Branch data Line data Source code
1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * slot.c
4 : : * Replication slot management.
5 : : *
6 : : *
7 : : * Copyright (c) 2012-2026, PostgreSQL Global Development Group
8 : : *
9 : : *
10 : : * IDENTIFICATION
11 : : * src/backend/replication/slot.c
12 : : *
13 : : * NOTES
14 : : *
15 : : * Replication slots are used to keep state about replication streams
16 : : * originating from this cluster. Their primary purpose is to prevent the
17 : : * premature removal of WAL or of old tuple versions in a manner that would
18 : : * interfere with replication; they are also useful for monitoring purposes.
19 : : * Slots need to be permanent (to allow restarts), crash-safe, and allocatable
20 : : * on standbys (to support cascading setups). The requirement that slots be
21 : : * usable on standbys precludes storing them in the system catalogs.
22 : : *
23 : : * Each replication slot gets its own directory inside the directory
24 : : * $PGDATA / PG_REPLSLOT_DIR. Inside that directory the state file will
25 : : * contain the slot's own data. Additional data can be stored alongside that
26 : : * file if required. While the server is running, the state data is also
27 : : * cached in memory for efficiency.
28 : : *
29 : : * ReplicationSlotAllocationLock must be taken in exclusive mode to allocate
30 : : * or free a slot. ReplicationSlotControlLock must be taken in shared mode
31 : : * to iterate over the slots, and in exclusive mode to change the in_use flag
32 : : * of a slot. The remaining data in each slot is protected by its mutex.
33 : : *
34 : : *-------------------------------------------------------------------------
35 : : */
36 : :
37 : : #include "postgres.h"
38 : :
39 : : #include <unistd.h>
40 : : #include <sys/stat.h>
41 : :
42 : : #include "access/transam.h"
43 : : #include "access/xlog_internal.h"
44 : : #include "access/xlogrecovery.h"
45 : : #include "common/file_utils.h"
46 : : #include "common/string.h"
47 : : #include "miscadmin.h"
48 : : #include "pgstat.h"
49 : : #include "postmaster/interrupt.h"
50 : : #include "replication/logicallauncher.h"
51 : : #include "replication/slotsync.h"
52 : : #include "replication/slot.h"
53 : : #include "replication/walsender_private.h"
54 : : #include "storage/fd.h"
55 : : #include "storage/ipc.h"
56 : : #include "storage/proc.h"
57 : : #include "storage/procarray.h"
58 : : #include "storage/subsystems.h"
59 : : #include "utils/builtins.h"
60 : : #include "utils/guc_hooks.h"
61 : : #include "utils/injection_point.h"
62 : : #include "utils/varlena.h"
63 : : #include "utils/wait_event.h"
64 : :
65 : : /*
66 : : * Replication slot on-disk data structure.
67 : : */
68 : : typedef struct ReplicationSlotOnDisk
69 : : {
70 : : /* first part of this struct needs to be version independent */
71 : :
72 : : /* data not covered by checksum */
73 : : uint32 magic;
74 : : pg_crc32c checksum;
75 : :
76 : : /* data covered by checksum */
77 : : uint32 version;
78 : : uint32 length;
79 : :
80 : : /*
81 : : * The actual data in the slot that follows can differ based on the above
82 : : * 'version'.
83 : : */
84 : :
85 : : ReplicationSlotPersistentData slotdata;
86 : : } ReplicationSlotOnDisk;
87 : :
88 : : /*
89 : : * Struct for the configuration of synchronized_standby_slots.
90 : : *
91 : : * Note: this must be a flat representation that can be held in a single chunk
92 : : * of guc_malloc'd memory, so that it can be stored as the "extra" data for the
93 : : * synchronized_standby_slots GUC.
94 : : */
95 : : typedef struct
96 : : {
97 : : /* Number of slot names in the slot_names[] */
98 : : int nslotnames;
99 : :
100 : : /*
101 : : * slot_names contains 'nslotnames' consecutive null-terminated C strings.
102 : : */
103 : : char slot_names[FLEXIBLE_ARRAY_MEMBER];
104 : : } SyncStandbySlotsConfigData;
105 : :
106 : : /*
107 : : * Lookup table for slot invalidation causes.
108 : : */
109 : : typedef struct SlotInvalidationCauseMap
110 : : {
111 : : ReplicationSlotInvalidationCause cause;
112 : : const char *cause_name;
113 : : } SlotInvalidationCauseMap;
114 : :
115 : : static const SlotInvalidationCauseMap SlotInvalidationCauses[] = {
116 : : {RS_INVAL_NONE, "none"},
117 : : {RS_INVAL_WAL_REMOVED, "wal_removed"},
118 : : {RS_INVAL_HORIZON, "rows_removed"},
119 : : {RS_INVAL_WAL_LEVEL, "wal_level_insufficient"},
120 : : {RS_INVAL_IDLE_TIMEOUT, "idle_timeout"},
121 : : };
122 : :
123 : : /*
124 : : * Ensure that the lookup table is up-to-date with the enums defined in
125 : : * ReplicationSlotInvalidationCause.
126 : : */
127 : : StaticAssertDecl(lengthof(SlotInvalidationCauses) == (RS_INVAL_MAX_CAUSES + 1),
128 : : "array length mismatch");
129 : :
130 : : /* size of version independent data */
131 : : #define ReplicationSlotOnDiskConstantSize \
132 : : offsetof(ReplicationSlotOnDisk, slotdata)
133 : : /* size of the part of the slot not covered by the checksum */
134 : : #define ReplicationSlotOnDiskNotChecksummedSize \
135 : : offsetof(ReplicationSlotOnDisk, version)
136 : : /* size of the part covered by the checksum */
137 : : #define ReplicationSlotOnDiskChecksummedSize \
138 : : sizeof(ReplicationSlotOnDisk) - ReplicationSlotOnDiskNotChecksummedSize
139 : : /* size of the slot data that is version dependent */
140 : : #define ReplicationSlotOnDiskV2Size \
141 : : sizeof(ReplicationSlotOnDisk) - ReplicationSlotOnDiskConstantSize
142 : :
143 : : #define SLOT_MAGIC 0x1051CA1 /* format identifier */
144 : : #define SLOT_VERSION 5 /* version for new files */
145 : :
146 : : /* Control array for replication slot management */
147 : : ReplicationSlotCtlData *ReplicationSlotCtl = NULL;
148 : :
149 : : static void ReplicationSlotsShmemRequest(void *arg);
150 : : static void ReplicationSlotsShmemInit(void *arg);
151 : :
152 : : const ShmemCallbacks ReplicationSlotsShmemCallbacks = {
153 : : .request_fn = ReplicationSlotsShmemRequest,
154 : : .init_fn = ReplicationSlotsShmemInit,
155 : : };
156 : :
157 : : /* My backend's replication slot in the shared memory array */
158 : : ReplicationSlot *MyReplicationSlot = NULL;
159 : :
160 : : /* GUC variables */
161 : : int max_replication_slots = 10; /* the maximum number of replication
162 : : * slots */
163 : : int max_repack_replication_slots = 5; /* the maximum number of slots
164 : : * for REPACK */
165 : :
166 : : /*
167 : : * Invalidate replication slots that have remained idle longer than this
168 : : * duration; '0' disables it.
