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walreceiver.c
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1 /*-------------------------------------------------------------------------
2  *
3  * walreceiver.c
4  *
5  * The WAL receiver process (walreceiver) is new as of Postgres 9.0. It
6  * is the process in the standby server that takes charge of receiving
7  * XLOG records from a primary server during streaming replication.
8  *
9  * When the startup process determines that it's time to start streaming,
10  * it instructs postmaster to start walreceiver. Walreceiver first connects
11  * to the primary server (it will be served by a walsender process
12  * in the primary server), and then keeps receiving XLOG records and
13  * writing them to the disk as long as the connection is alive. As XLOG
14  * records are received and flushed to disk, it updates the
15  * WalRcv->receivedUpto variable in shared memory, to inform the startup
16  * process of how far it can proceed with XLOG replay.
17  *
18  * If the primary server ends streaming, but doesn't disconnect, walreceiver
19  * goes into "waiting" mode, and waits for the startup process to give new
20  * instructions. The startup process will treat that the same as
21  * disconnection, and will rescan the archive/pg_wal directory. But when the
22  * startup process wants to try streaming replication again, it will just
23  * nudge the existing walreceiver process that's waiting, instead of launching
24  * a new one.
25  *
26  * Normal termination is by SIGTERM, which instructs the walreceiver to
27  * exit(0). Emergency termination is by SIGQUIT; like any postmaster child
28  * process, the walreceiver will simply abort and exit on SIGQUIT. A close
29  * of the connection and a FATAL error are treated not as a crash but as
30  * normal operation.
31  *
32  * This file contains the server-facing parts of walreceiver. The libpq-
33  * specific parts are in the libpqwalreceiver module. It's loaded
34  * dynamically to avoid linking the server with libpq.
35  *
36  * Portions Copyright (c) 2010-2019, PostgreSQL Global Development Group
37  *
38  *
39  * IDENTIFICATION
40  * src/backend/replication/walreceiver.c
41  *
42  *-------------------------------------------------------------------------
43  */
44 #include "postgres.h"
45 
46 #include <signal.h>
47 #include <unistd.h>
48 
49 #include "access/htup_details.h"
50 #include "access/timeline.h"
51 #include "access/transam.h"
52 #include "access/xlog_internal.h"
53 #include "catalog/pg_authid.h"
54 #include "catalog/pg_type.h"
55 #include "common/ip.h"
56 #include "funcapi.h"
57 #include "libpq/pqformat.h"
58 #include "libpq/pqsignal.h"
59 #include "miscadmin.h"
60 #include "pgstat.h"
62 #include "replication/walsender.h"
63 #include "storage/ipc.h"
64 #include "storage/pmsignal.h"
65 #include "storage/procarray.h"
66 #include "utils/builtins.h"
67 #include "utils/guc.h"
68 #include "utils/pg_lsn.h"
69 #include "utils/ps_status.h"
70 #include "utils/resowner.h"
71 #include "utils/timestamp.h"
72 
73 
74 /* GUC variables */
78 
79 /* libpqwalreceiver connection */
80 static WalReceiverConn *wrconn = NULL;
82 
83 #define NAPTIME_PER_CYCLE 100 /* max sleep time between cycles (100ms) */
84 
85 /*
86  * These variables are used similarly to openLogFile/SegNo/Off,
87  * but for walreceiver to write the XLOG. recvFileTLI is the TimeLineID
88  * corresponding the filename of recvFile.
89  */
90 static int recvFile = -1;
92 static XLogSegNo recvSegNo = 0;
93 static uint32 recvOff = 0;
94 
95 /*
96  * Flags set by interrupt handlers of walreceiver for later service in the
97  * main loop.
98  */
99 static volatile sig_atomic_t got_SIGHUP = false;
100 static volatile sig_atomic_t got_SIGTERM = false;
101 
102 /*
103  * LogstreamResult indicates the byte positions that we have already
104  * written/fsynced.
105  */
106 static struct
107 {
108  XLogRecPtr Write; /* last byte + 1 written out in the standby */
109  XLogRecPtr Flush; /* last byte + 1 flushed in the standby */
111 
114 
115 /* Prototypes for private functions */
116 static void WalRcvFetchTimeLineHistoryFiles(TimeLineID first, TimeLineID last);
117 static void WalRcvWaitForStartPosition(XLogRecPtr *startpoint, TimeLineID *startpointTLI);
118 static void WalRcvDie(int code, Datum arg);
119 static void XLogWalRcvProcessMsg(unsigned char type, char *buf, Size len);
120 static void XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr);
121 static void XLogWalRcvFlush(bool dying);
122 static void XLogWalRcvSendReply(bool force, bool requestReply);
123 static void XLogWalRcvSendHSFeedback(bool immed);
124 static void ProcessWalSndrMessage(XLogRecPtr walEnd, TimestampTz sendTime);
125 
126 /* Signal handlers */
127 static void WalRcvSigHupHandler(SIGNAL_ARGS);
128 static void WalRcvSigUsr1Handler(SIGNAL_ARGS);
131 
132 
133 /*
134  * Process any interrupts the walreceiver process may have received.
135  * This should be called any time the process's latch has become set.
136  *
137  * Currently, only SIGTERM is of interest. We can't just exit(1) within the
138  * SIGTERM signal handler, because the signal might arrive in the middle of
139  * some critical operation, like while we're holding a spinlock. Instead, the
140  * signal handler sets a flag variable as well as setting the process's latch.
141  * We must check the flag (by calling ProcessWalRcvInterrupts) anytime the
142  * latch has become set. Operations that could block for a long time, such as
143  * reading from a remote server, must pay attention to the latch too; see
144  * libpqrcv_PQgetResult for example.
145  */
146 void
148 {
149  /*
150  * Although walreceiver interrupt handling doesn't use the same scheme as
151  * regular backends, call CHECK_FOR_INTERRUPTS() to make sure we receive
152  * any incoming signals on Win32.
