Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * receivelog.c - receive WAL files using the streaming
4 : * replication protocol.
5 : *
6 : * Author: Magnus Hagander <magnus@hagander.net>
7 : *
8 : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
9 : *
10 : * IDENTIFICATION
11 : * src/bin/pg_basebackup/receivelog.c
12 : *-------------------------------------------------------------------------
13 : */
14 :
15 : #include "postgres_fe.h"
16 :
17 : #include <sys/select.h>
18 : #include <sys/stat.h>
19 : #include <unistd.h>
20 :
21 : #include "access/xlog_internal.h"
22 : #include "common/logging.h"
23 : #include "libpq-fe.h"
24 : #include "libpq/protocol.h"
25 : #include "receivelog.h"
26 : #include "streamutil.h"
27 :
28 : /* currently open WAL file */
29 : static Walfile *walfile = NULL;
30 : static bool reportFlushPosition = false;
31 : static XLogRecPtr lastFlushPosition = InvalidXLogRecPtr;
32 :
33 : static bool still_sending = true; /* feedback still needs to be sent? */
34 :
35 : static PGresult *HandleCopyStream(PGconn *conn, StreamCtl *stream,
36 : XLogRecPtr *stoppos);
37 : static int CopyStreamPoll(PGconn *conn, long timeout_ms, pgsocket stop_socket);
38 : static int CopyStreamReceive(PGconn *conn, long timeout, pgsocket stop_socket,
39 : char **buffer);
40 : static bool ProcessKeepaliveMsg(PGconn *conn, StreamCtl *stream, char *copybuf,
41 : int len, XLogRecPtr blockpos, TimestampTz *last_status);
42 : static bool ProcessWALDataMsg(PGconn *conn, StreamCtl *stream, char *copybuf, int len,
43 : XLogRecPtr *blockpos);
44 : static PGresult *HandleEndOfCopyStream(PGconn *conn, StreamCtl *stream, char *copybuf,
45 : XLogRecPtr blockpos, XLogRecPtr *stoppos);
46 : static bool CheckCopyStreamStop(PGconn *conn, StreamCtl *stream, XLogRecPtr blockpos);
47 : static long CalculateCopyStreamSleeptime(TimestampTz now, int standby_message_timeout,
48 : TimestampTz last_status);
49 :
50 : static bool ReadEndOfStreamingResult(PGresult *res, XLogRecPtr *startpos,
51 : uint32 *timeline);
52 :
53 : static bool
54 0 : mark_file_as_archived(StreamCtl *stream, const char *fname)
55 : {
56 0 : Walfile *f;
57 : static char tmppath[MAXPGPATH];
58 :
59 0 : snprintf(tmppath, sizeof(tmppath), "archive_status/%s.done",
60 0 : fname);
61 :
62 0 : f = stream->walmethod->ops->open_for_write(stream->walmethod, tmppath,
63 : NULL, 0);
64 0 : if (f == NULL)
65 : {
66 0 : pg_log_error("could not create archive status file \"%s\": %s",
67 : tmppath, GetLastWalMethodError(stream->walmethod));
68 0 : return false;
69 : }
70 :
71 0 : if (stream->walmethod->ops->close(f, CLOSE_NORMAL) != 0)
72 : {
73 0 : pg_log_error("could not close archive status file \"%s\": %s",
74 : tmppath, GetLastWalMethodError(stream->walmethod));
75 0 : return false;
76 : }
77 :
78 0 : return true;
79 0 : }
80 :
81 : /*
82 : * Open a new WAL file in the specified directory.
83 : *
84 : * Returns true if OK; on failure, returns false after printing an error msg.
85 : * On success, 'walfile' is set to the opened WAL file.
86 : *
87 : * The file will be padded to 16Mb with zeroes.
88 : */
89 : static bool
90 0 : open_walfile(StreamCtl *stream, XLogRecPtr startpoint)
91 : {
92 0 : Walfile *f;
93 0 : char *fn;
94 0 : ssize_t size;
95 0 : XLogSegNo segno;
96 0 : char walfile_name[MAXPGPATH];
97 :
98 0 : XLByteToSeg(startpoint, segno, WalSegSz);
99 0 : XLogFileName(walfile_name, stream->timeline, segno, WalSegSz);
100 :
101 : /* Note that this considers the compression used if necessary */
102 0 : fn = stream->walmethod->ops->get_file_name(stream->walmethod,
103 0 : walfile_name,
104 0 : stream->partial_suffix);
105 :
106 : /*
107 : * When streaming to files, if an existing file exists we verify that it's
108 : * either empty (just created), or a complete WalSegSz segment (in which
109 : * case it has been created and padded). Anything else indicates a corrupt
110 : * file. Compressed files have no need for padding, so just ignore this
111 : * case.
112 : *
113 : * When streaming to tar, no file with this name will exist before, so we
114 : * never have to verify a size.
