
559 : 0 : timeline_history = readTimeLineHistory(current_timeline);
560 : 0 : slots_position_timeline = tliOfPointInHistory(slot_contents.data.restart_lsn,
561 : 0 : timeline_history);
562 : 0 : values[i] = Int64GetDatum((int64) slots_position_timeline);
563 : 0 : nulls[i] = false;
564 : 0 : }
565 : 0 : i++;
566 : :
567 [ # # ]: 0 : Assert(i == READ_REPLICATION_SLOT_COLS);
568 : 0 : }
569 : :
570 : 0 : dest = CreateDestReceiver(DestRemoteSimple);
571 : 0 : tstate = begin_tup_output_tupdesc(dest, tupdesc, &TTSOpsVirtual);
572 : 0 : do_tup_output(tstate, values, nulls);
573 : 0 : end_tup_output(tstate);
574 : 0 : }
575 : :
576 : :
577 : : /*
578 : : * Handle TIMELINE_HISTORY command.
579 : : */
580 : : static void
581 : 0 : SendTimeLineHistory(TimeLineHistoryCmd *cmd)
582 : : {
583 : 0 : DestReceiver *dest;
584 : 0 : TupleDesc tupdesc;
585 : 0 : StringInfoData buf;
586 : 0 : char histfname[MAXFNAMELEN];
587 : 0 : char path[MAXPGPATH];
588 : 0 : int fd;
589 : 0 : off_t histfilelen;
590 : 0 : off_t bytesleft;
591 : 0 : Size len;
592 : :
593 : 0 : dest = CreateDestReceiver(DestRemoteSimple);
594 : :
595 : : /*
596 : : * Reply with a result set with one row, and two columns. The first col is
597 : : * the name of the history file, 2nd is the contents.
598 : : */
599 : 0 : tupdesc = CreateTemplateTupleDesc(2);
600 : 0 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, "filename", TEXTOID, -1, 0);
601 : 0 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 2, "content", TEXTOID, -1, 0);
602 : :
603 : 0 : TLHistoryFileName(histfname, cmd->timeline);
604 : 0 : TLHistoryFilePath(path, cmd->timeline);
605 : :
606 : : /* Send a RowDescription message */
607 : 0 : dest->rStartup(dest, CMD_SELECT, tupdesc);
608 : :
609 : : /* Send a DataRow message */
610 : 0 : pq_beginmessage(&buf, PqMsg_DataRow);
611 : 0 : pq_sendint16(&buf, 2); /* # of columns */
612 : 0 : len = strlen(histfname);
613 : 0 : pq_sendint32(&buf, len); /* col1 len */
614 : 0 : pq_sendbytes(&buf, histfname, len);
615 : :
616 : 0 : fd = OpenTransientFile(path, O_RDONLY | PG_BINARY);
617 [ # # ]: 0 : if (fd < 0)
618 [ # # # # ]: 0 : ereport(ERROR,
619 : : (errcode_for_file_access(),
620 : : errmsg("could not open file \"%s\": %m", path)));
621 : :
622 : : /* Determine file length and send it to client */
623 : 0 : histfilelen = lseek(fd, 0, SEEK_END);
624 [ # # ]: 0 : if (histfilelen < 0)
625 [ # # # # ]: 0 : ereport(ERROR,
626 : : (errcode_for_file_access(),
627 : : errmsg("could not seek to end of file \"%s\": %m", path)));
628 [ # # ]: 0 : if (lseek(fd, 0, SEEK_SET) != 0)
629 [ # # # # ]: 0 : ereport(ERROR,
630 : : (errcode_for_file_access(),
631 : : errmsg("could not seek to beginning of file \"%s\": %m", path)));
632 : :
633 : 0 : pq_sendint32(&buf, histfilelen); /* col2 len */
634 : :
635 : 0 : bytesleft = histfilelen;
636 [ # # ]: 0 : while (bytesleft > 0)
637 : : {
638 : 0 : PGAlignedBlock rbuf;
639 : 0 : int nread;
640 : :
641 : 0 : pgstat_report_wait_start(WAIT_EVENT_WALSENDER_TIMELINE_HISTORY_READ);
642 : 0 : nread = read(fd, rbuf.data, sizeof(rbuf));
643 : 0 : pgstat_report_wait_end();
644 [ # # ]: 0 : if (nread < 0)
645 [ # # # # ]: 0 : ereport(ERROR,
646 : : (errcode_for_file_access(),
647 : : errmsg("could not read file \"%s\": %m",
648 : : path)));
649 [ # # ]: 0 : else if (nread == 0)
650 [ # # # # ]: 0 : ereport(ERROR,
651 : : (errcode(ERRCODE_DATA_CORRUPTED),
652 : : errmsg("could not read file \"%s\": read %d of %zu",
653 : : path, nread, (Size) bytesleft)));
654 : :
655 : 0 : pq_sendbytes(&buf, rbuf.data, nread);
656 : 0 : bytesleft -= nread;
657 : 0 : }
658 : :
659 [ # # ]: 0 : if (CloseTransientFile(fd) != 0)
660 [ # # # # ]: 0 : ereport(ERROR,
661 : : (errcode_for_file_access(),
662 : : errmsg("could not close file \"%s\": %m", path)));
663 : :
664 : 0 : pq_endmessage(&buf);
665 : 0 : }
666 : :
667 : : /*
668 : : * Handle UPLOAD_MANIFEST command.
669 : : */
670 : : static void
671 : 0 : UploadManifest(void)
672 : : {
673 : 0 : MemoryContext mcxt;
674 : 0 : IncrementalBackupInfo *ib;
675 : 0 : off_t offset = 0;
676 : 0 : StringInfoData buf;
677 : :
678 : : /*
679 : : * parsing the manifest will use the cryptohash stuff, which requires a
680 : : * resource owner
681 : : */
682 [ # # ]: 0 : Assert(AuxProcessResourceOwner != NULL);
683 [ # # # # ]: 0 : Assert(CurrentResourceOwner == AuxProcessResourceOwner ||
684 : : CurrentResourceOwner == NULL);
685 : 0 : CurrentResourceOwner = AuxProcessResourceOwner;
686 : :
687 : : /* Prepare to read manifest data into a temporary context. */
688 : 0 : mcxt = AllocSetContextCreate(CurrentMemoryContext,
689 : : "incremental backup information",
690 : : ALLOCSET_DEFAULT_SIZES);
691 : 0 : ib = CreateIncrementalBackupInfo(mcxt);
692 : :
693 : : /* Send a CopyInResponse message */
694 : 0 : pq_beginmessage(&buf, PqMsg_CopyInResponse);
695 : 0 : pq_sendbyte(&buf, 0);
696 : 0 : pq_sendint16(&buf, 0);
697 : 0 : pq_endmessage_reuse(&buf);
698 : 0 : pq_flush();
699 : :
700 : : /* Receive packets from client until done. */
701 [ # # ]: 0 : while (HandleUploadManifestPacket(&buf, &offset, ib))
702 : : ;
703 : :
704 : : /* Finish up manifest processing. */
705 : 0 : FinalizeIncrementalManifest(ib);
706 : :
707 : : /*
708 : : * Discard any old manifest information and arrange to preserve the new
709 : : * information we just got.
710 : : *
711 : : * We assume that MemoryContextDelete and MemoryContextSetParent won't
712 : : * fail, and thus we shouldn't end up bailing out of here in such a way as
713 : : * to leave dangling pointers.
714 : : */
715 [ # # ]: 0 : if (uploaded_manifest_mcxt != NULL)
716 : 0 : MemoryContextDelete(uploaded_manifest_mcxt);
717 : 0 : MemoryContextSetParent(mcxt, CacheMemoryContext);
718 : 0 : uploaded_manifest = ib;
719 : 0 : uploaded_manifest_mcxt = mcxt;
720 : :
721 : : /* clean up the resource owner we created */
722 : 0 : ReleaseAuxProcessResources(true);
723 : 0 : }
724 : :
725 : : /*
726 : : * Process one packet received during the handling of an UPLOAD_MANIFEST
727 : : * operation.
728 : : *
729 : : * 'buf' is scratch space. This function expects it to be initialized, doesn't
730 : : * care what the current contents are, and may override them with completely
731 : : * new contents.
732 : : *
733 : : * The return value is true if the caller should continue processing
734 : : * additional packets and false if the UPLOAD_MANIFEST operation is complete.
735 : : */
736 : : static bool
737 : 0 : HandleUploadManifestPacket(StringInfo buf, off_t *offset,
738 : : IncrementalBackupInfo *ib)
739 : : {
740 : 0 : int mtype;
741 : 0 : int maxmsglen;
742 : :
743 : 0 : HOLD_CANCEL_INTERRUPTS();
744 : :
745 : 0 : pq_startmsgread();
746 : 0 : mtype = pq_getbyte();
747 [ # # ]: 0 : if (mtype == EOF)
748 [ # # # # ]: 0 : ereport(ERROR,
749 : : (errcode(ERRCODE_CONNECTION_FAILURE),
750 : : errmsg("unexpected EOF on client connection with an open transaction")));
751 : :
752 [ # # # ]: 0 : switch (mtype)
753 : : {
754 : : case PqMsg_CopyData:
755 : 0 : maxmsglen = PQ_LARGE_MESSAGE_LIMIT;
756 : 0 : break;
757 : : case PqMsg_CopyDone:
758 : : case PqMsg_CopyFail:
759 : : case PqMsg_Flush:
760 : : case PqMsg_Sync:
761 : 0 : maxmsglen = PQ_SMALL_MESSAGE_LIMIT;
762 : 0 : break;
763 : : default:
764 [ # # # # ]: 0 : ereport(ERROR,
765 : : (errcode(ERRCODE_PROTOCOL_VIOLATION),
766 : : errmsg("unexpected message type 0x%02X during COPY from stdin",
767 : : mtype)));
768 : 0 : maxmsglen = 0; /* keep compiler quiet */
769 : 0 : break;
770 : : }
771 : :
772 : : /* Now collect the message body */
773 [ # # ]: 0 : if (pq_getmessage(buf, maxmsglen))
774 [ # # # # ]: 0 : ereport(ERROR,
775 : : (errcode(ERRCODE_CONNECTION_FAILURE),
776 : : errmsg("unexpected EOF on client connection with an open transaction")));
777 [ # # ]: 0 : RESUME_CANCEL_INTERRUPTS();
778 : :
779 : : /* Process the message */
780 [ # # # # : 0 : switch (mtype)
# ]
781 : : {
782 : : case PqMsg_CopyData:
783 : 0 : AppendIncrementalManifestData(ib, buf->data, buf->len);
784 : 0 : return true;
785 : :
786 : : case PqMsg_CopyDone:
787 : 0 : return false;
788 : :
789 : : case PqMsg_Sync:
790 : : case PqMsg_Flush:
791 : : /* Ignore these while in CopyOut mode as we do elsewhere. */
792 : 0 : return true;
793 : :
794 : : case PqMsg_CopyFail:
795 [ # # # # ]: 0 : ereport(ERROR,
796 : : (errcode(ERRCODE_QUERY_CANCELED),
797 : : errmsg("COPY from stdin failed: %s",
798 : : pq_getmsgstring(buf))));
799 : 0 : }
800 : :
801 : : /* Not reached. */
802 : 0 : Assert(false);
803 : 0 : return false;
804 : 0 : }
805 : :
806 : : /*
807 : : * Handle START_REPLICATION command.
808 : : *
809 : : * At the moment, this never returns, but an ereport(ERROR) will take us back
810 : : * to the main loop.
811 : : */
812 : : static void
813 : 0 : StartReplication(StartReplicationCmd *cmd)
814 : : {
815 : 0 : StringInfoData buf;
816 : 0 : XLogRecPtr FlushPtr;
817 : 0 : TimeLineID FlushTLI;
818 : :
819 : : /* create xlogreader for physical replication */
820 : 0 : xlogreader =
821 : 0 : XLogReaderAllocate(wal_segment_size, NULL,
822 : 0 : XL_ROUTINE(.segment_open = WalSndSegmentOpen,
823 : : .segment_close = wal_segment_close),
824 : : NULL);
825 : :
826 [ # # ]: 0 : if (!xlogreader)
827 [ # # # # ]: 0 : ereport(ERROR,
828 : : (errcode(ERRCODE_OUT_OF_MEMORY),
829 : : errmsg("out of memory"),
830 : : errdetail("Failed while allocating a WAL reading processor.")));
831 : :
832 : : /*
833 : : * We assume here that we're logging enough information in the WAL for
834 : : * log-shipping, since this is checked in PostmasterMain().
835 : : *
836 : : * NOTE: wal_level can only change at shutdown, so in most cases it is
837 : : * difficult for there to be WAL data that we can still see that was
838 : : * written at wal_level='minimal'.
839 : : */
840 : :
841 [ # # ]: 0 : if (cmd->slotname)
842 : : {
843 : 0 : ReplicationSlotAcquire(cmd->slotname, true, true);
844 [ # # ]: 0 : if (SlotIsLogical(MyReplicationSlot))
845 [ # # # # ]: 0 : ereport(ERROR,
846 : : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
847 : : errmsg("cannot use a logical replication slot for physical replication")));
848 : :
849 : : /*
850 : : * We don't need to verify the slot's restart_lsn here; instead we
851 : : * rely on the caller requesting the starting point to use. If the
852 : : * WAL segment doesn't exist, we'll fail later.
853 : : */
854 : 0 : }
855 : :
856 : : /*
857 : : * Select the timeline. If it was given explicitly by the client, use
858 : : * that. Otherwise use the timeline of the last replayed record.
859 : : */
860 : 0 : am_cascading_walsender = RecoveryInProgress();
861 [ # # ]: 0 : if (am_cascading_walsender)
862 : 0 : FlushPtr = GetStandbyFlushRecPtr(&FlushTLI);
863 : : else
864 : 0 : FlushPtr = GetFlushRecPtr(&FlushTLI);
865 : :
866 [ # # ]: 0 : if (cmd->timeline != 0)
867 : : {
868 : 0 : XLogRecPtr switchpoint;
869 : :
870 : 0 : sendTimeLine = cmd->timeline;
871 [ # # ]: 0 : if (sendTimeLine == FlushTLI)
872 : : {
873 : 0 : sendTimeLineIsHistoric = false;
874 : 0 : sendTimeLineValidUpto = InvalidXLogRecPtr;
875 : 0 : }
876 : : else
877 : : {
878 : 0 : List *timeLineHistory;
879 : :
880 : 0 : sendTimeLineIsHistoric = true;
881 : :
882 : : /*
883 : : * Check that the timeline the client requested exists, and the
884 : : * requested start location is on that timeline.
885 : : */
886 : 0 : timeLineHistory = readTimeLineHistory(FlushTLI);
887 : 0 : switchpoint = tliSwitchPoint(cmd->timeline, timeLineHistory,
888 : : &sendTimeLineNextTLI);
889 : 0 : list_free_deep(timeLineHistory);
890 : :
891 : : /*
892 : : * Found the requested timeline in the history. Check that
893 : : * requested startpoint is on that timeline in our history.
894 : : *
895 : : * This is quite loose on purpose. We only check that we didn't
896 : : * fork off the requested timeline before the switchpoint. We
897 : : * don't check that we switched *to* it before the requested
898 : : * starting point. This is because the client can legitimately
899 : : * request to start replication from the beginning of the WAL
900 : : * segment that contains switchpoint, but on the new timeline, so
901 : : * that it doesn't end up with a partial segment. If you ask for
902 : : * too old a starting point, you'll get an error later when we
903 : : * fail to find the requested WAL segment in pg_wal.
904 : : *
905 : : * XXX: we could be more strict here and only allow a startpoint
906 : : * that's older than the switchpoint, if it's still in the same
907 : : * WAL segment.
908 : : */
909 [ # # # # ]: 0 : if (XLogRecPtrIsValid(switchpoint) &&
910 : 0 : switchpoint < cmd->startpoint)
911 : : {
912 [ # # # # ]: 0 : ereport(ERROR,
913 : : errmsg("requested starting point %X/%08X on timeline %u is not in this server's history",
914 : : LSN_FORMAT_ARGS(cmd->startpoint),
915 : : cmd->timeline),
916 : : errdetail("This server's history forked from timeline %u at %X/%08X.",
917 : : cmd->timeline,
918 : : LSN_FORMAT_ARGS(switchpoint)));
919 : 0 : }
920 : 0 : sendTimeLineValidUpto = switchpoint;
921 : 0 : }
922 : 0 : }
923 : : else
924 : : {
925 : 0 : sendTimeLine = FlushTLI;
926 : 0 : sendTimeLineValidUpto = InvalidXLogRecPtr;
927 : 0 : sendTimeLineIsHistoric = false;
928 : : }
929 : :
930 : 0 : streamingDoneSending = streamingDoneReceiving = false;
931 : :
932 : : /* If there is nothing to stream, don't even enter COPY mode */
933 [ # # # # ]: 0 : if (!sendTimeLineIsHistoric || cmd->startpoint < sendTimeLineValidUpto)
934 : : {
935 : : /*
936 : : * When we first start replication the standby will be behind the
937 : : * primary. For some applications, for example synchronous
938 : : * replication, it is important to have a clear state for this initial
939 : : * catchup mode, so we can trigger actions when we change streaming
940 : : * state later. We may stay in this state for a long time, which is
941 : : * exactly why we want to be able to monitor whether or not we are
942 : : * still here.
943 : : */
944 : 0 : WalSndSetState(WALSNDSTATE_CATCHUP);
945 : :
946 : : /* Send a CopyBothResponse message, and start streaming */
947 : 0 : pq_beginmessage(&buf, PqMsg_CopyBothResponse);
948 : 0 : pq_sendbyte(&buf, 0);
949 : 0 : pq_sendint16(&buf, 0);
950 : 0 : pq_endmessage(&buf);
951 : 0 : pq_flush();
952 : :
953 : : /*
954 : : * Don't allow a request to stream from a future point in WAL that
955 : : * hasn't been flushed to disk in this server yet.
956 : : */
957 [ # # ]: 0 : if (FlushPtr < cmd->startpoint)
958 : : {
959 [ # # # # ]: 0 : ereport(ERROR,
960 : : errmsg("requested starting point %X/%08X is ahead of the WAL flush position of this server %X/%08X",
961 : : LSN_FORMAT_ARGS(cmd->startpoint),
962 : : LSN_FORMAT_ARGS(FlushPtr)));
963 : 0 : }
964 : :
965 : : /* Start streaming from the requested point */
966 : 0 : sentPtr = cmd->startpoint;
967 : :
968 : : /* Initialize shared memory status, too */
969 [ # # ]: 0 : SpinLockAcquire(&MyWalSnd->mutex);
970 : 0 : MyWalSnd->sentPtr = sentPtr;
971 : 0 : SpinLockRelease(&MyWalSnd->mutex);
972 : :
973 : 0 : SyncRepInitConfig();
974 : :
975 : : /* Main loop of walsender */
976 : 0 : replication_active = true;
977 : :
978 : 0 : WalSndLoop(XLogSendPhysical);
979 : :
980 : 0 : replication_active = false;
981 [ # # ]: 0 : if (got_STOPPING)
982 : 0 : proc_exit(0);
983 : 0 : WalSndSetState(WALSNDSTATE_STARTUP);
984 : :
985 [ # # ]: 0 : Assert(streamingDoneSending && streamingDoneReceiving);
986 : 0 : }
987 : :
988 [ # # ]: 0 : if (cmd->slotname)
989 : 0 : ReplicationSlotRelease();
990 : :
991 : : /*
992 : : * Copy is finished now. Send a single-row result set indicating the next
993 : : * timeline.
994 : : */
995 [ # # ]: 0 : if (sendTimeLineIsHistoric)
996 : : {
997 : 0 : char startpos_str[8 + 1 + 8 + 1];
998 : 0 : DestReceiver *dest;
999 : 0 : TupOutputState *tstate;
1000 : 0 : TupleDesc tupdesc;
1001 : 0 : Datum values[2];
1002 : 0 : bool nulls[2] = {0};
1003 : :
1004 : 0 : snprintf(startpos_str, sizeof(startpos_str), "%X/%08X",
1005 : 0 : LSN_FORMAT_ARGS(sendTimeLineValidUpto));
1006 : :
1007 : 0 : dest = CreateDestReceiver(DestRemoteSimple);
1008 : :
1009 : : /*
1010 : : * Need a tuple descriptor representing two columns. int8 may seem
1011 : : * like a surprising data type for this, but in theory int4 would not
1012 : : * be wide enough for this, as TimeLineID is unsigned.
1013 : : */
1014 : 0 : tupdesc = CreateTemplateTupleDesc(2);
1015 : 0 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, "next_tli",
1016 : : INT8OID, -1, 0);
1017 : 0 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 2, "next_tli_startpos",
1018 : : TEXTOID, -1, 0);
1019 : :
1020 : : /* prepare for projection of tuple */
1021 : 0 : tstate = begin_tup_output_tupdesc(dest, tupdesc, &TTSOpsVirtual);
1022 : :
1023 : 0 : values[0] = Int64GetDatum((int64) sendTimeLineNextTLI);
1024 : 0 : values[1] = CStringGetTextDatum(startpos_str);
1025 : :
1026 : : /* send it to dest */
1027 : 0 : do_tup_output(tstate, values, nulls);
1028 : :
1029 : 0 : end_tup_output(tstate);
1030 : 0 : }
1031 : :
1032 : : /* Send CommandComplete message */
1033 : 0 : EndReplicationCommand("START_STREAMING");
1034 : 0 : }
1035 : :
1036 : : /*
1037 : : * XLogReaderRoutine->page_read callback for logical decoding contexts, as a
1038 : : * walsender process.
1039 : : *
1040 : : * Inside the walsender we can do better than read_local_xlog_page,
1041 : : * which has to do a plain sleep/busy loop, because the walsender's latch gets
1042 : : * set every time WAL is flushed.
1043 : : */
1044 : : static int
1045 : 0 : logical_read_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr, int reqLen,
1046 : : XLogRecPtr targetRecPtr, char *cur_page)
1047 : : {
1048 : 0 : XLogRecPtr flushptr;
1049 : 0 : int count;
1050 : 0 : WALReadError errinfo;
1051 : 0 : XLogSegNo segno;
1052 : 0 : TimeLineID currTLI;
1053 : :
1054 : : /*
1055 : : * Make sure we have enough WAL available before retrieving the current
1056 : : * timeline.