153  */
155 
156  if (got_SIGTERM)
157  {
158  ereport(FATAL,
159  (errcode(ERRCODE_ADMIN_SHUTDOWN),
160  errmsg("terminating walreceiver process due to administrator command")));
161  }
162 }
163 
164 
165 /* Main entry point for walreceiver process */
166 void
168 {
169  char conninfo[MAXCONNINFO];
170  char *tmp_conninfo;
171  char slotname[NAMEDATALEN];
172  XLogRecPtr startpoint;
173  TimeLineID startpointTLI;
174  TimeLineID primaryTLI;
175  bool first_stream;
176  WalRcvData *walrcv = WalRcv;
177  TimestampTz last_recv_timestamp;
179  bool ping_sent;
180  char *err;
181  char *sender_host = NULL;
182  int sender_port = 0;
183 
184  /*
185  * WalRcv should be set up already (if we are a backend, we inherit this
186  * by fork() or EXEC_BACKEND mechanism from the postmaster).
187  */
188  Assert(walrcv != NULL);
189 
190  now = GetCurrentTimestamp();
191 
192  /*
193  * Mark walreceiver as running in shared memory.
194  *
195  * Do this as early as possible, so that if we fail later on, we'll set
196  * state to STOPPED. If we die before this, the startup process will keep
197  * waiting for us to start up, until it times out.
198  */
199  SpinLockAcquire(&walrcv->mutex);
200  Assert(walrcv->pid == 0);
201  switch (walrcv->walRcvState)
202  {
203  case WALRCV_STOPPING:
204  /* If we've already been requested to stop, don't start up. */
205  walrcv->walRcvState = WALRCV_STOPPED;
206  /* fall through */
207 
208  case WALRCV_STOPPED:
209  SpinLockRelease(&walrcv->mutex);
210  proc_exit(1);
211  break;
212 
213  case WALRCV_STARTING:
214  /* The usual case */
215  break;
216 
217  case WALRCV_WAITING:
218  case WALRCV_STREAMING:
219  case WALRCV_RESTARTING:
220  default:
221  /* Shouldn't happen */
222  SpinLockRelease(&walrcv->mutex);
223  elog(PANIC, "walreceiver still running according to shared memory state");
224  }
225  /* Advertise our PID so that the startup process can kill us */
226  walrcv->pid = MyProcPid;
227  walrcv->walRcvState = WALRCV_STREAMING;
228 
229  /* Fetch information required to start streaming */
230  walrcv->ready_to_display = false;
231  strlcpy(conninfo, (char *) walrcv->conninfo, MAXCONNINFO);
232  strlcpy(slotname, (char *) walrcv->slotname, NAMEDATALEN);
233  startpoint = walrcv->receiveStart;
234  startpointTLI = walrcv->receiveStartTLI;
235 
236  /* Initialise to a sanish value */
237  walrcv->lastMsgSendTime =
238  walrcv->lastMsgReceiptTime = walrcv->latestWalEndTime = now;
239 
240  /* Report the latch to use to awaken this process */
241  walrcv->latch = &MyProc->procLatch;
242 
243  SpinLockRelease(&walrcv->mutex);
244 
245  /* Arrange to clean up at walreceiver exit */
247 
248  /* Properly accept or ignore signals the postmaster might send us */
249  pqsignal(SIGHUP, WalRcvSigHupHandler); /* set flag to read config file */
250  pqsignal(SIGINT, SIG_IGN);
251  pqsignal(SIGTERM, WalRcvShutdownHandler); /* request shutdown */
252  pqsignal(SIGQUIT, WalRcvQuickDieHandler); /* hard crash time */
257 
258  /* Reset some signals that are accepted by postmaster but not here */
260 
261  /* We allow SIGQUIT (quickdie) at all times */
262  sigdelset(&BlockSig, SIGQUIT);
263 
264  /* Load the libpq-specific functions */
265  load_file("libpqwalreceiver", false);
266  if (WalReceiverFunctions == NULL)
267  elog(ERROR, "libpqwalreceiver didn't initialize correctly");
268 
269  /* Unblock signals (they were blocked when the postmaster forked us) */
271 
272  /* Establish the connection to the primary for XLOG streaming */
273  wrconn = walrcv_connect(conninfo, false, cluster_name[0] ? cluster_name : "walreceiver", &err);
274  if (!wrconn)
275  ereport(ERROR,
276  (errmsg("could not connect to the primary server: %s", err)));
277 
278  /*
279  * Save user-visible connection string. This clobbers the original
280  * conninfo, for security. Also save host and port of the sender server
281  * this walreceiver is connected to.
282  */
283  tmp_conninfo = walrcv_get_conninfo(wrconn);
284  walrcv_get_senderinfo(wrconn, &sender_host, &sender_port);
285  SpinLockAcquire(&walrcv->mutex);
286  memset(walrcv->conninfo, 0, MAXCONNINFO);
287  if (tmp_conninfo)
288  strlcpy((char *) walrcv->conninfo, tmp_conninfo, MAXCONNINFO);
289 
290  memset(walrcv->sender_host, 0, NI_MAXHOST);
291  if (sender_host)
292  strlcpy((char *) walrcv->sender_host, sender_host, NI_MAXHOST);
293 
294  walrcv->sender_port = sender_port;
295  walrcv->ready_to_display = true;
296  SpinLockRelease(&walrcv->mutex);
297 
298  if (tmp_conninfo)
299  pfree(tmp_conninfo);
300 
301  if (sender_host)
302  pfree(sender_host);
303 
304  first_stream = true;
305  for (;;)
306  {
307  char *primary_sysid;
308  char standby_sysid[32];
310 
311  /*
312  * Check that we're connected to a valid server using the
313  * IDENTIFY_SYSTEM replication command.
314  */
315  primary_sysid = walrcv_identify_system(wrconn, &primaryTLI);
316 
317  snprintf(standby_sysid, sizeof(standby_sysid), UINT64_FORMAT,
319  if (strcmp(primary_sysid, standby_sysid) != 0)
320  {
321  ereport(ERROR,
322  (errmsg("database system identifier differs between the primary and standby"),
323  errdetail("The primary's identifier is %s, the standby's identifier is %s.",
324  primary_sysid, standby_sysid)));
325  }
326 
327  /*
328  * Confirm that the current timeline of the primary is the same or
329  * ahead of ours.
330  */
331  if (primaryTLI < startpointTLI)
332  ereport(ERROR,
333  (errmsg("highest timeline %u of the primary is behind recovery timeline %u",
334  primaryTLI, startpointTLI)));
335 
336  /*
337  * Get any missing history files. We do this always, even when we're
338  * not interested in that timeline, so that if we're promoted to
339  * become the master later on, we don't select the same timeline that
340  * was already used in the current master. This isn't bullet-proof -
341  * you'll need some external software to manage your cluster if you
342  * need to ensure that a unique timeline id is chosen in every case,
343  * but let's avoid the confusion of timeline id collisions where we
344  * can.