115 : */
116 0 : if (stream->walmethod->compression_algorithm == PG_COMPRESSION_NONE &&
117 0 : stream->walmethod->ops->existsfile(stream->walmethod, fn))
118 : {
119 0 : size = stream->walmethod->ops->get_file_size(stream->walmethod, fn);
120 0 : if (size < 0)
121 : {
122 0 : pg_log_error("could not get size of write-ahead log file \"%s\": %s",
123 : fn, GetLastWalMethodError(stream->walmethod));
124 0 : pg_free(fn);
125 0 : return false;
126 : }
127 0 : if (size == WalSegSz)
128 : {
129 : /* Already padded file. Open it for use */
130 0 : f = stream->walmethod->ops->open_for_write(stream->walmethod, walfile_name, stream->partial_suffix, 0);
131 0 : if (f == NULL)
132 : {
133 0 : pg_log_error("could not open existing write-ahead log file \"%s\": %s",
134 : fn, GetLastWalMethodError(stream->walmethod));
135 0 : pg_free(fn);
136 0 : return false;
137 : }
138 :
139 : /* fsync file in case of a previous crash */
140 0 : if (stream->walmethod->ops->sync(f) != 0)
141 : {
142 0 : pg_log_error("could not fsync existing write-ahead log file \"%s\": %s",
143 : fn, GetLastWalMethodError(stream->walmethod));
144 0 : stream->walmethod->ops->close(f, CLOSE_UNLINK);
145 0 : exit(1);
146 : }
147 :
148 0 : walfile = f;
149 0 : pg_free(fn);
150 0 : return true;
151 : }
152 0 : if (size != 0)
153 : {
154 : /* if write didn't set errno, assume problem is no disk space */
155 0 : if (errno == 0)
156 0 : errno = ENOSPC;
157 0 : pg_log_error(ngettext("write-ahead log file \"%s\" has %zd byte, should be 0 or %d",
158 : "write-ahead log file \"%s\" has %zd bytes, should be 0 or %d",
159 : size),
160 : fn, size, WalSegSz);
161 0 : pg_free(fn);
162 0 : return false;
163 : }
164 : /* File existed and was empty, so fall through and open */
165 0 : }
166 :
167 : /* No file existed, so create one */
168 :
169 0 : f = stream->walmethod->ops->open_for_write(stream->walmethod,
170 0 : walfile_name,
171 0 : stream->partial_suffix,
172 0 : WalSegSz);
173 0 : if (f == NULL)
174 : {
175 0 : pg_log_error("could not open write-ahead log file \"%s\": %s",
176 : fn, GetLastWalMethodError(stream->walmethod));
177 0 : pg_free(fn);
178 0 : return false;
179 : }
180 :
181 0 : pg_free(fn);
182 0 : walfile = f;
183 0 : return true;
184 0 : }
185 :
186 : /*
187 : * Close the current WAL file (if open), and rename it to the correct
188 : * filename if it's complete. On failure, prints an error message to stderr
189 : * and returns false, otherwise returns true.
190 : */
191 : static bool
192 0 : close_walfile(StreamCtl *stream, XLogRecPtr pos)
193 : {
194 0 : char *fn;
195 0 : pgoff_t currpos;
196 0 : int r;
197 0 : char walfile_name[MAXPGPATH];
198 :
199 0 : if (walfile == NULL)
200 0 : return true;
201 :
202 0 : strlcpy(walfile_name, walfile->pathname, MAXPGPATH);
203 0 : currpos = walfile->currpos;
204 :
205 : /* Note that this considers the compression used if necessary */
206 0 : fn = stream->walmethod->ops->get_file_name(stream->walmethod,
207 0 : walfile_name,
208 0 : stream->partial_suffix);
209 :
210 0 : if (stream->partial_suffix)
211 : {
212 0 : if (currpos == WalSegSz)
213 0 : r = stream->walmethod->ops->close(walfile, CLOSE_NORMAL);
214 : else
215 : {
216 0 : pg_log_info("not renaming \"%s\", segment is not complete", fn);
217 0 : r = stream->walmethod->ops->close(walfile, CLOSE_NO_RENAME);
218 : }
219 0 : }
220 : else
221 0 : r = stream->walmethod->ops->close(walfile, CLOSE_NORMAL);
222 :
223 0 : walfile = NULL;
224 :
225 0 : if (r != 0)
226 : {
227 0 : pg_log_error("could not close file \"%s\": %s",
228 : fn, GetLastWalMethodError(stream->walmethod));
229 :
230 0 : pg_free(fn);
231 0 : return false;
232 : }
233 :
234 0 : pg_free(fn);
235 :
236 : /*
237 : * Mark file as archived if requested by the caller - pg_basebackup needs
238 : * to do so as files can otherwise get archived again after promotion of a
239 : * new node. This is in line with walreceiver.c always doing a
240 : * XLogArchiveForceDone() after a complete segment.
241 : */
242 0 : if (currpos == WalSegSz && stream->mark_done)
243 : {
244 : /* writes error message if failed */
245 0 : if (!mark_file_as_archived(stream, walfile_name))
246 0 : return false;
247 0 : }
248 :
249 0 : lastFlushPosition = pos;
250 0 : return true;
251 0 : }
252 :
253 :
254 : /*
255 : * Check if a timeline history file exists.
256 : */
257 : static bool
258 0 : existsTimeLineHistoryFile(StreamCtl *stream)
259 : {
260 0 : char histfname[MAXFNAMELEN];
261 :
262 : /*
263 : * Timeline 1 never has a history file. We treat that as if it existed,
264 : * since we never need to stream it.
265 : */
266 0 : if (stream->timeline == 1)
267 0 : return true;
268 :
269 0 : TLHistoryFileName(histfname, stream->timeline);
270 :
271 0 : return stream->walmethod->ops->existsfile(stream->walmethod, histfname);
272 0 : }
273 :
274 : static bool
275 0 : writeTimeLineHistoryFile(StreamCtl *stream, char *filename, char *content)
276 : {
277 0 : int size = strlen(content);
278 0 : char histfname[MAXFNAMELEN];
279 0 : Walfile *f;
280 :
281 : /*
282 : * Check that the server's idea of how timeline history files should be
283 : * named matches ours.
284 : */
285 0 : TLHistoryFileName(histfname, stream->timeline);
286 0 : if (strcmp(histfname, filename) != 0)
287 : {
288 0 : pg_log_error("server reported unexpected history file name for timeline %u: %s",
289 : stream->timeline, filename);
290 0 : return false;
291 : }
292 :
293 0 : f = stream->walmethod->ops->open_for_write(stream->walmethod,
294 0 : histfname, ".tmp", 0);
295 0 : if (f == NULL)
296 : {
297 0 : pg_log_error("could not create timeline history file \"%s\": %s",
298 : histfname, GetLastWalMethodError(stream->walmethod));
299 0 : return false;
300 : }
301 :
302 0 : if ((int) stream->walmethod->ops->write(f, content, size) != size)
303 : {
304 0 : pg_log_error("could not write timeline history file \"%s\": %s",
305 : histfname, GetLastWalMethodError(stream->walmethod));
306 :
307 : /*
308 : * If we fail to make the file, delete it to release disk space
309 : */
310 0 : stream->walmethod->ops->close(f, CLOSE_UNLINK);
311 :
312 0 : return false;
313 : }
314 :
315 0 : if (stream->walmethod->ops->close(f, CLOSE_NORMAL) != 0)
316 : {
317 0 : pg_log_error("could not close file \"%s\": %s",
318 : histfname, GetLastWalMethodError(stream->walmethod));
319 0 : return false;
320 : }
321 :
322 : /* Maintain archive_status, check close_walfile() for details. */
323 0 : if (stream->mark_done)
324 : {
325 : /* writes error message if failed */
326 0 : if (!mark_file_as_archived(stream, histfname))
327 0 : return false;
328 0 : }
329 :
330 0 : return true;
331 0 : }
332 :
333 : /*
334 : * Send a Standby Status Update message to server.
