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1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * walreceiver.h
4 : : * Exports from replication/walreceiverfuncs.c.
5 : : *
6 : : * Portions Copyright (c) 2010-2026, PostgreSQL Global Development Group
7 : : *
8 : : * src/include/replication/walreceiver.h
9 : : *
10 : : *-------------------------------------------------------------------------
11 : : */
12 : : #ifndef _WALRECEIVER_H
13 : : #define _WALRECEIVER_H
14 : :
15 : : #include <netdb.h>
16 : :
17 : : #include "access/xlog.h"
18 : : #include "access/xlogdefs.h"
19 : : #include "pgtime.h"
20 : : #include "port/atomics.h"
21 : : #include "replication/logicalproto.h"
22 : : #include "replication/walsender.h"
23 : : #include "storage/condition_variable.h"
24 : : #include "storage/spin.h"
25 : : #include "utils/tuplestore.h"
26 : :
27 : : /* user-settable parameters */
28 : : extern PGDLLIMPORT int wal_receiver_status_interval;
29 : : extern PGDLLIMPORT int wal_receiver_timeout;
30 : : extern PGDLLIMPORT bool hot_standby_feedback;
31 : :
32 : : /*
33 : : * MAXCONNINFO: maximum size of a connection string.
34 : : *
35 : : * XXX: Should this move to pg_config_manual.h?
36 : : */
37 : : #define MAXCONNINFO 1024
38 : :
39 : : /* Can we allow the standby to accept replication connection from another standby? */
40 : : #define AllowCascadeReplication() (EnableHotStandby && max_wal_senders > 0)
41 : :
42 : : /*
43 : : * Values for WalRcv->walRcvState.
44 : : */
45 : : typedef enum
46 : : {
47 : : WALRCV_STOPPED, /* stopped and mustn't start up again */
48 : : WALRCV_STARTING, /* launched, but the process hasn't
49 : : * initialized yet */
50 : : WALRCV_CONNECTING, /* connecting to upstream server */
51 : : WALRCV_STREAMING, /* walreceiver is streaming */
52 : : WALRCV_WAITING, /* stopped streaming, waiting for orders */
53 : : WALRCV_RESTARTING, /* asked to restart streaming */
54 : : WALRCV_STOPPING, /* requested to stop, but still running */
55 : : } WalRcvState;
56 : :
57 : : /* Shared memory area for management of walreceiver process */
58 : : typedef struct
59 : : {
60 : : /*
61 : : * Currently active walreceiver process's proc number and PID.
62 : : *
63 : : * The startup process uses the proc number to wake it up after telling it
64 : : * where to start streaming (after setting receiveStart and
65 : : * receiveStartTLI), and also to tell it to send apply feedback to the
66 : : * primary whenever specially marked commit records are applied.
67 : : */
68 : : ProcNumber procno;
69 : : pid_t pid;
70 : :
71 : : /* Its current state */
72 : : WalRcvState walRcvState;
73 : : ConditionVariable walRcvStoppedCV;
74 : :
75 : : /*
76 : : * Its start time (actually, the time at which it was requested to be
77 : : * started).
78 : : */
79 : : pg_time_t startTime;
80 : :
81 : : /*
82 : : * receiveStart and receiveStartTLI indicate the first byte position and
83 : : * timeline that will be received. When startup process starts the
84 : : * walreceiver, it sets these to the point where it wants the streaming to
85 : : * begin.
86 : : */
87 : : XLogRecPtr receiveStart;
88 : : TimeLineID receiveStartTLI;
89 : :
90 : : /*
91 : : * flushedUpto-1 is the last byte position that has already been received,
92 : : * and receivedTLI is the timeline it came from. At the first startup of
93 : : * walreceiver, these are set to receiveStart and receiveStartTLI. After
94 : : * that, walreceiver updates these whenever it flushes the received WAL to
95 : : * disk.
96 : : */
97 : : XLogRecPtr flushedUpto;
98 : : TimeLineID receivedTLI;
99 : :
100 : : /*
101 : : * latestChunkStart is the starting byte position of the current "batch"
102 : : * of received WAL. It's actually the same as the previous value of
103 : : * flushedUpto before the last flush to disk. Startup process can use
104 : : * this to detect whether it's keeping up or not.
105 : : */
106 : : XLogRecPtr latestChunkStart;
107 : :
108 : : /*
109 : : * Time of send and receive of any message received.