1057 : : */
1058 : 0 : flushptr = WalSndWaitForWal(targetPagePtr + reqLen);
1059 : :
1060 : : /* Fail if not enough (implies we are going to shut down) */
1061 [ # # ]: 0 : if (flushptr < targetPagePtr + reqLen)
1062 : 0 : return -1;
1063 : :
1064 : : /*
1065 : : * Since logical decoding is also permitted on a standby server, we need
1066 : : * to check if the server is in recovery to decide how to get the current
1067 : : * timeline ID (so that it also covers the promotion or timeline change
1068 : : * cases). We must determine am_cascading_walsender after waiting for the
1069 : : * required WAL so that it is correct when the walsender wakes up after a
1070 : : * promotion.
1071 : : */
1072 : 0 : am_cascading_walsender = RecoveryInProgress();
1073 : :
1074 [ # # ]: 0 : if (am_cascading_walsender)
1075 : 0 : GetXLogReplayRecPtr(&currTLI);
1076 : : else
1077 : 0 : currTLI = GetWALInsertionTimeLine();
1078 : :
1079 : 0 : XLogReadDetermineTimeline(state, targetPagePtr, reqLen, currTLI);
1080 : 0 : sendTimeLineIsHistoric = (state->currTLI != currTLI);
1081 : 0 : sendTimeLine = state->currTLI;
1082 : 0 : sendTimeLineValidUpto = state->currTLIValidUntil;
1083 : 0 : sendTimeLineNextTLI = state->nextTLI;
1084 : :
1085 [ # # ]: 0 : if (targetPagePtr + XLOG_BLCKSZ <= flushptr)
1086 : 0 : count = XLOG_BLCKSZ; /* more than one block available */
1087 : : else
1088 : 0 : count = flushptr - targetPagePtr; /* part of the page available */
1089 : :
1090 : : /* now actually read the data, we know it's there */
1091 [ # # # # ]: 0 : if (!WALRead(state,
1092 : 0 : cur_page,
1093 : 0 : targetPagePtr,
1094 : 0 : count,
1095 : 0 : currTLI, /* Pass the current TLI because only
1096 : : * WalSndSegmentOpen controls whether new TLI
1097 : : * is needed. */
1098 : : &errinfo))
1099 : 0 : WALReadRaiseError(&errinfo);
1100 : :
1101 : : /*
1102 : : * After reading into the buffer, check that what we read was valid. We do
1103 : : * this after reading, because even though the segment was present when we
1104 : : * opened it, it might get recycled or removed while we read it. The
1105 : : * read() succeeds in that case, but the data we tried to read might
1106 : : * already have been overwritten with new WAL records.
1107 : : */
1108 : 0 : XLByteToSeg(targetPagePtr, segno, state->segcxt.ws_segsize);
1109 : 0 : CheckXLogRemoved(segno, state->seg.ws_tli);
1110 : :
1111 : 0 : return count;
1112 : 0 : }
1113 : :
1114 : : /*
1115 : : * Process extra options given to CREATE_REPLICATION_SLOT.
1116 : : */
1117 : : static void
1118 : 0 : parseCreateReplSlotOptions(CreateReplicationSlotCmd *cmd,
1119 : : bool *reserve_wal,
1120 : : CRSSnapshotAction *snapshot_action,
1121 : : bool *two_phase, bool *failover)
1122 : : {
1123 : 0 : ListCell *lc;
1124 : 0 : bool snapshot_action_given = false;
1125 : 0 : bool reserve_wal_given = false;
1126 : 0 : bool two_phase_given = false;
1127 : 0 : bool failover_given = false;
1128 : :
1129 : : /* Parse options */
1130 [ # # # # : 0 : foreach(lc, cmd->options)
# # ]
1131 : : {
1132 : 0 : DefElem *defel = (DefElem *) lfirst(lc);
1133 : :
1134 [ # # ]: 0 : if (strcmp(defel->defname, "snapshot") == 0)
1135 : : {
1136 : 0 : char *action;
1137 : :
1138 [ # # ]: 0 : if (snapshot_action_given || cmd->kind != REPLICATION_KIND_LOGICAL)
1139 [ # # # # ]: 0 : ereport(ERROR,
1140 : : (errcode(ERRCODE_SYNTAX_ERROR),
1141 : : errmsg("conflicting or redundant options")));
1142 : :
1143 : 0 : action = defGetString(defel);
1144 : 0 : snapshot_action_given = true;
1145 : :
1146 [ # # ]: 0 : if (strcmp(action, "export") == 0)
1147 : 0 : *snapshot_action = CRS_EXPORT_SNAPSHOT;
1148 [ # # ]: 0 : else if (strcmp(action, "nothing") == 0)
1149 : 0 : *snapshot_action = CRS_NOEXPORT_SNAPSHOT;
1150 [ # # ]: 0 : else if (strcmp(action, "use") == 0)
1151 : 0 : *snapshot_action = CRS_USE_SNAPSHOT;
1152 : : else
1153 [ # # # # ]: 0 : ereport(ERROR,
1154 : : (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
1155 : : errmsg("unrecognized value for %s option \"%s\": \"%s\"",
1156 : : "CREATE_REPLICATION_SLOT", defel->defname, action)));
1157 : 0 : }
1158 [ # # ]: 0 : else if (strcmp(defel->defname, "reserve_wal") == 0)
1159 : : {
1160 [ # # ]: 0 : if (reserve_wal_given || cmd->kind != REPLICATION_KIND_PHYSICAL)
1161 [ # # # # ]: 0 : ereport(ERROR,
1162 : : (errcode(ERRCODE_SYNTAX_ERROR),
1163 : : errmsg("conflicting or redundant options")));
1164 : :
1165 : 0 : reserve_wal_given = true;
1166 : 0 : *reserve_wal = defGetBoolean(defel);
1167 : 0 : }
1168 [ # # ]: 0 : else if (strcmp(defel->defname, "two_phase") == 0)
1169 : : {
1170 [ # # ]: 0 : if (two_phase_given || cmd->kind != REPLICATION_KIND_LOGICAL)
1171 [ # # # # ]: 0 : ereport(ERROR,
1172 : : (errcode(ERRCODE_SYNTAX_ERROR),
1173 : : errmsg("conflicting or redundant options")));
1174 : 0 : two_phase_given = true;
1175 : 0 : *two_phase = defGetBoolean(defel);
1176 : 0 : }
1177 [ # # ]: 0 : else if (strcmp(defel->defname, "failover") == 0)
1178 : : {
1179 [ # # ]: 0 : if (failover_given || cmd->kind != REPLICATION_KIND_LOGICAL)
1180 [ # # # # ]: 0 : ereport(ERROR,
1181 : : (errcode(ERRCODE_SYNTAX_ERROR),
1182 : : errmsg("conflicting or redundant options")));
1183 : 0 : failover_given = true;
1184 : 0 : *failover = defGetBoolean(defel);
1185 : 0 : }
1186 : : else
1187 [ # # # # ]: 0 : elog(ERROR, "unrecognized option: %s", defel->defname);
1188 : 0 : }
1189 : 0 : }
1190 : :
1191 : : /*
1192 : : * Create a new replication slot.
1193 : : */
1194 : : static void
1195 : 0 : CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
1196 : : {
1197 : 0 : const char *snapshot_name = NULL;
1198 : 0 : char xloc[MAXFNAMELEN];
1199 : 0 : char *slot_name;
1200 : 0 : bool reserve_wal = false;
1201 : 0 : bool two_phase = false;
1202 : 0 : bool failover = false;
1203 : 0 : CRSSnapshotAction snapshot_action = CRS_EXPORT_SNAPSHOT;
1204 : 0 : DestReceiver *dest;
1205 : 0 : TupOutputState *tstate;
1206 : 0 : TupleDesc tupdesc;
1207 : 0 : Datum values[4];
1208 : 0 : bool nulls[4] = {0};
1209 : :
1210 [ # # ]: 0 : Assert(!MyReplicationSlot);
1211 : :
1212 : 0 : parseCreateReplSlotOptions(cmd, &reserve_wal, &snapshot_action, &two_phase,
1213 : : &failover);
1214 : :
1215 [ # # ]: 0 : if (cmd->kind == REPLICATION_KIND_PHYSICAL)
1216 : : {
1217 : 0 : ReplicationSlotCreate(cmd->slotname, false,
1218 : 0 : cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
1219 : : false, false, false);
1220 : :
1221 [ # # ]: 0 : if (reserve_wal)
1222 : : {
1223 : 0 : ReplicationSlotReserveWal();
1224 : :
1225 : 0 : ReplicationSlotMarkDirty();
1226 : :
1227 : : /* Write this slot to disk if it's a permanent one. */
1228 [ # # ]: 0 : if (!cmd->temporary)
1229 : 0 : ReplicationSlotSave();
1230 : 0 : }
1231 : 0 : }
1232 : : else
1233 : : {
1234 : 0 : LogicalDecodingContext *ctx;
1235 : 0 : bool need_full_snapshot = false;
1236 : :
1237 [ # # ]: 0 : Assert(cmd->kind == REPLICATION_KIND_LOGICAL);
1238 : :
1239 : 0 : CheckLogicalDecodingRequirements();
1240 : :
1241 : : /*
1242 : : * Initially create persistent slot as ephemeral - that allows us to
1243 : : * nicely handle errors during initialization because it'll get
1244 : : * dropped if this transaction fails. We'll make it persistent at the
1245 : : * end. Temporary slots can be created as temporary from beginning as
1246 : : * they get dropped on error as well.
1247 : : */
1248 : 0 : ReplicationSlotCreate(cmd->slotname, true,
1249 : 0 : cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
1250 : 0 : two_phase, failover, false);
1251 : :
1252 : : /*
1253 : : * Do options check early so that we can bail before calling the
1254 : : * DecodingContextFindStartpoint which can take long time.
1255 : : */
1256 [ # # ]: 0 : if (snapshot_action == CRS_EXPORT_SNAPSHOT)
1257 : : {
1258 [ # # ]: 0 : if (IsTransactionBlock())
1259 [ # # # # ]: 0 : ereport(ERROR,
1260 : : /*- translator: %s is a CREATE_REPLICATION_SLOT statement */
1261 : : (errmsg("%s must not be called inside a transaction",
1262 : : "CREATE_REPLICATION_SLOT ... (SNAPSHOT 'export')")));
1263 : :
1264 : 0 : need_full_snapshot = true;
1265 : 0 : }
1266 [ # # ]: 0 : else if (snapshot_action == CRS_USE_SNAPSHOT)
1267 : : {
1268 [ # # ]: 0 : if (!IsTransactionBlock())
1269 [ # # # # ]: 0 : ereport(ERROR,
1270 : : /*- translator: %s is a CREATE_REPLICATION_SLOT statement */
1271 : : (errmsg("%s must be called inside a transaction",
1272 : : "CREATE_REPLICATION_SLOT ... (SNAPSHOT 'use')")));
1273 : :
1274 [ # # ]: 0 : if (XactIsoLevel != XACT_REPEATABLE_READ)
1275 [ # # # # ]: 0 : ereport(ERROR,
1276 : : /*- translator: %s is a CREATE_REPLICATION_SLOT statement */
1277 : : (errmsg("%s must be called in REPEATABLE READ isolation mode transaction",
1278 : : "CREATE_REPLICATION_SLOT ... (SNAPSHOT 'use')")));
1279 [ # # ]: 0 : if (!XactReadOnly)
1280 [ # # # # ]: 0 : ereport(ERROR,
1281 : : /*- translator: %s is a CREATE_REPLICATION_SLOT statement */
1282 : : (errmsg("%s must be called in a read-only transaction",
1283 : : "CREATE_REPLICATION_SLOT ... (SNAPSHOT 'use')")));
1284 : :
1285 [ # # ]: 0 : if (FirstSnapshotSet)
1286 [ # # # # ]: 0 : ereport(ERROR,
1287 : : /*- translator: %s is a CREATE_REPLICATION_SLOT statement */
1288 : : (errmsg("%s must be called before any query",
1289 : : "CREATE_REPLICATION_SLOT ... (SNAPSHOT 'use')")));
1290 : :
1291 [ # # ]: 0 : if (IsSubTransaction())
1292 [ # # # # ]: 0 : ereport(ERROR,
1293 : : /*- translator: %s is a CREATE_REPLICATION_SLOT statement */
1294 : : (errmsg("%s must not be called in a subtransaction",
1295 : : "CREATE_REPLICATION_SLOT ... (SNAPSHOT 'use')")));
1296 : :
1297 : 0 : need_full_snapshot = true;
1298 : 0 : }
1299 : :
1300 : : /*
1301 : : * Ensure the logical decoding is enabled before initializing the
1302 : : * logical decoding context.
1303 : : */
1304 : 0 : EnsureLogicalDecodingEnabled();
1305 [ # # ]: 0 : Assert(IsLogicalDecodingEnabled());
1306 : :
1307 : 0 : ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
1308 : : InvalidXLogRecPtr,
1309 : 0 : XL_ROUTINE(.page_read = logical_read_xlog_page,
1310 : : .segment_open = WalSndSegmentOpen,
1311 : : .segment_close = wal_segment_close),
1312 : : WalSndPrepareWrite, WalSndWriteData,
1313 : : WalSndUpdateProgress);
1314 : :
1315 : : /*
1316 : : * Signal that we don't need the timeout mechanism. We're just
1317 : : * creating the replication slot and don't yet accept feedback
1318 : : * messages or send keepalives. As we possibly need to wait for
1319 : : * further WAL the walsender would otherwise possibly be killed too
1320 : : * soon.
1321 : : */
1322 : 0 : last_reply_timestamp = 0;
1323 : :
1324 : : /* build initial snapshot, might take a while */
1325 : 0 : DecodingContextFindStartpoint(ctx);
1326 : :
1327 : : /*
1328 : : * Export or use the snapshot if we've been asked to do so.
1329 : : *
1330 : : * NB. We will convert the snapbuild.c kind of snapshot to normal
1331 : : * snapshot when doing this.
1332 : : */
1333 [ # # ]: 0 : if (snapshot_action == CRS_EXPORT_SNAPSHOT)
1334 : : {
1335 : 0 : snapshot_name = SnapBuildExportSnapshot(ctx->snapshot_builder);
1336 : 0 : }
1337 [ # # ]: 0 : else if (snapshot_action == CRS_USE_SNAPSHOT)
1338 : : {
1339 : 0 : Snapshot snap;
1340 : :
1341 : 0 : snap = SnapBuildInitialSnapshot(ctx->snapshot_builder);
1342 : 0 : RestoreTransactionSnapshot(snap, MyProc);
1343 : 0 : }
1344 : :
1345 : : /* don't need the decoding context anymore */
1346 : 0 : FreeDecodingContext(ctx);
1347 : :
1348 [ # # ]: 0 : if (!cmd->temporary)
1349 : 0 : ReplicationSlotPersist();
1350 : 0 : }
1351 : :
1352 : 0 : snprintf(xloc, sizeof(xloc), "%X/%08X",
1353 : 0 : LSN_FORMAT_ARGS(MyReplicationSlot->data.confirmed_flush));
1354 : :
1355 : 0 : dest = CreateDestReceiver(DestRemoteSimple);
1356 : :
1357 : : /*----------
1358 : : * Need a tuple descriptor representing four columns:
1359 : : * - first field: the slot name
1360 : : * - second field: LSN at which we became consistent
1361 : : * - third field: exported snapshot's name
1362 : : * - fourth field: output plugin
1363 : : */
1364 : 0 : tupdesc = CreateTemplateTupleDesc(4);
1365 : 0 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, "slot_name",
1366 : : TEXTOID, -1, 0);
1367 : 0 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 2, "consistent_point",
1368 : : TEXTOID, -1, 0);
1369 : 0 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 3, "snapshot_name",
1370 : : TEXTOID, -1, 0);
1371 : 0 : TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 4, "output_plugin",
1372 : : TEXTOID, -1, 0);
1373 : :
1374 : : /* prepare for projection of tuples */
1375 : 0 : tstate = begin_tup_output_tupdesc(dest, tupdesc, &TTSOpsVirtual);
1376 : :
1377 : : /* slot_name */
1378 : 0 : slot_name = NameStr(MyReplicationSlot->data.name);
1379 : 0 : values[0] = CStringGetTextDatum(slot_name);
1380 : :
1381 : : /* consistent wal location */
1382 : 0 : values[1] = CStringGetTextDatum(xloc);
1383 : :
1384 : : /* snapshot name, or NULL if none */
1385 [ # # ]: 0 : if (snapshot_name != NULL)
1386 : 0 : values[2] = CStringGetTextDatum(snapshot_name);
1387 : : else
1388 : 0 : nulls[2] = true;
1389 : :
1390 : : /* plugin, or NULL if none */
1391 [ # # ]: 0 : if (cmd->plugin != NULL)
1392 : 0 : values[3] = CStringGetTextDatum(cmd->plugin);
1393 : : else
1394 : 0 : nulls[3] = true;
1395 : :
1396 : : /* send it to dest */
1397 : 0 : do_tup_output(tstate, values, nulls);
1398 : 0 : end_tup_output(tstate);
1399 : :
1400 : 0 : ReplicationSlotRelease();
1401 : 0 : }
1402 : :
1403 : : /*
1404 : : * Get rid of a replication slot that is no longer wanted.
1405 : : */
1406 : : static void
1407 : 0 : DropReplicationSlot(DropReplicationSlotCmd *cmd)
1408 : : {
1409 : 0 : ReplicationSlotDrop(cmd->slotname, !cmd->wait);
1410 : 0 : }
1411 : :
1412 : : /*
1413 : : * Change the definition of a replication slot.
1414 : : */
1415 : : static void
1416 : 0 : AlterReplicationSlot(AlterReplicationSlotCmd *cmd)
1417 : : {
1418 : 0 : bool failover_given = false;
1419 : 0 : bool two_phase_given = false;
1420 : 0 : bool failover;
1421 : 0 : bool two_phase;
1422 : :
1423 : : /* Parse options */
1424 [ # # # # : 0 : foreach_ptr(DefElem, defel, cmd->options)
# # # # ]
1425 : : {
1426 [ # # ]: 0 : if (strcmp(defel->defname, "failover") == 0)
1427 : : {
1428 [ # # ]: 0 : if (failover_given)
1429 [ # # # # ]: 0 : ereport(ERROR,
1430 : : (errcode(ERRCODE_SYNTAX_ERROR),
1431 : : errmsg("conflicting or redundant options")));
1432 : 0 : failover_given = true;
1433 : 0 : failover = defGetBoolean(defel);
1434 : 0 : }
1435 [ # # ]: 0 : else if (strcmp(defel->defname, "two_phase") == 0)
1436 : : {
1437 [ # # ]: 0 : if (two_phase_given)
1438 [ # # # # ]: 0 : ereport(ERROR,
1439 : : (errcode(ERRCODE_SYNTAX_ERROR),
1440 : : errmsg("conflicting or redundant options")));
1441 : 0 : two_phase_given = true;
1442 : 0 : two_phase = defGetBoolean(defel);
1443 : 0 : }
1444 : : else
1445 [ # # # # ]: 0 : elog(ERROR, "unrecognized option: %s", defel->defname);
1446 : 0 : }
1447 : :
1448 : 0 : ReplicationSlotAlter(cmd->slotname,
1449 [ # # ]: 0 : failover_given ? &failover : NULL,
1450 [ # # ]: 0 : two_phase_given ? &two_phase : NULL);
1451 : 0 : }
1452 : :
1453 : : /*
1454 : : * Load previously initiated logical slot and prepare for sending data (via
1455 : : * WalSndLoop).
1456 : : */
1457 : : static void
1458 : 0 : StartLogicalReplication(StartReplicationCmd *cmd)
1459 : : {
1460 : 0 : StringInfoData buf;
1461 : 0 : QueryCompletion qc;
1462 : :
1463 : : /* make sure that our requirements are still fulfilled */
1464 : 0 : CheckLogicalDecodingRequirements();
1465 : :
1466 [ # # ]: 0 : Assert(!MyReplicationSlot);
1467 : :
1468 : 0 : ReplicationSlotAcquire(cmd->slotname, true, true);
1469 : :
1470 : : /*
1471 : : * Force a disconnect, so that the decoding code doesn't need to care
1472 : : * about an eventual switch from running in recovery, to running in a
1473 : : * normal environment. Client code is expected to handle reconnects.
1474 : : */
1475 [ # # # # ]: 0 : if (am_cascading_walsender && !RecoveryInProgress())
1476 : : {
1477 [ # # # # ]: 0 : ereport(LOG,
1478 : : (errmsg("terminating walsender process after promotion")));
1479 : 0 : got_STOPPING = true;
1480 : 0 : }
1481 : :
1482 : : /*
1483 : : * Create our decoding context, making it start at the previously ack'ed
1484 : : * position.
1485 : : *
1486 : : * Do this before sending a CopyBothResponse message, so that any errors
1487 : : * are reported early.
1488 : : */
1489 : 0 : logical_decoding_ctx =
1490 : 0 : CreateDecodingContext(cmd->startpoint, cmd->options, false,
1491 : 0 : XL_ROUTINE(.page_read = logical_read_xlog_page,
1492 : : .segment_open = WalSndSegmentOpen,
1493 : : .segment_close = wal_segment_close),
1494 : : WalSndPrepareWrite, WalSndWriteData,
1495 : : WalSndUpdateProgress);
1496 : 0 : xlogreader = logical_decoding_ctx->reader;
1497 : :
1498 : 0 : WalSndSetState(WALSNDSTATE_CATCHUP);
1499 : :
1500 : : /* Send a CopyBothResponse message, and start streaming */
1501 : 0 : pq_beginmessage(&buf, PqMsg_CopyBothResponse);
1502 : 0 : pq_sendbyte(&buf, 0);
1503 : 0 : pq_sendint16(&buf, 0);
1504 : 0 : pq_endmessage(&buf);
1505 : 0 : pq_flush();
1506 : :
1507 : : /* Start reading WAL from the oldest required WAL. */
1508 : 0 : XLogBeginRead(logical_decoding_ctx->reader,
1509 : 0 : MyReplicationSlot->data.restart_lsn);
1510 : :
1511 : : /*
1512 : : * Report the location after which we'll send out further commits as the
1513 : : * current sentPtr.