335 : */
336 : static bool
337 0 : sendFeedback(PGconn *conn, XLogRecPtr blockpos, TimestampTz now, bool replyRequested)
338 : {
339 0 : char replybuf[1 + 8 + 8 + 8 + 8 + 1];
340 0 : int len = 0;
341 :
342 0 : replybuf[len] = PqReplMsg_StandbyStatusUpdate;
343 0 : len += 1;
344 0 : fe_sendint64(blockpos, &replybuf[len]); /* write */
345 0 : len += 8;
346 0 : if (reportFlushPosition)
347 0 : fe_sendint64(lastFlushPosition, &replybuf[len]); /* flush */
348 : else
349 0 : fe_sendint64(InvalidXLogRecPtr, &replybuf[len]); /* flush */
350 0 : len += 8;
351 0 : fe_sendint64(InvalidXLogRecPtr, &replybuf[len]); /* apply */
352 0 : len += 8;
353 0 : fe_sendint64(now, &replybuf[len]); /* sendTime */
354 0 : len += 8;
355 0 : replybuf[len] = replyRequested ? 1 : 0; /* replyRequested */
356 0 : len += 1;
357 :
358 0 : if (PQputCopyData(conn, replybuf, len) <= 0 || PQflush(conn))
359 : {
360 0 : pg_log_error("could not send feedback packet: %s",
361 : PQerrorMessage(conn));
362 0 : return false;
363 : }
364 :
365 0 : return true;
366 0 : }
367 :
368 : /*
369 : * Check that the server version we're connected to is supported by
370 : * ReceiveXlogStream().
371 : *
372 : * If it's not, an error message is printed to stderr, and false is returned.
373 : */
374 : bool
375 0 : CheckServerVersionForStreaming(PGconn *conn)
376 : {
377 0 : int minServerMajor,
378 : maxServerMajor;
379 0 : int serverMajor;
380 :
381 : /*
382 : * The message format used in streaming replication changed in 9.3, so we
383 : * cannot stream from older servers. And we don't support servers newer
384 : * than the client; it might work, but we don't know, so err on the safe
385 : * side.
386 : */
387 0 : minServerMajor = 903;
388 0 : maxServerMajor = PG_VERSION_NUM / 100;
389 0 : serverMajor = PQserverVersion(conn) / 100;
390 0 : if (serverMajor < minServerMajor)
391 : {
392 0 : const char *serverver = PQparameterStatus(conn, "server_version");
393 :
394 0 : pg_log_error("incompatible server version %s; client does not support streaming from server versions older than %s",
395 : serverver ? serverver : "'unknown'",
396 : "9.3");
397 0 : return false;
398 0 : }
399 0 : else if (serverMajor > maxServerMajor)
400 : {
401 0 : const char *serverver = PQparameterStatus(conn, "server_version");
402 :
403 0 : pg_log_error("incompatible server version %s; client does not support streaming from server versions newer than %s",
404 : serverver ? serverver : "'unknown'",
405 : PG_VERSION);
406 0 : return false;
407 0 : }
408 0 : return true;
409 0 : }
410 :
411 : /*
412 : * Receive a log stream starting at the specified position.
413 : *
414 : * Individual parameters are passed through the StreamCtl structure.
415 : *
416 : * If sysidentifier is specified, validate that both the system
417 : * identifier and the timeline matches the specified ones
418 : * (by sending an extra IDENTIFY_SYSTEM command)
419 : *
420 : * All received segments will be written to the directory
421 : * specified by basedir. This will also fetch any missing timeline history
422 : * files.
423 : *
424 : * The stream_stop callback will be called every time data
425 : * is received, and whenever a segment is completed. If it returns
426 : * true, the streaming will stop and the function
427 : * return. As long as it returns false, streaming will continue
428 : * indefinitely.
429 : *
430 : * If stream_stop() checks for external input, stop_socket should be set to
431 : * the FD it checks. This will allow such input to be detected promptly
432 : * rather than after standby_message_timeout (which might be indefinite).
433 : * Note that signals will interrupt waits for input as well, but that is
434 : * race-y since a signal received while busy won't interrupt the wait.
435 : *
436 : * standby_message_timeout controls how often we send a message
437 : * back to the primary letting it know our progress, in milliseconds.
438 : * Zero means no messages are sent.
439 : * This message will only contain the write location, and never
440 : * flush or replay.
441 : *
442 : * If 'partial_suffix' is not NULL, files are initially created with the
443 : * given suffix, and the suffix is removed once the file is finished. That
444 : * allows you to tell the difference between partial and completed files,
445 : * so that you can continue later where you left.
446 : *
447 : * If 'synchronous' is true, the received WAL is flushed as soon as written,
448 : * otherwise only when the WAL file is closed.
449 : *
450 : * Note: The WAL location *must* be at a log segment start!
451 : */
452 : bool
453 0 : ReceiveXlogStream(PGconn *conn, StreamCtl *stream)
454 : {
455 0 : char query[128];
456 0 : char slotcmd[128];
457 0 : PGresult *res;
458 0 : XLogRecPtr stoppos;
459 :
460 : /*
461 : * The caller should've checked the server version already, but doesn't do
462 : * any harm to check it here too.