345  */
346  WalRcvFetchTimeLineHistoryFiles(startpointTLI, primaryTLI);
347 
348  /*
349  * Start streaming.
350  *
351  * We'll try to start at the requested starting point and timeline,
352  * even if it's different from the server's latest timeline. In case
353  * we've already reached the end of the old timeline, the server will
354  * finish the streaming immediately, and we will go back to await
355  * orders from the startup process. If recovery_target_timeline is
356  * 'latest', the startup process will scan pg_wal and find the new
357  * history file, bump recovery target timeline, and ask us to restart
358  * on the new timeline.
359  */
360  options.logical = false;
361  options.startpoint = startpoint;
362  options.slotname = slotname[0] != '\0' ? slotname : NULL;
363  options.proto.physical.startpointTLI = startpointTLI;
364  ThisTimeLineID = startpointTLI;
365  if (walrcv_startstreaming(wrconn, &options))
366  {
367  if (first_stream)
368  ereport(LOG,
369  (errmsg("started streaming WAL from primary at %X/%X on timeline %u",
370  (uint32) (startpoint >> 32), (uint32) startpoint,
371  startpointTLI)));
372  else
373  ereport(LOG,
374  (errmsg("restarted WAL streaming at %X/%X on timeline %u",
375  (uint32) (startpoint >> 32), (uint32) startpoint,
376  startpointTLI)));
377  first_stream = false;
378 
379  /* Initialize LogstreamResult and buffers for processing messages */
381  initStringInfo(&reply_message);
382  initStringInfo(&incoming_message);
383 
384  /* Initialize the last recv timestamp */
385  last_recv_timestamp = GetCurrentTimestamp();
386  ping_sent = false;
387 
388  /* Loop until end-of-streaming or error */
389  for (;;)
390  {
391  char *buf;
392  int len;
393  bool endofwal = false;
394  pgsocket wait_fd = PGINVALID_SOCKET;
395  int rc;
396 
397  /*
398  * Exit walreceiver if we're not in recovery. This should not
399  * happen, but cross-check the status here.
400  */
401  if (!RecoveryInProgress())
402  ereport(FATAL,
403  (errmsg("cannot continue WAL streaming, recovery has already ended")));
404 
405  /* Process any requests or signals received recently */
407 
408  if (got_SIGHUP)
409  {
410  got_SIGHUP = false;
413  }
414 
415  /* See if we can read data immediately */
416  len = walrcv_receive(wrconn, &buf, &wait_fd);
417  if (len != 0)
418  {
419  /*
420  * Process the received data, and any subsequent data we
421  * can read without blocking.
422  */
423  for (;;)
424  {
425  if (len > 0)
426  {
427  /*
428  * Something was received from master, so reset
429  * timeout
430  */
431  last_recv_timestamp = GetCurrentTimestamp();
432  ping_sent = false;
433  XLogWalRcvProcessMsg(buf[0], &buf[1], len - 1);
434  }
435  else if (len == 0)
436  break;
437  else if (len < 0)
438  {
439  ereport(LOG,
440  (errmsg("replication terminated by primary server"),
441  errdetail("End of WAL reached on timeline %u at %X/%X.",
442  startpointTLI,
443  (uint32) (LogstreamResult.Write >> 32), (uint32) LogstreamResult.Write)));
444  endofwal = true;
445  break;
446  }
447  len = walrcv_receive(wrconn, &buf, &wait_fd);
448  }
449 
450  /* Let the master know that we received some data. */
451  XLogWalRcvSendReply(false, false);
452 
453  /*
454  * If we've written some records, flush them to disk and
455  * let the startup process and primary server know about
456  * them.
457  */
458  XLogWalRcvFlush(false);
459  }
460 
461  /* Check if we need to exit the streaming loop. */
462  if (endofwal)
463  break;
464 
465  /*
466  * Ideally we would reuse a WaitEventSet object repeatedly
467  * here to avoid the overheads of WaitLatchOrSocket on epoll
468  * systems, but we can't be sure that libpq (or any other
469  * walreceiver implementation) has the same socket (even if
470  * the fd is the same number, it may have been closed and
471  * reopened since the last time). In future, if there is a
472  * function for removing sockets from WaitEventSet, then we
473  * could add and remove just the socket each time, potentially
474  * avoiding some system calls.
475  */
476  Assert(wait_fd != PGINVALID_SOCKET);
477  rc = WaitLatchOrSocket(walrcv->latch,
480  wait_fd,
483  if (rc & WL_LATCH_SET)
484  {
485  ResetLatch(walrcv->latch);
487 
488  if (walrcv->force_reply)
489  {
490  /*
491  * The recovery process has asked us to send apply
492  * feedback now. Make sure the flag is really set to
493  * false in shared memory before sending the reply, so
494  * we don't miss a new request for a reply.
495  */
496  walrcv->force_reply = false;
498  XLogWalRcvSendReply(true, false);
499  }
500  }
501  if (rc & WL_TIMEOUT)
502  {
503  /*
504  * We didn't receive anything new. If we haven't heard
505  * anything from the server for more than
506  * wal_receiver_timeout / 2, ping the server. Also, if
507  * it's been longer than wal_receiver_status_interval
508  * since the last update we sent, send a status update to
509  * the master anyway, to report any progress in applying
510  * WAL.
511  */
512  bool requestReply = false;
513 
514  /*
515  * Check if time since last receive from standby has
516  * reached the configured limit.
517  */
518  if (wal_receiver_timeout > 0)
519  {
521  TimestampTz timeout;
522 
523  timeout =
524  TimestampTzPlusMilliseconds(last_recv_timestamp,
526 
527  if (now >= timeout)
528  ereport(ERROR,
529  (errmsg("terminating walreceiver due to timeout")));
530 
531  /*
532  * We didn't receive anything new, for half of
533  * receiver replication timeout. Ping the server.
534  */
535  if (!ping_sent)
536  {
537  timeout = TimestampTzPlusMilliseconds(last_recv_timestamp,
538  (wal_receiver_timeout / 2));
539  if (now >= timeout)
540  {
541  requestReply = true;
542  ping_sent = true;
543  }
544  }
545  }
546 
547  XLogWalRcvSendReply(requestReply, requestReply);
549  }
550  }
551 
552  /*
553  * The backend finished streaming. Exit streaming COPY-mode from
554  * our side, too.