1514 : : */
1515 : 0 : sentPtr = MyReplicationSlot->data.confirmed_flush;
1516 : :
1517 : : /* Also update the sent position status in shared memory */
1518 [ # # ]: 0 : SpinLockAcquire(&MyWalSnd->mutex);
1519 : 0 : MyWalSnd->sentPtr = MyReplicationSlot->data.restart_lsn;
1520 : 0 : SpinLockRelease(&MyWalSnd->mutex);
1521 : :
1522 : 0 : replication_active = true;
1523 : :
1524 : 0 : SyncRepInitConfig();
1525 : :
1526 : : /* Main loop of walsender */
1527 : 0 : WalSndLoop(XLogSendLogical);
1528 : :
1529 : 0 : FreeDecodingContext(logical_decoding_ctx);
1530 : 0 : ReplicationSlotRelease();
1531 : :
1532 : 0 : replication_active = false;
1533 [ # # ]: 0 : if (got_STOPPING)
1534 : 0 : proc_exit(0);
1535 : 0 : WalSndSetState(WALSNDSTATE_STARTUP);
1536 : :
1537 : : /* Get out of COPY mode (CommandComplete). */
1538 : 0 : SetQueryCompletion(&qc, CMDTAG_COPY, 0);
1539 : 0 : EndCommand(&qc, DestRemote, false);
1540 : 0 : }
1541 : :
1542 : : /*
1543 : : * LogicalDecodingContext 'prepare_write' callback.
1544 : : *
1545 : : * Prepare a write into a StringInfo.
1546 : : *
1547 : : * Don't do anything lasting in here, it's quite possible that nothing will be done
1548 : : * with the data.
1549 : : */
1550 : : static void
1551 : 0 : WalSndPrepareWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid, bool last_write)
1552 : : {
1553 : : /* can't have sync rep confused by sending the same LSN several times */
1554 [ # # ]: 0 : if (!last_write)
1555 : 0 : lsn = InvalidXLogRecPtr;
1556 : :
1557 : 0 : resetStringInfo(ctx->out);
1558 : :
1559 : 0 : pq_sendbyte(ctx->out, PqReplMsg_WALData);
1560 : 0 : pq_sendint64(ctx->out, lsn); /* dataStart */
1561 : 0 : pq_sendint64(ctx->out, lsn); /* walEnd */
1562 : :
1563 : : /*
1564 : : * Fill out the sendtime later, just as it's done in XLogSendPhysical, but
1565 : : * reserve space here.
1566 : : */
1567 : 0 : pq_sendint64(ctx->out, 0); /* sendtime */
1568 : 0 : }
1569 : :
1570 : : /*
1571 : : * LogicalDecodingContext 'write' callback.
1572 : : *
1573 : : * Actually write out data previously prepared by WalSndPrepareWrite out to
1574 : : * the network. Take as long as needed, but process replies from the other
1575 : : * side and check timeouts during that.
1576 : : */
1577 : : static void
1578 : 0 : WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
1579 : : bool last_write)
1580 : : {
1581 : 0 : TimestampTz now;
1582 : :
1583 : : /*
1584 : : * Fill the send timestamp last, so that it is taken as late as possible.
1585 : : * This is somewhat ugly, but the protocol is set as it's already used for
1586 : : * several releases by streaming physical replication.
1587 : : */
1588 : 0 : resetStringInfo(&tmpbuf);
1589 : 0 : now = GetCurrentTimestamp();
1590 : 0 : pq_sendint64(&tmpbuf, now);
1591 : 0 : memcpy(&ctx->out->data[1 + sizeof(int64) + sizeof(int64)],
1592 : : tmpbuf.data, sizeof(int64));
1593 : :
1594 : : /* output previously gathered data in a CopyData packet */
1595 : 0 : pq_putmessage_noblock(PqMsg_CopyData, ctx->out->data, ctx->out->len);
1596 : :
1597 [ # # ]: 0 : CHECK_FOR_INTERRUPTS();
1598 : :
1599 : : /* Try to flush pending output to the client */
1600 [ # # ]: 0 : if (pq_flush_if_writable() != 0)
1601 : 0 : WalSndShutdown();
1602 : :
1603 : : /* Try taking fast path unless we get too close to walsender timeout. */
1604 : 0 : if (now < TimestampTzPlusMilliseconds(last_reply_timestamp,
1605 [ # # # # ]: 0 : wal_sender_timeout / 2) &&
1606 : 0 : !pq_is_send_pending())
1607 : : {
1608 : 0 : return;
1609 : : }
1610 : :
1611 : : /* If we have pending write here, go to slow path */
1612 : 0 : ProcessPendingWrites();
1613 [ # # ]: 0 : }
1614 : :
1615 : : /*
1616 : : * Wait until there is no pending write. Also process replies from the other
1617 : : * side and check timeouts during that.
1618 : : */
1619 : : static void
1620 : 0 : ProcessPendingWrites(void)
1621 : : {
1622 : 0 : for (;;)
1623 : : {
1624 : 0 : long sleeptime;
1625 : :
1626 : : /* Check for input from the client */
1627 : 0 : ProcessRepliesIfAny();
1628 : :
1629 : : /* die if timeout was reached */
1630 : 0 : WalSndCheckTimeOut();
1631 : :
1632 : : /* Send keepalive if the time has come */
1633 : 0 : WalSndKeepaliveIfNecessary();
1634 : :
1635 [ # # ]: 0 : if (!pq_is_send_pending())
1636 : 0 : break;
1637 : :
1638 : 0 : sleeptime = WalSndComputeSleeptime(GetCurrentTimestamp());
1639 : :
1640 : : /* Sleep until something happens or we time out */
1641 : 0 : WalSndWait(WL_SOCKET_WRITEABLE | WL_SOCKET_READABLE, sleeptime,
1642 : : WAIT_EVENT_WAL_SENDER_WRITE_DATA);
1643 : :
1644 : : /* Clear any already-pending wakeups */
1645 : 0 : ResetLatch(MyLatch);
1646 : :
1647 [ # # ]: 0 : CHECK_FOR_INTERRUPTS();
1648 : :
1649 : : /* Process any requests or signals received recently */
1650 [ # # ]: 0 : if (ConfigReloadPending)
1651 : : {
1652 : 0 : ConfigReloadPending = false;
1653 : 0 : ProcessConfigFile(PGC_SIGHUP);
1654 : 0 : SyncRepInitConfig();
1655 : 0 : }
1656 : :
1657 : : /* Try to flush pending output to the client */
1658 [ # # ]: 0 : if (pq_flush_if_writable() != 0)
1659 : 0 : WalSndShutdown();
1660 [ # # # ]: 0 : }
1661 : :
1662 : : /* reactivate latch so WalSndLoop knows to continue */
1663 : 0 : SetLatch(MyLatch);
1664 : 0 : }
1665 : :
1666 : : /*
1667 : : * LogicalDecodingContext 'update_progress' callback.
1668 : : *
1669 : : * Write the current position to the lag tracker (see XLogSendPhysical).
1670 : : *
1671 : : * When skipping empty transactions, send a keepalive message if necessary.
1672 : : */
1673 : : static void
1674 : 0 : WalSndUpdateProgress(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
1675 : : bool skipped_xact)
1676 : : {
1677 : : static TimestampTz sendTime = 0;
1678 : 0 : TimestampTz now = GetCurrentTimestamp();
1679 : 0 : bool pending_writes = false;
1680 : 0 : bool end_xact = ctx->end_xact;
1681 : :
1682 : : /*
1683 : : * Track lag no more than once per WALSND_LOGICAL_LAG_TRACK_INTERVAL_MS to
1684 : : * avoid flooding the lag tracker when we commit frequently.
1685 : : *
1686 : : * We don't have a mechanism to get the ack for any LSN other than end
1687 : : * xact LSN from the downstream. So, we track lag only for end of
1688 : : * transaction LSN.
1689 : : */
1690 : : #define WALSND_LOGICAL_LAG_TRACK_INTERVAL_MS 1000
1691 [ # # # # ]: 0 : if (end_xact && TimestampDifferenceExceeds(sendTime, now,
1692 : : WALSND_LOGICAL_LAG_TRACK_INTERVAL_MS))
1693 : : {
1694 : 0 : LagTrackerWrite(lsn, now);
1695 : 0 : sendTime = now;
1696 : 0 : }
1697 : :
1698 : : /*
1699 : : * When skipping empty transactions in synchronous replication, we send a
1700 : : * keepalive message to avoid delaying such transactions.
1701 : : *
1702 : : * It is okay to check sync_standbys_status without lock here as in the
1703 : : * worst case we will just send an extra keepalive message when it is
1704 : : * really not required.
1705 : : */
1706 [ # # ]: 0 : if (skipped_xact &&
1707 [ # # # # : 0 : SyncRepRequested() &&
# # ]
1708 : 0 : (((volatile WalSndCtlData *) WalSndCtl)->sync_standbys_status & SYNC_STANDBY_DEFINED))
1709 : : {
1710 : 0 : WalSndKeepalive(false, lsn);
1711 : :
1712 : : /* Try to flush pending output to the client */
1713 [ # # ]: 0 : if (pq_flush_if_writable() != 0)
1714 : 0 : WalSndShutdown();
1715 : :
1716 : : /* If we have pending write here, make sure it's actually flushed */
1717 [ # # ]: 0 : if (pq_is_send_pending())
1718 : 0 : pending_writes = true;
1719 : 0 : }
1720 : :
1721 : : /*
1722 : : * Process pending writes if any or try to send a keepalive if required.
1723 : : * We don't need to try sending keep alive messages at the transaction end
1724 : : * as that will be done at a later point in time. This is required only
1725 : : * for large transactions where we don't send any changes to the
1726 : : * downstream and the receiver can timeout due to that.
1727 : : */
1728 [ # # # # : 0 : if (pending_writes || (!end_xact &&
# # ]
1729 : 0 : now >= TimestampTzPlusMilliseconds(last_reply_timestamp,
1730 : : wal_sender_timeout / 2)))
1731 : 0 : ProcessPendingWrites();
1732 : 0 : }
1733 : :
1734 : : /*
1735 : : * Wake up the logical walsender processes with logical failover slots if the
1736 : : * currently acquired physical slot is specified in synchronized_standby_slots GUC.
1737 : : */
1738 : : void
1739 : 0 : PhysicalWakeupLogicalWalSnd(void)
1740 : : {
1741 [ # # ]: 0 : Assert(MyReplicationSlot && SlotIsPhysical(MyReplicationSlot));
1742 : :
1743 : : /*
1744 : : * If we are running in a standby, there is no need to wake up walsenders.
1745 : : * This is because we do not support syncing slots to cascading standbys,
1746 : : * so, there are no walsenders waiting for standbys to catch up.
1747 : : */
1748 [ # # ]: 0 : if (RecoveryInProgress())
1749 : 0 : return;
1750 : :
1751 [ # # ]: 0 : if (SlotExistsInSyncStandbySlots(NameStr(MyReplicationSlot->data.name)))
1752 : 0 : ConditionVariableBroadcast(&WalSndCtl->wal_confirm_rcv_cv);
1753 : 0 : }
1754 : :
1755 : : /*
1756 : : * Returns true if not all standbys have caught up to the flushed position
1757 : : * (flushed_lsn) when the current acquired slot is a logical failover
1758 : : * slot and we are streaming; otherwise, returns false.
1759 : : *
1760 : : * If returning true, the function sets the appropriate wait event in
1761 : : * wait_event; otherwise, wait_event is set to 0.
1762 : : */
1763 : : static bool
1764 : 0 : NeedToWaitForStandbys(XLogRecPtr flushed_lsn, uint32 *wait_event)
1765 : : {
1766 : 0 : int elevel = got_STOPPING ? ERROR : WARNING;
1767 : 0 : bool failover_slot;
1768 : :
1769 [ # # ]: 0 : failover_slot = (replication_active && MyReplicationSlot->data.failover);
1770 : :
1771 : : /*
1772 : : * Note that after receiving the shutdown signal, an ERROR is reported if
1773 : : * any slots are dropped, invalidated, or inactive. This measure is taken
1774 : : * to prevent the walsender from waiting indefinitely.
1775 : : */
1776 [ # # # # ]: 0 : if (failover_slot && !StandbySlotsHaveCaughtup(flushed_lsn, elevel))
1777 : : {
1778 : 0 : *wait_event = WAIT_EVENT_WAIT_FOR_STANDBY_CONFIRMATION;
1779 : 0 : return true;
1780 : : }
1781 : :
1782 : 0 : *wait_event = 0;
1783 : 0 : return false;
1784 : 0 : }
1785 : :
1786 : : /*
1787 : : * Returns true if we need to wait for WALs to be flushed to disk, or if not
1788 : : * all standbys have caught up to the flushed position (flushed_lsn) when the
1789 : : * current acquired slot is a logical failover slot and we are
1790 : : * streaming; otherwise, returns false.
1791 : : *
1792 : : * If returning true, the function sets the appropriate wait event in
1793 : : * wait_event; otherwise, wait_event is set to 0.
1794 : : */
1795 : : static bool
1796 : 0 : NeedToWaitForWal(XLogRecPtr target_lsn, XLogRecPtr flushed_lsn,
1797 : : uint32 *wait_event)
1798 : : {
1799 : : /* Check if we need to wait for WALs to be flushed to disk */
1800 [ # # ]: 0 : if (target_lsn > flushed_lsn)
1801 : : {
1802 : 0 : *wait_event = WAIT_EVENT_WAL_SENDER_WAIT_FOR_WAL;
1803 : 0 : return true;
1804 : : }
1805 : :
1806 : : /* Check if the standby slots have caught up to the flushed position */
1807 : 0 : return NeedToWaitForStandbys(flushed_lsn, wait_event);
1808 : 0 : }
1809 : :
1810 : : /*
1811 : : * Wait till WAL < loc is flushed to disk so it can be safely sent to client.
1812 : : *
1813 : : * If the walsender holds a logical failover slot, we also wait for all the
1814 : : * specified streaming replication standby servers to confirm receipt of WAL
1815 : : * up to RecentFlushPtr. It is beneficial to wait here for the confirmation
1816 : : * up to RecentFlushPtr rather than waiting before transmitting each change
1817 : : * to logical subscribers, which is already covered by RecentFlushPtr.
1818 : : *
1819 : : * Returns end LSN of flushed WAL. Normally this will be >= loc, but if we
1820 : : * detect a shutdown request (either from postmaster or client) we will return
1821 : : * early, so caller must always check.
1822 : : */
1823 : : static XLogRecPtr
1824 : 0 : WalSndWaitForWal(XLogRecPtr loc)
1825 : : {
1826 : 0 : int wakeEvents;
1827 : 0 : uint32 wait_event = 0;
1828 : : static XLogRecPtr RecentFlushPtr = InvalidXLogRecPtr;
1829 : 0 : TimestampTz last_flush = 0;
1830 : :
1831 : : /*
1832 : : * Fast path to avoid acquiring the spinlock in case we already know we
1833 : : * have enough WAL available and all the standby servers have confirmed
1834 : : * receipt of WAL up to RecentFlushPtr. This is particularly interesting
1835 : : * if we're far behind.
1836 : : */
1837 [ # # # # ]: 0 : if (XLogRecPtrIsValid(RecentFlushPtr) &&
1838 : 0 : !NeedToWaitForWal(loc, RecentFlushPtr, &wait_event))
1839 : 0 : return RecentFlushPtr;
1840 : :
1841 : : /*
1842 : : * Within the loop, we wait for the necessary WALs to be flushed to disk
1843 : : * first, followed by waiting for standbys to catch up if there are enough
1844 : : * WALs (see NeedToWaitForWal()) or upon receiving the shutdown signal.
1845 : : */
1846 : 0 : for (;;)
1847 : : {
1848 : 0 : bool wait_for_standby_at_stop = false;
1849 : 0 : long sleeptime;
1850 : 0 : TimestampTz now;
1851 : :
1852 : : /* Clear any already-pending wakeups */
1853 : 0 : ResetLatch(MyLatch);
1854 : :
1855 [ # # ]: 0 : CHECK_FOR_INTERRUPTS();
1856 : :
1857 : : /* Process any requests or signals received recently */
1858 [ # # ]: 0 : if (ConfigReloadPending)
1859 : : {
1860 : 0 : ConfigReloadPending = false;
1861 : 0 : ProcessConfigFile(PGC_SIGHUP);
1862 : 0 : SyncRepInitConfig();
1863 : 0 : }
1864 : :
1865 : : /* Check for input from the client */
1866 : 0 : ProcessRepliesIfAny();
1867 : :
1868 : : /*
1869 : : * If we're shutting down, trigger pending WAL to be written out,
1870 : : * otherwise we'd possibly end up waiting for WAL that never gets
1871 : : * written, because walwriter has shut down already.
1872 : : */
1873 [ # # ]: 0 : if (got_STOPPING)
1874 : 0 : XLogBackgroundFlush();
1875 : :
1876 : : /*
1877 : : * To avoid the scenario where standbys need to catch up to a newer
1878 : : * WAL location in each iteration, we update our idea of the currently
1879 : : * flushed position only if we are not waiting for standbys to catch
1880 : : * up.
1881 : : */
1882 [ # # ]: 0 : if (wait_event != WAIT_EVENT_WAIT_FOR_STANDBY_CONFIRMATION)
1883 : : {
1884 [ # # ]: 0 : if (!RecoveryInProgress())
1885 : 0 : RecentFlushPtr = GetFlushRecPtr(NULL);
1886 : : else
1887 : 0 : RecentFlushPtr = GetXLogReplayRecPtr(NULL);
1888 : 0 : }
1889 : :
1890 : : /*
1891 : : * If postmaster asked us to stop and the standby slots have caught up
1892 : : * to the flushed position, don't wait anymore.
1893 : : *
1894 : : * It's important to do this check after the recomputation of
1895 : : * RecentFlushPtr, so we can send all remaining data before shutting
1896 : : * down.
1897 : : */
1898 [ # # ]: 0 : if (got_STOPPING)
1899 : : {
1900 [ # # ]: 0 : if (NeedToWaitForStandbys(RecentFlushPtr, &wait_event))
1901 : 0 : wait_for_standby_at_stop = true;
1902 : : else
1903 : 0 : break;
1904 : 0 : }
1905 : :
1906 : : /*
1907 : : * We only send regular messages to the client for full decoded
1908 : : * transactions, but a synchronous replication and walsender shutdown
1909 : : * possibly are waiting for a later location. So, before sleeping, we
1910 : : * send a ping containing the flush location. If the receiver is
1911 : : * otherwise idle, this keepalive will trigger a reply. Processing the
1912 : : * reply will update these MyWalSnd locations.
1913 : : */
1914 [ # # ]: 0 : if (MyWalSnd->flush < sentPtr &&
1915 [ # # # # ]: 0 : MyWalSnd->write < sentPtr &&
1916 : 0 : !waiting_for_ping_response)
1917 : 0 : WalSndKeepalive(false, InvalidXLogRecPtr);
1918 : :
1919 : : /*
1920 : : * Exit the loop if already caught up and doesn't need to wait for
1921 : : * standby slots.
1922 : : */
1923 [ # # # # ]: 0 : if (!wait_for_standby_at_stop &&
1924 : 0 : !NeedToWaitForWal(loc, RecentFlushPtr, &wait_event))
1925 : 0 : break;
1926 : :
1927 : : /*
1928 : : * Waiting for new WAL or waiting for standbys to catch up. Since we
1929 : : * need to wait, we're now caught up.
1930 : : */
1931 : 0 : WalSndCaughtUp = true;
1932 : :
1933 : : /*
1934 : : * Try to flush any pending output to the client.
1935 : : */
1936 [ # # ]: 0 : if (pq_flush_if_writable() != 0)
1937 : 0 : WalSndShutdown();
1938 : :
1939 : : /*
1940 : : * If we have received CopyDone from the client, sent CopyDone
1941 : : * ourselves, and the output buffer is empty, it's time to exit
1942 : : * streaming, so fail the current WAL fetch request.
1943 : : */
1944 [ # # # # : 0 : if (streamingDoneReceiving && streamingDoneSending &&
# # ]
1945 : 0 : !pq_is_send_pending())
1946 : 0 : break;
1947 : :
1948 : : /* die if timeout was reached */
1949 : 0 : WalSndCheckTimeOut();
1950 : :
1951 : : /* Send keepalive if the time has come */
1952 : 0 : WalSndKeepaliveIfNecessary();
1953 : :
1954 : : /*
1955 : : * Sleep until something happens or we time out. Also wait for the
1956 : : * socket becoming writable, if there's still pending output.
1957 : : * Otherwise we might sit on sendable output data while waiting for
1958 : : * new WAL to be generated. (But if we have nothing to send, we don't
1959 : : * want to wake on socket-writable.)
1960 : : */
1961 : 0 : now = GetCurrentTimestamp();
1962 : 0 : sleeptime = WalSndComputeSleeptime(now);
1963 : :
1964 : 0 : wakeEvents = WL_SOCKET_READABLE;
1965 : :
1966 [ # # ]: 0 : if (pq_is_send_pending())
1967 : 0 : wakeEvents |= WL_SOCKET_WRITEABLE;
1968 : :
1969 [ # # ]: 0 : Assert(wait_event != 0);
1970 : :
1971 : : /* Report IO statistics, if needed */
1972 [ # # ]: 0 : if (TimestampDifferenceExceeds(last_flush, now,
1973 : : WALSENDER_STATS_FLUSH_INTERVAL))
1974 : : {
1975 : 0 : pgstat_flush_io(false);
1976 : 0 : (void) pgstat_flush_backend(false, PGSTAT_BACKEND_FLUSH_IO);
1977 : 0 : last_flush = now;
1978 : 0 : }
1979 : :
1980 : 0 : WalSndWait(wakeEvents, sleeptime, wait_event);
1981 [ # # # ]: 0 : }
1982 : :
1983 : : /* reactivate latch so WalSndLoop knows to continue */
1984 : 0 : SetLatch(MyLatch);
1985 : 0 : return RecentFlushPtr;
1986 : 0 : }
1987 : :
1988 : : /*
1989 : : * Execute an incoming replication command.
1990 : : *
1991 : : * Returns true if the cmd_string was recognized as WalSender command, false
1992 : : * if not.
1993 : : */
1994 : : bool
1995 : 0 : exec_replication_command(const char *cmd_string)
1996 : : {
1997 : 0 : yyscan_t scanner;
1998 : 0 : int parse_rc;
1999 : 0 : Node *cmd_node;
2000 : 0 : const char *cmdtag;
2001 : 0 : MemoryContext old_context = CurrentMemoryContext;
2002 : :
2003 : : /* We save and re-use the cmd_context across calls */
2004 : : static MemoryContext cmd_context = NULL;
2005 : :
2006 : : /*
2007 : : * If WAL sender has been told that shutdown is getting close, switch its
2008 : : * status accordingly to handle the next replication commands correctly.