463 : */
464 0 : if (!CheckServerVersionForStreaming(conn))
465 0 : return false;
466 :
467 : /*
468 : * Decide whether we want to report the flush position. If we report the
469 : * flush position, the primary will know what WAL we'll possibly
470 : * re-request, and it can then remove older WAL safely. We must always do
471 : * that when we are using slots.
472 : *
473 : * Reporting the flush position makes one eligible as a synchronous
474 : * replica. People shouldn't include generic names in
475 : * synchronous_standby_names, but we've protected them against it so far,
476 : * so let's continue to do so unless specifically requested.
477 : */
478 0 : if (stream->replication_slot != NULL)
479 : {
480 0 : reportFlushPosition = true;
481 0 : sprintf(slotcmd, "SLOT \"%s\" ", stream->replication_slot);
482 0 : }
483 : else
484 : {
485 0 : if (stream->synchronous)
486 0 : reportFlushPosition = true;
487 : else
488 0 : reportFlushPosition = false;
489 0 : slotcmd[0] = 0;
490 : }
491 :
492 0 : if (stream->sysidentifier != NULL)
493 : {
494 0 : char *sysidentifier = NULL;
495 0 : TimeLineID servertli;
496 :
497 : /*
498 : * Get the server system identifier and timeline, and validate them.
499 : */
500 0 : if (!RunIdentifySystem(conn, &sysidentifier, &servertli, NULL, NULL))
501 : {
502 0 : pg_free(sysidentifier);
503 0 : return false;
504 : }
505 :
506 0 : if (strcmp(stream->sysidentifier, sysidentifier) != 0)
507 : {
508 0 : pg_log_error("system identifier does not match between base backup and streaming connection");
509 0 : pg_free(sysidentifier);
510 0 : return false;
511 : }
512 0 : pg_free(sysidentifier);
513 :
514 0 : if (stream->timeline > servertli)
515 : {
516 0 : pg_log_error("starting timeline %u is not present in the server",
517 : stream->timeline);
518 0 : return false;
519 : }
520 0 : }
521 :
522 : /*
523 : * initialize flush position to starting point, it's the caller's
524 : * responsibility that that's sane.
525 : */
526 0 : lastFlushPosition = stream->startpos;
527 :
528 0 : while (1)
529 : {
530 : /*
531 : * Fetch the timeline history file for this timeline, if we don't have
532 : * it already. When streaming log to tar, this will always return
533 : * false, as we are never streaming into an existing file and
534 : * therefore there can be no pre-existing timeline history file.
535 : */
536 0 : if (!existsTimeLineHistoryFile(stream))
537 : {
538 0 : snprintf(query, sizeof(query), "TIMELINE_HISTORY %u", stream->timeline);
539 0 : res = PQexec(conn, query);
540 0 : if (PQresultStatus(res) != PGRES_TUPLES_OK)
541 : {
542 : /* FIXME: we might send it ok, but get an error */
543 0 : pg_log_error("could not send replication command \"%s\": %s",
544 : "TIMELINE_HISTORY", PQresultErrorMessage(res));
545 0 : PQclear(res);
546 0 : return false;
547 : }
548 :
549 : /*
550 : * The response to TIMELINE_HISTORY is a single row result set
551 : * with two fields: filename and content
552 : */
553 0 : if (PQnfields(res) != 2 || PQntuples(res) != 1)
554 : {
555 0 : pg_log_warning("unexpected response to TIMELINE_HISTORY command: got %d rows and %d fields, expected %d rows and %d fields",
556 : PQntuples(res), PQnfields(res), 1, 2);
557 0 : }
558 :
559 : /* Write the history file to disk */
560 0 : writeTimeLineHistoryFile(stream,
561 0 : PQgetvalue(res, 0, 0),
562 0 : PQgetvalue(res, 0, 1));
563 :
564 0 : PQclear(res);
565 0 : }
566 :
567 : /*
568 : * Before we start streaming from the requested location, check if the
569 : * callback tells us to stop here.
570 : */
571 0 : if (stream->stream_stop(stream->startpos, stream->timeline, false))
572 0 : return true;
573 :
574 : /* Initiate the replication stream at specified location */
575 0 : snprintf(query, sizeof(query), "START_REPLICATION %s%X/%08X TIMELINE %u",
576 0 : slotcmd,
577 0 : LSN_FORMAT_ARGS(stream->startpos),
578 0 : stream->timeline);
579 0 : res = PQexec(conn, query);
580 0 : if (PQresultStatus(res) != PGRES_COPY_BOTH)
581 : {
582 0 : pg_log_error("could not send replication command \"%s\": %s",
583 : "START_REPLICATION", PQresultErrorMessage(res));
584 0 : PQclear(res);
585 0 : return false;
586 : }
587 0 : PQclear(res);
588 :
589 : /* Stream the WAL */
590 0 : res = HandleCopyStream(conn, stream, &stoppos);
591 0 : if (res == NULL)
592 0 : goto error;
593 :
594 : /*
595 : * Streaming finished.
596 : *
597 : * There are two possible reasons for that: a controlled shutdown, or
598 : * we reached the end of the current timeline. In case of
599 : * end-of-timeline, the server sends a result set after Copy has
600 : * finished, containing information about the next timeline. Read
601 : * that, and restart streaming from the next timeline. In case of
602 : * controlled shutdown, stop here.
603 : */
604 0 : if (PQresultStatus(res) == PGRES_TUPLES_OK)
605 : {
606 : /*
607 : * End-of-timeline. Read the next timeline's ID and starting
608 : * position. Usually, the starting position will match the end of
609 : * the previous timeline, but there are corner cases like if the
610 : * server had sent us half of a WAL record, when it was promoted.
611 : * The new timeline will begin at the end of the last complete
612 : * record in that case, overlapping the partial WAL record on the
613 : * old timeline.
