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sync.c
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1 /*-------------------------------------------------------------------------
2  *
3  * sync.c
4  * File synchronization management code.
5  *
6  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
7  * Portions Copyright (c) 1994, Regents of the University of California
8  *
9  *
10  * IDENTIFICATION
11  * src/backend/storage/sync/sync.c
12  *
13  *-------------------------------------------------------------------------
14  */
15 #include "postgres.h"
16 
17 #include <unistd.h>
18 #include <fcntl.h>
19 #include <sys/file.h>
20 
21 #include "access/clog.h"
22 #include "access/commit_ts.h"
23 #include "access/multixact.h"
24 #include "access/xlog.h"
25 #include "miscadmin.h"
26 #include "pgstat.h"
27 #include "portability/instr_time.h"
28 #include "postmaster/bgwriter.h"
29 #include "storage/fd.h"
30 #include "storage/latch.h"
31 #include "storage/md.h"
32 #include "utils/hsearch.h"
33 #include "utils/memutils.h"
34 
35 /*
36  * In some contexts (currently, standalone backends and the checkpointer)
37  * we keep track of pending fsync operations: we need to remember all relation
38  * segments that have been written since the last checkpoint, so that we can
39  * fsync them down to disk before completing the next checkpoint. This hash
40  * table remembers the pending operations. We use a hash table mostly as
41  * a convenient way of merging duplicate requests.
42  *
43  * We use a similar mechanism to remember no-longer-needed files that can
44  * be deleted after the next checkpoint, but we use a linked list instead of
45  * a hash table, because we don't expect there to be any duplicate requests.
46  *
47  * These mechanisms are only used for non-temp relations; we never fsync
48  * temp rels, nor do we need to postpone their deletion (see comments in
49  * mdunlink).
50  *
51  * (Regular backends do not track pending operations locally, but forward
52  * them to the checkpointer.)
53  */
54 typedef uint16 CycleCtr; /* can be any convenient integer size */
55 
56 typedef struct
57 {
58  FileTag tag; /* identifies handler and file */
59  CycleCtr cycle_ctr; /* sync_cycle_ctr of oldest request */
60  bool canceled; /* canceled is true if we canceled "recently" */
62 
63 typedef struct
64 {
65  FileTag tag; /* identifies handler and file */
66  CycleCtr cycle_ctr; /* checkpoint_cycle_ctr when request was made */
67  bool canceled; /* true if request has been canceled */
69 
70 static HTAB *pendingOps = NULL;
72 static MemoryContext pendingOpsCxt; /* context for the above */
73 
76 
77 /* Intervals for calling AbsorbSyncRequests */
78 #define FSYNCS_PER_ABSORB 10
79 #define UNLINKS_PER_ABSORB 10
80 
81 /*
82  * Function pointers for handling sync and unlink requests.
83  */
84 typedef struct SyncOps
85 {
86  int (*sync_syncfiletag) (const FileTag *ftag, char *path);
87  int (*sync_unlinkfiletag) (const FileTag *ftag, char *path);
88  bool (*sync_filetagmatches) (const FileTag *ftag,
89  const FileTag *candidate);
91 
92 /*
93  * These indexes must correspond to the values of the SyncRequestHandler enum.
94  */
95 static const SyncOps syncsw[] = {
96  /* magnetic disk */
97  [SYNC_HANDLER_MD] = {
99  .sync_unlinkfiletag = mdunlinkfiletag,
100  .sync_filetagmatches = mdfiletagmatches
101  },
102  /* pg_xact */
103  [SYNC_HANDLER_CLOG] = {
104  .sync_syncfiletag = clogsyncfiletag
105  },
106  /* pg_commit_ts */
108  .sync_syncfiletag = committssyncfiletag
109  },
110  /* pg_multixact/offsets */
112  .sync_syncfiletag = multixactoffsetssyncfiletag
113  },
114  /* pg_multixact/members */
116  .sync_syncfiletag = multixactmemberssyncfiletag
117  }
118 };
119 
120 /*
121  * Initialize data structures for the file sync tracking.