169 : : */
170 : : int idle_replication_slot_timeout_secs = 0;
171 : :
172 : : /*
173 : : * This GUC lists streaming replication standby server slot names that
174 : : * logical WAL sender processes will wait for.
175 : : */
176 : : char *synchronized_standby_slots;
177 : :
178 : : /* This is the parsed and cached configuration for synchronized_standby_slots */
179 : : static SyncStandbySlotsConfigData *synchronized_standby_slots_config;
180 : :
181 : : /*
182 : : * Oldest LSN that has been confirmed to be flushed to the standbys
183 : : * corresponding to the physical slots specified in the synchronized_standby_slots GUC.
184 : : */
185 : : static XLogRecPtr ss_oldest_flush_lsn = InvalidXLogRecPtr;
186 : :
187 : : static void ReplicationSlotShmemExit(int code, Datum arg);
188 : : static bool IsSlotForConflictCheck(const char *name);
189 : : static void ReplicationSlotDropPtr(ReplicationSlot *slot);
190 : :
191 : : /* internal persistency functions */
192 : : static void RestoreSlotFromDisk(const char *name);
193 : : static void CreateSlotOnDisk(ReplicationSlot *slot);
194 : : static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
195 : :
196 : : /*
197 : : * Register shared memory space needed for replication slots.
198 : : */
199 : : static void
200 : 1250 : ReplicationSlotsShmemRequest(void *arg)
201 : : {
202 : : Size size;
203 : :
204 [ - + ]: 1250 : if (max_replication_slots + max_repack_replication_slots == 0)
205 : 0 : return;
206 : :
207 : 1250 : size = offsetof(ReplicationSlotCtlData, replication_slots);
208 : 1250 : size = add_size(size,
209 : 1250 : mul_size(max_replication_slots + max_repack_replication_slots,
210 : : sizeof(ReplicationSlot)));
211 : 1250 : ShmemRequestStruct(.name = "ReplicationSlot Ctl",
212 : : .size = size,
213 : : .ptr = (void **) &ReplicationSlotCtl,
214 : : );
215 : : }
216 : :
217 : : /*
218 : : * Initialize shared memory for replication slots.
219 : : */
220 : : static void
221 : 1247 : ReplicationSlotsShmemInit(void *arg)
222 : : {
223 [ + + ]: 19744 : for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
224 : : {
225 : 18497 : ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
226 : :
227 : : /* everything else is zeroed by the memset above */
228 : 18497 : slot->active_proc = INVALID_PROC_NUMBER;
229 : 18497 : SpinLockInit(&slot->mutex);
230 : 18497 : LWLockInitialize(&slot->io_in_progress_lock,
231 : : LWTRANCHE_REPLICATION_SLOT_IO);
232 : 18497 : ConditionVariableInit(&slot->active_cv);
233 : : }
234 : 1247 : }
235 : :
236 : : /*
237 : : * Register the callback for replication slot cleanup and releasing.
238 : : */
239 : : void
240 : 24746 : ReplicationSlotInitialize(void)
241 : : {
242 : 24746 : before_shmem_exit(ReplicationSlotShmemExit, 0);
243 : 24746 : }
244 : :
245 : : /*
246 : : * Release and cleanup replication slots.
247 : : */
248 : : static void
249 : 24746 : ReplicationSlotShmemExit(int code, Datum arg)
250 : : {
251 : : /* Make sure active replication slots are released */
252 [ + + ]: 24746 : if (MyReplicationSlot != NULL)
253 : 311 : ReplicationSlotRelease();
254 : :
255 : : /* Also cleanup all the temporary slots. */
256 : 24746 : ReplicationSlotCleanup(false);
257 : 24746 : }
258 : :
259 : : /*
260 : : * Check whether the passed slot name is valid and report errors at elevel.
261 : : *
262 : : * See comments for ReplicationSlotValidateNameInternal().
263 : : */
264 : : bool
265 : 889 : ReplicationSlotValidateName(const char *name, bool allow_reserved_name,
266 : : int elevel)
267 : : {
268 : : int err_code;
269 : 889 : char *err_msg = NULL;
270 : 889 : char *err_hint = NULL;
271 : :
272 [ + + ]: 889 : if (!ReplicationSlotValidateNameInternal(name, allow_reserved_name,
273 : : &err_code, &err_msg, &err_hint))
274 : : {
275 : : /*
276 : : * Use errmsg_internal() and errhint_internal() instead of errmsg()
277 : : * and errhint(), since the messages from
278 : : * ReplicationSlotValidateNameInternal() are already translated. This
279 : : * avoids double translation.
280 : : */
281 [ + - + + ]: 5 : ereport(elevel,
282 : : errcode(err_code),
283 : : errmsg_internal("%s", err_msg),
284 : : (err_hint != NULL) ? errhint_internal("%s", err_hint) : 0);
285 : :
286 : 0 : pfree(err_msg);
287 [ # # ]: 0 : if (err_hint != NULL)
288 : 0 : pfree(err_hint);
289 : 0 : return false;
290 : : }
291 : :
292 : 884 : return true;
293 : : }
294 : :
295 : : /*
296 : : * Check whether the passed slot name is valid.