614 : */
615 0 : uint32 newtimeline;
616 0 : bool parsed;
617 :
618 0 : parsed = ReadEndOfStreamingResult(res, &stream->startpos, &newtimeline);
619 0 : PQclear(res);
620 0 : if (!parsed)
621 0 : goto error;
622 :
623 : /* Sanity check the values the server gave us */
624 0 : if (newtimeline <= stream->timeline)
625 : {
626 0 : pg_log_error("server reported unexpected next timeline %u, following timeline %u",
627 : newtimeline, stream->timeline);
628 0 : goto error;
629 : }
630 0 : if (stream->startpos > stoppos)
631 : {
632 0 : pg_log_error("server stopped streaming timeline %u at %X/%08X, but reported next timeline %u to begin at %X/%08X",
633 : stream->timeline, LSN_FORMAT_ARGS(stoppos),
634 : newtimeline, LSN_FORMAT_ARGS(stream->startpos));
635 0 : goto error;
636 : }
637 :
638 : /* Read the final result, which should be CommandComplete. */
639 0 : res = PQgetResult(conn);
640 0 : if (PQresultStatus(res) != PGRES_COMMAND_OK)
641 : {
642 0 : pg_log_error("unexpected termination of replication stream: %s",
643 : PQresultErrorMessage(res));
644 0 : PQclear(res);
645 0 : goto error;
646 : }
647 0 : PQclear(res);
648 :
649 : /*
650 : * Loop back to start streaming from the new timeline. Always
651 : * start streaming at the beginning of a segment.
652 : */
653 0 : stream->timeline = newtimeline;
654 0 : stream->startpos = stream->startpos -
655 0 : XLogSegmentOffset(stream->startpos, WalSegSz);
656 0 : continue;
657 0 : }
658 0 : else if (PQresultStatus(res) == PGRES_COMMAND_OK)
659 : {
660 0 : PQclear(res);
661 :
662 : /*
663 : * End of replication (ie. controlled shut down of the server).
664 : *
665 : * Check if the callback thinks it's OK to stop here. If not,
666 : * complain.
667 : */
668 0 : if (stream->stream_stop(stoppos, stream->timeline, false))
669 0 : return true;
670 : else
671 : {
672 0 : pg_log_error("replication stream was terminated before stop point");
673 0 : goto error;
674 : }
675 : }
676 : else
677 : {
678 : /* Server returned an error. */
679 0 : pg_log_error("unexpected termination of replication stream: %s",
680 : PQresultErrorMessage(res));
681 0 : PQclear(res);
682 0 : goto error;
683 : }
684 : }
685 :
686 : error:
687 0 : if (walfile != NULL && stream->walmethod->ops->close(walfile, CLOSE_NO_RENAME) != 0)
688 0 : pg_log_error("could not close file \"%s\": %s",
689 : walfile->pathname, GetLastWalMethodError(stream->walmethod));
690 0 : walfile = NULL;
691 0 : return false;
692 0 : }
693 :
694 : /*
695 : * Helper function to parse the result set returned by server after streaming
696 : * has finished. On failure, prints an error to stderr and returns false.
697 : */
698 : static bool
699 0 : ReadEndOfStreamingResult(PGresult *res, XLogRecPtr *startpos, uint32 *timeline)
700 : {
701 0 : uint32 startpos_xlogid,
702 : startpos_xrecoff;
703 :
704 : /*----------
705 : * The result set consists of one row and two columns, e.g:
706 : *
707 : * next_tli | next_tli_startpos
708 : * ----------+-------------------
709 : * 4 | 0/9949AE0
710 : *
711 : * next_tli is the timeline ID of the next timeline after the one that
712 : * just finished streaming. next_tli_startpos is the WAL location where
713 : * the server switched to it.
714 : *----------
715 : */
716 0 : if (PQnfields(res) < 2 || PQntuples(res) != 1)
717 : {
718 0 : pg_log_error("unexpected result set after end-of-timeline: got %d rows and %d fields, expected %d rows and %d fields",
719 : PQntuples(res), PQnfields(res), 1, 2);
720 0 : return false;
721 : }
722 :
723 0 : *timeline = atoi(PQgetvalue(res, 0, 0));
724 0 : if (sscanf(PQgetvalue(res, 0, 1), "%X/%08X", &startpos_xlogid,
725 0 : &startpos_xrecoff) != 2)
726 : {
727 0 : pg_log_error("could not parse next timeline's starting point \"%s\"",
728 : PQgetvalue(res, 0, 1));
729 0 : return false;
730 : }
731 0 : *startpos = ((uint64) startpos_xlogid << 32) | startpos_xrecoff;
732 :
733 0 : return true;
734 0 : }
735 :
736 : /*
737 : * The main loop of ReceiveXlogStream. Handles the COPY stream after
738 : * initiating streaming with the START_REPLICATION command.
739 : *
740 : * If the COPY ends (not necessarily successfully) due a message from the
741 : * server, returns a PGresult and sets *stoppos to the last byte written.
742 : * On any other sort of error, returns NULL.
743 : */
744 : static PGresult *
745 0 : HandleCopyStream(PGconn *conn, StreamCtl *stream,
746 : XLogRecPtr *stoppos)
747 : {
748 0 : char *copybuf = NULL;
749 0 : TimestampTz last_status = -1;
750 0 : XLogRecPtr blockpos = stream->startpos;
751 :
752 0 : still_sending = true;
753 :
754 0 : while (1)
755 : {
756 0 : int r;
757 0 : TimestampTz now;
758 0 : long sleeptime;
759 :
760 : /*
761 : * Check if we should continue streaming, or abort at this point.
762 : */
763 0 : if (!CheckCopyStreamStop(conn, stream, blockpos))
764 0 : goto error;
765 :
766 0 : now = feGetCurrentTimestamp();
767 :
768 : /*
769 : * If synchronous option is true, issue sync command as soon as there
770 : * are WAL data which has not been flushed yet.
771 : */
772 0 : if (stream->synchronous && lastFlushPosition < blockpos && walfile != NULL)
773 : {
774 0 : if (stream->walmethod->ops->sync(walfile) != 0)
775 0 : pg_fatal("could not fsync file \"%s\": %s",
776 : walfile->pathname, GetLastWalMethodError(stream->walmethod));
777 0 : lastFlushPosition = blockpos;
778 :
779 : /*
780 : * Send feedback so that the server sees the latest WAL locations
781 : * immediately.