110 : : */
111 : : TimestampTz lastMsgSendTime;
112 : : TimestampTz lastMsgReceiptTime;
113 : :
114 : : /*
115 : : * Latest reported end of WAL on the sender
116 : : */
117 : : XLogRecPtr latestWalEnd;
118 : : TimestampTz latestWalEndTime;
119 : :
120 : : /*
121 : : * connection string; initially set to connect to the primary, and later
122 : : * clobbered to hide security-sensitive fields.
123 : : */
124 : : char conninfo[MAXCONNINFO];
125 : :
126 : : /*
127 : : * Host name (this can be a host name, an IP address, or a directory path)
128 : : * and port number of the active replication connection.
129 : : */
130 : : char sender_host[NI_MAXHOST];
131 : : int sender_port;
132 : :
133 : : /*
134 : : * replication slot name; is also used for walreceiver to connect with the
135 : : * primary
136 : : */
137 : : char slotname[NAMEDATALEN];
138 : :
139 : : /*
140 : : * If it's a temporary replication slot, it needs to be recreated when
141 : : * connecting.
142 : : */
143 : : bool is_temp_slot;
144 : :
145 : : /* set true once conninfo is ready to display (obfuscated pwds etc) */
146 : : bool ready_to_display;
147 : :
148 : : slock_t mutex; /* locks shared variables shown above */
149 : :
150 : : /*
151 : : * Like flushedUpto, but advanced after writing and before flushing,
152 : : * without the need to acquire the spin lock. Data can be read by another
153 : : * process up to this point, but shouldn't be used for data integrity
154 : : * purposes.
155 : : */
156 : : pg_atomic_uint64 writtenUpto;
157 : :
158 : : /*
159 : : * force walreceiver reply? This doesn't need to be locked; memory
160 : : * barriers for ordering are sufficient. But we do need atomic fetch and
161 : : * store semantics, so use sig_atomic_t.
162 : : */
163 : : sig_atomic_t force_reply; /* used as a bool */
164 : : } WalRcvData;
165 : :
166 : : extern PGDLLIMPORT WalRcvData *WalRcv;
167 : :
168 : : typedef struct
169 : : {
170 : : bool logical; /* True if this is logical replication stream,
171 : : * false if physical stream. */
172 : : char *slotname; /* Name of the replication slot or NULL. */
173 : : XLogRecPtr startpoint; /* LSN of starting point. */
174 : :
175 : : union
176 : : {
177 : : struct
178 : : {
179 : : TimeLineID startpointTLI; /* Starting timeline */
180 : : } physical;
181 : : struct
182 : : {
183 : : uint32 proto_version; /* Logical protocol version */
184 : : List *publication_names; /* String list of publications */
185 : : bool binary; /* Ask publisher to use binary */
186 : : char *streaming_str; /* Streaming of large transactions */
187 : : bool twophase; /* Streaming of two-phase transactions at
188 : : * prepare time */
189 : : char *origin; /* Only publish data originating from the
190 : : * specified origin */
191 : : } logical;
192 : : } proto;
193 : : } WalRcvStreamOptions;
194 : :
195 : : struct WalReceiverConn;
196 : : typedef struct WalReceiverConn WalReceiverConn;
197 : :
198 : : /*
199 : : * Status of walreceiver query execution.
200 : : *
201 : : * We only define statuses that are currently used.
202 : : */
203 : : typedef enum
204 : : {
205 : : WALRCV_ERROR, /* There was error when executing the query. */
206 : : WALRCV_OK_COMMAND, /* Query executed utility or replication
207 : : * command. */
208 : : WALRCV_OK_TUPLES, /* Query returned tuples. */
209 : : WALRCV_OK_COPY_IN, /* Query started COPY FROM. */
210 : : WALRCV_OK_COPY_OUT, /* Query started COPY TO. */
211 : : WALRCV_OK_COPY_BOTH, /* Query started COPY BOTH replication
212 : : * protocol. */
213 : : } WalRcvExecStatus;
214 : :
215 : : /*
216 : : * Return value for walrcv_exec, returns the status of the execution and
217 : : * tuples if any.
218 : : */
219 : : typedef struct WalRcvExecResult
220 : : {
221 : : WalRcvExecStatus status;
222 : : int sqlstate;
223 : : char *err;
224 : : Tuplestorestate *tuplestore;
225 : : TupleDesc tupledesc;
226 : : } WalRcvExecResult;
227 : :
228 : : /* WAL receiver - libpqwalreceiver hooks */
229 : :
230 : : /*
231 : : * walrcv_connect_fn
232 : : *
233 : : * Establish connection to a cluster. 'replication' is true if the
234 : : * connection is a replication connection, and false if it is a
235 : : * regular connection. If it is a replication connection, it could
236 : : * be either logical or physical based on input argument 'logical'.