122  */
123 void
124 InitSync(void)
125 {
126  /*
127  * Create pending-operations hashtable if we need it. Currently, we need
128  * it if we are standalone (not under a postmaster) or if we are a
129  * checkpointer auxiliary process.
130  */
132  {
133  HASHCTL hash_ctl;
134 
135  /*
136  * XXX: The checkpointer needs to add entries to the pending ops table
137  * when absorbing fsync requests. That is done within a critical
138  * section, which isn't usually allowed, but we make an exception. It
139  * means that there's a theoretical possibility that you run out of
140  * memory while absorbing fsync requests, which leads to a PANIC.
141  * Fortunately the hash table is small so that's unlikely to happen in
142  * practice.
143  */
145  "Pending ops context",
148 
149  hash_ctl.keysize = sizeof(FileTag);
150  hash_ctl.entrysize = sizeof(PendingFsyncEntry);
151  hash_ctl.hcxt = pendingOpsCxt;
152  pendingOps = hash_create("Pending Ops Table",
153  100L,
154  &hash_ctl,
157  }
158 }
159 
160 /*
161  * SyncPreCheckpoint() -- Do pre-checkpoint work
162  *
163  * To distinguish unlink requests that arrived before this checkpoint
164  * started from those that arrived during the checkpoint, we use a cycle
165  * counter similar to the one we use for fsync requests. That cycle
166  * counter is incremented here.
167  *
168  * This must be called *before* the checkpoint REDO point is determined.
169  * That ensures that we won't delete files too soon. Since this calls
170  * AbsorbSyncRequests(), which performs memory allocations, it cannot be
171  * called within a critical section.
172  *
173  * Note that we can't do anything here that depends on the assumption
174  * that the checkpoint will be completed.
175  */
176 void
178 {
179  /*
180  * Operations such as DROP TABLESPACE assume that the next checkpoint will
181  * process all recently forwarded unlink requests, but if they aren't
182  * absorbed prior to advancing the cycle counter, they won't be processed
183  * until a future checkpoint. The following absorb ensures that any
184  * unlink requests forwarded before the checkpoint began will be processed
185  * in the current checkpoint.
186  */
188 
189  /*
190  * Any unlink requests arriving after this point will be assigned the next
191  * cycle counter, and won't be unlinked until next checkpoint.
192  */
194 }
195 
196 /*
197  * SyncPostCheckpoint() -- Do post-checkpoint work
198  *
199  * Remove any lingering files that can now be safely removed.
200  */
201 void
203 {
204  int absorb_counter;
205  ListCell *lc;
206 
207  absorb_counter = UNLINKS_PER_ABSORB;
208  foreach(lc, pendingUnlinks)
209  {
211  char path[MAXPGPATH];
212 
213  /* Skip over any canceled entries */
214  if (entry->canceled)
215  continue;
216 
217  /*
218  * New entries are appended to the end, so if the entry is new we've
219  * reached the end of old entries.
220  *
221  * Note: if just the right number of consecutive checkpoints fail, we
222  * could be fooled here by cycle_ctr wraparound. However, the only
223  * consequence is that we'd delay unlinking for one more checkpoint,
224  * which is perfectly tolerable.
225  */
226  if (entry->cycle_ctr == checkpoint_cycle_ctr)
227  break;
228 
229  /* Unlink the file */
230  if (syncsw[entry->tag.handler].sync_unlinkfiletag(&entry->tag,
231  path) < 0)
232  {
233  /*
234  * There's a race condition, when the database is dropped at the
235  * same time that we process the pending unlink requests. If the
236  * DROP DATABASE deletes the file before we do, we will get ENOENT
237  * here. rmtree() also has to ignore ENOENT errors, to deal with
238  * the possibility that we delete the file first.