555  */
556  walrcv_endstreaming(wrconn, &primaryTLI);
557 
558  /*
559  * If the server had switched to a new timeline that we didn't
560  * know about when we began streaming, fetch its timeline history
561  * file now.
562  */
563  WalRcvFetchTimeLineHistoryFiles(startpointTLI, primaryTLI);
564  }
565  else
566  ereport(LOG,
567  (errmsg("primary server contains no more WAL on requested timeline %u",
568  startpointTLI)));
569 
570  /*
571  * End of WAL reached on the requested timeline. Close the last
572  * segment, and await for new orders from the startup process.
573  */
574  if (recvFile >= 0)
575  {
576  char xlogfname[MAXFNAMELEN];
577 
578  XLogWalRcvFlush(false);
579  if (close(recvFile) != 0)
580  ereport(PANIC,
582  errmsg("could not close log segment %s: %m",
584 
585  /*
586  * Create .done file forcibly to prevent the streamed segment from
587  * being archived later.
588  */
591  XLogArchiveForceDone(xlogfname);
592  else
593  XLogArchiveNotify(xlogfname);
594  }
595  recvFile = -1;
596 
597  elog(DEBUG1, "walreceiver ended streaming and awaits new instructions");
598  WalRcvWaitForStartPosition(&startpoint, &startpointTLI);
599  }
600  /* not reached */
601 }
602 
603 /*
604  * Wait for startup process to set receiveStart and receiveStartTLI.
605  */
606 static void
608 {
609  WalRcvData *walrcv = WalRcv;
610  int state;
611 
612  SpinLockAcquire(&walrcv->mutex);
613  state = walrcv->walRcvState;
614  if (state != WALRCV_STREAMING)
615  {
616  SpinLockRelease(&walrcv->mutex);
617  if (state == WALRCV_STOPPING)
618  proc_exit(0);
619  else
620  elog(FATAL, "unexpected walreceiver state");
621  }
622  walrcv->walRcvState = WALRCV_WAITING;
624  walrcv->receiveStartTLI = 0;
625  SpinLockRelease(&walrcv->mutex);
626 
628  set_ps_display("idle", false);
629 
630  /*
631  * nudge startup process to notice that we've stopped streaming and are
632  * now waiting for instructions.
633  */
634  WakeupRecovery();
635  for (;;)
636  {
637  ResetLatch(walrcv->latch);
638 
640 
641  SpinLockAcquire(&walrcv->mutex);
642  Assert(walrcv->walRcvState == WALRCV_RESTARTING ||
643  walrcv->walRcvState == WALRCV_WAITING ||
644  walrcv->walRcvState == WALRCV_STOPPING);
645  if (walrcv->walRcvState == WALRCV_RESTARTING)
646  {
647  /* we don't expect primary_conninfo to change */
648  *startpoint = walrcv->receiveStart;
649  *startpointTLI = walrcv->receiveStartTLI;
650  walrcv->walRcvState = WALRCV_STREAMING;
651  SpinLockRelease(&walrcv->mutex);
652  break;
653  }
654  if (walrcv->walRcvState == WALRCV_STOPPING)
655  {
656  /*
657  * We should've received SIGTERM if the startup process wants us
658  * to die, but might as well check it here too.
659  */
660  SpinLockRelease(&walrcv->mutex);
661  exit(1);
662  }
663  SpinLockRelease(&walrcv->mutex);
664 
665  (void) WaitLatch(walrcv->latch, WL_LATCH_SET | WL_EXIT_ON_PM_DEATH, 0,
667  }
668 
670  {
671  char activitymsg[50];
672 
673  snprintf(activitymsg, sizeof(activitymsg), "restarting at %X/%X",
674  (uint32) (*startpoint >> 32),
675  (uint32) *startpoint);
676  set_ps_display(activitymsg, false);
677  }
678 }
679 
680 /*
681  * Fetch any missing timeline history files between 'first' and 'last'
682  * (inclusive) from the server.
683  */
684 static void
686 {
687  TimeLineID tli;
688 
689  for (tli = first; tli <= last; tli++)
690  {
691  /* there's no history file for timeline 1 */
692  if (tli != 1 && !existsTimeLineHistory(tli))
693  {
694  char *fname;
695  char *content;
696  int len;
697  char expectedfname[MAXFNAMELEN];
698 
699  ereport(LOG,
700  (errmsg("fetching timeline history file for timeline %u from primary server",
701  tli)));
702 
703  walrcv_readtimelinehistoryfile(wrconn, tli, &fname, &content, &len);
704 
705  /*
706  * Check that the filename on the master matches what we
707  * calculated ourselves. This is just a sanity check, it should
708  * always match.
709  */
710  TLHistoryFileName(expectedfname, tli);
711  if (strcmp(fname, expectedfname) != 0)
712  ereport(ERROR,
713  (errcode(ERRCODE_PROTOCOL_VIOLATION),
714  errmsg_internal("primary reported unexpected file name for timeline history file of timeline %u",
715  tli)));
716 
717  /*
718  * Write the file to pg_wal.
719  */
720  writeTimeLineHistoryFile(tli, content, len);
721 
722  pfree(fname);
723  pfree(content);
724  }
725  }
726 }
727 
728 /*
729  * Mark us as STOPPED in shared memory at exit.
730  */
731 static void
732 WalRcvDie(int code, Datum arg)
733 {
734  WalRcvData *walrcv = WalRcv;
735 
736  /* Ensure that all WAL records received are flushed to disk */
737  XLogWalRcvFlush(true);
738 
739  /* Mark ourselves inactive in shared memory */
740  SpinLockAcquire(&walrcv->mutex);
741  Assert(walrcv->walRcvState == WALRCV_STREAMING ||
742  walrcv->walRcvState == WALRCV_RESTARTING ||
743  walrcv->walRcvState == WALRCV_STARTING ||
744  walrcv->walRcvState == WALRCV_WAITING ||
745  walrcv->walRcvState == WALRCV_STOPPING);
746  Assert(walrcv->pid == MyProcPid);
747  walrcv->walRcvState = WALRCV_STOPPED;
748  walrcv->pid = 0;
749  walrcv->ready_to_display = false;
750  walrcv->latch = NULL;
751  SpinLockRelease(&walrcv->mutex);
752 
753  /* Terminate the connection gracefully. */
754  if (wrconn != NULL)
755  walrcv_disconnect(wrconn);
756 
757  /* Wake up the startup process to notice promptly that we're gone */
758  WakeupRecovery();
759 }
760 
761 /* SIGHUP: set flag to re-read config file at next convenient time */
762 static void
764 {
765  got_SIGHUP = true;
766 }
767 
768 
769 /* SIGUSR1: used by latch mechanism */
770 static void
772 {
773  int save_errno = errno;
774 
776 
777  errno = save_errno;
778 }
779 
780 /* SIGTERM: set flag for ProcessWalRcvInterrupts */
781 static void
783 {
784  int save_errno = errno;
785 
786  got_SIGTERM = true;
787 
788  if (WalRcv->latch)
790 
791  errno = save_errno;
792 }
793 
794 /*
795  * WalRcvQuickDieHandler() occurs when signalled SIGQUIT by the postmaster.