2009 : : */
2010 [ # # ]: 0 : if (got_STOPPING)
2011 : 0 : WalSndSetState(WALSNDSTATE_STOPPING);
2012 : :
2013 : : /*
2014 : : * Throw error if in stopping mode. We need prevent commands that could
2015 : : * generate WAL while the shutdown checkpoint is being written. To be
2016 : : * safe, we just prohibit all new commands.
2017 : : */
2018 [ # # ]: 0 : if (MyWalSnd->state == WALSNDSTATE_STOPPING)
2019 [ # # # # ]: 0 : ereport(ERROR,
2020 : : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
2021 : : errmsg("cannot execute new commands while WAL sender is in stopping mode")));
2022 : :
2023 : : /*
2024 : : * CREATE_REPLICATION_SLOT ... LOGICAL exports a snapshot until the next
2025 : : * command arrives. Clean up the old stuff if there's anything.
2026 : : */
2027 : 0 : SnapBuildClearExportedSnapshot();
2028 : :
2029 [ # # ]: 0 : CHECK_FOR_INTERRUPTS();
2030 : :
2031 : : /*
2032 : : * Prepare to parse and execute the command.
2033 : : *
2034 : : * Because replication command execution can involve beginning or ending
2035 : : * transactions, we need a working context that will survive that, so we
2036 : : * make it a child of TopMemoryContext. That in turn creates a hazard of
2037 : : * long-lived memory leaks if we lose track of the working context. We
2038 : : * deal with that by creating it only once per walsender, and resetting it
2039 : : * for each new command. (Normally this reset is a no-op, but if the
2040 : : * prior exec_replication_command call failed with an error, it won't be.)
2041 : : *
2042 : : * This is subtler than it looks. The transactions we manage can extend
2043 : : * across replication commands, indeed SnapBuildClearExportedSnapshot
2044 : : * might have just ended one. Because transaction exit will revert to the
2045 : : * memory context that was current at transaction start, we need to be
2046 : : * sure that that context is still valid. That motivates re-using the
2047 : : * same cmd_context rather than making a new one each time.
2048 : : */
2049 [ # # ]: 0 : if (cmd_context == NULL)
2050 : 0 : cmd_context = AllocSetContextCreate(TopMemoryContext,
2051 : : "Replication command context",
2052 : : ALLOCSET_DEFAULT_SIZES);
2053 : : else
2054 : 0 : MemoryContextReset(cmd_context);
2055 : :
2056 : 0 : MemoryContextSwitchTo(cmd_context);
2057 : :
2058 : 0 : replication_scanner_init(cmd_string, &scanner);
2059 : :
2060 : : /*
2061 : : * Is it a WalSender command?
2062 : : */
2063 [ # # ]: 0 : if (!replication_scanner_is_replication_command(scanner))
2064 : : {
2065 : : /* Nope; clean up and get out. */
2066 : 0 : replication_scanner_finish(scanner);
2067 : :
2068 : 0 : MemoryContextSwitchTo(old_context);
2069 : 0 : MemoryContextReset(cmd_context);
2070 : :
2071 : : /* XXX this is a pretty random place to make this check */
2072 [ # # ]: 0 : if (MyDatabaseId == InvalidOid)
2073 [ # # # # ]: 0 : ereport(ERROR,
2074 : : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
2075 : : errmsg("cannot execute SQL commands in WAL sender for physical replication")));
2076 : :
2077 : : /* Tell the caller that this wasn't a WalSender command. */
2078 : 0 : return false;
2079 : : }
2080 : :
2081 : : /*
2082 : : * Looks like a WalSender command, so parse it.
2083 : : */
2084 : 0 : parse_rc = replication_yyparse(&cmd_node, scanner);
2085 [ # # ]: 0 : if (parse_rc != 0)
2086 [ # # # # ]: 0 : ereport(ERROR,
2087 : : (errcode(ERRCODE_SYNTAX_ERROR),
2088 : : errmsg_internal("replication command parser returned %d",
2089 : : parse_rc)));
2090 : 0 : replication_scanner_finish(scanner);
2091 : :
2092 : : /*
2093 : : * Report query to various monitoring facilities. For this purpose, we
2094 : : * report replication commands just like SQL commands.
2095 : : */
2096 : 0 : debug_query_string = cmd_string;
2097 : :
2098 : 0 : pgstat_report_activity(STATE_RUNNING, cmd_string);
2099 : :
2100 : : /*
2101 : : * Log replication command if log_replication_commands is enabled. Even
2102 : : * when it's disabled, log the command with DEBUG1 level for backward
2103 : : * compatibility.
2104 : : */
2105 [ # # # # : 0 : ereport(log_replication_commands ? LOG : DEBUG1,
# # # # #
# ]
2106 : : (errmsg("received replication command: %s", cmd_string)));
2107 : :
2108 : : /*
2109 : : * Disallow replication commands in aborted transaction blocks.
2110 : : */
2111 [ # # ]: 0 : if (IsAbortedTransactionBlockState())
2112 [ # # # # ]: 0 : ereport(ERROR,
2113 : : (errcode(ERRCODE_IN_FAILED_SQL_TRANSACTION),
2114 : : errmsg("current transaction is aborted, "
2115 : : "commands ignored until end of transaction block")));
2116 : :
2117 [ # # ]: 0 : CHECK_FOR_INTERRUPTS();
2118 : :
2119 : : /*
2120 : : * Allocate buffers that will be used for each outgoing and incoming
2121 : : * message. We do this just once per command to reduce palloc overhead.
2122 : : */
2123 : 0 : initStringInfo(&output_message);
2124 : 0 : initStringInfo(&reply_message);
2125 : 0 : initStringInfo(&tmpbuf);
2126 : :
2127 [ # # # # : 0 : switch (cmd_node->type)
# # # # #
# # ]
2128 : : {
2129 : : case T_IdentifySystemCmd:
2130 : 0 : cmdtag = "IDENTIFY_SYSTEM";
2131 : 0 : set_ps_display(cmdtag);
2132 : 0 : IdentifySystem();
2133 : 0 : EndReplicationCommand(cmdtag);
2134 : 0 : break;
2135 : :
2136 : : case T_ReadReplicationSlotCmd:
2137 : 0 : cmdtag = "READ_REPLICATION_SLOT";
2138 : 0 : set_ps_display(cmdtag);
2139 : 0 : ReadReplicationSlot((ReadReplicationSlotCmd *) cmd_node);
2140 : 0 : EndReplicationCommand(cmdtag);
2141 : 0 : break;
2142 : :
2143 : : case T_BaseBackupCmd:
2144 : 0 : cmdtag = "BASE_BACKUP";
2145 : 0 : set_ps_display(cmdtag);
2146 : 0 : PreventInTransactionBlock(true, cmdtag);
2147 : 0 : SendBaseBackup((BaseBackupCmd *) cmd_node, uploaded_manifest);
2148 : 0 : EndReplicationCommand(cmdtag);
2149 : 0 : break;
2150 : :
2151 : : case T_CreateReplicationSlotCmd:
2152 : 0 : cmdtag = "CREATE_REPLICATION_SLOT";
2153 : 0 : set_ps_display(cmdtag);
2154 : 0 : CreateReplicationSlot((CreateReplicationSlotCmd *) cmd_node);
2155 : 0 : EndReplicationCommand(cmdtag);
2156 : 0 : break;
2157 : :
2158 : : case T_DropReplicationSlotCmd:
2159 : 0 : cmdtag = "DROP_REPLICATION_SLOT";
2160 : 0 : set_ps_display(cmdtag);
2161 : 0 : DropReplicationSlot((DropReplicationSlotCmd *) cmd_node);
2162 : 0 : EndReplicationCommand(cmdtag);
2163 : 0 : break;
2164 : :
2165 : : case T_AlterReplicationSlotCmd:
2166 : 0 : cmdtag = "ALTER_REPLICATION_SLOT";
2167 : 0 : set_ps_display(cmdtag);
2168 : 0 : AlterReplicationSlot((AlterReplicationSlotCmd *) cmd_node);
2169 : 0 : EndReplicationCommand(cmdtag);
2170 : 0 : break;
2171 : :
2172 : : case T_StartReplicationCmd:
2173 : : {
2174 : 0 : StartReplicationCmd *cmd = (StartReplicationCmd *) cmd_node;
2175 : :
2176 : 0 : cmdtag = "START_REPLICATION";
2177 : 0 : set_ps_display(cmdtag);
2178 : 0 : PreventInTransactionBlock(true, cmdtag);
2179 : :
2180 [ # # ]: 0 : if (cmd->kind == REPLICATION_KIND_PHYSICAL)
2181 : 0 : StartReplication(cmd);
2182 : : else
2183 : 0 : StartLogicalReplication(cmd);
2184 : :
2185 : : /* dupe, but necessary per libpqrcv_endstreaming */
2186 : 0 : EndReplicationCommand(cmdtag);
2187 : :
2188 [ # # ]: 0 : Assert(xlogreader != NULL);
2189 : : break;
2190 : 0 : }
2191 : :
2192 : : case T_TimeLineHistoryCmd:
2193 : 0 : cmdtag = "TIMELINE_HISTORY";
2194 : 0 : set_ps_display(cmdtag);
2195 : 0 : PreventInTransactionBlock(true, cmdtag);
2196 : 0 : SendTimeLineHistory((TimeLineHistoryCmd *) cmd_node);
2197 : 0 : EndReplicationCommand(cmdtag);
2198 : 0 : break;
2199 : :
2200 : : case T_VariableShowStmt:
2201 : : {
2202 : 0 : DestReceiver *dest = CreateDestReceiver(DestRemoteSimple);
2203 : 0 : VariableShowStmt *n = (VariableShowStmt *) cmd_node;
2204 : :
2205 : 0 : cmdtag = "SHOW";
2206 : 0 : set_ps_display(cmdtag);
2207 : :
2208 : : /* syscache access needs a transaction environment */
2209 : 0 : StartTransactionCommand();
2210 : 0 : GetPGVariable(n->name, dest);
2211 : 0 : CommitTransactionCommand();
2212 : 0 : EndReplicationCommand(cmdtag);
2213 : 0 : }
2214 : 0 : break;
2215 : :
2216 : : case T_UploadManifestCmd:
2217 : 0 : cmdtag = "UPLOAD_MANIFEST";
2218 : 0 : set_ps_display(cmdtag);
2219 : 0 : PreventInTransactionBlock(true, cmdtag);
2220 : 0 : UploadManifest();
2221 : 0 : EndReplicationCommand(cmdtag);
2222 : 0 : break;
2223 : :
2224 : : default:
2225 [ # # # # ]: 0 : elog(ERROR, "unrecognized replication command node tag: %u",
2226 : : cmd_node->type);
2227 : 0 : }
2228 : :
2229 : : /*
2230 : : * Done. Revert to caller's memory context, and clean out the cmd_context
2231 : : * to recover memory right away.
2232 : : */
2233 : 0 : MemoryContextSwitchTo(old_context);
2234 : 0 : MemoryContextReset(cmd_context);
2235 : :
2236 : : /*
2237 : : * We need not update ps display or pg_stat_activity, because PostgresMain
2238 : : * will reset those to "idle". But we must reset debug_query_string to
2239 : : * ensure it doesn't become a dangling pointer.
2240 : : */
2241 : 0 : debug_query_string = NULL;
2242 : :
2243 : 0 : return true;
2244 : 0 : }
2245 : :
2246 : : /*
2247 : : * Process any incoming messages while streaming. Also checks if the remote
2248 : : * end has closed the connection.
2249 : : */
2250 : : static void
2251 : 0 : ProcessRepliesIfAny(void)
2252 : : {
2253 : 0 : unsigned char firstchar;
2254 : 0 : int maxmsglen;
2255 : 0 : int r;
2256 : 0 : bool received = false;
2257 : :
2258 : 0 : last_processing = GetCurrentTimestamp();
2259 : :
2260 : : /*
2261 : : * If we already received a CopyDone from the frontend, any subsequent
2262 : : * message is the beginning of a new command, and should be processed in
2263 : : * the main processing loop.
2264 : : */
2265 [ # # ]: 0 : while (!streamingDoneReceiving)
2266 : : {
2267 : 0 : pq_startmsgread();
2268 : 0 : r = pq_getbyte_if_available(&firstchar);
2269 [ # # ]: 0 : if (r < 0)
2270 : : {
2271 : : /* unexpected error or EOF */
2272 [ # # # # ]: 0 : ereport(COMMERROR,
2273 : : (errcode(ERRCODE_PROTOCOL_VIOLATION),
2274 : : errmsg("unexpected EOF on standby connection")));
2275 : 0 : proc_exit(0);
2276 : : }
2277 [ # # ]: 0 : if (r == 0)
2278 : : {
2279 : : /* no data available without blocking */
2280 : 0 : pq_endmsgread();
2281 : 0 : break;
2282 : : }
2283 : :
2284 : : /* Validate message type and set packet size limit */
2285 [ # # # ]: 0 : switch (firstchar)
2286 : : {
2287 : : case PqMsg_CopyData:
2288 : 0 : maxmsglen = PQ_LARGE_MESSAGE_LIMIT;
2289 : 0 : break;
2290 : : case PqMsg_CopyDone:
2291 : : case PqMsg_Terminate:
2292 : 0 : maxmsglen = PQ_SMALL_MESSAGE_LIMIT;
2293 : 0 : break;
2294 : : default:
2295 [ # # # # ]: 0 : ereport(FATAL,
2296 : : (errcode(ERRCODE_PROTOCOL_VIOLATION),
2297 : : errmsg("invalid standby message type \"%c\"",
2298 : : firstchar)));
2299 : 0 : maxmsglen = 0; /* keep compiler quiet */
2300 : 0 : break;
2301 : : }
2302 : :
2303 : : /* Read the message contents */
2304 : 0 : resetStringInfo(&reply_message);
2305 [ # # ]: 0 : if (pq_getmessage(&reply_message, maxmsglen))
2306 : : {
2307 [ # # # # ]: 0 : ereport(COMMERROR,
2308 : : (errcode(ERRCODE_PROTOCOL_VIOLATION),
2309 : : errmsg("unexpected EOF on standby connection")));
2310 : 0 : proc_exit(0);
2311 : : }
2312 : :
2313 : : /* ... and process it */
2314 [ # # # # ]: 0 : switch (firstchar)
2315 : : {
2316 : : /*
2317 : : * PqMsg_CopyData means a standby reply wrapped in a CopyData
2318 : : * packet.
2319 : : */
2320 : : case PqMsg_CopyData:
2321 : 0 : ProcessStandbyMessage();
2322 : 0 : received = true;
2323 : 0 : break;
2324 : :
2325 : : /*
2326 : : * PqMsg_CopyDone means the standby requested to finish
2327 : : * streaming. Reply with CopyDone, if we had not sent that
2328 : : * already.
2329 : : */
2330 : : case PqMsg_CopyDone:
2331 [ # # ]: 0 : if (!streamingDoneSending)
2332 : : {
2333 : 0 : pq_putmessage_noblock(PqMsg_CopyDone, NULL, 0);
2334 : 0 : streamingDoneSending = true;
2335 : 0 : }
2336 : :
2337 : 0 : streamingDoneReceiving = true;
2338 : 0 : received = true;
2339 : 0 : break;
2340 : :
2341 : : /*
2342 : : * PqMsg_Terminate means that the standby is closing down the
2343 : : * socket.
2344 : : */
2345 : : case PqMsg_Terminate:
2346 : 0 : proc_exit(0);
2347 : :
2348 : : default:
2349 : 0 : Assert(false); /* NOT REACHED */
2350 : 0 : }
2351 : : }
2352 : :
2353 : : /*
2354 : : * Save the last reply timestamp if we've received at least one reply.
2355 : : */
2356 [ # # ]: 0 : if (received)
2357 : : {
2358 : 0 : last_reply_timestamp = last_processing;
2359 : 0 : waiting_for_ping_response = false;
2360 : 0 : }
2361 : 0 : }
2362 : :
2363 : : /*
2364 : : * Process a status update message received from standby.
2365 : : */
2366 : : static void
2367 : 0 : ProcessStandbyMessage(void)
2368 : : {
2369 : 0 : char msgtype;
2370 : :
2371 : : /*
2372 : : * Check message type from the first byte.
2373 : : */
2374 : 0 : msgtype = pq_getmsgbyte(&reply_message);
2375 : :
2376 [ # # # # ]: 0 : switch (msgtype)
2377 : : {
2378 : : case PqReplMsg_StandbyStatusUpdate:
2379 : 0 : ProcessStandbyReplyMessage();
2380 : 0 : break;
2381 : :
2382 : : case PqReplMsg_HotStandbyFeedback:
2383 : 0 : ProcessStandbyHSFeedbackMessage();
2384 : 0 : break;
2385 : :
2386 : : case PqReplMsg_PrimaryStatusRequest:
2387 : 0 : ProcessStandbyPSRequestMessage();
2388 : 0 : break;
2389 : :
2390 : : default:
2391 [ # # # # ]: 0 : ereport(COMMERROR,
2392 : : (errcode(ERRCODE_PROTOCOL_VIOLATION),
2393 : : errmsg("unexpected message type \"%c\"", msgtype)));
2394 : 0 : proc_exit(0);
2395 : : }
2396 : 0 : }
2397 : :
2398 : : /*
2399 : : * Remember that a walreceiver just confirmed receipt of lsn `lsn`.
2400 : : */
2401 : : static void
2402 : 0 : PhysicalConfirmReceivedLocation(XLogRecPtr lsn)
2403 : : {
2404 : 0 : bool changed = false;
2405 : 0 : ReplicationSlot *slot = MyReplicationSlot;
2406 : :
2407 [ # # ]: 0 : Assert(XLogRecPtrIsValid(lsn));
2408 [ # # ]: 0 : SpinLockAcquire(&slot->mutex);
2409 [ # # ]: 0 : if (slot->data.restart_lsn != lsn)
2410 : : {
2411 : 0 : changed = true;
2412 : 0 : slot->data.restart_lsn = lsn;
2413 : 0 : }
2414 : 0 : SpinLockRelease(&slot->mutex);
2415 : :
2416 [ # # ]: 0 : if (changed)
2417 : : {
2418 : 0 : ReplicationSlotMarkDirty();
2419 : 0 : ReplicationSlotsComputeRequiredLSN();
2420 : 0 : PhysicalWakeupLogicalWalSnd();
2421 : 0 : }
2422 : :
2423 : : /*
2424 : : * One could argue that the slot should be saved to disk now, but that'd
2425 : : * be energy wasted - the worst thing lost information could cause here is
2426 : : * to give wrong information in a statistics view - we'll just potentially
2427 : : * be more conservative in removing files.
2428 : : */
2429 : 0 : }
2430 : :
2431 : : /*
2432 : : * Regular reply from standby advising of WAL locations on standby server.
2433 : : */
2434 : : static void
2435 : 0 : ProcessStandbyReplyMessage(void)
2436 : : {
2437 : 0 : XLogRecPtr writePtr,
2438 : : flushPtr,
2439 : : applyPtr;
2440 : 0 : bool replyRequested;
2441 : 0 : TimeOffset writeLag,
2442 : : flushLag,
2443 : : applyLag;
2444 : 0 : bool clearLagTimes;
2445 : 0 : TimestampTz now;
2446 : 0 : TimestampTz replyTime;
2447 : :
2448 : : static bool fullyAppliedLastTime = false;
2449 : :
2450 : : /* the caller already consumed the msgtype byte */
2451 : 0 : writePtr = pq_getmsgint64(&reply_message);
2452 : 0 : flushPtr = pq_getmsgint64(&reply_message);
2453 : 0 : applyPtr = pq_getmsgint64(&reply_message);
2454 : 0 : replyTime = pq_getmsgint64(&reply_message);
2455 : 0 : replyRequested = pq_getmsgbyte(&reply_message);
2456 : :
2457 [ # # ]: 0 : if (message_level_is_interesting(DEBUG2))
2458 : : {
2459 : 0 : char *replyTimeStr;
2460 : :
2461 : : /* Copy because timestamptz_to_str returns a static buffer */
2462 : 0 : replyTimeStr = pstrdup(timestamptz_to_str(replyTime));
2463 : :
2464 [ # # # # ]: 0 : elog(DEBUG2, "write %X/%08X flush %X/%08X apply %X/%08X%s reply_time %s",
2465 : : LSN_FORMAT_ARGS(writePtr),
2466 : : LSN_FORMAT_ARGS(flushPtr),
2467 : : LSN_FORMAT_ARGS(applyPtr),
2468 : : replyRequested ? " (reply requested)" : "",
2469 : : replyTimeStr);
2470 : :
2471 : 0 : pfree(replyTimeStr);
2472 : 0 : }
2473 : :
2474 : : /* See if we can compute the round-trip lag for these positions. */
2475 : 0 : now = GetCurrentTimestamp();
2476 : 0 : writeLag = LagTrackerRead(SYNC_REP_WAIT_WRITE, writePtr, now);
2477 : 0 : flushLag = LagTrackerRead(SYNC_REP_WAIT_FLUSH, flushPtr, now);
2478 : 0 : applyLag = LagTrackerRead(SYNC_REP_WAIT_APPLY, applyPtr, now);
2479 : :
2480 : : /*
2481 : : * If the standby reports that it has fully replayed the WAL in two
2482 : : * consecutive reply messages, then the second such message must result
2483 : : * from wal_receiver_status_interval expiring on the standby. This is a
2484 : : * convenient time to forget the lag times measured when it last
2485 : : * wrote/flushed/applied a WAL record, to avoid displaying stale lag data
2486 : : * until more WAL traffic arrives.
2487 : : */
2488 : 0 : clearLagTimes = false;
2489 [ # # ]: 0 : if (applyPtr == sentPtr)
2490 : : {
2491 [ # # ]: 0 : if (fullyAppliedLastTime)
2492 : 0 : clearLagTimes = true;
2493 : 0 : fullyAppliedLastTime = true;
2494 : 0 : }
2495 : : else
2496 : 0 : fullyAppliedLastTime = false;
2497 : :
2498 : : /* Send a reply if the standby requested one. */
2499 [ # # ]: 0 : if (replyRequested)
2500 : 0 : WalSndKeepalive(false, InvalidXLogRecPtr);
2501 : :
2502 : : /*
2503 : : * Update shared state for this WalSender process based on reply data from
2504 : : * standby.