297 : : *
298 : : * An error will be reported for a reserved replication slot name if
299 : : * allow_reserved_name is set to false.
300 : : *
301 : : * Slot names may consist out of [a-z0-9_]{1,NAMEDATALEN-1} which should allow
302 : : * the name to be used as a directory name on every supported OS.
303 : : *
304 : : * Returns true if the slot name is valid. Otherwise, returns false and stores
305 : : * the error code, error message, and optional hint in err_code, err_msg, and
306 : : * err_hint, respectively. The caller is responsible for freeing err_msg and
307 : : * err_hint, which are palloc'd.
308 : : */
309 : : bool
310 : 1103 : ReplicationSlotValidateNameInternal(const char *name, bool allow_reserved_name,
311 : : int *err_code, char **err_msg, char **err_hint)
312 : : {
313 : : const char *cp;
314 : :
315 [ + + ]: 1103 : if (strlen(name) == 0)
316 : : {
317 : 4 : *err_code = ERRCODE_INVALID_NAME;
318 : 4 : *err_msg = psprintf(_("replication slot name \"%s\" is too short"), name);
319 : 4 : *err_hint = NULL;
320 : 4 : return false;
321 : : }
322 : :
323 [ - + ]: 1099 : if (strlen(name) >= NAMEDATALEN)
324 : : {
325 : 0 : *err_code = ERRCODE_NAME_TOO_LONG;
326 : 0 : *err_msg = psprintf(_("replication slot name \"%s\" is too long"), name);
327 : 0 : *err_hint = NULL;
328 : 0 : return false;
329 : : }
330 : :
331 [ + + ]: 21168 : for (cp = name; *cp; cp++)
332 : : {
333 [ + + - + ]: 20071 : if (!((*cp >= 'a' && *cp <= 'z')
334 [ + + + + ]: 9533 : || (*cp >= '0' && *cp <= '9')
335 [ + + ]: 1955 : || (*cp == '_')))
336 : : {
337 : 2 : *err_code = ERRCODE_INVALID_NAME;
338 : 2 : *err_msg = psprintf(_("replication slot name \"%s\" contains invalid character"), name);
339 : 2 : *err_hint = psprintf(_("Replication slot names may only contain lower case letters, numbers, and the underscore character."));
340 : 2 : return false;
341 : : }
342 : : }
343 : :
344 [ + + + + ]: 1097 : if (!allow_reserved_name && IsSlotForConflictCheck(name))
345 : : {
346 : 1 : *err_code = ERRCODE_RESERVED_NAME;
347 : 1 : *err_msg = psprintf(_("replication slot name \"%s\" is reserved"), name);
348 : 1 : *err_hint = psprintf(_("The name \"%s\" is reserved for the conflict detection slot."),
349 : : CONFLICT_DETECTION_SLOT);
350 : 1 : return false;
351 : : }
352 : :
353 : 1096 : return true;
354 : : }
355 : :
356 : : /*
357 : : * Return true if the replication slot name is "pg_conflict_detection".
358 : : */
359 : : static bool
360 : 2393 : IsSlotForConflictCheck(const char *name)
361 : : {
362 : 2393 : return (strcmp(name, CONFLICT_DETECTION_SLOT) == 0);
363 : : }
364 : :
365 : : /*
366 : : * Create a new replication slot and mark it as used by this backend.
367 : : *
368 : : * name: Name of the slot
369 : : * db_specific: logical decoding is db specific; if the slot is going to
370 : : * be used for that pass true, otherwise false.
371 : : * two_phase: If enabled, allows decoding of prepared transactions.
372 : : * repack: If true, use a slot from the pool for REPACK.
373 : : * failover: If enabled, allows the slot to be synced to standbys so
374 : : * that logical replication can be resumed after failover.
375 : : * synced: True if the slot is synchronized from the primary server.
376 : : */
377 : : void
378 : 734 : ReplicationSlotCreate(const char *name, bool db_specific,
379 : : ReplicationSlotPersistency persistency,
380 : : bool two_phase, bool repack, bool failover, bool synced)
381 : : {
382 : 734 : ReplicationSlot *slot = NULL;
383 : : int startpoint,
384 : : endpoint;
385 : :
386 : : Assert(MyReplicationSlot == NULL);
387 : :
388 : : /*
389 : : * The logical launcher or pg_upgrade may create or migrate an internal
390 : : * slot, so using a reserved name is allowed in these cases.
391 : : */
392 [ + + + + ]: 734 : ReplicationSlotValidateName(name, IsBinaryUpgrade || IsLogicalLauncher(),
393 : 734 : ERROR);
394 : :
395 [ + + ]: 733 : if (failover)
396 : : {
397 : : /*
398 : : * Do not allow users to create the failover enabled slots on the
399 : : * standby as we do not support sync to the cascading standby.
400 : : *
401 : : * However, failover enabled slots can be created during slot
402 : : * synchronization because we need to retain the same values as the
403 : : * remote slot.
404 : : */
405 [ + + - + ]: 31 : if (RecoveryInProgress() && !IsSyncingReplicationSlots())
406 [ # # ]: 0 : ereport(ERROR,
407 : : errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
408 : : errmsg("cannot enable failover for a replication slot created on the standby"));
409 : :
410 : : /*
411 : : * Do not allow users to create failover enabled temporary slots,
412 : : * because temporary slots will not be synced to the standby.
413 : : *
414 : : * However, failover enabled temporary slots can be created during
415 : : * slot synchronization. See the comments atop slotsync.c for details.
416 : : */
417 [ + + + + ]: 31 : if (persistency == RS_TEMPORARY && !IsSyncingReplicationSlots())
418 [ + - ]: 1 : ereport(ERROR,
419 : : errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
420 : : errmsg("cannot enable failover for a temporary replication slot"));
421 : : }
422 : :
423 : : /*
424 : : * If some other backend ran this code concurrently with us, we'd likely
425 : : * both allocate the same slot, and that would be bad. We'd also be at
426 : : * risk of missing a name collision. Also, we don't want to try to create
427 : : * a new slot while somebody's busy cleaning up an old one, because we
428 : : * might both be monkeying with the same directory.