239  */
240  if (errno != ENOENT)
243  errmsg("could not remove file \"%s\": %m", path)));
244  }
245 
246  /* Mark the list entry as canceled, just in case */
247  entry->canceled = true;
248 
249  /*
250  * As in ProcessSyncRequests, we don't want to stop absorbing fsync
251  * requests for a long time when there are many deletions to be done.
252  * We can safely call AbsorbSyncRequests() at this point in the loop.
253  */
254  if (--absorb_counter <= 0)
255  {
257  absorb_counter = UNLINKS_PER_ABSORB;
258  }
259  }
260 
261  /*
262  * If we reached the end of the list, we can just remove the whole list
263  * (remembering to pfree all the PendingUnlinkEntry objects). Otherwise,
264  * we must keep the entries at or after "lc".
265  */
266  if (lc == NULL)
267  {
270  }
271  else
272  {
273  int ntodelete = list_cell_number(pendingUnlinks, lc);
274 
275  for (int i = 0; i < ntodelete; i++)
277 
279  }
280 }
281 
282 /*
283  * ProcessSyncRequests() -- Process queued fsync requests.
284  */
285 void
287 {
288  static bool sync_in_progress = false;
289 
290  HASH_SEQ_STATUS hstat;
291  PendingFsyncEntry *entry;
292  int absorb_counter;
293 
294  /* Statistics on sync times */
295  int processed = 0;
296  instr_time sync_start,
297  sync_end,
298  sync_diff;
299  uint64 elapsed;
300  uint64 longest = 0;
301  uint64 total_elapsed = 0;
302 
303  /*
304  * This is only called during checkpoints, and checkpoints should only
305  * occur in processes that have created a pendingOps.
306  */
307  if (!pendingOps)
308  elog(ERROR, "cannot sync without a pendingOps table");
309 
310  /*
311  * If we are in the checkpointer, the sync had better include all fsync
312  * requests that were queued by backends up to this point. The tightest
313  * race condition that could occur is that a buffer that must be written
314  * and fsync'd for the checkpoint could have been dumped by a backend just
315  * before it was visited by BufferSync(). We know the backend will have
316  * queued an fsync request before clearing the buffer's dirtybit, so we
317  * are safe as long as we do an Absorb after completing BufferSync().
318  */
320 
321  /*
322  * To avoid excess fsync'ing (in the worst case, maybe a never-terminating
323  * checkpoint), we want to ignore fsync requests that are entered into the
324  * hashtable after this point --- they should be processed next time,
325  * instead. We use sync_cycle_ctr to tell old entries apart from new
326  * ones: new ones will have cycle_ctr equal to the incremented value of
327  * sync_cycle_ctr.
328  *
329  * In normal circumstances, all entries present in the table at this point
330  * will have cycle_ctr exactly equal to the current (about to be old)
331  * value of sync_cycle_ctr. However, if we fail partway through the
332  * fsync'ing loop, then older values of cycle_ctr might remain when we
333  * come back here to try again. Repeated checkpoint failures would
334  * eventually wrap the counter around to the point where an old entry
335  * might appear new, causing us to skip it, possibly allowing a checkpoint
336  * to succeed that should not have. To forestall wraparound, any time the
337  * previous ProcessSyncRequests() failed to complete, run through the
338  * table and forcibly set cycle_ctr = sync_cycle_ctr.
339  *
340  * Think not to merge this loop with the main loop, as the problem is
341  * exactly that that loop may fail before having visited all the entries.
342  * From a performance point of view it doesn't matter anyway, as this path
343  * will never be taken in a system that's functioning normally.
344  */
345  if (sync_in_progress)
346  {
347  /* prior try failed, so update any stale cycle_ctr values */
348  hash_seq_init(&hstat, pendingOps);
349  while ((entry = (PendingFsyncEntry *) hash_seq_search(&hstat)) != NULL)
350  {
351  entry->cycle_ctr = sync_cycle_ctr;
352  }
353  }
354 
355  /* Advance counter so that new hashtable entries are distinguishable */
356  sync_cycle_ctr++;
357 
358  /* Set flag to detect failure if we don't reach the end of the loop */
359  sync_in_progress = true;
360 
361  /* Now scan the hashtable for fsync requests to process */
362  absorb_counter = FSYNCS_PER_ABSORB;
363  hash_seq_init(&hstat, pendingOps);
364  while ((entry = (PendingFsyncEntry *) hash_seq_search(&hstat)) != NULL)
365  {
366  int failures;
367 
368  /*
369  * If the entry is new then don't process it this time; it is new.