796  *
797  * Some backend has bought the farm, so we need to stop what we're doing and
798  * exit.
799  */
800 static void
802 {
803  /*
804  * We DO NOT want to run proc_exit() or atexit() callbacks -- we're here
805  * because shared memory may be corrupted, so we don't want to try to
806  * clean up our transaction. Just nail the windows shut and get out of
807  * town. The callbacks wouldn't be safe to run from a signal handler,
808  * anyway.
809  *
810  * Note we use _exit(2) not _exit(0). This is to force the postmaster
811  * into a system reset cycle if someone sends a manual SIGQUIT to a random
812  * backend. This is necessary precisely because we don't clean up our
813  * shared memory state. (The "dead man switch" mechanism in pmsignal.c
814  * should ensure the postmaster sees this as a crash, too, but no harm in
815  * being doubly sure.)
816  */
817  _exit(2);
818 }
819 
820 /*
821  * Accept the message from XLOG stream, and process it.
822  */
823 static void
824 XLogWalRcvProcessMsg(unsigned char type, char *buf, Size len)
825 {
826  int hdrlen;
827  XLogRecPtr dataStart;
828  XLogRecPtr walEnd;
829  TimestampTz sendTime;
830  bool replyRequested;
831 
832  resetStringInfo(&incoming_message);
833 
834  switch (type)
835  {
836  case 'w': /* WAL records */
837  {
838  /* copy message to StringInfo */
839  hdrlen = sizeof(int64) + sizeof(int64) + sizeof(int64);
840  if (len < hdrlen)
841  ereport(ERROR,
842  (errcode(ERRCODE_PROTOCOL_VIOLATION),
843  errmsg_internal("invalid WAL message received from primary")));
844  appendBinaryStringInfo(&incoming_message, buf, hdrlen);
845 
846  /* read the fields */
847  dataStart = pq_getmsgint64(&incoming_message);
848  walEnd = pq_getmsgint64(&incoming_message);
849  sendTime = pq_getmsgint64(&incoming_message);
850  ProcessWalSndrMessage(walEnd, sendTime);
851 
852  buf += hdrlen;
853  len -= hdrlen;
854  XLogWalRcvWrite(buf, len, dataStart);
855  break;
856  }
857  case 'k': /* Keepalive */
858  {
859  /* copy message to StringInfo */
860  hdrlen = sizeof(int64) + sizeof(int64) + sizeof(char);
861  if (len != hdrlen)
862  ereport(ERROR,
863  (errcode(ERRCODE_PROTOCOL_VIOLATION),
864  errmsg_internal("invalid keepalive message received from primary")));
865  appendBinaryStringInfo(&incoming_message, buf, hdrlen);
866 
867  /* read the fields */
868  walEnd = pq_getmsgint64(&incoming_message);
869  sendTime = pq_getmsgint64(&incoming_message);
870  replyRequested = pq_getmsgbyte(&incoming_message);
871 
872  ProcessWalSndrMessage(walEnd, sendTime);
873 
874  /* If the primary requested a reply, send one immediately */
875  if (replyRequested)
876  XLogWalRcvSendReply(true, false);
877  break;
878  }
879  default:
880  ereport(ERROR,
881  (errcode(ERRCODE_PROTOCOL_VIOLATION),
882  errmsg_internal("invalid replication message type %d",
883  type)));
884  }
885 }
886 
887 /*
888  * Write XLOG data to disk.
889  */
890 static void
891 XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
892 {
893  int startoff;
894  int byteswritten;
895 
896  while (nbytes > 0)
897  {
898  int segbytes;
899 
900  if (recvFile < 0 || !XLByteInSeg(recptr, recvSegNo, wal_segment_size))
901  {
902  bool use_existent;
903 
904  /*
905  * fsync() and close current file before we switch to next one. We
906  * would otherwise have to reopen this file to fsync it later
907  */
908  if (recvFile >= 0)
909  {
910  char xlogfname[MAXFNAMELEN];
911 
912  XLogWalRcvFlush(false);
913 
914  /*
915  * XLOG segment files will be re-read by recovery in startup
916  * process soon, so we don't advise the OS to release cache
917  * pages associated with the file like XLogFileClose() does.
918  */
919  if (close(recvFile) != 0)
920  ereport(PANIC,
922  errmsg("could not close log segment %s: %m",
924 
925  /*
926  * Create .done file forcibly to prevent the streamed segment
927  * from being archived later.
928  */
931  XLogArchiveForceDone(xlogfname);
932  else
933  XLogArchiveNotify(xlogfname);
934  }
935  recvFile = -1;
936 
937  /* Create/use new log file */
939  use_existent = true;
940  recvFile = XLogFileInit(recvSegNo, &use_existent, true);
942  recvOff = 0;
943  }
944 
945  /* Calculate the start offset of the received logs */
946  startoff = XLogSegmentOffset(recptr, wal_segment_size);
947 
948  if (startoff + nbytes > wal_segment_size)
949  segbytes = wal_segment_size - startoff;
950  else
951  segbytes = nbytes;
952 
953  /* Need to seek in the file? */
954  if (recvOff != startoff)
955  {
956  if (lseek(recvFile, (off_t) startoff, SEEK_SET) < 0)
957  ereport(PANIC,
959  errmsg("could not seek in log segment %s to offset %u: %m",
961  startoff)));
962  recvOff = startoff;
963  }
964 
965  /* OK to write the logs */
966  errno = 0;
967 
968  byteswritten = write(recvFile, buf, segbytes);
969  if (byteswritten <= 0)
970  {
971  /* if write didn't set errno, assume no disk space */
972  if (errno == 0)
973  errno = ENOSPC;
974  ereport(PANIC,
976  errmsg("could not write to log segment %s "
977  "at offset %u, length %lu: %m",
979  recvOff, (unsigned long) segbytes)));
980  }
981 
982  /* Update state for write */
983  recptr += byteswritten;
984 
985  recvOff += byteswritten;
986  nbytes -= byteswritten;
987  buf += byteswritten;
988 
989  LogstreamResult.Write = recptr;
990  }
991 }
992 
993 /*
994  * Flush the log to disk.