429 : : */
430 : 732 : LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
431 : :
432 : : /*
433 : : * Check for name collision (across the whole array), and identify an
434 : : * allocatable slot (in the array slice specific to our current use case:
435 : : * either general, or REPACK only). We need to hold
436 : : * ReplicationSlotControlLock in shared mode for this, so that nobody else
437 : : * can change the in_use flags while we're looking at them.
438 : : */
439 : 732 : LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
440 [ + + ]: 732 : startpoint = !repack ? 0 : max_replication_slots;
441 [ + + ]: 732 : endpoint = max_replication_slots + (repack ? max_repack_replication_slots : 0);
442 [ + + ]: 10755 : for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
443 : : {
444 : 10026 : ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
445 : :
446 [ + + + + ]: 10026 : if (s->in_use && strcmp(name, NameStr(s->data.name)) == 0)
447 [ + - ]: 3 : ereport(ERROR,
448 : : (errcode(ERRCODE_DUPLICATE_OBJECT),
449 : : errmsg("replication slot \"%s\" already exists", name)));
450 : :
451 [ + + + + ]: 10023 : if (i >= startpoint && i < endpoint &&
452 [ + + + + ]: 6355 : !s->in_use && slot == NULL)
453 : 728 : slot = s;
454 : : }
455 : 729 : LWLockRelease(ReplicationSlotControlLock);
456 : :
457 : : /* If all slots are in use, we're out of luck. */
458 [ + + ]: 729 : if (slot == NULL)
459 [ + - - + ]: 1 : ereport(ERROR,
460 : : (errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
461 : : errmsg("all replication slots are in use"),
462 : : errhint("Free one or increase \"%s\".",
463 : : repack ? "max_repack_replication_slots" : "max_replication_slots")));
464 : :
465 : : /*
466 : : * Since this slot is not in use, nobody should be looking at any part of
467 : : * it other than the in_use field unless they're trying to allocate it.
468 : : * And since we hold ReplicationSlotAllocationLock, nobody except us can
469 : : * be doing that. So it's safe to initialize the slot.
470 : : */
471 : : Assert(!slot->in_use);
472 : : Assert(slot->active_proc == INVALID_PROC_NUMBER);
473 : :
474 : : /* first initialize persistent data */
475 : 728 : memset(&slot->data, 0, sizeof(ReplicationSlotPersistentData));
476 : 728 : namestrcpy(&slot->data.name, name);
477 [ + + ]: 728 : slot->data.database = db_specific ? MyDatabaseId : InvalidOid;
478 : 728 : slot->data.persistency = persistency;
479 : 728 : slot->data.two_phase = two_phase;
480 : 728 : slot->data.two_phase_at = InvalidXLogRecPtr;
481 : 728 : slot->data.failover = failover;
482 : 728 : slot->data.synced = synced;
483 : :
484 : : /* and then data only present in shared memory */
485 : 728 : slot->just_dirtied = false;
486 : 728 : slot->dirty = false;
487 : 728 : slot->effective_xmin = InvalidTransactionId;
488 : 728 : slot->effective_catalog_xmin = InvalidTransactionId;
489 : 728 : slot->candidate_catalog_xmin = InvalidTransactionId;
490 : 728 : slot->candidate_xmin_lsn = InvalidXLogRecPtr;
491 : 728 : slot->candidate_restart_valid = InvalidXLogRecPtr;
492 : 728 : slot->candidate_restart_lsn = InvalidXLogRecPtr;
493 : 728 : slot->last_saved_confirmed_flush = InvalidXLogRecPtr;
494 : 728 : slot->last_saved_restart_lsn = InvalidXLogRecPtr;
495 : 728 : slot->inactive_since = 0;
496 : 728 : slot->slotsync_skip_reason = SS_SKIP_NONE;
497 : :
498 : : /*
499 : : * Create the slot on disk. We haven't actually marked the slot allocated
500 : : * yet, so no special cleanup is required if this errors out.
501 : : */
502 : 728 : CreateSlotOnDisk(slot);
503 : :
504 : : /*
505 : : * We need to briefly prevent any other backend from iterating over the
506 : : * slots while we flip the in_use flag. We also need to set the active
507 : : * flag while holding the ControlLock as otherwise a concurrent
508 : : * ReplicationSlotAcquire() could acquire the slot as well.
509 : : */
510 : 728 : LWLockAcquire(ReplicationSlotControlLock, LW_EXCLUSIVE);
511 : :
512 : 728 : slot->in_use = true;
513 : :
514 : : /* We can now mark the slot active, and that makes it our slot. */
515 : 728 : SpinLockAcquire(&slot->mutex);
516 : : Assert(slot->active_proc == INVALID_PROC_NUMBER);
517 : 728 : slot->active_proc = MyProcNumber;
518 : 728 : SpinLockRelease(&slot->mutex);
519 : 728 : MyReplicationSlot = slot;
520 : :
521 : 728 : LWLockRelease(ReplicationSlotControlLock);
522 : :
523 : : /*
524 : : * Create statistics entry for the new logical slot. We don't collect any
525 : : * stats for physical slots, so no need to create an entry for the same.
526 : : * See ReplicationSlotDropPtr for why we need to do this before releasing
527 : : * ReplicationSlotAllocationLock.
528 : : */
529 [ + + ]: 728 : if (SlotIsLogical(slot))
530 : 523 : pgstat_create_replslot(slot);
531 : :
532 : : /*
533 : : * Now that the slot has been marked as in_use and active, it's safe to
534 : : * let somebody else try to allocate a slot.
535 : : */
536 : 728 : LWLockRelease(ReplicationSlotAllocationLock);
537 : :
538 : : /* Let everybody know we've modified this slot */
539 : 728 : ConditionVariableBroadcast(&slot->active_cv);
540 : 728 : }
541 : :
542 : : /*
543 : : * Search for the named replication slot.
544 : : *
545 : : * Return the replication slot if found, otherwise NULL.
546 : : */
547 : : ReplicationSlot *
548 : 2185 : SearchNamedReplicationSlot(const char *name, bool need_lock)
549 : : {
550 : : int i;
551 : 2185 : ReplicationSlot *slot = NULL;
552 : :
553 [ + + ]: 2185 : if (need_lock)
554 : 659 : LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
555 : :
556 [ + + ]: 11259 : for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
557 : : {
558 : 10718 : ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
559 : :
560 [ + + + + ]: 10718 : if (s->in_use && strcmp(name, NameStr(s->data.name)) == 0)
561 : : {
562 : 1644 : slot = s;
563 : 1644 : break;
564 : : }
565 : : }
566 : :
567 [ + + ]: 2185 : if (need_lock)
568 : 659 : LWLockRelease(ReplicationSlotControlLock);
569 : :
570 : 2185 : return slot;
571 : : }
572 : :
573 : : /*
574 : : * Return the index of the replication slot in
575 : : * ReplicationSlotCtl->replication_slots.