237 : : * 'appname' is a name associated to the connection, to use for example
238 : : * with fallback_application_name or application_name. Returns the
239 : : * details about the connection established, as defined by
240 : : * WalReceiverConn for each WAL receiver module. On error, NULL is
241 : : * returned with 'err' including the error generated.
242 : : */
243 : : typedef WalReceiverConn *(*walrcv_connect_fn) (const char *conninfo,
244 : : bool replication,
245 : : bool logical,
246 : : bool must_use_password,
247 : : const char *appname,
248 : : char **err);
249 : :
250 : : /*
251 : : * walrcv_check_conninfo_fn
252 : : *
253 : : * Parse and validate the connection string given as of 'conninfo'.
254 : : */
255 : : typedef void (*walrcv_check_conninfo_fn) (const char *conninfo,
256 : : bool must_use_password);
257 : :
258 : : /*
259 : : * walrcv_get_conninfo_fn
260 : : *
261 : : * Returns a user-displayable conninfo string. Note that any
262 : : * security-sensitive fields should be obfuscated.
263 : : */
264 : : typedef char *(*walrcv_get_conninfo_fn) (WalReceiverConn *conn);
265 : :
266 : : /*
267 : : * walrcv_get_senderinfo_fn
268 : : *
269 : : * Provide information of the WAL sender this WAL receiver is connected
270 : : * to, as of 'sender_host' for the host of the sender and 'sender_port'
271 : : * for its port.
272 : : */
273 : : typedef void (*walrcv_get_senderinfo_fn) (WalReceiverConn *conn,
274 : : char **sender_host,
275 : : int *sender_port);
276 : :
277 : : /*
278 : : * walrcv_identify_system_fn
279 : : *
280 : : * Run IDENTIFY_SYSTEM on the cluster connected to and validate the
281 : : * identity of the cluster. Returns the system ID of the cluster
282 : : * connected to. 'primary_tli' is the timeline ID of the sender.
283 : : */
284 : : typedef char *(*walrcv_identify_system_fn) (WalReceiverConn *conn,
285 : : TimeLineID *primary_tli);
286 : :
287 : : /*
288 : : * walrcv_get_dbname_from_conninfo_fn
289 : : *
290 : : * Returns the database name from the primary_conninfo
291 : : */
292 : : typedef char *(*walrcv_get_dbname_from_conninfo_fn) (const char *conninfo);
293 : :
294 : : /*
295 : : * walrcv_server_version_fn
296 : : *
297 : : * Returns the version number of the cluster connected to.
298 : : */
299 : : typedef int (*walrcv_server_version_fn) (WalReceiverConn *conn);
300 : :
301 : : /*
302 : : * walrcv_readtimelinehistoryfile_fn
303 : : *
304 : : * Fetch from cluster the timeline history file for timeline 'tli'.
305 : : * Returns the name of the timeline history file as of 'filename', its
306 : : * contents as of 'content' and its 'size'.
307 : : */
308 : : typedef void (*walrcv_readtimelinehistoryfile_fn) (WalReceiverConn *conn,
309 : : TimeLineID tli,
310 : : char **filename,
311 : : char **content,
312 : : int *size);
313 : :
314 : : /*
315 : : * walrcv_startstreaming_fn
316 : : *
317 : : * Start streaming WAL data from given streaming options. Returns true
318 : : * if the connection has switched successfully to copy-both mode and false
319 : : * if the server received the command and executed it successfully, but
320 : : * didn't switch to copy-mode.
321 : : */
322 : : typedef bool (*walrcv_startstreaming_fn) (WalReceiverConn *conn,
323 : : const WalRcvStreamOptions *options);
324 : :
325 : : /*
326 : : * walrcv_endstreaming_fn
327 : : *
328 : : * Stop streaming of WAL data. Returns the next timeline ID of the cluster
329 : : * connected to in 'next_tli', or 0 if there was no report.
330 : : */
331 : : typedef void (*walrcv_endstreaming_fn) (WalReceiverConn *conn,
332 : : TimeLineID *next_tli);
333 : :
334 : : /*
335 : : * walrcv_receive_fn
336 : : *
337 : : * Receive a message available from the WAL stream. 'buffer' is a pointer
338 : : * to a buffer holding the message received. Returns the length of the data,
339 : : * 0 if no data is available yet ('wait_fd' is a socket descriptor which can
340 : : * be waited on before a retry), and -1 if the cluster ended the COPY.