370  * Note "continue" bypasses the hash-remove call at the bottom of the
371  * loop.
372  */
373  if (entry->cycle_ctr == sync_cycle_ctr)
374  continue;
375 
376  /* Else assert we haven't missed it */
377  Assert((CycleCtr) (entry->cycle_ctr + 1) == sync_cycle_ctr);
378 
379  /*
380  * If fsync is off then we don't have to bother opening the file at
381  * all. (We delay checking until this point so that changing fsync on
382  * the fly behaves sensibly.)
383  */
384  if (enableFsync)
385  {
386  /*
387  * If in checkpointer, we want to absorb pending requests every so
388  * often to prevent overflow of the fsync request queue. It is
389  * unspecified whether newly-added entries will be visited by
390  * hash_seq_search, but we don't care since we don't need to
391  * process them anyway.
392  */
393  if (--absorb_counter <= 0)
394  {
396  absorb_counter = FSYNCS_PER_ABSORB;
397  }
398 
399  /*
400  * The fsync table could contain requests to fsync segments that
401  * have been deleted (unlinked) by the time we get to them. Rather
402  * than just hoping an ENOENT (or EACCES on Windows) error can be
403  * ignored, what we do on error is absorb pending requests and
404  * then retry. Since mdunlink() queues a "cancel" message before
405  * actually unlinking, the fsync request is guaranteed to be
406  * marked canceled after the absorb if it really was this case.
407  * DROP DATABASE likewise has to tell us to forget fsync requests
408  * before it starts deletions.
409  */
410  for (failures = 0; !entry->canceled; failures++)
411  {
412  char path[MAXPGPATH];
413 
414  INSTR_TIME_SET_CURRENT(sync_start);
415  if (syncsw[entry->tag.handler].sync_syncfiletag(&entry->tag,
416  path) == 0)
417  {
418  /* Success; update statistics about sync timing */
419  INSTR_TIME_SET_CURRENT(sync_end);
420  sync_diff = sync_end;
421  INSTR_TIME_SUBTRACT(sync_diff, sync_start);
422  elapsed = INSTR_TIME_GET_MICROSEC(sync_diff);
423  if (elapsed > longest)
424  longest = elapsed;
425  total_elapsed += elapsed;
426  processed++;
427 
428  if (log_checkpoints)
429  elog(DEBUG1, "checkpoint sync: number=%d file=%s time=%.3f ms",
430  processed,
431  path,
432  (double) elapsed / 1000);
433 
434  break; /* out of retry loop */
435  }
436 
437  /*
438  * It is possible that the relation has been dropped or
439  * truncated since the fsync request was entered. Therefore,
440  * allow ENOENT, but only if we didn't fail already on this
441  * file.
442  */
443  if (!FILE_POSSIBLY_DELETED(errno) || failures > 0)
446  errmsg("could not fsync file \"%s\": %m",
447  path)));
448  else
449  ereport(DEBUG1,
451  errmsg_internal("could not fsync file \"%s\" but retrying: %m",
452  path)));
453 
454  /*
455  * Absorb incoming requests and check to see if a cancel
456  * arrived for this relation fork.