576 : : *
577 : : * This is mainly useful to have an efficient key for storing replication slot
578 : : * stats.
579 : : */
580 : : int
581 : 8989 : ReplicationSlotIndex(ReplicationSlot *slot)
582 : : {
583 : : Assert(slot >= ReplicationSlotCtl->replication_slots &&
584 : : slot < ReplicationSlotCtl->replication_slots +
585 : : (max_replication_slots + max_repack_replication_slots));
586 : :
587 : 8989 : return slot - ReplicationSlotCtl->replication_slots;
588 : : }
589 : :
590 : : /*
591 : : * If the slot at 'index' is unused, return false. Otherwise 'name' is set to
592 : : * the slot's name and true is returned.
593 : : *
594 : : * This likely is only useful for pgstat_replslot.c during shutdown, in other
595 : : * cases there are obvious TOCTOU issues.
596 : : */
597 : : bool
598 : 117 : ReplicationSlotName(int index, Name name)
599 : : {
600 : : ReplicationSlot *slot;
601 : : bool found;
602 : :
603 : 117 : slot = &ReplicationSlotCtl->replication_slots[index];
604 : :
605 : : /*
606 : : * Ensure that the slot cannot be dropped while we copy the name. Don't
607 : : * need the spinlock as the name of an existing slot cannot change.
608 : : */
609 : 117 : LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
610 : 117 : found = slot->in_use;
611 [ + - ]: 117 : if (slot->in_use)
612 : 117 : namestrcpy(name, NameStr(slot->data.name));
613 : 117 : LWLockRelease(ReplicationSlotControlLock);
614 : :
615 : 117 : return found;
616 : : }
617 : :
618 : : /*
619 : : * Find a previously created slot and mark it as used by this process.
620 : : *
621 : : * An error is raised if nowait is true and the slot is currently in use. If
622 : : * nowait is false, we sleep until the slot is released by the owning process.
623 : : *
624 : : * An error is raised if error_if_invalid is true and the slot is found to
625 : : * be invalid. It should always be set to true, except when we are temporarily
626 : : * acquiring the slot and don't intend to change it.
627 : : */
628 : : void
629 : 1439 : ReplicationSlotAcquire(const char *name, bool nowait, bool error_if_invalid)
630 : : {
631 : : ReplicationSlot *s;
632 : : ProcNumber active_proc;
633 : : int active_pid;
634 : :
635 : : Assert(name != NULL);
636 : :
637 : 1439 : retry:
638 : : Assert(MyReplicationSlot == NULL);
639 : :
640 : 1439 : LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
641 : :
642 : : /* Check if the slot exists with the given name. */
643 : 1439 : s = SearchNamedReplicationSlot(name, false);
644 [ + + - + ]: 1439 : if (s == NULL || !s->in_use)
645 : : {
646 : 10 : LWLockRelease(ReplicationSlotControlLock);
647 : :
648 [ + - ]: 10 : ereport(ERROR,
649 : : (errcode(ERRCODE_UNDEFINED_OBJECT),
650 : : errmsg("replication slot \"%s\" does not exist",
651 : : name)));
652 : : }
653 : :
654 : : /*
655 : : * Do not allow users to acquire the reserved slot. This scenario may
656 : : * occur if the launcher that owns the slot has terminated unexpectedly
657 : : * due to an error, and a backend process attempts to reuse the slot.
658 : : */
659 [ + + - + ]: 1429 : if (!IsLogicalLauncher() && IsSlotForConflictCheck(name))
660 [ # # ]: 0 : ereport(ERROR,
661 : : errcode(ERRCODE_UNDEFINED_OBJECT),
662 : : errmsg("cannot acquire replication slot \"%s\"", name),
663 : : errdetail("The slot is reserved for conflict detection and can only be acquired by logical replication launcher."));
664 : :
665 : : /*
666 : : * This is the slot we want; check if it's active under some other
667 : : * process. In single user mode, we don't need this check.
668 : : */
669 [ + + ]: 1429 : if (IsUnderPostmaster)
670 : : {
671 : : /*
672 : : * Get ready to sleep on the slot in case it is active. (We may end
673 : : * up not sleeping, but we don't want to do this while holding the
674 : : * spinlock.)
675 : : */
676 [ + + ]: 1424 : if (!nowait)
677 : 297 : ConditionVariablePrepareToSleep(&s->active_cv);
678 : :
679 : : /*
680 : : * It is important to reset the inactive_since under spinlock here to
681 : : * avoid race conditions with slot invalidation. See comments related
682 : : * to inactive_since in InvalidatePossiblyObsoleteSlot.
683 : : */
684 : 1424 : SpinLockAcquire(&s->mutex);
685 [ + + ]: 1424 : if (s->active_proc == INVALID_PROC_NUMBER)
686 : 1264 : s->active_proc = MyProcNumber;
687 : 1424 : active_proc = s->active_proc;
688 : 1424 : ReplicationSlotSetInactiveSince(s, 0, false);
689 : 1424 : SpinLockRelease(&s->mutex);
690 : : }
691 : : else
692 : : {
693 : 5 : s->active_proc = active_proc = MyProcNumber;
694 : 5 : ReplicationSlotSetInactiveSince(s, 0, true);
695 : : }
696 : 1429 : active_pid = GetPGProcByNumber(active_proc)->pid;
697 : 1429 : LWLockRelease(ReplicationSlotControlLock);
698 : :
699 : : /*
700 : : * If we found the slot but it's already active in another process, we
701 : : * wait until the owning process signals us that it's been released, or
702 : : * error out.