341 : : */
342 : : typedef int (*walrcv_receive_fn) (WalReceiverConn *conn,
343 : : char **buffer,
344 : : pgsocket *wait_fd);
345 : :
346 : : /*
347 : : * walrcv_send_fn
348 : : *
349 : : * Send a message of size 'nbytes' to the WAL stream with 'buffer' as
350 : : * contents.
351 : : */
352 : : typedef void (*walrcv_send_fn) (WalReceiverConn *conn,
353 : : const char *buffer,
354 : : int nbytes);
355 : :
356 : : /*
357 : : * walrcv_create_slot_fn
358 : : *
359 : : * Create a new replication slot named 'slotname'. 'temporary' defines
360 : : * if the slot is temporary. 'snapshot_action' defines the behavior wanted
361 : : * for an exported snapshot (see replication protocol for more details).
362 : : * 'lsn' includes the LSN position at which the created slot became
363 : : * consistent. Returns the name of the exported snapshot for a logical
364 : : * slot, or NULL for a physical slot.
365 : : */
366 : : typedef char *(*walrcv_create_slot_fn) (WalReceiverConn *conn,
367 : : const char *slotname,
368 : : bool temporary,
369 : : bool two_phase,
370 : : bool failover,
371 : : CRSSnapshotAction snapshot_action,
372 : : XLogRecPtr *lsn);
373 : :
374 : : /*
375 : : * walrcv_alter_slot_fn
376 : : *
377 : : * Change the definition of a replication slot. Currently, it supports
378 : : * changing the failover and two_phase properties of the slot.
379 : : */
380 : : typedef void (*walrcv_alter_slot_fn) (WalReceiverConn *conn,
381 : : const char *slotname,
382 : : const bool *failover,
383 : : const bool *two_phase);
384 : :
385 : :
386 : : /*
387 : : * walrcv_get_backend_pid_fn
388 : : *
389 : : * Returns the PID of the remote backend process.
390 : : */
391 : : typedef pid_t (*walrcv_get_backend_pid_fn) (WalReceiverConn *conn);
392 : :
393 : : /*
394 : : * walrcv_exec_fn
395 : : *
396 : : * Send generic queries (and commands) to the remote cluster. 'nRetTypes'
397 : : * is the expected number of returned attributes, and 'retTypes' an array
398 : : * including their type OIDs. Returns the status of the execution and
399 : : * tuples if any.
400 : : */
401 : : typedef WalRcvExecResult *(*walrcv_exec_fn) (WalReceiverConn *conn,
402 : : const char *query,
403 : : const int nRetTypes,
404 : : const Oid *retTypes);
405 : :
406 : : /*
407 : : * walrcv_disconnect_fn
408 : : *
409 : : * Disconnect with the cluster.
410 : : */
411 : : typedef void (*walrcv_disconnect_fn) (WalReceiverConn *conn);
412 : :
413 : : typedef struct WalReceiverFunctionsType
414 : : {
415 : : walrcv_connect_fn walrcv_connect;
416 : : walrcv_check_conninfo_fn walrcv_check_conninfo;
417 : : walrcv_get_conninfo_fn walrcv_get_conninfo;
418 : : walrcv_get_senderinfo_fn walrcv_get_senderinfo;
419 : : walrcv_identify_system_fn walrcv_identify_system;
420 : : walrcv_get_dbname_from_conninfo_fn walrcv_get_dbname_from_conninfo;
421 : : walrcv_server_version_fn walrcv_server_version;
422 : : walrcv_readtimelinehistoryfile_fn walrcv_readtimelinehistoryfile;
423 : : walrcv_startstreaming_fn walrcv_startstreaming;
424 : : walrcv_endstreaming_fn walrcv_endstreaming;
425 : : walrcv_receive_fn walrcv_receive;
426 : : walrcv_send_fn walrcv_send;
427 : : walrcv_create_slot_fn walrcv_create_slot;
428 : : walrcv_alter_slot_fn walrcv_alter_slot;
429 : : walrcv_get_backend_pid_fn walrcv_get_backend_pid;
430 : : walrcv_exec_fn walrcv_exec;
431 : : walrcv_disconnect_fn walrcv_disconnect;
432 : : } WalReceiverFunctionsType;
433 : :
434 : : extern PGDLLIMPORT WalReceiverFunctionsType *WalReceiverFunctions;
435 : :
436 : : #define walrcv_connect(conninfo, replication, logical, must_use_password, appname, err) \
437 : : WalReceiverFunctions->walrcv_connect(conninfo, replication, logical, must_use_password, appname, err)