457  */
459  absorb_counter = FSYNCS_PER_ABSORB; /* might as well... */
460  } /* end retry loop */
461  }
462 
463  /* We are done with this entry, remove it */
464  if (hash_search(pendingOps, &entry->tag, HASH_REMOVE, NULL) == NULL)
465  elog(ERROR, "pendingOps corrupted");
466  } /* end loop over hashtable entries */
467 
468  /* Return sync performance metrics for report at checkpoint end */
469  CheckpointStats.ckpt_sync_rels = processed;
471  CheckpointStats.ckpt_agg_sync_time = total_elapsed;
472 
473  /* Flag successful completion of ProcessSyncRequests */
474  sync_in_progress = false;
475 }
476 
477 /*
478  * RememberSyncRequest() -- callback from checkpointer side of sync request
479  *
480  * We stuff fsync requests into the local hash table for execution
481  * during the checkpointer's next checkpoint. UNLINK requests go into a
482  * separate linked list, however, because they get processed separately.
483  *
484  * See sync.h for more information on the types of sync requests supported.
485  */
486 void
488 {
490 
491  if (type == SYNC_FORGET_REQUEST)
492  {
493  PendingFsyncEntry *entry;
494 
495  /* Cancel previously entered request */
497  ftag,
498  HASH_FIND,
499  NULL);
500  if (entry != NULL)
501  entry->canceled = true;
502  }
503  else if (type == SYNC_FILTER_REQUEST)
504  {
505  HASH_SEQ_STATUS hstat;
506  PendingFsyncEntry *pfe;
507  ListCell *cell;
508 
509  /* Cancel matching fsync requests */
510  hash_seq_init(&hstat, pendingOps);
511  while ((pfe = (PendingFsyncEntry *) hash_seq_search(&hstat)) != NULL)
512  {
513  if (pfe->tag.handler == ftag->handler &&
514  syncsw[ftag->handler].sync_filetagmatches(ftag, &pfe->tag))
515  pfe->canceled = true;
516  }
517 
518  /* Cancel matching unlink requests */
519  foreach(cell, pendingUnlinks)
520  {
522 
523  if (pue->tag.handler == ftag->handler &&
524  syncsw[ftag->handler].sync_filetagmatches(ftag, &pue->tag))
525  pue->canceled = true;
526  }
527  }
528  else if (type == SYNC_UNLINK_REQUEST)
529  {
530  /* Unlink request: put it in the linked list */
532  PendingUnlinkEntry *entry;
533 
534  entry = palloc(sizeof(PendingUnlinkEntry));
535  entry->tag = *ftag;
537  entry->canceled = false;
538 
540 
541  MemoryContextSwitchTo(oldcxt);
542  }
543  else
544  {
545  /* Normal case: enter a request to fsync this segment */
547  PendingFsyncEntry *entry;
548  bool found;
549 
551 
553  ftag,
554  HASH_ENTER,
555  &found);
556  /* if new entry, or was previously canceled, initialize it */
557  if (!found || entry->canceled)
558  {
559  entry->cycle_ctr = sync_cycle_ctr;
560  entry->canceled = false;
561  }
562 
563  /*
564  * NB: it's intentional that we don't change cycle_ctr if the entry
565  * already exists. The cycle_ctr must represent the oldest fsync
566  * request that could be in the entry.
567  */
568 
569  MemoryContextSwitchTo(oldcxt);
570  }
571 }
572 
573 /*
574  * Register the sync request locally, or forward it to the checkpointer.
575  *
576  * If retryOnError is true, we'll keep trying if there is no space in the
577  * queue. Return true if we succeeded, or false if there wasn't space.
578  */
579 bool
581  bool retryOnError)
582 {
583  bool ret;
584 
585  if (pendingOps != NULL)
586  {
587  /* standalone backend or startup process: fsync state is local */
588  RememberSyncRequest(ftag, type);
589  return true;
590  }
591 
592  for (;;)
593  {
594  /*
595  * Notify the checkpointer about it. If we fail to queue a message in
596  * retryOnError mode, we have to sleep and try again ... ugly, but
597  * hopefully won't happen often.
598  *
599  * XXX should we CHECK_FOR_INTERRUPTS in this loop? Escaping with an
600  * error in the case of SYNC_UNLINK_REQUEST would leave the
601  * no-longer-used file still present on disk, which would be bad, so
602  * I'm inclined to assume that the checkpointer will always empty the
603  * queue soon.