782 : */
783 0 : if (!sendFeedback(conn, blockpos, now, false))
784 0 : goto error;
785 0 : last_status = now;
786 0 : }
787 :
788 : /*
789 : * Potentially send a status message to the primary
790 : */
791 0 : if (still_sending && stream->standby_message_timeout > 0 &&
792 0 : feTimestampDifferenceExceeds(last_status, now,
793 0 : stream->standby_message_timeout))
794 : {
795 : /* Time to send feedback! */
796 0 : if (!sendFeedback(conn, blockpos, now, false))
797 0 : goto error;
798 0 : last_status = now;
799 0 : }
800 :
801 : /*
802 : * Calculate how long send/receive loops should sleep
803 : */
804 0 : sleeptime = CalculateCopyStreamSleeptime(now, stream->standby_message_timeout,
805 0 : last_status);
806 :
807 : /* Done with any prior message */
808 0 : PQfreemem(copybuf);
809 0 : copybuf = NULL;
810 :
811 0 : r = CopyStreamReceive(conn, sleeptime, stream->stop_socket, ©buf);
812 0 : while (r != 0)
813 : {
814 0 : if (r == -1)
815 0 : goto error;
816 0 : if (r == -2)
817 : {
818 0 : PGresult *res = HandleEndOfCopyStream(conn, stream, copybuf, blockpos, stoppos);
819 :
820 0 : if (res == NULL)
821 0 : goto error;
822 0 : PQfreemem(copybuf);
823 0 : return res;
824 0 : }
825 :
826 : /* Check the message type. */
827 0 : if (copybuf[0] == PqReplMsg_Keepalive)
828 : {
829 0 : if (!ProcessKeepaliveMsg(conn, stream, copybuf, r, blockpos,
830 : &last_status))
831 0 : goto error;
832 0 : }
833 0 : else if (copybuf[0] == PqReplMsg_WALData)
834 : {
835 0 : if (!ProcessWALDataMsg(conn, stream, copybuf, r, &blockpos))
836 0 : goto error;
837 :
838 : /*
839 : * Check if we should continue streaming, or abort at this
840 : * point.
841 : */
842 0 : if (!CheckCopyStreamStop(conn, stream, blockpos))
843 0 : goto error;
844 0 : }
845 : else
846 : {
847 0 : pg_log_error("unrecognized streaming header: \"%c\"",
848 : copybuf[0]);
849 0 : goto error;
850 : }
851 :
852 : /* Done with that message */
853 0 : PQfreemem(copybuf);
854 0 : copybuf = NULL;
855 :
856 : /*
857 : * Process the received data, and any subsequent data we can read
858 : * without blocking.
859 : */
860 0 : r = CopyStreamReceive(conn, 0, stream->stop_socket, ©buf);
861 : }
862 0 : }
863 :
864 : error:
865 0 : PQfreemem(copybuf);
866 0 : return NULL;
867 0 : }
868 :
869 : /*
870 : * Wait until we can read a CopyData message,
871 : * or timeout, or occurrence of a signal or input on the stop_socket.
872 : * (timeout_ms < 0 means wait indefinitely; 0 means don't wait.)
873 : *
874 : * Returns 1 if data has become available for reading, 0 if timed out
875 : * or interrupted by signal or stop_socket input, and -1 on an error.
876 : */
877 : static int
878 0 : CopyStreamPoll(PGconn *conn, long timeout_ms, pgsocket stop_socket)
879 : {
880 0 : int ret;
881 0 : fd_set input_mask;
882 0 : int connsocket;
883 0 : int maxfd;
884 0 : struct timeval timeout;
885 0 : struct timeval *timeoutptr;
886 :
887 0 : connsocket = PQsocket(conn);
888 0 : if (connsocket < 0)
889 : {
890 0 : pg_log_error("invalid socket: %s", PQerrorMessage(conn));
891 0 : return -1;
892 : }
893 :
894 0 : FD_ZERO(&input_mask);
895 0 : FD_SET(connsocket, &input_mask);
896 0 : maxfd = connsocket;
897 0 : if (stop_socket != PGINVALID_SOCKET)
898 : {
899 0 : FD_SET(stop_socket, &input_mask);
900 0 : maxfd = Max(maxfd, stop_socket);
901 0 : }
902 :
903 0 : if (timeout_ms < 0)
904 0 : timeoutptr = NULL;
905 : else
906 : {
907 0 : timeout.tv_sec = timeout_ms / 1000L;
908 0 : timeout.tv_usec = (timeout_ms % 1000L) * 1000L;
909 0 : timeoutptr = &timeout;
910 : }
911 :
912 0 : ret = select(maxfd + 1, &input_mask, NULL, NULL, timeoutptr);
913 :
914 0 : if (ret < 0)
915 : {
916 0 : if (errno == EINTR)
917 0 : return 0; /* Got a signal, so not an error */
918 0 : pg_log_error("%s() failed: %m", "select");
919 0 : return -1;
920 : }
921 0 : if (ret > 0 && FD_ISSET(connsocket, &input_mask))
922 0 : return 1; /* Got input on connection socket */
923 :
924 0 : return 0; /* Got timeout or input on stop_socket */
925 0 : }
926 :
927 : /*
928 : * Receive CopyData message available from XLOG stream, blocking for
929 : * maximum of 'timeout' ms.
930 : *
931 : * If data was received, returns the length of the data. *buffer is set to
932 : * point to a buffer holding the received message. The caller must eventually
933 : * free the buffer with PQfreemem().
934 : *
935 : * Returns 0 if no data was available within timeout, or if wait was
936 : * interrupted by signal or stop_socket input.
937 : * -1 on error. -2 if the server ended the COPY.