703 : : */
704 [ - + ]: 1429 : if (active_proc != MyProcNumber)
705 : : {
706 [ # # ]: 0 : if (!nowait)
707 : : {
708 : : /* Wait here until we get signaled, and then restart */
709 : 0 : ConditionVariableSleep(&s->active_cv,
710 : : WAIT_EVENT_REPLICATION_SLOT_DROP);
711 : 0 : ConditionVariableCancelSleep();
712 : 0 : goto retry;
713 : : }
714 : :
715 [ # # ]: 0 : ereport(ERROR,
716 : : (errcode(ERRCODE_OBJECT_IN_USE),
717 : : errmsg("replication slot \"%s\" is active for PID %d",
718 : : NameStr(s->data.name), active_pid)));
719 : : }
720 [ + + ]: 1429 : else if (!nowait)
721 : 297 : ConditionVariableCancelSleep(); /* no sleep needed after all */
722 : :
723 : : /* We made this slot active, so it's ours now. */
724 : 1429 : MyReplicationSlot = s;
725 : :
726 : : /*
727 : : * We need to check for invalidation after making the slot ours to avoid
728 : : * the possible race condition with the checkpointer that can otherwise
729 : : * invalidate the slot immediately after the check.
730 : : */
731 [ + + + + ]: 1429 : if (error_if_invalid && s->data.invalidated != RS_INVAL_NONE)
732 [ + - ]: 8 : ereport(ERROR,
733 : : errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
734 : : errmsg("can no longer access replication slot \"%s\"",
735 : : NameStr(s->data.name)),
736 : : errdetail("This replication slot has been invalidated due to \"%s\".",
737 : : GetSlotInvalidationCauseName(s->data.invalidated)));
738 : :
739 : : /* Let everybody know we've modified this slot */
740 : 1421 : ConditionVariableBroadcast(&s->active_cv);
741 : :
742 : : /*
743 : : * The call to pgstat_acquire_replslot() protects against stats for a
744 : : * different slot, from before a restart or such, being present during
745 : : * pgstat_report_replslot().
746 : : */
747 [ + + ]: 1421 : if (SlotIsLogical(s))
748 : 1189 : pgstat_acquire_replslot(s);
749 : :
750 : :
751 [ + + ]: 1421 : if (am_walsender)
752 : : {
753 [ + - + - : 982 : ereport(log_replication_commands ? LOG : DEBUG1,
+ + ]
754 : : SlotIsLogical(s)
755 : : ? errmsg("acquired logical replication slot \"%s\"",
756 : : NameStr(s->data.name))
757 : : : errmsg("acquired physical replication slot \"%s\"",
758 : : NameStr(s->data.name)));
759 : : }
760 : 1421 : }
761 : :
762 : : /*
763 : : * Release the replication slot that this backend considers to own.
764 : : *
765 : : * This or another backend can re-acquire the slot later.
766 : : * Resources this slot requires will be preserved.
767 : : */
768 : : void
769 : 1724 : ReplicationSlotRelease(void)
770 : : {
771 : 1724 : ReplicationSlot *slot = MyReplicationSlot;
772 : 1724 : char *slotname = NULL; /* keep compiler quiet */
773 : : bool is_logical;
774 : 1724 : TimestampTz now = 0;
775 : :
776 : : Assert(slot != NULL && slot->active_proc != INVALID_PROC_NUMBER);
777 : :
778 : 1724 : is_logical = SlotIsLogical(slot);
779 : :
780 [ + + ]: 1724 : if (am_walsender)
781 : 1213 : slotname = pstrdup(NameStr(slot->data.name));
782 : :
783 [ + + ]: 1724 : if (slot->data.persistency == RS_EPHEMERAL)
784 : : {
785 : : /*
786 : : * If slot is ephemeral, we drop it upon release, and request logical
787 : : * decoding be disabled.
788 : : */
789 : 8 : ReplicationSlotDropAcquired(is_logical);
790 : : }
791 : : else
792 : : {
793 : : /*
794 : : * If slot needed to temporarily restrain both data and catalog xmin
795 : : * to create the catalog snapshot, remove that temporary constraint.
796 : : * Snapshots can only be exported while the initial snapshot is still
797 : : * acquired.
798 : : */
799 [ + + ]: 1716 : if (!TransactionIdIsValid(slot->data.xmin) &&
800 [ + + ]: 1682 : TransactionIdIsValid(slot->effective_xmin))
801 : : {
802 : 215 : SpinLockAcquire(&slot->mutex);
803 : 215 : slot->effective_xmin = InvalidTransactionId;
804 : 215 : SpinLockRelease(&slot->mutex);
805 : 215 : ReplicationSlotsComputeRequiredXmin(false);
806 : : }
807 : :
808 : : /*
809 : : * Set the time since the slot has become inactive. We get the current
810 : : * time beforehand to avoid system call while holding the spinlock.
811 : : */
812 : 1716 : now = GetCurrentTimestamp();
813 : :
814 [ + + ]: 1716 : if (slot->data.persistency == RS_PERSISTENT)
815 : : {
816 : : /*
817 : : * Mark persistent slot inactive. We're not freeing it, just
818 : : * disconnecting, but wake up others that may be waiting for it.
819 : : */
820 : 1395 : SpinLockAcquire(&slot->mutex);
821 : 1395 : slot->active_proc = INVALID_PROC_NUMBER;
822 : 1395 : ReplicationSlotSetInactiveSince(slot, now, false);
823 : 1395 : SpinLockRelease(&slot->mutex);
824 : 1395 : ConditionVariableBroadcast(&slot->active_cv);
825 : : }
826 : : else
827 : 321 : ReplicationSlotSetInactiveSince(slot, now, true);
828 : :
829 : 1716 : MyReplicationSlot = NULL;
830 : : }
831 : :
832 : : /* might not have been set when we've been a plain slot */
833 : 1724 : LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
834 : 1724 : MyProc->statusFlags &= ~PROC_IN_LOGICAL_DECODING;
835 : 1724 : ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags;
836 : 1724 : LWLockRelease(ProcArrayLock);
837 : :
838 [ + + ]: 1724 : if (am_walsender)
839 : : {
840 [ + - + - : 1213 : ereport(log_replication_commands ? LOG : DEBUG1,
+ + ]
841 : : is_logical
842 : : ? errmsg("released logical replication slot \"%s\"",
843 : : slotname)
844 : : : errmsg("released physical replication slot \"%s\"",
845 : : slotname));
846 : :
847 : 1213 : pfree(slotname);
848 : : }
849 : 1724 : }
850 : :
851 : : /*
852 : : * Cleanup temporary slots created in current session.