995  *
996  * If we're in the midst of dying, it's unwise to do anything that might throw
997  * an error, so we skip sending a reply in that case.
998  */
999 static void
1000 XLogWalRcvFlush(bool dying)
1001 {
1002  if (LogstreamResult.Flush < LogstreamResult.Write)
1003  {
1004  WalRcvData *walrcv = WalRcv;
1005 
1007 
1008  LogstreamResult.Flush = LogstreamResult.Write;
1009 
1010  /* Update shared-memory status */
1011  SpinLockAcquire(&walrcv->mutex);
1012  if (walrcv->receivedUpto < LogstreamResult.Flush)
1013  {
1014  walrcv->latestChunkStart = walrcv->receivedUpto;
1015  walrcv->receivedUpto = LogstreamResult.Flush;
1016  walrcv->receivedTLI = ThisTimeLineID;
1017  }
1018  SpinLockRelease(&walrcv->mutex);
1019 
1020  /* Signal the startup process and walsender that new WAL has arrived */
1021  WakeupRecovery();
1023  WalSndWakeup();
1024 
1025  /* Report XLOG streaming progress in PS display */
1027  {
1028  char activitymsg[50];
1029 
1030  snprintf(activitymsg, sizeof(activitymsg), "streaming %X/%X",
1031  (uint32) (LogstreamResult.Write >> 32),
1032  (uint32) LogstreamResult.Write);
1033  set_ps_display(activitymsg, false);
1034  }
1035 
1036  /* Also let the master know that we made some progress */
1037  if (!dying)
1038  {
1039  XLogWalRcvSendReply(false, false);
1040  XLogWalRcvSendHSFeedback(false);
1041  }
1042  }
1043 }
1044 
1045 /*
1046  * Send reply message to primary, indicating our current WAL locations, oldest
1047  * xmin and the current time.
1048  *
1049  * If 'force' is not set, the message is only sent if enough time has
1050  * passed since last status update to reach wal_receiver_status_interval.
1051  * If wal_receiver_status_interval is disabled altogether and 'force' is
1052  * false, this is a no-op.
1053  *
1054  * If 'requestReply' is true, requests the server to reply immediately upon
1055  * receiving this message. This is used for heartbearts, when approaching
1056  * wal_receiver_timeout.
1057  */
1058 static void
1059 XLogWalRcvSendReply(bool force, bool requestReply)
1060 {
1061  static XLogRecPtr writePtr = 0;
1062  static XLogRecPtr flushPtr = 0;
1063  XLogRecPtr applyPtr;
1064  static TimestampTz sendTime = 0;
1065  TimestampTz now;
1066 
1067  /*
1068  * If the user doesn't want status to be reported to the master, be sure
1069  * to exit before doing anything at all.
1070  */
1071  if (!force && wal_receiver_status_interval <= 0)
1072  return;
1073 
1074  /* Get current timestamp. */
1075  now = GetCurrentTimestamp();
1076 
1077  /*
1078  * We can compare the write and flush positions to the last message we
1079  * sent without taking any lock, but the apply position requires a spin
1080  * lock, so we don't check that unless something else has changed or 10
1081  * seconds have passed. This means that the apply WAL location will
1082  * appear, from the master's point of view, to lag slightly, but since
1083  * this is only for reporting purposes and only on idle systems, that's
1084  * probably OK.
1085  */
1086  if (!force
1087  && writePtr == LogstreamResult.Write
1088  && flushPtr == LogstreamResult.Flush
1089  && !TimestampDifferenceExceeds(sendTime, now,
1091  return;
1092  sendTime = now;
1093 
1094  /* Construct a new message */
1095  writePtr = LogstreamResult.Write;
1096  flushPtr = LogstreamResult.Flush;
1097  applyPtr = GetXLogReplayRecPtr(NULL);
1098 
1099  resetStringInfo(&reply_message);
1100  pq_sendbyte(&reply_message, 'r');
1101  pq_sendint64(&reply_message, writePtr);
1102  pq_sendint64(&reply_message, flushPtr);
1103  pq_sendint64(&reply_message, applyPtr);
1104  pq_sendint64(&reply_message, GetCurrentTimestamp());
1105  pq_sendbyte(&reply_message, requestReply ? 1 : 0);
1106 
1107  /* Send it */
1108  elog(DEBUG2, "sending write %X/%X flush %X/%X apply %X/%X%s",
1109  (uint32) (writePtr >> 32), (uint32) writePtr,
1110  (uint32) (flushPtr >> 32), (uint32) flushPtr,
1111  (uint32) (applyPtr >> 32), (uint32) applyPtr,
1112  requestReply ? " (reply requested)" : "");
1113 
1114  walrcv_send(wrconn, reply_message.data, reply_message.len);
1115 }
1116 
1117 /*
1118  * Send hot standby feedback message to primary, plus the current time,
1119  * in case they don't have a watch.
1120  *
1121  * If the user disables feedback, send one final message to tell sender
1122  * to forget about the xmin on this standby. We also send this message
1123  * on first connect because a previous connection might have set xmin
1124  * on a replication slot. (If we're not using a slot it's harmless to
1125  * send a feedback message explicitly setting InvalidTransactionId).
1126  */
1127 static void
1129 {
1130  TimestampTz now;
1131  FullTransactionId nextFullXid;
1132  TransactionId nextXid;
1133  uint32 xmin_epoch,
1134  catalog_xmin_epoch;
1135  TransactionId xmin,
1136  catalog_xmin;
1137  static TimestampTz sendTime = 0;
1138 
1139  /* initially true so we always send at least one feedback message */
1140  static bool master_has_standby_xmin = true;
1141 
1142  /*
1143  * If the user doesn't want status to be reported to the master, be sure
1144  * to exit before doing anything at all.