2505 : : */
2506 : : {
2507 : 0 : WalSnd *walsnd = MyWalSnd;
2508 : :
2509 [ # # ]: 0 : SpinLockAcquire(&walsnd->mutex);
2510 : 0 : walsnd->write = writePtr;
2511 : 0 : walsnd->flush = flushPtr;
2512 : 0 : walsnd->apply = applyPtr;
2513 [ # # # # ]: 0 : if (writeLag != -1 || clearLagTimes)
2514 : 0 : walsnd->writeLag = writeLag;
2515 [ # # # # ]: 0 : if (flushLag != -1 || clearLagTimes)
2516 : 0 : walsnd->flushLag = flushLag;
2517 [ # # # # ]: 0 : if (applyLag != -1 || clearLagTimes)
2518 : 0 : walsnd->applyLag = applyLag;
2519 : 0 : walsnd->replyTime = replyTime;
2520 : 0 : SpinLockRelease(&walsnd->mutex);
2521 : 0 : }
2522 : :
2523 [ # # ]: 0 : if (!am_cascading_walsender)
2524 : 0 : SyncRepReleaseWaiters();
2525 : :
2526 : : /*
2527 : : * Advance our local xmin horizon when the client confirmed a flush.
2528 : : */
2529 [ # # # # ]: 0 : if (MyReplicationSlot && XLogRecPtrIsValid(flushPtr))
2530 : : {
2531 [ # # ]: 0 : if (SlotIsLogical(MyReplicationSlot))
2532 : 0 : LogicalConfirmReceivedLocation(flushPtr);
2533 : : else
2534 : 0 : PhysicalConfirmReceivedLocation(flushPtr);
2535 : 0 : }
2536 : 0 : }
2537 : :
2538 : : /* compute new replication slot xmin horizon if needed */
2539 : : static void
2540 : 0 : PhysicalReplicationSlotNewXmin(TransactionId feedbackXmin, TransactionId feedbackCatalogXmin)
2541 : : {
2542 : 0 : bool changed = false;
2543 : 0 : ReplicationSlot *slot = MyReplicationSlot;
2544 : :
2545 [ # # ]: 0 : SpinLockAcquire(&slot->mutex);
2546 : 0 : MyProc->xmin = InvalidTransactionId;
2547 : :
2548 : : /*
2549 : : * For physical replication we don't need the interlock provided by xmin
2550 : : * and effective_xmin since the consequences of a missed increase are
2551 : : * limited to query cancellations, so set both at once.
2552 : : */
2553 [ # # ]: 0 : if (!TransactionIdIsNormal(slot->data.xmin) ||
2554 [ # # # # ]: 0 : !TransactionIdIsNormal(feedbackXmin) ||
2555 : 0 : TransactionIdPrecedes(slot->data.xmin, feedbackXmin))
2556 : : {
2557 : 0 : changed = true;
2558 : 0 : slot->data.xmin = feedbackXmin;
2559 : 0 : slot->effective_xmin = feedbackXmin;
2560 : 0 : }
2561 [ # # ]: 0 : if (!TransactionIdIsNormal(slot->data.catalog_xmin) ||
2562 [ # # # # ]: 0 : !TransactionIdIsNormal(feedbackCatalogXmin) ||
2563 : 0 : TransactionIdPrecedes(slot->data.catalog_xmin, feedbackCatalogXmin))
2564 : : {
2565 : 0 : changed = true;
2566 : 0 : slot->data.catalog_xmin = feedbackCatalogXmin;
2567 : 0 : slot->effective_catalog_xmin = feedbackCatalogXmin;
2568 : 0 : }
2569 : 0 : SpinLockRelease(&slot->mutex);
2570 : :
2571 [ # # ]: 0 : if (changed)
2572 : : {
2573 : 0 : ReplicationSlotMarkDirty();
2574 : 0 : ReplicationSlotsComputeRequiredXmin(false);
2575 : 0 : }
2576 : 0 : }
2577 : :
2578 : : /*
2579 : : * Check that the provided xmin/epoch are sane, that is, not in the future
2580 : : * and not so far back as to be already wrapped around.
2581 : : *
2582 : : * Epoch of nextXid should be same as standby, or if the counter has
2583 : : * wrapped, then one greater than standby.
2584 : : *
2585 : : * This check doesn't care about whether clog exists for these xids
2586 : : * at all.
2587 : : */
2588 : : static bool
2589 : 0 : TransactionIdInRecentPast(TransactionId xid, uint32 epoch)
2590 : : {
2591 : 0 : FullTransactionId nextFullXid;
2592 : 0 : TransactionId nextXid;
2593 : 0 : uint32 nextEpoch;
2594 : :
2595 : 0 : nextFullXid = ReadNextFullTransactionId();
2596 : 0 : nextXid = XidFromFullTransactionId(nextFullXid);
2597 : 0 : nextEpoch = EpochFromFullTransactionId(nextFullXid);
2598 : :
2599 [ # # ]: 0 : if (xid <= nextXid)
2600 : : {
2601 [ # # ]: 0 : if (epoch != nextEpoch)
2602 : 0 : return false;
2603 : 0 : }
2604 : : else
2605 : : {
2606 [ # # ]: 0 : if (epoch + 1 != nextEpoch)
2607 : 0 : return false;
2608 : : }
2609 : :
2610 [ # # ]: 0 : if (!TransactionIdPrecedesOrEquals(xid, nextXid))
2611 : 0 : return false; /* epoch OK, but it's wrapped around */
2612 : :
2613 : 0 : return true;
2614 : 0 : }
2615 : :
2616 : : /*
2617 : : * Hot Standby feedback
2618 : : */
2619 : : static void
2620 : 0 : ProcessStandbyHSFeedbackMessage(void)
2621 : : {
2622 : 0 : TransactionId feedbackXmin;
2623 : 0 : uint32 feedbackEpoch;
2624 : 0 : TransactionId feedbackCatalogXmin;
2625 : 0 : uint32 feedbackCatalogEpoch;
2626 : 0 : TimestampTz replyTime;
2627 : :
2628 : : /*
2629 : : * Decipher the reply message. The caller already consumed the msgtype
2630 : : * byte. See XLogWalRcvSendHSFeedback() in walreceiver.c for the creation
2631 : : * of this message.
2632 : : */
2633 : 0 : replyTime = pq_getmsgint64(&reply_message);
2634 : 0 : feedbackXmin = pq_getmsgint(&reply_message, 4);
2635 : 0 : feedbackEpoch = pq_getmsgint(&reply_message, 4);
2636 : 0 : feedbackCatalogXmin = pq_getmsgint(&reply_message, 4);
2637 : 0 : feedbackCatalogEpoch = pq_getmsgint(&reply_message, 4);
2638 : :
2639 [ # # ]: 0 : if (message_level_is_interesting(DEBUG2))
2640 : : {
2641 : 0 : char *replyTimeStr;
2642 : :
2643 : : /* Copy because timestamptz_to_str returns a static buffer */
2644 : 0 : replyTimeStr = pstrdup(timestamptz_to_str(replyTime));
2645 : :
2646 [ # # # # ]: 0 : elog(DEBUG2, "hot standby feedback xmin %u epoch %u, catalog_xmin %u epoch %u reply_time %s",
2647 : : feedbackXmin,
2648 : : feedbackEpoch,
2649 : : feedbackCatalogXmin,
2650 : : feedbackCatalogEpoch,
2651 : : replyTimeStr);
2652 : :
2653 : 0 : pfree(replyTimeStr);
2654 : 0 : }
2655 : :
2656 : : /*
2657 : : * Update shared state for this WalSender process based on reply data from
2658 : : * standby.
2659 : : */
2660 : : {
2661 : 0 : WalSnd *walsnd = MyWalSnd;
2662 : :
2663 [ # # ]: 0 : SpinLockAcquire(&walsnd->mutex);
2664 : 0 : walsnd->replyTime = replyTime;
2665 : 0 : SpinLockRelease(&walsnd->mutex);
2666 : 0 : }
2667 : :
2668 : : /*
2669 : : * Unset WalSender's xmins if the feedback message values are invalid.
2670 : : * This happens when the downstream turned hot_standby_feedback off.
2671 : : */
2672 : 0 : if (!TransactionIdIsNormal(feedbackXmin)
2673 [ # # # # ]: 0 : && !TransactionIdIsNormal(feedbackCatalogXmin))
2674 : : {
2675 : 0 : MyProc->xmin = InvalidTransactionId;
2676 [ # # ]: 0 : if (MyReplicationSlot != NULL)
2677 : 0 : PhysicalReplicationSlotNewXmin(feedbackXmin, feedbackCatalogXmin);
2678 : 0 : return;
2679 : : }
2680 : :
2681 : : /*
2682 : : * Check that the provided xmin/epoch are sane, that is, not in the future
2683 : : * and not so far back as to be already wrapped around. Ignore if not.
2684 : : */
2685 [ # # # # ]: 0 : if (TransactionIdIsNormal(feedbackXmin) &&
2686 : 0 : !TransactionIdInRecentPast(feedbackXmin, feedbackEpoch))
2687 : 0 : return;
2688 : :
2689 [ # # # # ]: 0 : if (TransactionIdIsNormal(feedbackCatalogXmin) &&
2690 : 0 : !TransactionIdInRecentPast(feedbackCatalogXmin, feedbackCatalogEpoch))
2691 : 0 : return;
2692 : :
2693 : : /*
2694 : : * Set the WalSender's xmin equal to the standby's requested xmin, so that
2695 : : * the xmin will be taken into account by GetSnapshotData() /
2696 : : * ComputeXidHorizons(). This will hold back the removal of dead rows and
2697 : : * thereby prevent the generation of cleanup conflicts on the standby
2698 : : * server.
2699 : : *
2700 : : * There is a small window for a race condition here: although we just
2701 : : * checked that feedbackXmin precedes nextXid, the nextXid could have
2702 : : * gotten advanced between our fetching it and applying the xmin below,
2703 : : * perhaps far enough to make feedbackXmin wrap around. In that case the
2704 : : * xmin we set here would be "in the future" and have no effect. No point
2705 : : * in worrying about this since it's too late to save the desired data
2706 : : * anyway. Assuming that the standby sends us an increasing sequence of
2707 : : * xmins, this could only happen during the first reply cycle, else our
2708 : : * own xmin would prevent nextXid from advancing so far.
2709 : : *
2710 : : * We don't bother taking the ProcArrayLock here. Setting the xmin field
2711 : : * is assumed atomic, and there's no real need to prevent concurrent
2712 : : * horizon determinations. (If we're moving our xmin forward, this is
2713 : : * obviously safe, and if we're moving it backwards, well, the data is at
2714 : : * risk already since a VACUUM could already have determined the horizon.)
2715 : : *
2716 : : * If we're using a replication slot we reserve the xmin via that,
2717 : : * otherwise via the walsender's PGPROC entry. We can only track the
2718 : : * catalog xmin separately when using a slot, so we store the least of the
2719 : : * two provided when not using a slot.
2720 : : *
2721 : : * XXX: It might make sense to generalize the ephemeral slot concept and
2722 : : * always use the slot mechanism to handle the feedback xmin.
2723 : : */
2724 [ # # ]: 0 : if (MyReplicationSlot != NULL) /* XXX: persistency configurable? */
2725 : 0 : PhysicalReplicationSlotNewXmin(feedbackXmin, feedbackCatalogXmin);
2726 : : else
2727 : : {
2728 : 0 : if (TransactionIdIsNormal(feedbackCatalogXmin)
2729 [ # # # # ]: 0 : && TransactionIdPrecedes(feedbackCatalogXmin, feedbackXmin))
2730 : 0 : MyProc->xmin = feedbackCatalogXmin;
2731 : : else
2732 : 0 : MyProc->xmin = feedbackXmin;
2733 : : }
2734 [ # # ]: 0 : }
2735 : :
2736 : : /*
2737 : : * Process the request for a primary status update message.
2738 : : */
2739 : : static void
2740 : 0 : ProcessStandbyPSRequestMessage(void)
2741 : : {
2742 : 0 : XLogRecPtr lsn = InvalidXLogRecPtr;
2743 : 0 : TransactionId oldestXidInCommit;
2744 : 0 : TransactionId oldestGXidInCommit;
2745 : 0 : FullTransactionId nextFullXid;
2746 : 0 : FullTransactionId fullOldestXidInCommit;
2747 : 0 : WalSnd *walsnd = MyWalSnd;
2748 : 0 : TimestampTz replyTime;
2749 : :
2750 : : /*
2751 : : * This shouldn't happen because we don't support getting primary status
2752 : : * message from standby.
2753 : : */
2754 [ # # ]: 0 : if (RecoveryInProgress())
2755 [ # # # # ]: 0 : elog(ERROR, "the primary status is unavailable during recovery");
2756 : :
2757 : 0 : replyTime = pq_getmsgint64(&reply_message);
2758 : :
2759 : : /*
2760 : : * Update shared state for this WalSender process based on reply data from
2761 : : * standby.
2762 : : */
2763 [ # # ]: 0 : SpinLockAcquire(&walsnd->mutex);
2764 : 0 : walsnd->replyTime = replyTime;
2765 : 0 : SpinLockRelease(&walsnd->mutex);
2766 : :
2767 : : /*
2768 : : * Consider transactions in the current database, as only these are the
2769 : : * ones replicated.
2770 : : */
2771 : 0 : oldestXidInCommit = GetOldestActiveTransactionId(true, false);
2772 : 0 : oldestGXidInCommit = TwoPhaseGetOldestXidInCommit();
2773 : :
2774 : : /*
2775 : : * Update the oldest xid for standby transmission if an older prepared
2776 : : * transaction exists and is currently in commit phase.
2777 : : */
2778 [ # # # # ]: 0 : if (TransactionIdIsValid(oldestGXidInCommit) &&
2779 : 0 : TransactionIdPrecedes(oldestGXidInCommit, oldestXidInCommit))
2780 : 0 : oldestXidInCommit = oldestGXidInCommit;
2781 : :
2782 : 0 : nextFullXid = ReadNextFullTransactionId();
2783 : 0 : fullOldestXidInCommit = FullTransactionIdFromAllowableAt(nextFullXid,
2784 : 0 : oldestXidInCommit);
2785 : 0 : lsn = GetXLogWriteRecPtr();
2786 : :
2787 [ # # # # ]: 0 : elog(DEBUG2, "sending primary status");
2788 : :
2789 : : /* construct the message... */
2790 : 0 : resetStringInfo(&output_message);
2791 : 0 : pq_sendbyte(&output_message, PqReplMsg_PrimaryStatusUpdate);
2792 : 0 : pq_sendint64(&output_message, lsn);
2793 : 0 : pq_sendint64(&output_message, (int64) U64FromFullTransactionId(fullOldestXidInCommit));
2794 : 0 : pq_sendint64(&output_message, (int64) U64FromFullTransactionId(nextFullXid));
2795 : 0 : pq_sendint64(&output_message, GetCurrentTimestamp());
2796 : :
2797 : : /* ... and send it wrapped in CopyData */
2798 : 0 : pq_putmessage_noblock(PqMsg_CopyData, output_message.data, output_message.len);
2799 : 0 : }
2800 : :
2801 : : /*
2802 : : * Compute how long send/receive loops should sleep.
2803 : : *
2804 : : * If wal_sender_timeout is enabled we want to wake up in time to send
2805 : : * keepalives and to abort the connection if wal_sender_timeout has been
2806 : : * reached.
2807 : : */
2808 : : static long
2809 : 0 : WalSndComputeSleeptime(TimestampTz now)
2810 : : {
2811 : 0 : long sleeptime = 10000; /* 10 s */
2812 : :
2813 [ # # # # ]: 0 : if (wal_sender_timeout > 0 && last_reply_timestamp > 0)
2814 : : {
2815 : 0 : TimestampTz wakeup_time;
2816 : :
2817 : : /*
2818 : : * At the latest stop sleeping once wal_sender_timeout has been
2819 : : * reached.
2820 : : */
2821 : 0 : wakeup_time = TimestampTzPlusMilliseconds(last_reply_timestamp,
2822 : : wal_sender_timeout);
2823 : :
2824 : : /*
2825 : : * If no ping has been sent yet, wakeup when it's time to do so.
2826 : : * WalSndKeepaliveIfNecessary() wants to send a keepalive once half of
2827 : : * the timeout passed without a response.
2828 : : */
2829 [ # # ]: 0 : if (!waiting_for_ping_response)
2830 : 0 : wakeup_time = TimestampTzPlusMilliseconds(last_reply_timestamp,
2831 : : wal_sender_timeout / 2);
2832 : :
2833 : : /* Compute relative time until wakeup. */
2834 : 0 : sleeptime = TimestampDifferenceMilliseconds(now, wakeup_time);
2835 : 0 : }
2836 : :
2837 : 0 : return sleeptime;
2838 : 0 : }
2839 : :
2840 : : /*
2841 : : * Check whether there have been responses by the client within
2842 : : * wal_sender_timeout and shutdown if not. Using last_processing as the
2843 : : * reference point avoids counting server-side stalls against the client.
2844 : : * However, a long server-side stall can make WalSndKeepaliveIfNecessary()
2845 : : * postdate last_processing by more than wal_sender_timeout. If that happens,
2846 : : * the client must reply almost immediately to avoid a timeout. This rarely
2847 : : * affects the default configuration, under which clients spontaneously send a
2848 : : * message every standby_message_timeout = wal_sender_timeout/6 = 10s. We
2849 : : * could eliminate that problem by recognizing timeout expiration at
2850 : : * wal_sender_timeout/2 after the keepalive.
2851 : : */
2852 : : static void
2853 : 0 : WalSndCheckTimeOut(void)
2854 : : {
2855 : 0 : TimestampTz timeout;
2856 : :
2857 : : /* don't bail out if we're doing something that doesn't require timeouts */
2858 [ # # ]: 0 : if (last_reply_timestamp <= 0)
2859 : 0 : return;
2860 : :
2861 : 0 : timeout = TimestampTzPlusMilliseconds(last_reply_timestamp,
2862 : : wal_sender_timeout);
2863 : :
2864 [ # # # # ]: 0 : if (wal_sender_timeout > 0 && last_processing >= timeout)
2865 : : {
2866 : : /*
2867 : : * Since typically expiration of replication timeout means
2868 : : * communication problem, we don't send the error message to the
2869 : : * standby.
2870 : : */
2871 [ # # # # ]: 0 : ereport(COMMERROR,
2872 : : (errmsg("terminating walsender process due to replication timeout")));
2873 : :
2874 : 0 : WalSndShutdown();
2875 : : }
2876 [ # # ]: 0 : }
2877 : :
2878 : : /* Main loop of walsender process that streams the WAL over Copy messages. */
2879 : : static void
2880 : 0 : WalSndLoop(WalSndSendDataCallback send_data)
2881 : : {
2882 : 0 : TimestampTz last_flush = 0;
2883 : :
2884 : : /*
2885 : : * Initialize the last reply timestamp. That enables timeout processing
2886 : : * from hereon.
2887 : : */
2888 : 0 : last_reply_timestamp = GetCurrentTimestamp();
2889 : 0 : waiting_for_ping_response = false;
2890 : :
2891 : : /*
2892 : : * Loop until we reach the end of this timeline or the client requests to
2893 : : * stop streaming.
2894 : : */
2895 : 0 : for (;;)
2896 : : {
2897 : : /* Clear any already-pending wakeups */
2898 : 0 : ResetLatch(MyLatch);
2899 : :
2900 [ # # ]: 0 : CHECK_FOR_INTERRUPTS();
2901 : :
2902 : : /* Process any requests or signals received recently */
2903 [ # # ]: 0 : if (ConfigReloadPending)
2904 : : {
2905 : 0 : ConfigReloadPending = false;
2906 : 0 : ProcessConfigFile(PGC_SIGHUP);
2907 : 0 : SyncRepInitConfig();
2908 : 0 : }
2909 : :
2910 : : /* Check for input from the client */
2911 : 0 : ProcessRepliesIfAny();
2912 : :
2913 : : /*
2914 : : * If we have received CopyDone from the client, sent CopyDone
2915 : : * ourselves, and the output buffer is empty, it's time to exit
2916 : : * streaming.
2917 : : */
2918 [ # # # # : 0 : if (streamingDoneReceiving && streamingDoneSending &&
# # ]
2919 : 0 : !pq_is_send_pending())
2920 : 0 : break;
2921 : :
2922 : : /*
2923 : : * If we don't have any pending data in the output buffer, try to send
2924 : : * some more. If there is some, we don't bother to call send_data
2925 : : * again until we've flushed it ... but we'd better assume we are not
2926 : : * caught up.
2927 : : */
2928 [ # # ]: 0 : if (!pq_is_send_pending())
2929 : 0 : send_data();
2930 : : else
2931 : 0 : WalSndCaughtUp = false;
2932 : :
2933 : : /* Try to flush pending output to the client */
2934 [ # # ]: 0 : if (pq_flush_if_writable() != 0)
2935 : 0 : WalSndShutdown();
2936 : :
2937 : : /* If nothing remains to be sent right now ... */
2938 [ # # # # ]: 0 : if (WalSndCaughtUp && !pq_is_send_pending())
2939 : : {
2940 : : /*
2941 : : * If we're in catchup state, move to streaming. This is an
2942 : : * important state change for users to know about, since before
2943 : : * this point data loss might occur if the primary dies and we
2944 : : * need to failover to the standby. The state change is also
2945 : : * important for synchronous replication, since commits that
2946 : : * started to wait at that point might wait for some time.
2947 : : */
2948 [ # # ]: 0 : if (MyWalSnd->state == WALSNDSTATE_CATCHUP)
2949 : : {
2950 [ # # # # ]: 0 : ereport(DEBUG1,
2951 : : (errmsg_internal("\"%s\" has now caught up with upstream server",
2952 : : application_name)));
2953 : 0 : WalSndSetState(WALSNDSTATE_STREAMING);
2954 : 0 : }
2955 : :
2956 : : /*
2957 : : * When SIGUSR2 arrives, we send any outstanding logs up to the
2958 : : * shutdown checkpoint record (i.e., the latest record), wait for
2959 : : * them to be replicated to the standby, and exit. This may be a
2960 : : * normal termination at shutdown, or a promotion, the walsender
2961 : : * is not sure which.