938 : */
939 : static int
940 0 : CopyStreamReceive(PGconn *conn, long timeout, pgsocket stop_socket,
941 : char **buffer)
942 : {
943 0 : char *copybuf = NULL;
944 0 : int rawlen;
945 :
946 : /* Caller should have cleared any prior buffer */
947 0 : Assert(*buffer == NULL);
948 :
949 : /* Try to receive a CopyData message */
950 0 : rawlen = PQgetCopyData(conn, ©buf, 1);
951 0 : if (rawlen == 0)
952 : {
953 0 : int ret;
954 :
955 : /*
956 : * No data available. Wait for some to appear, but not longer than
957 : * the specified timeout, so that we can ping the server. Also stop
958 : * waiting if input appears on stop_socket.
959 : */
960 0 : ret = CopyStreamPoll(conn, timeout, stop_socket);
961 0 : if (ret <= 0)
962 0 : return ret;
963 :
964 : /* Now there is actually data on the socket */
965 0 : if (PQconsumeInput(conn) == 0)
966 : {
967 0 : pg_log_error("could not receive data from WAL stream: %s",
968 : PQerrorMessage(conn));
969 0 : return -1;
970 : }
971 :
972 : /* Now that we've consumed some input, try again */
973 0 : rawlen = PQgetCopyData(conn, ©buf, 1);
974 0 : if (rawlen == 0)
975 0 : return 0;
976 0 : }
977 0 : if (rawlen == -1) /* end-of-streaming or error */
978 0 : return -2;
979 0 : if (rawlen == -2)
980 : {
981 0 : pg_log_error("could not read COPY data: %s", PQerrorMessage(conn));
982 0 : return -1;
983 : }
984 :
985 : /* Return received messages to caller */
986 0 : *buffer = copybuf;
987 0 : return rawlen;
988 0 : }
989 :
990 : /*
991 : * Process the keepalive message.
992 : */
993 : static bool
994 0 : ProcessKeepaliveMsg(PGconn *conn, StreamCtl *stream, char *copybuf, int len,
995 : XLogRecPtr blockpos, TimestampTz *last_status)
996 : {
997 0 : int pos;
998 0 : bool replyRequested;
999 0 : TimestampTz now;
1000 :
1001 : /*
1002 : * Parse the keepalive message, enclosed in the CopyData message. We just
1003 : * check if the server requested a reply, and ignore the rest.
1004 : */
1005 0 : pos = 1; /* skip msgtype PqReplMsg_Keepalive */
1006 0 : pos += 8; /* skip walEnd */
1007 0 : pos += 8; /* skip sendTime */
1008 :
1009 0 : if (len < pos + 1)
1010 : {
1011 0 : pg_log_error("streaming header too small: %d", len);
1012 0 : return false;
1013 : }
1014 0 : replyRequested = copybuf[pos];
1015 :
1016 : /* If the server requested an immediate reply, send one. */
1017 0 : if (replyRequested && still_sending)
1018 : {
1019 0 : if (reportFlushPosition && lastFlushPosition < blockpos &&
1020 0 : walfile != NULL)
1021 : {
1022 : /*
1023 : * If a valid flush location needs to be reported, flush the
1024 : * current WAL file so that the latest flush location is sent back
1025 : * to the server. This is necessary to see whether the last WAL
1026 : * data has been successfully replicated or not, at the normal
1027 : * shutdown of the server.
1028 : */
1029 0 : if (stream->walmethod->ops->sync(walfile) != 0)
1030 0 : pg_fatal("could not fsync file \"%s\": %s",
1031 : walfile->pathname, GetLastWalMethodError(stream->walmethod));
1032 0 : lastFlushPosition = blockpos;
1033 0 : }
1034 :
1035 0 : now = feGetCurrentTimestamp();
1036 0 : if (!sendFeedback(conn, blockpos, now, false))
1037 0 : return false;
1038 0 : *last_status = now;
1039 0 : }
1040 :
1041 0 : return true;
1042 0 : }
1043 :
1044 : /*
1045 : * Process WALData message.
1046 : */
1047 : static bool
1048 0 : ProcessWALDataMsg(PGconn *conn, StreamCtl *stream, char *copybuf, int len,
1049 : XLogRecPtr *blockpos)
1050 : {
1051 0 : int xlogoff;
1052 0 : int bytes_left;
1053 0 : int bytes_written;
1054 0 : int hdr_len;
1055 :
1056 : /*
1057 : * Once we've decided we don't want to receive any more, just ignore any
1058 : * subsequent WALData messages.
1059 : */
1060 0 : if (!(still_sending))
1061 0 : return true;
1062 :
1063 : /*
1064 : * Read the header of the WALData message, enclosed in the CopyData
1065 : * message. We only need the WAL location field (dataStart), the rest of
1066 : * the header is ignored.
1067 : */
1068 0 : hdr_len = 1; /* msgtype PqReplMsg_WALData */
1069 0 : hdr_len += 8; /* dataStart */
1070 0 : hdr_len += 8; /* walEnd */
1071 0 : hdr_len += 8; /* sendTime */
1072 0 : if (len < hdr_len)
1073 : {
1074 0 : pg_log_error("streaming header too small: %d", len);
1075 0 : return false;
1076 : }
1077 0 : *blockpos = fe_recvint64(©buf[1]);
1078 :
1079 : /* Extract WAL location for this block */
1080 0 : xlogoff = XLogSegmentOffset(*blockpos, WalSegSz);
1081 :
1082 : /*
1083 : * Verify that the initial location in the stream matches where we think
1084 : * we are.
1085 : */
1086 0 : if (walfile == NULL)
1087 : {
1088 : /* No file open yet */
1089 0 : if (xlogoff != 0)
1090 : {
1091 0 : pg_log_error("received write-ahead log record for offset %u with no file open",
1092 : xlogoff);
1093 0 : return false;
1094 : }
1095 0 : }
1096 : else
1097 : {
1098 : /* More data in existing segment */
1099 0 : if (walfile->currpos != xlogoff)
1100 : {
1101 0 : pg_log_error("got WAL data offset %08x, expected %08x",
1102 : xlogoff, (int) walfile->currpos);
1103 0 : return false;
1104 : }
1105 : }
1106 :
1107 0 : bytes_left = len - hdr_len;
1108 0 : bytes_written = 0;
1109 :
1110 0 : while (bytes_left)
1111 : {
1112 0 : int bytes_to_write;
1113 :
1114 : /*
1115 : * If crossing a WAL boundary, only write up until we reach wal
1116 : * segment size.