604  */
605  ret = ForwardSyncRequest(ftag, type);
606 
607  /*
608  * If we are successful in queueing the request, or we failed and were
609  * instructed not to retry on error, break.
610  */
611  if (ret || (!ret && !retryOnError))
612  break;
613 
615  WAIT_EVENT_REGISTER_SYNC_REQUEST);
616  }
617 
618  return ret;
619 }
unsigned short uint16
Definition: c.h:505
#define Assert(condition)
Definition: c.h:858
unsigned char bool
Definition: c.h:456
bool ForwardSyncRequest(const FileTag *ftag, SyncRequestType type)
void AbsorbSyncRequests(void)
int clogsyncfiletag(const FileTag *ftag, char *path)
Definition: clog.c:1149
int committssyncfiletag(const FileTag *ftag, char *path)
Definition: commit_ts.c:1063
void * hash_search(HTAB *hashp, const void *keyPtr, HASHACTION action, bool *foundPtr)
Definition: dynahash.c:955
HTAB * hash_create(const char *tabname, long nelem, const HASHCTL *info, int flags)
Definition: dynahash.c:352
void * hash_seq_search(HASH_SEQ_STATUS *status)
Definition: dynahash.c:1395
void hash_seq_init(HASH_SEQ_STATUS *status, HTAB *hashp)
Definition: dynahash.c:1385
int errmsg_internal(const char *fmt,...)
Definition: elog.c:1157
int errcode_for_file_access(void)
Definition: elog.c:880
int errmsg(const char *fmt,...)
Definition: elog.c:1070
#define WARNING
Definition: elog.h:36
#define DEBUG1
Definition: elog.h:30
#define ERROR
Definition: elog.h:39
#define elog(elevel,...)
Definition: elog.h:224
#define ereport(elevel,...)
Definition: elog.h:149
int data_sync_elevel(int elevel)
Definition: fd.c:3936
#define FILE_POSSIBLY_DELETED(err)
Definition: fd.h:78
bool enableFsync
Definition: globals.c:126
bool IsUnderPostmaster
Definition: globals.c:117
@ HASH_FIND
Definition: hsearch.h:113
@ HASH_REMOVE
Definition: hsearch.h:115
@ HASH_ENTER
Definition: hsearch.h:114
#define HASH_CONTEXT
Definition: hsearch.h:102
#define HASH_ELEM
Definition: hsearch.h:95
#define HASH_BLOBS
Definition: hsearch.h:97
#define INSTR_TIME_SET_CURRENT(t)
Definition: instr_time.h:122
#define INSTR_TIME_SUBTRACT(x, y)
Definition: instr_time.h:181
#define INSTR_TIME_GET_MICROSEC(t)
Definition: instr_time.h:194
int i
Definition: isn.c:73
int WaitLatch(Latch *latch, int wakeEvents, long timeout, uint32 wait_event_info)
Definition: latch.c:517
#define WL_TIMEOUT
Definition: latch.h:130
#define WL_EXIT_ON_PM_DEATH
Definition: latch.h:132
List * list_delete_first_n(List *list, int n)
Definition: list.c:983
List * lappend(List *list, void *datum)
Definition: list.c:339
void list_free_deep(List *list)
Definition: list.c:1560
void pfree(void *pointer)
Definition: mcxt.c:1520
MemoryContext TopMemoryContext
Definition: mcxt.c:149
void MemoryContextAllowInCriticalSection(MemoryContext context, bool allow)
Definition: mcxt.c:694
void * palloc(Size size)
Definition: mcxt.c:1316
bool mdfiletagmatches(const FileTag *ftag, const FileTag *candidate)
Definition: md.c:1808
int mdunlinkfiletag(const FileTag *ftag, char *path)
Definition: md.c:1789
int mdsyncfiletag(const FileTag *ftag, char *path)
Definition: md.c:1736
#define AllocSetContextCreate