2962 : : */
2963 [ # # ]: 0 : if (got_SIGUSR2)
2964 : 0 : WalSndDone(send_data);
2965 : 0 : }
2966 : :
2967 : : /* Check for replication timeout. */
2968 : 0 : WalSndCheckTimeOut();
2969 : :
2970 : : /* Send keepalive if the time has come */
2971 : 0 : WalSndKeepaliveIfNecessary();
2972 : :
2973 : : /*
2974 : : * Block if we have unsent data. XXX For logical replication, let
2975 : : * WalSndWaitForWal() handle any other blocking; idle receivers need
2976 : : * its additional actions. For physical replication, also block if
2977 : : * caught up; its send_data does not block.
2978 : : *
2979 : : * The IO statistics are reported in WalSndWaitForWal() for the
2980 : : * logical WAL senders.
2981 : : */
2982 [ # # # # ]: 0 : if ((WalSndCaughtUp && send_data != XLogSendLogical &&
2983 [ # # ]: 0 : !streamingDoneSending) ||
2984 : 0 : pq_is_send_pending())
2985 : : {
2986 : 0 : long sleeptime;
2987 : 0 : int wakeEvents;
2988 : 0 : TimestampTz now;
2989 : :
2990 [ # # ]: 0 : if (!streamingDoneReceiving)
2991 : 0 : wakeEvents = WL_SOCKET_READABLE;
2992 : : else
2993 : 0 : wakeEvents = 0;
2994 : :
2995 : : /*
2996 : : * Use fresh timestamp, not last_processing, to reduce the chance
2997 : : * of reaching wal_sender_timeout before sending a keepalive.
2998 : : */
2999 : 0 : now = GetCurrentTimestamp();
3000 : 0 : sleeptime = WalSndComputeSleeptime(now);
3001 : :
3002 [ # # ]: 0 : if (pq_is_send_pending())
3003 : 0 : wakeEvents |= WL_SOCKET_WRITEABLE;
3004 : :
3005 : : /* Report IO statistics, if needed */
3006 [ # # ]: 0 : if (TimestampDifferenceExceeds(last_flush, now,
3007 : : WALSENDER_STATS_FLUSH_INTERVAL))
3008 : : {
3009 : 0 : pgstat_flush_io(false);
3010 : 0 : (void) pgstat_flush_backend(false, PGSTAT_BACKEND_FLUSH_IO);
3011 : 0 : last_flush = now;
3012 : 0 : }
3013 : :
3014 : : /* Sleep until something happens or we time out */
3015 : 0 : WalSndWait(wakeEvents, sleeptime, WAIT_EVENT_WAL_SENDER_MAIN);
3016 : 0 : }
3017 : : }
3018 : 0 : }
3019 : :
3020 : : /* Initialize a per-walsender data structure for this walsender process */
3021 : : static void
3022 : 0 : InitWalSenderSlot(void)
3023 : : {
3024 : 0 : int i;
3025 : :
3026 : : /*
3027 : : * WalSndCtl should be set up already (we inherit this by fork() or
3028 : : * EXEC_BACKEND mechanism from the postmaster).
3029 : : */
3030 [ # # ]: 0 : Assert(WalSndCtl != NULL);
3031 [ # # ]: 0 : Assert(MyWalSnd == NULL);
3032 : :
3033 : : /*
3034 : : * Find a free walsender slot and reserve it. This must not fail due to
3035 : : * the prior check for free WAL senders in InitProcess().
3036 : : */
3037 [ # # ]: 0 : for (i = 0; i < max_wal_senders; i++)
3038 : : {
3039 : 0 : WalSnd *walsnd = &WalSndCtl->walsnds[i];
3040 : :
3041 [ # # ]: 0 : SpinLockAcquire(&walsnd->mutex);
3042 : :
3043 [ # # ]: 0 : if (walsnd->pid != 0)
3044 : : {
3045 : 0 : SpinLockRelease(&walsnd->mutex);
3046 : 0 : continue;
3047 : : }
3048 : : else
3049 : : {
3050 : : /*
3051 : : * Found a free slot. Reserve it for us.
3052 : : */
3053 : 0 : walsnd->pid = MyProcPid;
3054 : 0 : walsnd->state = WALSNDSTATE_STARTUP;
3055 : 0 : walsnd->sentPtr = InvalidXLogRecPtr;
3056 : 0 : walsnd->needreload = false;
3057 : 0 : walsnd->write = InvalidXLogRecPtr;
3058 : 0 : walsnd->flush = InvalidXLogRecPtr;
3059 : 0 : walsnd->apply = InvalidXLogRecPtr;
3060 : 0 : walsnd->writeLag = -1;
3061 : 0 : walsnd->flushLag = -1;
3062 : 0 : walsnd->applyLag = -1;
3063 : 0 : walsnd->sync_standby_priority = 0;
3064 : 0 : walsnd->replyTime = 0;
3065 : :
3066 : : /*
3067 : : * The kind assignment is done here and not in StartReplication()
3068 : : * and StartLogicalReplication(). Indeed, the logical walsender
3069 : : * needs to read WAL records (like snapshot of running
3070 : : * transactions) during the slot creation. So it needs to be woken
3071 : : * up based on its kind.
3072 : : *
3073 : : * The kind assignment could also be done in StartReplication(),
3074 : : * StartLogicalReplication() and CREATE_REPLICATION_SLOT but it
3075 : : * seems better to set it on one place.
3076 : : */
3077 [ # # ]: 0 : if (MyDatabaseId == InvalidOid)
3078 : 0 : walsnd->kind = REPLICATION_KIND_PHYSICAL;
3079 : : else
3080 : 0 : walsnd->kind = REPLICATION_KIND_LOGICAL;
3081 : :
3082 : 0 : SpinLockRelease(&walsnd->mutex);
3083 : : /* don't need the lock anymore */
3084 : 0 : MyWalSnd = walsnd;
3085 : :
3086 : 0 : break;
3087 : : }
3088 [ # # # ]: 0 : }
3089 : :
3090 [ # # ]: 0 : Assert(MyWalSnd != NULL);
3091 : :
3092 : : /* Arrange to clean up at walsender exit */
3093 : 0 : on_shmem_exit(WalSndKill, 0);
3094 : 0 : }
3095 : :
3096 : : /* Destroy the per-walsender data structure for this walsender process */
3097 : : static void
3098 : 0 : WalSndKill(int code, Datum arg)
3099 : : {
3100 : 0 : WalSnd *walsnd = MyWalSnd;
3101 : :
3102 [ # # ]: 0 : Assert(walsnd != NULL);
3103 : :
3104 : 0 : MyWalSnd = NULL;
3105 : :
3106 [ # # ]: 0 : SpinLockAcquire(&walsnd->mutex);
3107 : : /* Mark WalSnd struct as no longer being in use. */
3108 : 0 : walsnd->pid = 0;
3109 : 0 : SpinLockRelease(&walsnd->mutex);
3110 : 0 : }
3111 : :
3112 : : /* XLogReaderRoutine->segment_open callback */
3113 : : static void
3114 : 0 : WalSndSegmentOpen(XLogReaderState *state, XLogSegNo nextSegNo,
3115 : : TimeLineID *tli_p)
3116 : : {
3117 : 0 : char path[MAXPGPATH];
3118 : :
3119 : : /*-------
3120 : : * When reading from a historic timeline, and there is a timeline switch
3121 : : * within this segment, read from the WAL segment belonging to the new
3122 : : * timeline.
3123 : : *
3124 : : * For example, imagine that this server is currently on timeline 5, and
3125 : : * we're streaming timeline 4. The switch from timeline 4 to 5 happened at
3126 : : * 0/13002088. In pg_wal, we have these files:
3127 : : *
3128 : : * ...
3129 : : * 000000040000000000000012
3130 : : * 000000040000000000000013
3131 : : * 000000050000000000000013
3132 : : * 000000050000000000000014
3133 : : * ...
3134 : : *
3135 : : * In this situation, when requested to send the WAL from segment 0x13, on
3136 : : * timeline 4, we read the WAL from file 000000050000000000000013. Archive
3137 : : * recovery prefers files from newer timelines, so if the segment was
3138 : : * restored from the archive on this server, the file belonging to the old
3139 : : * timeline, 000000040000000000000013, might not exist. Their contents are
3140 : : * equal up to the switchpoint, because at a timeline switch, the used
3141 : : * portion of the old segment is copied to the new file.
3142 : : */
3143 : 0 : *tli_p = sendTimeLine;
3144 [ # # ]: 0 : if (sendTimeLineIsHistoric)
3145 : : {
3146 : 0 : XLogSegNo endSegNo;
3147 : :
3148 : 0 : XLByteToSeg(sendTimeLineValidUpto, endSegNo, state->segcxt.ws_segsize);
3149 [ # # ]: 0 : if (nextSegNo == endSegNo)
3150 : 0 : *tli_p = sendTimeLineNextTLI;
3151 : 0 : }
3152 : :
3153 : 0 : XLogFilePath(path, *tli_p, nextSegNo, state->segcxt.ws_segsize);
3154 : 0 : state->seg.ws_file = BasicOpenFile(path, O_RDONLY | PG_BINARY);
3155 [ # # ]: 0 : if (state->seg.ws_file >= 0)
3156 : 0 : return;
3157 : :
3158 : : /*
3159 : : * If the file is not found, assume it's because the standby asked for a
3160 : : * too old WAL segment that has already been removed or recycled.
3161 : : */
3162 [ # # ]: 0 : if (errno == ENOENT)
3163 : : {
3164 : 0 : char xlogfname[MAXFNAMELEN];
3165 : 0 : int save_errno = errno;
3166 : :
3167 : 0 : XLogFileName(xlogfname, *tli_p, nextSegNo, wal_segment_size);
3168 : 0 : errno = save_errno;
3169 [ # # # # ]: 0 : ereport(ERROR,
3170 : : (errcode_for_file_access(),
3171 : : errmsg("requested WAL segment %s has already been removed",
3172 : : xlogfname)));
3173 : 0 : }
3174 : : else
3175 [ # # # # ]: 0 : ereport(ERROR,
3176 : : (errcode_for_file_access(),
3177 : : errmsg("could not open file \"%s\": %m",
3178 : : path)));
3179 [ # # ]: 0 : }
3180 : :
3181 : : /*
3182 : : * Send out the WAL in its normal physical/stored form.
3183 : : *
3184 : : * Read up to MAX_SEND_SIZE bytes of WAL that's been flushed to disk,
3185 : : * but not yet sent to the client, and buffer it in the libpq output
3186 : : * buffer.
3187 : : *
3188 : : * If there is no unsent WAL remaining, WalSndCaughtUp is set to true,
3189 : : * otherwise WalSndCaughtUp is set to false.
3190 : : */
3191 : : static void
3192 : 0 : XLogSendPhysical(void)
3193 : : {
3194 : 0 : XLogRecPtr SendRqstPtr;
3195 : 0 : XLogRecPtr startptr;
3196 : 0 : XLogRecPtr endptr;
3197 : 0 : Size nbytes;
3198 : 0 : XLogSegNo segno;
3199 : 0 : WALReadError errinfo;
3200 : 0 : Size rbytes;
3201 : :
3202 : : /* If requested switch the WAL sender to the stopping state. */
3203 [ # # ]: 0 : if (got_STOPPING)
3204 : 0 : WalSndSetState(WALSNDSTATE_STOPPING);
3205 : :
3206 [ # # ]: 0 : if (streamingDoneSending)
3207 : : {
3208 : 0 : WalSndCaughtUp = true;
3209 : 0 : return;
3210 : : }
3211 : :
3212 : : /* Figure out how far we can safely send the WAL. */
3213 [ # # ]: 0 : if (sendTimeLineIsHistoric)
3214 : : {
3215 : : /*
3216 : : * Streaming an old timeline that's in this server's history, but is
3217 : : * not the one we're currently inserting or replaying. It can be
3218 : : * streamed up to the point where we switched off that timeline.
3219 : : */
3220 : 0 : SendRqstPtr = sendTimeLineValidUpto;
3221 : 0 : }
3222 [ # # ]: 0 : else if (am_cascading_walsender)
3223 : : {
3224 : 0 : TimeLineID SendRqstTLI;
3225 : :
3226 : : /*
3227 : : * Streaming the latest timeline on a standby.
3228 : : *
3229 : : * Attempt to send all WAL that has already been replayed, so that we
3230 : : * know it's valid. If we're receiving WAL through streaming
3231 : : * replication, it's also OK to send any WAL that has been received
3232 : : * but not replayed.
3233 : : *
3234 : : * The timeline we're recovering from can change, or we can be
3235 : : * promoted. In either case, the current timeline becomes historic. We
3236 : : * need to detect that so that we don't try to stream past the point
3237 : : * where we switched to another timeline. We check for promotion or
3238 : : * timeline switch after calculating FlushPtr, to avoid a race
3239 : : * condition: if the timeline becomes historic just after we checked
3240 : : * that it was still current, it's still be OK to stream it up to the
3241 : : * FlushPtr that was calculated before it became historic.
3242 : : */
3243 : 0 : bool becameHistoric = false;
3244 : :
3245 : 0 : SendRqstPtr = GetStandbyFlushRecPtr(&SendRqstTLI);
3246 : :
3247 [ # # ]: 0 : if (!RecoveryInProgress())
3248 : : {
3249 : : /* We have been promoted. */
3250 : 0 : SendRqstTLI = GetWALInsertionTimeLine();
3251 : 0 : am_cascading_walsender = false;
3252 : 0 : becameHistoric = true;
3253 : 0 : }
3254 : : else
3255 : : {
3256 : : /*
3257 : : * Still a cascading standby. But is the timeline we're sending
3258 : : * still the one recovery is recovering from?
3259 : : */
3260 [ # # ]: 0 : if (sendTimeLine != SendRqstTLI)
3261 : 0 : becameHistoric = true;
3262 : : }
3263 : :
3264 [ # # ]: 0 : if (becameHistoric)
3265 : : {
3266 : : /*
3267 : : * The timeline we were sending has become historic. Read the
3268 : : * timeline history file of the new timeline to see where exactly
3269 : : * we forked off from the timeline we were sending.
3270 : : */
3271 : 0 : List *history;
3272 : :
3273 : 0 : history = readTimeLineHistory(SendRqstTLI);
3274 : 0 : sendTimeLineValidUpto = tliSwitchPoint(sendTimeLine, history, &sendTimeLineNextTLI);
3275 : :
3276 [ # # ]: 0 : Assert(sendTimeLine < sendTimeLineNextTLI);
3277 : 0 : list_free_deep(history);
3278 : :
3279 : 0 : sendTimeLineIsHistoric = true;
3280 : :
3281 : 0 : SendRqstPtr = sendTimeLineValidUpto;
3282 : 0 : }
3283 : 0 : }
3284 : : else
3285 : : {
3286 : : /*
3287 : : * Streaming the current timeline on a primary.
3288 : : *
3289 : : * Attempt to send all data that's already been written out and
3290 : : * fsync'd to disk. We cannot go further than what's been written out
3291 : : * given the current implementation of WALRead(). And in any case
3292 : : * it's unsafe to send WAL that is not securely down to disk on the
3293 : : * primary: if the primary subsequently crashes and restarts, standbys
3294 : : * must not have applied any WAL that got lost on the primary.
3295 : : */
3296 : 0 : SendRqstPtr = GetFlushRecPtr(NULL);
3297 : : }
3298 : :
3299 : : /*
3300 : : * Record the current system time as an approximation of the time at which
3301 : : * this WAL location was written for the purposes of lag tracking.
3302 : : *
3303 : : * In theory we could make XLogFlush() record a time in shmem whenever WAL
3304 : : * is flushed and we could get that time as well as the LSN when we call
3305 : : * GetFlushRecPtr() above (and likewise for the cascading standby
3306 : : * equivalent), but rather than putting any new code into the hot WAL path
3307 : : * it seems good enough to capture the time here. We should reach this
3308 : : * after XLogFlush() runs WalSndWakeupProcessRequests(), and although that
3309 : : * may take some time, we read the WAL flush pointer and take the time
3310 : : * very close to together here so that we'll get a later position if it is
3311 : : * still moving.
3312 : : *
3313 : : * Because LagTrackerWrite ignores samples when the LSN hasn't advanced,
3314 : : * this gives us a cheap approximation for the WAL flush time for this
3315 : : * LSN.
3316 : : *
3317 : : * Note that the LSN is not necessarily the LSN for the data contained in
3318 : : * the present message; it's the end of the WAL, which might be further
3319 : : * ahead. All the lag tracking machinery cares about is finding out when
3320 : : * that arbitrary LSN is eventually reported as written, flushed and
3321 : : * applied, so that it can measure the elapsed time.
3322 : : */
3323 : 0 : LagTrackerWrite(SendRqstPtr, GetCurrentTimestamp());
3324 : :
3325 : : /*
3326 : : * If this is a historic timeline and we've reached the point where we
3327 : : * forked to the next timeline, stop streaming.
3328 : : *
3329 : : * Note: We might already have sent WAL > sendTimeLineValidUpto. The
3330 : : * startup process will normally replay all WAL that has been received
3331 : : * from the primary, before promoting, but if the WAL streaming is
3332 : : * terminated at a WAL page boundary, the valid portion of the timeline
3333 : : * might end in the middle of a WAL record. We might've already sent the
3334 : : * first half of that partial WAL record to the cascading standby, so that
3335 : : * sentPtr > sendTimeLineValidUpto. That's OK; the cascading standby can't
3336 : : * replay the partial WAL record either, so it can still follow our
3337 : : * timeline switch.
3338 : : */
3339 [ # # # # ]: 0 : if (sendTimeLineIsHistoric && sendTimeLineValidUpto <= sentPtr)
3340 : : {
3341 : : /* close the current file. */
3342 [ # # ]: 0 : if (xlogreader->seg.ws_file >= 0)
3343 : 0 : wal_segment_close(xlogreader);
3344 : :
3345 : : /* Send CopyDone */
3346 : 0 : pq_putmessage_noblock(PqMsg_CopyDone, NULL, 0);
3347 : 0 : streamingDoneSending = true;
3348 : :
3349 : 0 : WalSndCaughtUp = true;
3350 : :
3351 [ # # # # ]: 0 : elog(DEBUG1, "walsender reached end of timeline at %X/%08X (sent up to %X/%08X)",
3352 : : LSN_FORMAT_ARGS(sendTimeLineValidUpto),
3353 : : LSN_FORMAT_ARGS(sentPtr));
3354 : 0 : return;
3355 : : }
3356 : :
3357 : : /* Do we have any work to do? */
3358 [ # # ]: 0 : Assert(sentPtr <= SendRqstPtr);
3359 [ # # ]: 0 : if (SendRqstPtr <= sentPtr)
3360 : : {
3361 : 0 : WalSndCaughtUp = true;
3362 : 0 : return;
3363 : : }
3364 : :
3365 : : /*
3366 : : * Figure out how much to send in one message. If there's no more than
3367 : : * MAX_SEND_SIZE bytes to send, send everything. Otherwise send
3368 : : * MAX_SEND_SIZE bytes, but round back to logfile or page boundary.
3369 : : *
3370 : : * The rounding is not only for performance reasons. Walreceiver relies on
3371 : : * the fact that we never split a WAL record across two messages. Since a
3372 : : * long WAL record is split at page boundary into continuation records,
3373 : : * page boundary is always a safe cut-off point. We also assume that
3374 : : * SendRqstPtr never points to the middle of a WAL record.
3375 : : */
3376 : 0 : startptr = sentPtr;
3377 : 0 : endptr = startptr;
3378 : 0 : endptr += MAX_SEND_SIZE;
3379 : :
3380 : : /* if we went beyond SendRqstPtr, back off */
3381 [ # # ]: 0 : if (SendRqstPtr <= endptr)
3382 : : {
3383 : 0 : endptr = SendRqstPtr;
3384 [ # # ]: 0 : if (sendTimeLineIsHistoric)
3385 : 0 : WalSndCaughtUp = false;
3386 : : else
3387 : 0 : WalSndCaughtUp = true;
3388 : 0 : }
3389 : : else
3390 : : {
3391 : : /* round down to page boundary. */
3392 : 0 : endptr -= (endptr % XLOG_BLCKSZ);
3393 : 0 : WalSndCaughtUp = false;
3394 : : }
3395 : :
3396 : 0 : nbytes = endptr - startptr;
3397 [ # # ]: 0 : Assert(nbytes <= MAX_SEND_SIZE);
3398 : :
3399 : : /*
3400 : : * OK to read and send the slice.
3401 : : */
3402 : 0 : resetStringInfo(&output_message);
3403 : 0 : pq_sendbyte(&output_message, PqReplMsg_WALData);
3404 : :
3405 : 0 : pq_sendint64(&output_message, startptr); /* dataStart */
3406 : 0 : pq_sendint64(&output_message, SendRqstPtr); /* walEnd */
3407 : 0 : pq_sendint64(&output_message, 0); /* sendtime, filled in last */
3408 : :
3409 : : /*
3410 : : * Read the log directly into the output buffer to avoid extra memcpy
3411 : : * calls.
3412 : : */
3413 : 0 : enlargeStringInfo(&output_message, nbytes);
3414 : :
3415 : : retry:
3416 : : /* attempt to read WAL from WAL buffers first */
3417 : 0 : rbytes = WALReadFromBuffers(&output_message.data[output_message.len],
3418 : 0 : startptr, nbytes, xlogreader->seg.ws_tli);
3419 : 0 : output_message.len += rbytes;
3420 : 0 : startptr += rbytes;
3421 : 0 : nbytes -= rbytes;
3422 : :
3423 : : /* now read the remaining WAL from WAL file */
3424 [ # # # # ]: 0 : if (nbytes > 0 &&
3425 : 0 : !WALRead(xlogreader,
3426 : 0 : &output_message.data[output_message.len],
3427 : 0 : startptr,
3428 : 0 : nbytes,
3429 : 0 : xlogreader->seg.ws_tli, /* Pass the current TLI because
3430 : : * only WalSndSegmentOpen controls
3431 : : * whether new TLI is needed. */
3432 : : &errinfo))
3433 : 0 : WALReadRaiseError(&errinfo);
3434 : :
3435 : : /* See logical_read_xlog_page(). */
3436 : 0 : XLByteToSeg(startptr, segno, xlogreader->segcxt.ws_segsize);
3437 : 0 : CheckXLogRemoved(segno, xlogreader->seg.ws_tli);
3438 : :
3439 : : /*
3440 : : * During recovery, the currently-open WAL file might be replaced with the
3441 : : * file of the same name retrieved from archive. So we always need to
3442 : : * check what we read was valid after reading into the buffer. If it's
3443 : : * invalid, we try to open and read the file again.