438 : : #define walrcv_check_conninfo(conninfo, must_use_password) \
439 : : WalReceiverFunctions->walrcv_check_conninfo(conninfo, must_use_password)
440 : : #define walrcv_get_conninfo(conn) \
441 : : WalReceiverFunctions->walrcv_get_conninfo(conn)
442 : : #define walrcv_get_senderinfo(conn, sender_host, sender_port) \
443 : : WalReceiverFunctions->walrcv_get_senderinfo(conn, sender_host, sender_port)
444 : : #define walrcv_identify_system(conn, primary_tli) \
445 : : WalReceiverFunctions->walrcv_identify_system(conn, primary_tli)
446 : : #define walrcv_get_dbname_from_conninfo(conninfo) \
447 : : WalReceiverFunctions->walrcv_get_dbname_from_conninfo(conninfo)
448 : : #define walrcv_server_version(conn) \
449 : : WalReceiverFunctions->walrcv_server_version(conn)
450 : : #define walrcv_readtimelinehistoryfile(conn, tli, filename, content, size) \
451 : : WalReceiverFunctions->walrcv_readtimelinehistoryfile(conn, tli, filename, content, size)
452 : : #define walrcv_startstreaming(conn, options) \
453 : : WalReceiverFunctions->walrcv_startstreaming(conn, options)
454 : : #define walrcv_endstreaming(conn, next_tli) \
455 : : WalReceiverFunctions->walrcv_endstreaming(conn, next_tli)
456 : : #define walrcv_receive(conn, buffer, wait_fd) \
457 : : WalReceiverFunctions->walrcv_receive(conn, buffer, wait_fd)
458 : : #define walrcv_send(conn, buffer, nbytes) \
459 : : WalReceiverFunctions->walrcv_send(conn, buffer, nbytes)
460 : : #define walrcv_create_slot(conn, slotname, temporary, two_phase, failover, snapshot_action, lsn) \
461 : : WalReceiverFunctions->walrcv_create_slot(conn, slotname, temporary, two_phase, failover, snapshot_action, lsn)
462 : : #define walrcv_alter_slot(conn, slotname, failover, two_phase) \
463 : : WalReceiverFunctions->walrcv_alter_slot(conn, slotname, failover, two_phase)
464 : : #define walrcv_get_backend_pid(conn) \
465 : : WalReceiverFunctions->walrcv_get_backend_pid(conn)
466 : : #define walrcv_exec(conn, exec, nRetTypes, retTypes) \
467 : : WalReceiverFunctions->walrcv_exec(conn, exec, nRetTypes, retTypes)
468 : : #define walrcv_disconnect(conn) \
469 : : WalReceiverFunctions->walrcv_disconnect(conn)
470 : :
471 : : static inline void
472 : 0 : walrcv_clear_result(WalRcvExecResult *walres)
473 : : {
474 [ # # ]: 0 : if (!walres)
475 : 0 : return;
476 : :
477 [ # # ]: 0 : if (walres->err)
478 : 0 : pfree(walres->err);
479 : :
480 [ # # ]: 0 : if (walres->tuplestore)
481 : 0 : tuplestore_end(walres->tuplestore);
482 : :
483 [ # # ]: 0 : if (walres->tupledesc)
484 : 0 : FreeTupleDesc(walres->tupledesc);
485 : :
486 : 0 : pfree(walres);
487 : 0 : }
488 : :
489 : : /* prototypes for functions in walreceiver.c */
490 : : pg_noreturn extern void WalReceiverMain(const void *startup_data, size_t startup_data_len);
491 : : extern void WalRcvForceReply(void);
492 : :
493 : : /* prototypes for functions in walreceiverfuncs.c */
494 : : extern Size WalRcvShmemSize(void);
495 : : extern void WalRcvShmemInit(void);
496 : : extern void ShutdownWalRcv(void);
497 : : extern bool WalRcvStreaming(void);
498 : : extern bool WalRcvRunning(void);
499 : : extern WalRcvState WalRcvGetState(void);
500 : : extern void RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr,
501 : : const char *conninfo, const char *slotname,
502 : : bool create_temp_slot);
503 : : extern XLogRecPtr GetWalRcvFlushRecPtr(XLogRecPtr *latestChunkStart, TimeLineID *receiveTLI);
504 : : extern XLogRecPtr GetWalRcvWriteRecPtr(void);
505 : : extern int GetReplicationApplyDelay(void);
506 : : extern int GetReplicationTransferLatency(void);
507 : :
508 : : #endif /* _WALRECEIVER_H */
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