853 : : *
854 : : * Cleanup only synced temporary slots if 'synced_only' is true, else
855 : : * cleanup all temporary slots.
856 : : *
857 : : * If it drops the last logical slot in the cluster, requests to disable
858 : : * logical decoding.
859 : : */
860 : : void
861 : 56412 : ReplicationSlotCleanup(bool synced_only)
862 : : {
863 : : int i;
864 : : bool found_valid_logicalslot;
865 : 56412 : bool dropped_logical = false;
866 : :
867 : : Assert(MyReplicationSlot == NULL);
868 : :
869 : 56573 : restart:
870 : 56573 : found_valid_logicalslot = false;
871 : 56573 : LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
872 [ + + ]: 896766 : for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
873 : : {
874 : 840354 : ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
875 : :
876 [ + + ]: 840354 : if (!s->in_use)
877 : 824714 : continue;
878 : :
879 : 15640 : SpinLockAcquire(&s->mutex);
880 : :
881 : 31280 : found_valid_logicalslot |=
882 [ + + + + ]: 15640 : (SlotIsLogical(s) && s->data.invalidated == RS_INVAL_NONE);
883 : :
884 [ + + ]: 15640 : if ((s->active_proc == MyProcNumber &&
885 [ - + - - ]: 161 : (!synced_only || s->data.synced)))
886 : : {
887 : : Assert(s->data.persistency == RS_TEMPORARY);
888 : 161 : SpinLockRelease(&s->mutex);
889 : 161 : LWLockRelease(ReplicationSlotControlLock); /* avoid deadlock */
890 : :
891 [ + + ]: 161 : if (SlotIsLogical(s))
892 : 10 : dropped_logical = true;
893 : :
894 : 161 : ReplicationSlotDropPtr(s);
895 : :
896 : 161 : ConditionVariableBroadcast(&s->active_cv);
897 : 161 : goto restart;
898 : : }
899 : : else
900 : 15479 : SpinLockRelease(&s->mutex);
901 : : }
902 : :
903 : 56412 : LWLockRelease(ReplicationSlotControlLock);
904 : :
905 [ + + + + ]: 56412 : if (dropped_logical && !found_valid_logicalslot)
906 : 3 : RequestDisableLogicalDecoding();
907 : 56412 : }
908 : :
909 : : /*
910 : : * Permanently drop the replication slot identified by the passed-in name.
911 : : *
912 : : * If this is a logical slot, request that logical decoding be disabled.
913 : : */
914 : : void
915 : 447 : ReplicationSlotDrop(const char *name, bool nowait)
916 : : {
917 : 447 : ReplicationSlotAcquire(name, nowait, false);
918 : :
919 : : /*
920 : : * Do not allow users to drop the slots which are currently being synced
921 : : * from the primary to the standby.
922 : : */
923 [ + + + + ]: 440 : if (RecoveryInProgress() && MyReplicationSlot->data.synced)
924 [ + - ]: 1 : ereport(ERROR,
925 : : errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
926 : : errmsg("cannot drop replication slot \"%s\"", name),
927 : : errdetail("This replication slot is being synchronized from the primary server."));
928 : :
929 : 439 : ReplicationSlotDropAcquired(SlotIsLogical(MyReplicationSlot));
930 : 439 : }
931 : :
932 : : /*
933 : : * Change the definition of the slot identified by the specified name.
934 : : *
935 : : * Altering the two_phase property of a slot requires caution on the
936 : : * client-side. Enabling it at any random point during decoding has the
937 : : * risk that transactions prepared before this change may be skipped by
938 : : * the decoder, leading to missing prepare records on the client. So, we
939 : : * enable it for subscription related slots only once the initial tablesync
940 : : * is finished. See comments atop worker.c. Disabling it is safe only when
941 : : * there are no pending prepared transaction, otherwise, the changes of
942 : : * already prepared transactions can be replicated again along with their
943 : : * corresponding commit leading to duplicate data or errors.
944 : : */
945 : : void
946 : 7 : ReplicationSlotAlter(const char *name, const bool *failover,
947 : : const bool *two_phase)
948 : : {
949 : 7 : bool update_slot = false;
950 : :
951 : : Assert(MyReplicationSlot == NULL);
952 : : Assert(failover || two_phase);
953 : :
954 : 7 : ReplicationSlotAcquire(name, false, true);
955 : :
956 [ - + ]: 6 : if (SlotIsPhysical(MyReplicationSlot))
957 [ # # ]: 0 : ereport(ERROR,
958 : : errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
959 : : errmsg("cannot use %s with a physical replication slot",
960 : : "ALTER_REPLICATION_SLOT"));
961 : :
962 [ + + ]: 6 : if (RecoveryInProgress())
963 : : {
964 : : /*
965 : : * Do not allow users to alter the slots which are currently being
966 : : * synced from the primary to the standby.
967 : : */
968 [ + - ]: 1 : if (MyReplicationSlot->data.synced)
969 [ + - ]: 1 : ereport(ERROR,
970 : : errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
971 : : errmsg("cannot alter replication slot \"%s\"", name),
972 : : errdetail("This replication slot is being synchronized from the primary server."));
973 : :
974 : : /*
975 : : * Do not allow users to enable failover on the standby as we do not
976 : : * support sync to the cascading standby.
977 : : */
978 [ # # # # ]: 0 : if (failover && *failover)
979 [ # # ]: 0 : ereport(ERROR,
980 : : errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
981 : : errmsg("cannot enable failover for a replication slot"
982 : : " on the standby"));
983 : : }
984 : :
985 [ + + ]: 5 : if (failover)
986 : : {
987 : : /*
988 : : * Do not allow users to enable failover for temporary slots as we do
989 : : * not support syncing temporary slots to the standby.