3444 : : */
3445 [ # # ]: 0 : if (am_cascading_walsender)
3446 : : {
3447 : 0 : WalSnd *walsnd = MyWalSnd;
3448 : 0 : bool reload;
3449 : :
3450 [ # # ]: 0 : SpinLockAcquire(&walsnd->mutex);
3451 : 0 : reload = walsnd->needreload;
3452 : 0 : walsnd->needreload = false;
3453 : 0 : SpinLockRelease(&walsnd->mutex);
3454 : :
3455 [ # # # # ]: 0 : if (reload && xlogreader->seg.ws_file >= 0)
3456 : : {
3457 : 0 : wal_segment_close(xlogreader);
3458 : :
3459 : 0 : goto retry;
3460 : : }
3461 [ # # ]: 0 : }
3462 : :
3463 : 0 : output_message.len += nbytes;
3464 : 0 : output_message.data[output_message.len] = '\0';
3465 : :
3466 : : /*
3467 : : * Fill the send timestamp last, so that it is taken as late as possible.
3468 : : */
3469 : 0 : resetStringInfo(&tmpbuf);
3470 : 0 : pq_sendint64(&tmpbuf, GetCurrentTimestamp());
3471 : 0 : memcpy(&output_message.data[1 + sizeof(int64) + sizeof(int64)],
3472 : : tmpbuf.data, sizeof(int64));
3473 : :
3474 : 0 : pq_putmessage_noblock(PqMsg_CopyData, output_message.data, output_message.len);
3475 : :
3476 : 0 : sentPtr = endptr;
3477 : :
3478 : : /* Update shared memory status */
3479 : : {
3480 : 0 : WalSnd *walsnd = MyWalSnd;
3481 : :
3482 [ # # ]: 0 : SpinLockAcquire(&walsnd->mutex);
3483 : 0 : walsnd->sentPtr = sentPtr;
3484 : 0 : SpinLockRelease(&walsnd->mutex);
3485 : 0 : }
3486 : :
3487 : : /* Report progress of XLOG streaming in PS display */
3488 [ # # ]: 0 : if (update_process_title)
3489 : : {
3490 : 0 : char activitymsg[50];
3491 : :
3492 : 0 : snprintf(activitymsg, sizeof(activitymsg), "streaming %X/%08X",
3493 : 0 : LSN_FORMAT_ARGS(sentPtr));
3494 : 0 : set_ps_display(activitymsg);
3495 : 0 : }
3496 : 0 : }
3497 : :
3498 : : /*
3499 : : * Stream out logically decoded data.
3500 : : */
3501 : : static void
3502 : 0 : XLogSendLogical(void)
3503 : : {
3504 : 0 : XLogRecord *record;
3505 : 0 : char *errm;
3506 : :
3507 : : /*
3508 : : * We'll use the current flush point to determine whether we've caught up.
3509 : : * This variable is static in order to cache it across calls. Caching is
3510 : : * helpful because GetFlushRecPtr() needs to acquire a heavily-contended
3511 : : * spinlock.
3512 : : */
3513 : : static XLogRecPtr flushPtr = InvalidXLogRecPtr;
3514 : :
3515 : : /*
3516 : : * Don't know whether we've caught up yet. We'll set WalSndCaughtUp to
3517 : : * true in WalSndWaitForWal, if we're actually waiting. We also set to
3518 : : * true if XLogReadRecord() had to stop reading but WalSndWaitForWal
3519 : : * didn't wait - i.e. when we're shutting down.
3520 : : */
3521 : 0 : WalSndCaughtUp = false;
3522 : :
3523 : 0 : record = XLogReadRecord(logical_decoding_ctx->reader, &errm);
3524 : :
3525 : : /* xlog record was invalid */
3526 [ # # ]: 0 : if (errm != NULL)
3527 [ # # # # ]: 0 : elog(ERROR, "could not find record while sending logically-decoded data: %s",
3528 : : errm);
3529 : :
3530 [ # # ]: 0 : if (record != NULL)
3531 : : {
3532 : : /*
3533 : : * Note the lack of any call to LagTrackerWrite() which is handled by
3534 : : * WalSndUpdateProgress which is called by output plugin through
3535 : : * logical decoding write api.
3536 : : */
3537 : 0 : LogicalDecodingProcessRecord(logical_decoding_ctx, logical_decoding_ctx->reader);
3538 : :
3539 : 0 : sentPtr = logical_decoding_ctx->reader->EndRecPtr;
3540 : 0 : }
3541 : :
3542 : : /*
3543 : : * If first time through in this session, initialize flushPtr. Otherwise,
3544 : : * we only need to update flushPtr if EndRecPtr is past it.
3545 : : */
3546 [ # # # # ]: 0 : if (!XLogRecPtrIsValid(flushPtr) ||
3547 : 0 : logical_decoding_ctx->reader->EndRecPtr >= flushPtr)
3548 : : {
3549 : : /*
3550 : : * For cascading logical WAL senders, we use the replay LSN instead of
3551 : : * the flush LSN, since logical decoding on a standby only processes
3552 : : * WAL that has been replayed. This distinction becomes particularly
3553 : : * important during shutdown, as new WAL is no longer replayed and the
3554 : : * last replayed LSN marks the furthest point up to which decoding can
3555 : : * proceed.
3556 : : */
3557 [ # # ]: 0 : if (am_cascading_walsender)
3558 : 0 : flushPtr = GetXLogReplayRecPtr(NULL);
3559 : : else
3560 : 0 : flushPtr = GetFlushRecPtr(NULL);
3561 : 0 : }
3562 : :
3563 : : /* If EndRecPtr is still past our flushPtr, it means we caught up. */
3564 [ # # ]: 0 : if (logical_decoding_ctx->reader->EndRecPtr >= flushPtr)
3565 : 0 : WalSndCaughtUp = true;
3566 : :
3567 : : /*
3568 : : * If we're caught up and have been requested to stop, have WalSndLoop()
3569 : : * terminate the connection in an orderly manner, after writing out all
3570 : : * the pending data.
3571 : : */
3572 [ # # # # ]: 0 : if (WalSndCaughtUp && got_STOPPING)
3573 : 0 : got_SIGUSR2 = true;
3574 : :
3575 : : /* Update shared memory status */
3576 : : {
3577 : 0 : WalSnd *walsnd = MyWalSnd;
3578 : :
3579 [ # # ]: 0 : SpinLockAcquire(&walsnd->mutex);
3580 : 0 : walsnd->sentPtr = sentPtr;
3581 : 0 : SpinLockRelease(&walsnd->mutex);
3582 : 0 : }
3583 : 0 : }
3584 : :
3585 : : /*
3586 : : * Shutdown if the sender is caught up.
3587 : : *
3588 : : * NB: This should only be called when the shutdown signal has been received
3589 : : * from postmaster.
3590 : : *
3591 : : * Note that if we determine that there's still more data to send, this
3592 : : * function will return control to the caller.
3593 : : */
3594 : : static void
3595 : 0 : WalSndDone(WalSndSendDataCallback send_data)
3596 : : {
3597 : 0 : XLogRecPtr replicatedPtr;
3598 : :
3599 : : /* ... let's just be real sure we're caught up ... */
3600 : 0 : send_data();
3601 : :
3602 : : /*
3603 : : * To figure out whether all WAL has successfully been replicated, check
3604 : : * flush location if valid, write otherwise. Tools like pg_receivewal will
3605 : : * usually (unless in synchronous mode) return an invalid flush location.
3606 : : */
3607 [ # # ]: 0 : replicatedPtr = XLogRecPtrIsValid(MyWalSnd->flush) ?
3608 : 0 : MyWalSnd->flush : MyWalSnd->write;
3609 : :
3610 [ # # # # : 0 : if (WalSndCaughtUp && sentPtr == replicatedPtr &&
# # ]
3611 : 0 : !pq_is_send_pending())
3612 : : {
3613 : 0 : QueryCompletion qc;
3614 : :
3615 : : /* Inform the standby that XLOG streaming is done */
3616 : 0 : SetQueryCompletion(&qc, CMDTAG_COPY, 0);
3617 : 0 : EndCommand(&qc, DestRemote, false);
3618 : 0 : pq_flush();
3619 : :
3620 : 0 : proc_exit(0);
3621 : : }
3622 [ # # ]: 0 : if (!waiting_for_ping_response)
3623 : 0 : WalSndKeepalive(true, InvalidXLogRecPtr);
3624 : 0 : }
3625 : :
3626 : : /*
3627 : : * Returns the latest point in WAL that has been safely flushed to disk.
3628 : : * This should only be called when in recovery.
3629 : : *
3630 : : * This is called either by cascading walsender to find WAL position to be sent
3631 : : * to a cascaded standby or by slot synchronization operation to validate remote
3632 : : * slot's lsn before syncing it locally.
3633 : : *
3634 : : * As a side-effect, *tli is updated to the TLI of the last
3635 : : * replayed WAL record.
3636 : : */
3637 : : XLogRecPtr
3638 : 0 : GetStandbyFlushRecPtr(TimeLineID *tli)
3639 : : {
3640 : 0 : XLogRecPtr replayPtr;
3641 : 0 : TimeLineID replayTLI;
3642 : 0 : XLogRecPtr receivePtr;
3643 : 0 : TimeLineID receiveTLI;
3644 : 0 : XLogRecPtr result;
3645 : :
3646 [ # # # # ]: 0 : Assert(am_cascading_walsender || IsSyncingReplicationSlots());
3647 : :
3648 : : /*
3649 : : * We can safely send what's already been replayed. Also, if walreceiver
3650 : : * is streaming WAL from the same timeline, we can send anything that it
3651 : : * has streamed, but hasn't been replayed yet.
3652 : : */
3653 : :
3654 : 0 : receivePtr = GetWalRcvFlushRecPtr(NULL, &receiveTLI);
3655 : 0 : replayPtr = GetXLogReplayRecPtr(&replayTLI);
3656 : :
3657 [ # # ]: 0 : if (tli)
3658 : 0 : *tli = replayTLI;
3659 : :
3660 : 0 : result = replayPtr;
3661 [ # # # # ]: 0 : if (receiveTLI == replayTLI && receivePtr > replayPtr)
3662 : 0 : result = receivePtr;
3663 : :
3664 : 0 : return result;
3665 : 0 : }
3666 : :
3667 : : /*
3668 : : * Request walsenders to reload the currently-open WAL file
3669 : : */
3670 : : void
3671 : 0 : WalSndRqstFileReload(void)
3672 : : {
3673 : 0 : int i;
3674 : :
3675 [ # # ]: 0 : for (i = 0; i < max_wal_senders; i++)
3676 : : {
3677 : 0 : WalSnd *walsnd = &WalSndCtl->walsnds[i];
3678 : :
3679 [ # # ]: 0 : SpinLockAcquire(&walsnd->mutex);
3680 [ # # ]: 0 : if (walsnd->pid == 0)
3681 : : {
3682 : 0 : SpinLockRelease(&walsnd->mutex);
3683 : 0 : continue;
3684 : : }
3685 : 0 : walsnd->needreload = true;
3686 : 0 : SpinLockRelease(&walsnd->mutex);
3687 [ # # # ]: 0 : }
3688 : 0 : }
3689 : :
3690 : : /*
3691 : : * Handle PROCSIG_WALSND_INIT_STOPPING signal.
3692 : : */
3693 : : void
3694 : 0 : HandleWalSndInitStopping(void)
3695 : : {
3696 [ # # ]: 0 : Assert(am_walsender);
3697 : :
3698 : : /*
3699 : : * If replication has not yet started, die like with SIGTERM. If
3700 : : * replication is active, only set a flag and wake up the main loop. It
3701 : : * will send any outstanding WAL, wait for it to be replicated to the
3702 : : * standby, and then exit gracefully.
3703 : : */
3704 [ # # ]: 0 : if (!replication_active)
3705 : 0 : kill(MyProcPid, SIGTERM);
3706 : : else
3707 : 0 : got_STOPPING = true;
3708 : 0 : }
3709 : :
3710 : : /*
3711 : : * SIGUSR2: set flag to do a last cycle and shut down afterwards. The WAL
3712 : : * sender should already have been switched to WALSNDSTATE_STOPPING at
3713 : : * this point.
3714 : : */
3715 : : static void
3716 : 0 : WalSndLastCycleHandler(SIGNAL_ARGS)
3717 : : {
3718 : 0 : got_SIGUSR2 = true;
3719 : 0 : SetLatch(MyLatch);
3720 : 0 : }
3721 : :
3722 : : /* Set up signal handlers */
3723 : : void
3724 : 0 : WalSndSignals(void)
3725 : : {
3726 : : /* Set up signal handlers */
3727 : 0 : pqsignal(SIGHUP, SignalHandlerForConfigReload);
3728 : 0 : pqsignal(SIGINT, StatementCancelHandler); /* query cancel */
3729 : 0 : pqsignal(SIGTERM, die); /* request shutdown */
3730 : : /* SIGQUIT handler was already set up by InitPostmasterChild */
3731 : 0 : InitializeTimeouts(); /* establishes SIGALRM handler */
3732 : 0 : pqsignal(SIGPIPE, SIG_IGN);
3733 : 0 : pqsignal(SIGUSR1, procsignal_sigusr1_handler);
3734 : 0 : pqsignal(SIGUSR2, WalSndLastCycleHandler); /* request a last cycle and
3735 : : * shutdown */
3736 : :
3737 : : /* Reset some signals that are accepted by postmaster but not here */
3738 : 0 : pqsignal(SIGCHLD, SIG_DFL);
3739 : 0 : }
3740 : :
3741 : : /* Report shared-memory space needed by WalSndShmemInit */
3742 : : Size
3743 : 21 : WalSndShmemSize(void)
3744 : : {
3745 : 21 : Size size = 0;
3746 : :
3747 : 21 : size = offsetof(WalSndCtlData, walsnds);
3748 : 21 : size = add_size(size, mul_size(max_wal_senders, sizeof(WalSnd)));
3749 : :
3750 : 42 : return size;
3751 : 21 : }
3752 : :
3753 : : /* Allocate and initialize walsender-related shared memory */
3754 : : void
3755 : 6 : WalSndShmemInit(void)
3756 : : {
3757 : 6 : bool found;
3758 : 6 : int i;
3759 : :
3760 : 6 : WalSndCtl = (WalSndCtlData *)
3761 : 6 : ShmemInitStruct("Wal Sender Ctl", WalSndShmemSize(), &found);
3762 : :
3763 [ - + ]: 6 : if (!found)
3764 : : {
3765 : : /* First time through, so initialize */
3766 [ + - + - : 20 : MemSet(WalSndCtl, 0, WalSndShmemSize());
+ - + + +
+ ]
3767 : :
3768 [ + + ]: 24 : for (i = 0; i < NUM_SYNC_REP_WAIT_MODE; i++)
3769 : 18 : dlist_init(&(WalSndCtl->SyncRepQueue[i]));
3770 : :
3771 [ + + ]: 56 : for (i = 0; i < max_wal_senders; i++)
3772 : : {
3773 : 50 : WalSnd *walsnd = &WalSndCtl->walsnds[i];
3774 : :
3775 : 50 : SpinLockInit(&walsnd->mutex);
3776 : 50 : }
3777 : :
3778 : 6 : ConditionVariableInit(&WalSndCtl->wal_flush_cv);
3779 : 6 : ConditionVariableInit(&WalSndCtl->wal_replay_cv);
3780 : 6 : ConditionVariableInit(&WalSndCtl->wal_confirm_rcv_cv);
3781 : 6 : }
3782 : 6 : }
3783 : :
3784 : : /*
3785 : : * Wake up physical, logical or both kinds of walsenders
3786 : : *
3787 : : * The distinction between physical and logical walsenders is done, because:
3788 : : * - physical walsenders can't send data until it's been flushed
3789 : : * - logical walsenders on standby can't decode and send data until it's been
3790 : : * applied
3791 : : *
3792 : : * For cascading replication we need to wake up physical walsenders separately
3793 : : * from logical walsenders (see the comment before calling WalSndWakeup() in
3794 : : * ApplyWalRecord() for more details).
3795 : : *
3796 : : * This will be called inside critical sections, so throwing an error is not
3797 : : * advisable.
3798 : : */
3799 : : void
3800 : 867 : WalSndWakeup(bool physical, bool logical)
3801 : : {
3802 : : /*
3803 : : * Wake up all the walsenders waiting on WAL being flushed or replayed
3804 : : * respectively. Note that waiting walsender would have prepared to sleep
3805 : : * on the CV (i.e., added itself to the CV's waitlist) in WalSndWait()
3806 : : * before actually waiting.
3807 : : */
3808 [ - + ]: 867 : if (physical)
3809 : 867 : ConditionVariableBroadcast(&WalSndCtl->wal_flush_cv);
3810 : :
3811 [ + + ]: 867 : if (logical)
3812 : 866 : ConditionVariableBroadcast(&WalSndCtl->wal_replay_cv);
3813 : 867 : }
3814 : :
3815 : : /*
3816 : : * Wait for readiness on the FeBe socket, or a timeout. The mask should be
3817 : : * composed of optional WL_SOCKET_WRITEABLE and WL_SOCKET_READABLE flags. Exit
3818 : : * on postmaster death.
3819 : : */
3820 : : static void
3821 : 0 : WalSndWait(uint32 socket_events, long timeout, uint32 wait_event)
3822 : : {
3823 : 0 : WaitEvent event;
3824 : :
3825 : 0 : ModifyWaitEvent(FeBeWaitSet, FeBeWaitSetSocketPos, socket_events, NULL);
3826 : :
3827 : : /*
3828 : : * We use a condition variable to efficiently wake up walsenders in
3829 : : * WalSndWakeup().
3830 : : *
3831 : : * Every walsender prepares to sleep on a shared memory CV. Note that it
3832 : : * just prepares to sleep on the CV (i.e., adds itself to the CV's
3833 : : * waitlist), but does not actually wait on the CV (IOW, it never calls
3834 : : * ConditionVariableSleep()). It still uses WaitEventSetWait() for
3835 : : * waiting, because we also need to wait for socket events. The processes
3836 : : * (startup process, walreceiver etc.) wanting to wake up walsenders use
3837 : : * ConditionVariableBroadcast(), which in turn calls SetLatch(), helping
3838 : : * walsenders come out of WaitEventSetWait().
3839 : : *
3840 : : * This approach is simple and efficient because, one doesn't have to loop
3841 : : * through all the walsenders slots, with a spinlock acquisition and
3842 : : * release for every iteration, just to wake up only the waiting
3843 : : * walsenders. It makes WalSndWakeup() callers' life easy.
3844 : : *
3845 : : * XXX: A desirable future improvement would be to add support for CVs
3846 : : * into WaitEventSetWait().
3847 : : *
3848 : : * And, we use separate shared memory CVs for physical and logical
3849 : : * walsenders for selective wake ups, see WalSndWakeup() for more details.
3850 : : *
3851 : : * If the wait event is WAIT_FOR_STANDBY_CONFIRMATION, wait on another CV
3852 : : * until awakened by physical walsenders after the walreceiver confirms
3853 : : * the receipt of the LSN.
3854 : : */
3855 [ # # ]: 0 : if (wait_event == WAIT_EVENT_WAIT_FOR_STANDBY_CONFIRMATION)
3856 : 0 : ConditionVariablePrepareToSleep(&WalSndCtl->wal_confirm_rcv_cv);
3857 [ # # ]: 0 : else if (MyWalSnd->kind == REPLICATION_KIND_PHYSICAL)
3858 : 0 : ConditionVariablePrepareToSleep(&WalSndCtl->wal_flush_cv);
3859 [ # # ]: 0 : else if (MyWalSnd->kind == REPLICATION_KIND_LOGICAL)
3860 : 0 : ConditionVariablePrepareToSleep(&WalSndCtl->wal_replay_cv);
3861 : :
3862 [ # # # # ]: 0 : if (WaitEventSetWait(FeBeWaitSet, timeout, &event, 1, wait_event) == 1 &&
3863 : 0 : (event.events & WL_POSTMASTER_DEATH))
3864 : : {
3865 : 0 : ConditionVariableCancelSleep();
3866 : 0 : proc_exit(1);
3867 : : }
3868 : :
3869 : 0 : ConditionVariableCancelSleep();
3870 : 0 : }
3871 : :
3872 : : /*
3873 : : * Signal all walsenders to move to stopping state.
3874 : : *
3875 : : * This will trigger walsenders to move to a state where no further WAL can be
3876 : : * generated. See this file's header for details.
3877 : : */
3878 : : void
3879 : 3 : WalSndInitStopping(void)
3880 : : {
3881 : 3 : int i;
3882 : :
3883 [ + + ]: 33 : for (i = 0; i < max_wal_senders; i++)
3884 : : {
3885 : 30 : WalSnd *walsnd = &WalSndCtl->walsnds[i];
3886 : 30 : pid_t pid;
3887 : :
3888 [ - + ]: 30 : SpinLockAcquire(&walsnd->mutex);
3889 : 30 : pid = walsnd->pid;
3890 : 30 : SpinLockRelease(&walsnd->mutex);
3891 : :
3892 [ - + ]: 30 : if (pid == 0)
3893 : 30 : continue;
3894 : :
3895 : 0 : SendProcSignal(pid, PROCSIG_WALSND_INIT_STOPPING, INVALID_PROC_NUMBER);
3896 [ - + - ]: 30 : }
3897 : 3 : }
3898 : :
3899 : : /*
3900 : : * Wait that all the WAL senders have quit or reached the stopping state. This
3901 : : * is used by the checkpointer to control when the shutdown checkpoint can
3902 : : * safely be performed.