1117 : */
1118 0 : if (xlogoff + bytes_left > WalSegSz)
1119 0 : bytes_to_write = WalSegSz - xlogoff;
1120 : else
1121 0 : bytes_to_write = bytes_left;
1122 :
1123 0 : if (walfile == NULL)
1124 : {
1125 0 : if (!open_walfile(stream, *blockpos))
1126 : {
1127 : /* Error logged by open_walfile */
1128 0 : return false;
1129 : }
1130 0 : }
1131 :
1132 0 : if (stream->walmethod->ops->write(walfile,
1133 0 : copybuf + hdr_len + bytes_written,
1134 0 : bytes_to_write) != bytes_to_write)
1135 : {
1136 0 : pg_log_error("could not write %d bytes to WAL file \"%s\": %s",
1137 : bytes_to_write, walfile->pathname,
1138 : GetLastWalMethodError(stream->walmethod));
1139 0 : return false;
1140 : }
1141 :
1142 : /* Write was successful, advance our position */
1143 0 : bytes_written += bytes_to_write;
1144 0 : bytes_left -= bytes_to_write;
1145 0 : *blockpos += bytes_to_write;
1146 0 : xlogoff += bytes_to_write;
1147 :
1148 : /* Did we reach the end of a WAL segment? */
1149 0 : if (XLogSegmentOffset(*blockpos, WalSegSz) == 0)
1150 : {
1151 0 : if (!close_walfile(stream, *blockpos))
1152 : /* Error message written in close_walfile() */
1153 0 : return false;
1154 :
1155 0 : xlogoff = 0;
1156 :
1157 0 : if (still_sending && stream->stream_stop(*blockpos, stream->timeline, true))
1158 : {
1159 0 : if (PQputCopyEnd(conn, NULL) <= 0 || PQflush(conn))
1160 : {
1161 0 : pg_log_error("could not send copy-end packet: %s",
1162 : PQerrorMessage(conn));
1163 0 : return false;
1164 : }
1165 0 : still_sending = false;
1166 0 : return true; /* ignore the rest of this WALData packet */
1167 : }
1168 0 : }
1169 0 : }
1170 : /* No more data left to write, receive next copy packet */
1171 :
1172 0 : return true;
1173 0 : }
1174 :
1175 : /*
1176 : * Handle end of the copy stream.
1177 : */
1178 : static PGresult *
1179 0 : HandleEndOfCopyStream(PGconn *conn, StreamCtl *stream, char *copybuf,
1180 : XLogRecPtr blockpos, XLogRecPtr *stoppos)
1181 : {
1182 0 : PGresult *res = PQgetResult(conn);
1183 :
1184 : /*
1185 : * The server closed its end of the copy stream. If we haven't closed
1186 : * ours already, we need to do so now, unless the server threw an error,
1187 : * in which case we don't.
1188 : */
1189 0 : if (still_sending)
1190 : {
1191 0 : if (!close_walfile(stream, blockpos))
1192 : {
1193 : /* Error message written in close_walfile() */
1194 0 : PQclear(res);
1195 0 : return NULL;
1196 : }
1197 0 : if (PQresultStatus(res) == PGRES_COPY_IN)
1198 : {
1199 0 : if (PQputCopyEnd(conn, NULL) <= 0 || PQflush(conn))
1200 : {
1201 0 : pg_log_error("could not send copy-end packet: %s",
1202 : PQerrorMessage(conn));
1203 0 : PQclear(res);
1204 0 : return NULL;
1205 : }
1206 0 : res = PQgetResult(conn);
1207 0 : }
1208 0 : still_sending = false;
1209 0 : }
1210 0 : *stoppos = blockpos;
1211 0 : return res;
1212 0 : }
1213 :
1214 : /*
1215 : * Check if we should continue streaming, or abort at this point.
1216 : */
1217 : static bool
1218 0 : CheckCopyStreamStop(PGconn *conn, StreamCtl *stream, XLogRecPtr blockpos)
1219 : {
1220 0 : if (still_sending && stream->stream_stop(blockpos, stream->timeline, false))
1221 : {
1222 0 : if (!close_walfile(stream, blockpos))
1223 : {
1224 : /* Potential error message is written by close_walfile */
1225 0 : return false;
1226 : }
1227 0 : if (PQputCopyEnd(conn, NULL) <= 0 || PQflush(conn))
1228 : {
1229 0 : pg_log_error("could not send copy-end packet: %s",
1230 : PQerrorMessage(conn));
1231 0 : return false;
1232 : }
1233 0 : still_sending = false;
1234 0 : }
1235 :
1236 0 : return true;
1237 0 : }
1238 :
1239 : /*
1240 : * Calculate how long send/receive loops should sleep
1241 : */
1242 : static long
1243 0 : CalculateCopyStreamSleeptime(TimestampTz now, int standby_message_timeout,
1244 : TimestampTz last_status)
1245 : {
1246 0 : TimestampTz status_targettime = 0;
1247 0 : long sleeptime;
1248 :
1249 0 : if (standby_message_timeout && still_sending)
1250 0 : status_targettime = last_status +
1251 0 : (standby_message_timeout - 1) * ((int64) 1000);
1252 :
1253 0 : if (status_targettime > 0)
1254 : {
1255 0 : long secs;
1256 0 : int usecs;
1257 :
1258 0 : feTimestampDifference(now,
1259 0 : status_targettime,
1260 : &secs,
1261 : &usecs);
1262 : /* Always sleep at least 1 sec */
1263 0 : if (secs <= 0)
1264 : {
1265 0 : secs = 1;
1266 0 : usecs = 0;
1267 0 : }
1268 :
1269 0 : sleeptime = secs * 1000 + usecs / 1000;
1270 0 : }
1271 : else
1272 0 : sleeptime = -1;
1273 :
1274 0 : return sleeptime;
1275 0 : }
|