Definition: memutils.h:129
#define ALLOCSET_DEFAULT_SIZES
Definition: memutils.h:160
#define AmCheckpointerProcess()
Definition: miscadmin.h:381
int multixactoffsetssyncfiletag(const FileTag *ftag, char *path)
Definition: multixact.c:3518
int multixactmemberssyncfiletag(const FileTag *ftag, char *path)
Definition: multixact.c:3527
#define MAXPGPATH
#define lfirst(lc)
Definition: pg_list.h:172
#define NIL
Definition: pg_list.h:68
static void * list_nth(const List *list, int n)
Definition: pg_list.h:299
static int list_cell_number(const List *l, const ListCell *c)
Definition: pg_list.h:333
MemoryContextSwitchTo(old_ctx)
static chr * longest(struct vars *v, struct dfa *d, chr *start, chr *stop, int *hitstopp)
Definition: rege_dfa.c:42
uint64 ckpt_agg_sync_time
Definition: xlog.h:173
uint64 ckpt_longest_sync
Definition: xlog.h:172
int ckpt_sync_rels
Definition: xlog.h:171
Definition: sync.h:51
int16 handler
Definition: sync.h:52
Size keysize
Definition: hsearch.h:75
Size entrysize
Definition: hsearch.h:76
MemoryContext hcxt
Definition: hsearch.h:86
Definition: dynahash.c:220
Definition: pg_list.h:54
FileTag tag
Definition: sync.c:58
CycleCtr cycle_ctr
Definition: sync.c:59
bool canceled
Definition: sync.c:60
FileTag tag
Definition: sync.c:65
CycleCtr cycle_ctr
Definition: sync.c:66
bool canceled
Definition: sync.c:67
Definition: sync.c:85
int(* sync_syncfiletag)(const FileTag *ftag, char *path)
Definition: sync.c:86
bool(* sync_filetagmatches)(const FileTag *ftag, const FileTag *candidate)
Definition: sync.c:88
int(* sync_unlinkfiletag)(const FileTag *ftag, char *path)
Definition: sync.c:87
void ProcessSyncRequests(void)
Definition: sync.c:286
static CycleCtr checkpoint_cycle_ctr
Definition: sync.c:75
void SyncPreCheckpoint(void)
Definition: sync.c:177
static List * pendingUnlinks
Definition: sync.c:71
static HTAB * pendingOps
Definition: sync.c:70
struct SyncOps SyncOps
#define UNLINKS_PER_ABSORB
Definition: sync.c:79
void InitSync(void)
Definition: sync.c:124
static const SyncOps syncsw[]
Definition: sync.c:95
static MemoryContext pendingOpsCxt
Definition: sync.c:72
void RememberSyncRequest(const FileTag *ftag, SyncRequestType type)
Definition: sync.c:487
static CycleCtr sync_cycle_ctr
Definition: sync.c:74
#define FSYNCS_PER_ABSORB
Definition: sync.c:78
void SyncPostCheckpoint(void)
Definition: sync.c:202
bool RegisterSyncRequest(const FileTag *ftag, SyncRequestType type, bool retryOnError)
Definition: sync.c:580
uint16 CycleCtr
Definition: sync.c:54
struct FileTag FileTag
@ SYNC_HANDLER_MD
Definition: sync.h:37
@ SYNC_HANDLER_COMMIT_TS
Definition: sync.h:39
@ SYNC_HANDLER_MULTIXACT_MEMBER
Definition: sync.h:41
@ SYNC_HANDLER_CLOG
Definition: sync.h:38
@ SYNC_HANDLER_MULTIXACT_OFFSET
Definition: sync.h:40
SyncRequestType
Definition: sync.h:24
@ SYNC_FILTER_REQUEST
Definition: sync.h:28
@ SYNC_FORGET_REQUEST
Definition: sync.h:27
@ SYNC_UNLINK_REQUEST
Definition: sync.h:26
@ SYNC_REQUEST
Definition: sync.h:25
const char * type
bool log_checkpoints
Definition: xlog.c:129
CheckpointStatsData CheckpointStats
Definition: xlog.c:209