1145  */
1147  !master_has_standby_xmin)
1148  return;
1149 
1150  /* Get current timestamp. */
1151  now = GetCurrentTimestamp();
1152 
1153  if (!immed)
1154  {
1155  /*
1156  * Send feedback at most once per wal_receiver_status_interval.
1157  */
1158  if (!TimestampDifferenceExceeds(sendTime, now,
1160  return;
1161  sendTime = now;
1162  }
1163 
1164  /*
1165  * If Hot Standby is not yet accepting connections there is nothing to
1166  * send. Check this after the interval has expired to reduce number of
1167  * calls.
1168  *
1169  * Bailing out here also ensures that we don't send feedback until we've
1170  * read our own replication slot state, so we don't tell the master to
1171  * discard needed xmin or catalog_xmin from any slots that may exist on
1172  * this replica.
1173  */
1174  if (!HotStandbyActive())
1175  return;
1176 
1177  /*
1178  * Make the expensive call to get the oldest xmin once we are certain
1179  * everything else has been checked.
1180  */
1182  {
1183  TransactionId slot_xmin;
1184 
1185  /*
1186  * Usually GetOldestXmin() would include both global replication slot
1187  * xmin and catalog_xmin in its calculations, but we want to derive
1188  * separate values for each of those. So we ask for an xmin that
1189  * excludes the catalog_xmin.
1190  */
1191  xmin = GetOldestXmin(NULL,
1193 
1194  ProcArrayGetReplicationSlotXmin(&slot_xmin, &catalog_xmin);
1195 
1196  if (TransactionIdIsValid(slot_xmin) &&
1197  TransactionIdPrecedes(slot_xmin, xmin))
1198  xmin = slot_xmin;
1199  }
1200  else
1201  {
1202  xmin = InvalidTransactionId;
1203  catalog_xmin = InvalidTransactionId;
1204  }
1205 
1206  /*
1207  * Get epoch and adjust if nextXid and oldestXmin are different sides of
1208  * the epoch boundary.
1209  */
1210  nextFullXid = ReadNextFullTransactionId();
1211  nextXid = XidFromFullTransactionId(nextFullXid);
1212  xmin_epoch = EpochFromFullTransactionId(nextFullXid);
1213  catalog_xmin_epoch = xmin_epoch;
1214  if (nextXid < xmin)
1215  xmin_epoch--;
1216  if (nextXid < catalog_xmin)
1217  catalog_xmin_epoch--;
1218 
1219  elog(DEBUG2, "sending hot standby feedback xmin %u epoch %u catalog_xmin %u catalog_xmin_epoch %u",
1220  xmin, xmin_epoch, catalog_xmin, catalog_xmin_epoch);
1221 
1222  /* Construct the message and send it. */
1223  resetStringInfo(&reply_message);
1224  pq_sendbyte(&reply_message, 'h');
1225  pq_sendint64(&reply_message, GetCurrentTimestamp());
1226  pq_sendint32(&reply_message, xmin);
1227  pq_sendint32(&reply_message, xmin_epoch);
1228  pq_sendint32(&reply_message, catalog_xmin);
1229  pq_sendint32(&reply_message, catalog_xmin_epoch);
1230  walrcv_send(wrconn, reply_message.data, reply_message.len);
1231  if (TransactionIdIsValid(xmin) || TransactionIdIsValid(catalog_xmin))
1232  master_has_standby_xmin = true;
1233  else
1234  master_has_standby_xmin = false;
1235 }
1236 
1237 /*
1238  * Update shared memory status upon receiving a message from primary.
1239  *
1240  * 'walEnd' and 'sendTime' are the end-of-WAL and timestamp of the latest
1241  * message, reported by primary.
1242  */
1243 static void
1245 {
1246  WalRcvData *walrcv = WalRcv;
1247 
1248  TimestampTz lastMsgReceiptTime = GetCurrentTimestamp();
1249 
1250  /* Update shared-memory status */
1251  SpinLockAcquire(&walrcv->mutex);
1252  if (walrcv->latestWalEnd < walEnd)
1253  walrcv->latestWalEndTime = sendTime;
1254  walrcv->latestWalEnd = walEnd;
1255  walrcv->lastMsgSendTime = sendTime;
1256  walrcv->lastMsgReceiptTime = lastMsgReceiptTime;
1257  SpinLockRelease(&walrcv->mutex);
1258 
1259  if (log_min_messages <= DEBUG2)
1260  {
1261  char *sendtime;
1262  char *receipttime;
1263  int applyDelay;
1264 
1265  /* Copy because timestamptz_to_str returns a static buffer */
1266  sendtime = pstrdup(timestamptz_to_str(sendTime));
1267  receipttime = pstrdup(timestamptz_to_str(lastMsgReceiptTime));
1268  applyDelay = GetReplicationApplyDelay();
1269 
1270  /* apply delay is not available */
1271  if (applyDelay == -1)
1272  elog(DEBUG2, "sendtime %s receipttime %s replication apply delay (N/A) transfer latency %d ms",
1273  sendtime,
1274  receipttime,
1276  else
1277  elog(DEBUG2, "sendtime %s receipttime %s replication apply delay %d ms transfer latency %d ms",
1278  sendtime,
1279  receipttime,
1280  applyDelay,
1282 
1283  pfree(sendtime);
1284  pfree(receipttime);
1285  }
1286 }
1287 
1288 /*
1289  * Wake up the walreceiver main loop.
1290  *
1291  * This is called by the startup process whenever interesting xlog records
1292  * are applied, so that walreceiver can check if it needs to send an apply
1293  * notification back to the master which may be waiting in a COMMIT with
1294  * synchronous_commit = remote_apply.
1295  */
1296 void
1298 {
1299  Latch *latch;
1300 
1301  WalRcv->force_reply = true;
1302  /* fetching the latch pointer might not be atomic, so use spinlock */
1304  latch = WalRcv->latch;
1306  if (latch)
1307  SetLatch(latch);
1308 }
1309 
1310 /*
1311  * Return a string constant representing the state. This is used
1312  * in system functions and views, and should *not* be translated.