3903 : : */
3904 : : void
3905 : 3 : WalSndWaitStopping(void)
3906 : : {
3907 : 3 : for (;;)
3908 : : {
3909 : 3 : int i;
3910 : 3 : bool all_stopped = true;
3911 : :
3912 [ + + ]: 33 : for (i = 0; i < max_wal_senders; i++)
3913 : : {
3914 : 30 : WalSnd *walsnd = &WalSndCtl->walsnds[i];
3915 : :
3916 [ - + ]: 30 : SpinLockAcquire(&walsnd->mutex);
3917 : :
3918 [ - + ]: 30 : if (walsnd->pid == 0)
3919 : : {
3920 : 30 : SpinLockRelease(&walsnd->mutex);
3921 : 30 : continue;
3922 : : }
3923 : :
3924 [ # # ]: 0 : if (walsnd->state != WALSNDSTATE_STOPPING)
3925 : : {
3926 : 0 : all_stopped = false;
3927 : 0 : SpinLockRelease(&walsnd->mutex);
3928 : 0 : break;
3929 : : }
3930 : 0 : SpinLockRelease(&walsnd->mutex);
3931 [ + - - ]: 30 : }
3932 : :
3933 : : /* safe to leave if confirmation is done for all WAL senders */
3934 [ + - ]: 3 : if (all_stopped)
3935 : 3 : return;
3936 : :
3937 : 0 : pg_usleep(10000L); /* wait for 10 msec */
3938 [ - + ]: 3 : }
3939 : 3 : }
3940 : :
3941 : : /* Set state for current walsender (only called in walsender) */
3942 : : void
3943 : 0 : WalSndSetState(WalSndState state)
3944 : : {
3945 : 0 : WalSnd *walsnd = MyWalSnd;
3946 : :
3947 [ # # ]: 0 : Assert(am_walsender);
3948 : :
3949 [ # # ]: 0 : if (walsnd->state == state)
3950 : 0 : return;
3951 : :
3952 [ # # ]: 0 : SpinLockAcquire(&walsnd->mutex);
3953 : 0 : walsnd->state = state;
3954 : 0 : SpinLockRelease(&walsnd->mutex);
3955 [ # # ]: 0 : }
3956 : :
3957 : : /*
3958 : : * Return a string constant representing the state. This is used
3959 : : * in system views, and should *not* be translated.
3960 : : */
3961 : : static const char *
3962 : 0 : WalSndGetStateString(WalSndState state)
3963 : : {
3964 [ # # # # : 0 : switch (state)
# # ]
3965 : : {
3966 : : case WALSNDSTATE_STARTUP:
3967 : 0 : return "startup";
3968 : : case WALSNDSTATE_BACKUP:
3969 : 0 : return "backup";
3970 : : case WALSNDSTATE_CATCHUP:
3971 : 0 : return "catchup";
3972 : : case WALSNDSTATE_STREAMING:
3973 : 0 : return "streaming";
3974 : : case WALSNDSTATE_STOPPING:
3975 : 0 : return "stopping";
3976 : : }
3977 : 0 : return "UNKNOWN";
3978 : 0 : }
3979 : :
3980 : : static Interval *
3981 : 0 : offset_to_interval(TimeOffset offset)
3982 : : {
3983 : 0 : Interval *result = palloc_object(Interval);
3984 : :
3985 : 0 : result->month = 0;
3986 : 0 : result->day = 0;
3987 : 0 : result->time = offset;
3988 : :
3989 : 0 : return result;
3990 : 0 : }
3991 : :
3992 : : /*
3993 : : * Returns activity of walsenders, including pids and xlog locations sent to
3994 : : * standby servers.
3995 : : */
3996 : : Datum
3997 : 0 : pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
3998 : : {
3999 : : #define PG_STAT_GET_WAL_SENDERS_COLS 12
4000 : 0 : ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
4001 : 0 : SyncRepStandbyData *sync_standbys;
4002 : 0 : int num_standbys;
4003 : 0 : int i;
4004 : :
4005 : 0 : InitMaterializedSRF(fcinfo, 0);
4006 : :
4007 : : /*
4008 : : * Get the currently active synchronous standbys. This could be out of
4009 : : * date before we're done, but we'll use the data anyway.
4010 : : */
4011 : 0 : num_standbys = SyncRepGetCandidateStandbys(&sync_standbys);
4012 : :
4013 [ # # ]: 0 : for (i = 0; i < max_wal_senders; i++)
4014 : : {
4015 : 0 : WalSnd *walsnd = &WalSndCtl->walsnds[i];
4016 : 0 : XLogRecPtr sent_ptr;
4017 : 0 : XLogRecPtr write;
4018 : 0 : XLogRecPtr flush;
4019 : 0 : XLogRecPtr apply;
4020 : 0 : TimeOffset writeLag;
4021 : 0 : TimeOffset flushLag;
4022 : 0 : TimeOffset applyLag;
4023 : 0 : int priority;
4024 : 0 : int pid;
4025 : 0 : WalSndState state;
4026 : 0 : TimestampTz replyTime;
4027 : 0 : bool is_sync_standby;
4028 : 0 : Datum values[PG_STAT_GET_WAL_SENDERS_COLS];
4029 : 0 : bool nulls[PG_STAT_GET_WAL_SENDERS_COLS] = {0};
4030 : 0 : int j;
4031 : :
4032 : : /* Collect data from shared memory */
4033 [ # # ]: 0 : SpinLockAcquire(&walsnd->mutex);
4034 [ # # ]: 0 : if (walsnd->pid == 0)
4035 : : {
4036 : 0 : SpinLockRelease(&walsnd->mutex);
4037 : 0 : continue;
4038 : : }
4039 : 0 : pid = walsnd->pid;
4040 : 0 : sent_ptr = walsnd->sentPtr;
4041 : 0 : state = walsnd->state;
4042 : 0 : write = walsnd->write;
4043 : 0 : flush = walsnd->flush;
4044 : 0 : apply = walsnd->apply;
4045 : 0 : writeLag = walsnd->writeLag;
4046 : 0 : flushLag = walsnd->flushLag;
4047 : 0 : applyLag = walsnd->applyLag;
4048 : 0 : priority = walsnd->sync_standby_priority;
4049 : 0 : replyTime = walsnd->replyTime;
4050 : 0 : SpinLockRelease(&walsnd->mutex);
4051 : :
4052 : : /*
4053 : : * Detect whether walsender is/was considered synchronous. We can
4054 : : * provide some protection against stale data by checking the PID
4055 : : * along with walsnd_index.
4056 : : */
4057 : 0 : is_sync_standby = false;
4058 [ # # ]: 0 : for (j = 0; j < num_standbys; j++)
4059 : : {
4060 [ # # # # ]: 0 : if (sync_standbys[j].walsnd_index == i &&
4061 : 0 : sync_standbys[j].pid == pid)
4062 : : {
4063 : 0 : is_sync_standby = true;
4064 : 0 : break;
4065 : : }
4066 : 0 : }
4067 : :
4068 : 0 : values[0] = Int32GetDatum(pid);
4069 : :
4070 [ # # ]: 0 : if (!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))
4071 : : {
4072 : : /*
4073 : : * Only superusers and roles with privileges of pg_read_all_stats
4074 : : * can see details. Other users only get the pid value to know
4075 : : * it's a walsender, but no details.
4076 : : */
4077 [ # # # # : 0 : MemSet(&nulls[1], true, PG_STAT_GET_WAL_SENDERS_COLS - 1);
# # # # #
# ]
4078 : 0 : }
4079 : : else
4080 : : {
4081 : 0 : values[1] = CStringGetTextDatum(WalSndGetStateString(state));
4082 : :
4083 [ # # ]: 0 : if (!XLogRecPtrIsValid(sent_ptr))
4084 : 0 : nulls[2] = true;
4085 : 0 : values[2] = LSNGetDatum(sent_ptr);
4086 : :
4087 [ # # ]: 0 : if (!XLogRecPtrIsValid(write))
4088 : 0 : nulls[3] = true;
4089 : 0 : values[3] = LSNGetDatum(write);
4090 : :
4091 [ # # ]: 0 : if (!XLogRecPtrIsValid(flush))
4092 : 0 : nulls[4] = true;
4093 : 0 : values[4] = LSNGetDatum(flush);
4094 : :
4095 [ # # ]: 0 : if (!XLogRecPtrIsValid(apply))
4096 : 0 : nulls[5] = true;
4097 : 0 : values[5] = LSNGetDatum(apply);
4098 : :
4099 : : /*
4100 : : * Treat a standby such as a pg_basebackup background process
4101 : : * which always returns an invalid flush location, as an
4102 : : * asynchronous standby.
4103 : : */
4104 [ # # ]: 0 : priority = XLogRecPtrIsValid(flush) ? priority : 0;
4105 : :
4106 [ # # ]: 0 : if (writeLag < 0)
4107 : 0 : nulls[6] = true;
4108 : : else
4109 : 0 : values[6] = IntervalPGetDatum(offset_to_interval(writeLag));
4110 : :
4111 [ # # ]: 0 : if (flushLag < 0)
4112 : 0 : nulls[7] = true;
4113 : : else
4114 : 0 : values[7] = IntervalPGetDatum(offset_to_interval(flushLag));
4115 : :
4116 [ # # ]: 0 : if (applyLag < 0)
4117 : 0 : nulls[8] = true;
4118 : : else
4119 : 0 : values[8] = IntervalPGetDatum(offset_to_interval(applyLag));
4120 : :
4121 : 0 : values[9] = Int32GetDatum(priority);
4122 : :
4123 : : /*
4124 : : * More easily understood version of standby state. This is purely
4125 : : * informational.
4126 : : *
4127 : : * In quorum-based sync replication, the role of each standby
4128 : : * listed in synchronous_standby_names can be changing very
4129 : : * frequently. Any standbys considered as "sync" at one moment can
4130 : : * be switched to "potential" ones at the next moment. So, it's
4131 : : * basically useless to report "sync" or "potential" as their sync
4132 : : * states. We report just "quorum" for them.
4133 : : */
4134 [ # # ]: 0 : if (priority == 0)
4135 : 0 : values[10] = CStringGetTextDatum("async");
4136 [ # # ]: 0 : else if (is_sync_standby)
4137 [ # # ]: 0 : values[10] = SyncRepConfig->syncrep_method == SYNC_REP_PRIORITY ?
4138 : 0 : CStringGetTextDatum("sync") : CStringGetTextDatum("quorum");
4139 : : else
4140 : 0 : values[10] = CStringGetTextDatum("potential");
4141 : :
4142 [ # # ]: 0 : if (replyTime == 0)
4143 : 0 : nulls[11] = true;
4144 : : else
4145 : 0 : values[11] = TimestampTzGetDatum(replyTime);
4146 : : }
4147 : :
4148 : 0 : tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc,
4149 : 0 : values, nulls);
4150 [ # # # ]: 0 : }
4151 : :
4152 : 0 : return (Datum) 0;
4153 : 0 : }
4154 : :
4155 : : /*
4156 : : * Send a keepalive message to standby.
4157 : : *
4158 : : * If requestReply is set, the message requests the other party to send
4159 : : * a message back to us, for heartbeat purposes. We also set a flag to
4160 : : * let nearby code know that we're waiting for that response, to avoid
4161 : : * repeated requests.
4162 : : *
4163 : : * writePtr is the location up to which the WAL is sent. It is essentially
4164 : : * the same as sentPtr but in some cases, we need to send keep alive before
4165 : : * sentPtr is updated like when skipping empty transactions.
4166 : : */
4167 : : static void
4168 : 0 : WalSndKeepalive(bool requestReply, XLogRecPtr writePtr)
4169 : : {
4170 [ # # # # ]: 0 : elog(DEBUG2, "sending replication keepalive");
4171 : :
4172 : : /* construct the message... */
4173 : 0 : resetStringInfo(&output_message);
4174 : 0 : pq_sendbyte(&output_message, PqReplMsg_Keepalive);
4175 [ # # ]: 0 : pq_sendint64(&output_message, XLogRecPtrIsValid(writePtr) ? writePtr : sentPtr);
4176 : 0 : pq_sendint64(&output_message, GetCurrentTimestamp());
4177 : 0 : pq_sendbyte(&output_message, requestReply ? 1 : 0);
4178 : :
4179 : : /* ... and send it wrapped in CopyData */
4180 : 0 : pq_putmessage_noblock(PqMsg_CopyData, output_message.data, output_message.len);
4181 : :
4182 : : /* Set local flag */
4183 [ # # ]: 0 : if (requestReply)
4184 : 0 : waiting_for_ping_response = true;
4185 : 0 : }
4186 : :
4187 : : /*
4188 : : * Send keepalive message if too much time has elapsed.
4189 : : */
4190 : : static void
4191 : 0 : WalSndKeepaliveIfNecessary(void)
4192 : : {
4193 : 0 : TimestampTz ping_time;
4194 : :
4195 : : /*
4196 : : * Don't send keepalive messages if timeouts are globally disabled or
4197 : : * we're doing something not partaking in timeouts.
4198 : : */
4199 [ # # # # ]: 0 : if (wal_sender_timeout <= 0 || last_reply_timestamp <= 0)
4200 : 0 : return;
4201 : :
4202 [ # # ]: 0 : if (waiting_for_ping_response)
4203 : 0 : return;
4204 : :
4205 : : /*
4206 : : * If half of wal_sender_timeout has lapsed without receiving any reply
4207 : : * from the standby, send a keep-alive message to the standby requesting
4208 : : * an immediate reply.
4209 : : */
4210 : 0 : ping_time = TimestampTzPlusMilliseconds(last_reply_timestamp,
4211 : : wal_sender_timeout / 2);
4212 [ # # ]: 0 : if (last_processing >= ping_time)
4213 : : {
4214 : 0 : WalSndKeepalive(true, InvalidXLogRecPtr);
4215 : :
4216 : : /* Try to flush pending output to the client */
4217 [ # # ]: 0 : if (pq_flush_if_writable() != 0)
4218 : 0 : WalSndShutdown();
4219 : 0 : }
4220 [ # # ]: 0 : }
4221 : :
4222 : : /*
4223 : : * Record the end of the WAL and the time it was flushed locally, so that
4224 : : * LagTrackerRead can compute the elapsed time (lag) when this WAL location is
4225 : : * eventually reported to have been written, flushed and applied by the
4226 : : * standby in a reply message.
4227 : : */
4228 : : static void
4229 : 0 : LagTrackerWrite(XLogRecPtr lsn, TimestampTz local_flush_time)
4230 : : {
4231 : 0 : int new_write_head;
4232 : 0 : int i;
4233 : :
4234 [ # # ]: 0 : if (!am_walsender)
4235 : 0 : return;
4236 : :
4237 : : /*
4238 : : * If the lsn hasn't advanced since last time, then do nothing. This way
4239 : : * we only record a new sample when new WAL has been written.
4240 : : */
4241 [ # # ]: 0 : if (lag_tracker->last_lsn == lsn)
4242 : 0 : return;
4243 : 0 : lag_tracker->last_lsn = lsn;
4244 : :
4245 : : /*
4246 : : * If advancing the write head of the circular buffer would crash into any
4247 : : * of the read heads, then the buffer is full. In other words, the
4248 : : * slowest reader (presumably apply) is the one that controls the release
4249 : : * of space.
4250 : : */
4251 : 0 : new_write_head = (lag_tracker->write_head + 1) % LAG_TRACKER_BUFFER_SIZE;
4252 [ # # ]: 0 : for (i = 0; i < NUM_SYNC_REP_WAIT_MODE; ++i)
4253 : : {
4254 : : /*
4255 : : * If the buffer is full, move the slowest reader to a separate
4256 : : * overflow entry and free its space in the buffer so the write head
4257 : : * can advance.
4258 : : */
4259 [ # # ]: 0 : if (new_write_head == lag_tracker->read_heads[i])
4260 : : {
4261 : 0 : lag_tracker->overflowed[i] =
4262 : 0 : lag_tracker->buffer[lag_tracker->read_heads[i]];
4263 : 0 : lag_tracker->read_heads[i] = -1;
4264 : 0 : }
4265 : 0 : }
4266 : :
4267 : : /* Store a sample at the current write head position. */
4268 : 0 : lag_tracker->buffer[lag_tracker->write_head].lsn = lsn;
4269 : 0 : lag_tracker->buffer[lag_tracker->write_head].time = local_flush_time;
4270 : 0 : lag_tracker->write_head = new_write_head;
4271 [ # # ]: 0 : }
4272 : :
4273 : : /*
4274 : : * Find out how much time has elapsed between the moment WAL location 'lsn'
4275 : : * (or the highest known earlier LSN) was flushed locally and the time 'now'.
4276 : : * We have a separate read head for each of the reported LSN locations we
4277 : : * receive in replies from standby; 'head' controls which read head is
4278 : : * used. Whenever a read head crosses an LSN which was written into the
4279 : : * lag buffer with LagTrackerWrite, we can use the associated timestamp to
4280 : : * find out the time this LSN (or an earlier one) was flushed locally, and
4281 : : * therefore compute the lag.
4282 : : *
4283 : : * Return -1 if no new sample data is available, and otherwise the elapsed
4284 : : * time in microseconds.
4285 : : */
4286 : : static TimeOffset
4287 : 0 : LagTrackerRead(int head, XLogRecPtr lsn, TimestampTz now)
4288 : : {
4289 : 0 : TimestampTz time = 0;
4290 : :
4291 : : /*
4292 : : * If 'lsn' has not passed the WAL position stored in the overflow entry,
4293 : : * return the elapsed time (in microseconds) since the saved local flush
4294 : : * time. If the flush time is in the future (due to clock drift), return
4295 : : * -1 to treat as no valid sample.
4296 : : *
4297 : : * Otherwise, switch back to using the buffer to control the read head and
4298 : : * compute the elapsed time. The read head is then reset to point to the
4299 : : * oldest entry in the buffer.
4300 : : */
4301 [ # # ]: 0 : if (lag_tracker->read_heads[head] == -1)
4302 : : {
4303 [ # # ]: 0 : if (lag_tracker->overflowed[head].lsn > lsn)
4304 [ # # ]: 0 : return (now >= lag_tracker->overflowed[head].time) ?
4305 : 0 : now - lag_tracker->overflowed[head].time : -1;
4306 : :
4307 : 0 : time = lag_tracker->overflowed[head].time;
4308 : 0 : lag_tracker->last_read[head] = lag_tracker->overflowed[head];
4309 : 0 : lag_tracker->read_heads[head] =
4310 : 0 : (lag_tracker->write_head + 1) % LAG_TRACKER_BUFFER_SIZE;
4311 : 0 : }
4312 : :
4313 : : /* Read all unread samples up to this LSN or end of buffer. */
4314 [ # # # # ]: 0 : while (lag_tracker->read_heads[head] != lag_tracker->write_head &&
4315 : 0 : lag_tracker->buffer[lag_tracker->read_heads[head]].lsn <= lsn)
4316 : : {
4317 : 0 : time = lag_tracker->buffer[lag_tracker->read_heads[head]].time;
4318 : 0 : lag_tracker->last_read[head] =
4319 : 0 : lag_tracker->buffer[lag_tracker->read_heads[head]];
4320 : 0 : lag_tracker->read_heads[head] =
4321 : 0 : (lag_tracker->read_heads[head] + 1) % LAG_TRACKER_BUFFER_SIZE;
4322 : : }
4323 : :
4324 : : /*
4325 : : * If the lag tracker is empty, that means the standby has processed
4326 : : * everything we've ever sent so we should now clear 'last_read'. If we
4327 : : * didn't do that, we'd risk using a stale and irrelevant sample for
4328 : : * interpolation at the beginning of the next burst of WAL after a period
4329 : : * of idleness.
4330 : : */
4331 [ # # ]: 0 : if (lag_tracker->read_heads[head] == lag_tracker->write_head)
4332 : 0 : lag_tracker->last_read[head].time = 0;
4333 : :
4334 [ # # ]: 0 : if (time > now)
4335 : : {
4336 : : /* If the clock somehow went backwards, treat as not found. */
4337 : 0 : return -1;
4338 : : }
4339 [ # # ]: 0 : else if (time == 0)
4340 : : {
4341 : : /*
4342 : : * We didn't cross a time. If there is a future sample that we
4343 : : * haven't reached yet, and we've already reached at least one sample,
4344 : : * let's interpolate the local flushed time. This is mainly useful
4345 : : * for reporting a completely stuck apply position as having
4346 : : * increasing lag, since otherwise we'd have to wait for it to
4347 : : * eventually start moving again and cross one of our samples before
4348 : : * we can show the lag increasing.
4349 : : */
4350 [ # # ]: 0 : if (lag_tracker->read_heads[head] == lag_tracker->write_head)
4351 : : {
4352 : : /* There are no future samples, so we can't interpolate. */
4353 : 0 : return -1;
4354 : : }
4355 [ # # ]: 0 : else if (lag_tracker->last_read[head].time != 0)
4356 : : {
4357 : : /* We can interpolate between last_read and the next sample. */
4358 : 0 : double fraction;
4359 : 0 : WalTimeSample prev = lag_tracker->last_read[head];
4360 : 0 : WalTimeSample next = lag_tracker->buffer[lag_tracker->read_heads[head]];
4361 : :
4362 [ # # ]: 0 : if (lsn < prev.lsn)
4363 : : {
4364 : : /*
4365 : : * Reported LSNs shouldn't normally go backwards, but it's
4366 : : * possible when there is a timeline change. Treat as not
4367 : : * found.
4368 : : */
4369 : 0 : return -1;
4370 : : }
4371 : :
4372 [ # # ]: 0 : Assert(prev.lsn < next.lsn);
4373 : :
4374 [ # # ]: 0 : if (prev.time > next.time)
4375 : : {
4376 : : /* If the clock somehow went backwards, treat as not found. */
4377 : 0 : return -1;
4378 : : }
4379 : :
4380 : : /* See how far we are between the previous and next samples. */
4381 : 0 : fraction =
4382 : 0 : (double) (lsn - prev.lsn) / (double) (next.lsn - prev.lsn);
4383 : :
4384 : : /* Scale the local flush time proportionally. */
4385 : 0 : time = (TimestampTz)
4386 : 0 : ((double) prev.time + (next.time - prev.time) * fraction);
4387 [ # # ]: 0 : }
4388 : : else
4389 : : {
4390 : : /*
4391 : : * We have only a future sample, implying that we were entirely
4392 : : * caught up but and now there is a new burst of WAL and the
4393 : : * standby hasn't processed the first sample yet. Until the
4394 : : * standby reaches the future sample the best we can do is report
4395 : : * the hypothetical lag if that sample were to be replayed now.
4396 : : */
4397 : 0 : time = lag_tracker->buffer[lag_tracker->read_heads[head]].time;
4398 : : }
4399 : 0 : }
4400 : :
4401 : : /* Return the elapsed time since local flush time in microseconds. */
4402 [ # # ]: 0 : Assert(time != 0);
4403 : 0 : return now - time;
4404 : 0 : }
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