1313  */
1314 static const char *
1316 {
1317  switch (state)
1318  {
1319  case WALRCV_STOPPED:
1320  return "stopped";
1321  case WALRCV_STARTING:
1322  return "starting";
1323  case WALRCV_STREAMING:
1324  return "streaming";
1325  case WALRCV_WAITING:
1326  return "waiting";
1327  case WALRCV_RESTARTING:
1328  return "restarting";
1329  case WALRCV_STOPPING:
1330  return "stopping";
1331  }
1332  return "UNKNOWN";
1333 }
1334 
1335 /*
1336  * Returns activity of WAL receiver, including pid, state and xlog locations
1337  * received from the WAL sender of another server.
1338  */
1339 Datum
1341 {
1342  TupleDesc tupdesc;
1343  Datum *values;
1344  bool *nulls;
1345  int pid;
1346  bool ready_to_display;
1348  XLogRecPtr receive_start_lsn;
1349  TimeLineID receive_start_tli;
1350  XLogRecPtr received_lsn;
1351  TimeLineID received_tli;
1352  TimestampTz last_send_time;
1353  TimestampTz last_receipt_time;
1354  XLogRecPtr latest_end_lsn;
1355  TimestampTz latest_end_time;
1356  char sender_host[NI_MAXHOST];
1357  int sender_port = 0;
1358  char slotname[NAMEDATALEN];
1359  char conninfo[MAXCONNINFO];
1360 
1361  /* Take a lock to ensure value consistency */
1363  pid = (int) WalRcv->pid;
1364  ready_to_display = WalRcv->ready_to_display;
1365  state = WalRcv->walRcvState;
1366  receive_start_lsn = WalRcv->receiveStart;
1367  receive_start_tli = WalRcv->receiveStartTLI;
1368  received_lsn = WalRcv->receivedUpto;
1369  received_tli = WalRcv->receivedTLI;
1370  last_send_time = WalRcv->lastMsgSendTime;
1371  last_receipt_time = WalRcv->lastMsgReceiptTime;
1372  latest_end_lsn = WalRcv->latestWalEnd;
1373  latest_end_time = WalRcv->latestWalEndTime;
1374  strlcpy(slotname, (char *) WalRcv->slotname, sizeof(slotname));
1375  strlcpy(sender_host, (char *) WalRcv->sender_host, sizeof(sender_host));
1376  sender_port = WalRcv->sender_port;
1377  strlcpy(conninfo, (char *) WalRcv->conninfo, sizeof(conninfo));
1379 
1380  /*
1381  * No WAL receiver (or not ready yet), just return a tuple with NULL
1382  * values
1383  */
1384  if (pid == 0 || !ready_to_display)
1385  PG_RETURN_NULL();
1386 
1387  /* determine result type */
1388  if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
1389  elog(ERROR, "return type must be a row type");
1390 
1391  values = palloc0(sizeof(Datum) * tupdesc->natts);
1392  nulls = palloc0(sizeof(bool) * tupdesc->natts);
1393 
1394  /* Fetch values */
1395  values[0] = Int32GetDatum(pid);
1396 
1397  if (!is_member_of_role(GetUserId(), DEFAULT_ROLE_READ_ALL_STATS))
1398  {
1399  /*
1400  * Only superusers and members of pg_read_all_stats can see details.
1401  * Other users only get the pid value to know whether it is a WAL
1402  * receiver, but no details.
1403  */
1404  MemSet(&nulls[1], true, sizeof(bool) * (tupdesc->natts - 1));
1405  }
1406  else
1407  {
1408  values[1] = CStringGetTextDatum(WalRcvGetStateString(state));
1409 
1410  if (XLogRecPtrIsInvalid(receive_start_lsn))
1411  nulls[2] = true;
1412  else
1413  values[2] = LSNGetDatum(receive_start_lsn);
1414  values[3] = Int32GetDatum(receive_start_tli);
1415  if (XLogRecPtrIsInvalid(received_lsn))
1416  nulls[4] = true;
1417  else
1418  values[4] = LSNGetDatum(received_lsn);
1419  values[5] = Int32GetDatum(received_tli);
1420  if (last_send_time == 0)
1421  nulls[6] = true;
1422  else
1423  values[6] = TimestampTzGetDatum(last_send_time);
1424  if (last_receipt_time == 0)
1425  nulls[7] = true;
1426  else
1427  values[7] = TimestampTzGetDatum(last_receipt_time);
1428  if (XLogRecPtrIsInvalid(latest_end_lsn))
1429  nulls[8] = true;
1430  else
1431  values[8] = LSNGetDatum(latest_end_lsn);
1432  if (latest_end_time == 0)
1433  nulls[9] = true;
1434  else
1435  values[9] = TimestampTzGetDatum(latest_end_time);
1436  if (*slotname == '\0')
1437  nulls[10] = true;
1438  else
1439  values[10] = CStringGetTextDatum(slotname);
1440  if (*sender_host == '\0')
1441  nulls[11] = true;
1442  else
1443  values[11] = CStringGetTextDatum(sender_host);
1444  if (sender_port == 0)
1445  nulls[12] = true;
1446  else
1447  values[12] = Int32GetDatum(sender_port);
1448  if (*conninfo == '\0')
1449  nulls[13] = true;
1450  else
1451  values[13] = CStringGetTextDatum(conninfo);
1452  }
1453 
1454  /* Returns the record as Datum */
1455  PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));
1456 }
static struct @25 LogstreamResult
int sender_port
Definition: walreceiver.h:116
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Definition: win32_port.h:155
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Definition: walreceiver.c:685
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Definition: xlogdefs.h:28
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Definition: walreceiver.h:259
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Definition: walreceiver.h:271
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Definition: proc.c:68
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Definition: xlogarchive.c:511
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Definition: walreceiver.c:167
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Definition: getaddrinfo.h:88
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Definition: walreceiver.c:81
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Definition: funcapi.h:221
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Definition: walreceiver.h:275
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Definition: walreceiver.c:801
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Definition: walreceiver.c:1000
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Definition: xlog.c:4802
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Definition: postgres.h:479
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Definition: walreceiver.c:732
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Definition: elog.h:226
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Definition: walreceiver.h:261
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Definition: builtins.h:83
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Definition: walreceiver.c:93
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Definition: miscadmin.h:99
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Definition: win32.h:12
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Definition: latch.c:1515
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Definition: walreceiver.c:100
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Definition: walreceiver.c:90
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Definition: port.h:192
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Definition: latch.h:124
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Definition: walsender.c:3073
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Definition: latch.h:129
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Definition: walreceiver.h:109
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Definition: walreceiver.h:255