990 : : */
991 [ + + - + ]: 4 : if (*failover && MyReplicationSlot->data.persistency == RS_TEMPORARY)
992 [ # # ]: 0 : ereport(ERROR,
993 : : errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
994 : : errmsg("cannot enable failover for a temporary replication slot"));
995 : :
996 [ + - ]: 4 : if (MyReplicationSlot->data.failover != *failover)
997 : : {
998 : 4 : SpinLockAcquire(&MyReplicationSlot->mutex);
999 : 4 : MyReplicationSlot->data.failover = *failover;
1000 : 4 : SpinLockRelease(&MyReplicationSlot->mutex);
1001 : :
1002 : 4 : update_slot = true;
1003 : : }
1004 : : }
1005 : :
1006 [ + + + - ]: 5 : if (two_phase && MyReplicationSlot->data.two_phase != *two_phase)
1007 : : {
1008 : 1 : SpinLockAcquire(&MyReplicationSlot->mutex);
1009 : 1 : MyReplicationSlot->data.two_phase = *two_phase;
1010 : 1 : SpinLockRelease(&MyReplicationSlot->mutex);
1011 : :
1012 : 1 : update_slot = true;
1013 : : }
1014 : :
1015 [ + - ]: 5 : if (update_slot)
1016 : : {
1017 : 5 : ReplicationSlotMarkDirty();
1018 : 5 : ReplicationSlotSave();
1019 : : }
1020 : :
1021 : 5 : ReplicationSlotRelease();
1022 : 5 : }
1023 : :
1024 : : /*
1025 : : * Permanently drop the currently acquired replication slot.
1026 : : *
1027 : : * If caller requests it, have checkpointer attempt to disable logical
1028 : : * decoding. Obviously, this should only be done if the slot is logical.
1029 : : */
1030 : : void
1031 : 462 : ReplicationSlotDropAcquired(bool try_disable)
1032 : : {
1033 : : ReplicationSlot *slot;
1034 : :
1035 : : Assert(MyReplicationSlot != NULL);
1036 : 462 : slot = MyReplicationSlot;
1037 : :
1038 : : /* Can only disable logical decoding if slot is logical */
1039 : : Assert(!try_disable || SlotIsLogical(slot));
1040 : :
1041 : : /* slot isn't acquired anymore */
1042 : 462 : MyReplicationSlot = NULL;
1043 : :
1044 : 462 : ReplicationSlotDropPtr(slot);
1045 : :
1046 [ + + ]: 462 : if (try_disable)
1047 : 434 : RequestDisableLogicalDecoding();
1048 : 462 : }
1049 : :
1050 : : /*
1051 : : * Permanently drop the replication slot which will be released by the point
1052 : : * this function returns.
1053 : : */
1054 : : static void
1055 : 623 : ReplicationSlotDropPtr(ReplicationSlot *slot)
1056 : : {
1057 : : char path[MAXPGPATH];
1058 : : char tmppath[MAXPGPATH];
1059 : :
1060 : : /*
1061 : : * If some other backend ran this code concurrently with us, we might try
1062 : : * to delete a slot with a certain name while someone else was trying to
1063 : : * create a slot with the same name.
1064 : : */
1065 : 623 : LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
1066 : :
1067 : : /* Generate pathnames. */
1068 : 623 : sprintf(path, "%s/%s", PG_REPLSLOT_DIR, NameStr(slot->data.name));
1069 : 623 : sprintf(tmppath, "%s/%s.tmp", PG_REPLSLOT_DIR, NameStr(slot->data.name));
1070 : :
1071 : : /*
1072 : : * Rename the slot directory on disk, so that we'll no longer recognize
1073 : : * this as a valid slot. Note that if this fails, we've got to mark the
1074 : : * slot inactive before bailing out. If we're dropping an ephemeral or a
1075 : : * temporary slot, we better never fail hard as the caller won't expect
1076 : : * the slot to survive and this might get called during error handling.
1077 : : */
1078 [ + - ]: 623 : if (rename(path, tmppath) == 0)
1079 : : {
1080 : : /*
1081 : : * We need to fsync() the directory we just renamed and its parent to
1082 : : * make sure that our changes are on disk in a crash-safe fashion. If
1083 : : * fsync() fails, we can't be sure whether the changes are on disk or
1084 : : * not. For now, we handle that by panicking;
1085 : : * StartupReplicationSlots() will try to straighten it out after
1086 : : * restart.
1087 : : */
1088 : 623 : START_CRIT_SECTION();
1089 : 623 : fsync_fname(tmppath, true);
1090 : 623 : fsync_fname(PG_REPLSLOT_DIR, true);
1091 : 623 : END_CRIT_SECTION();
1092 : : }
1093 : : else
1094 : : {
1095 : 0 : bool fail_softly = slot->data.persistency != RS_PERSISTENT;
1096 : :
1097 : 0 : SpinLockAcquire(&slot->mutex);
1098 : 0 : slot->active_proc = INVALID_PROC_NUMBER;
1099 : 0 : SpinLockRelease(&slot->mutex);
1100 : :
1101 : : /* wake up anyone waiting on this slot */
1102 : 0 : ConditionVariableBroadcast(&slot->active_cv);
1103 : :
1104 [ # # # # ]: 0 : ereport(fail_softly ? WARNING : ERROR,
1105 : : (errcode_for_file_access(),
1106 : : errmsg("could not rename file \"%s\" to \"%s\": %m",
1107 : : path, tmppath)));
1108 : : }
1109 : :
1110 : : /*
1111 : : * The slot is definitely gone. Lock out concurrent scans of the array
1112 : : * long enough to kill it. It's OK to clear the active PID here without
1113 : : * grabbing the mutex because nobody else can be scanning the array here,
1114 : : * and nobody can be attached to this slot and thus access it without
1115 : : * scanning the array.
1116 : : *
1117 : : * Also wake up processes waiting for it.
1118 : : */
1119 : 623 : LWLockAcquire(ReplicationSlotControlLock, LW_EXCLUSIVE);
1120 : 623 : slot->active_proc = INVALID_PROC_NUMBER;
1121 : 623 : slot->in_use = false;
1122 : 623 : LWLockRelease(ReplicationSlotControlLock);
1123 : 623 : ConditionVariableBroadcast(&slot->active_cv);
1124 : :
1125 : : /*
1126 : : * Slot is dead and doesn't prevent resource removal anymore, recompute
1127 : : * limits.
1128 : : */
1129 : 623 : ReplicationSlotsComputeRequiredXmin(false);
1130 : 623 : ReplicationSlotsComputeRequiredLSN();
1131 : :
1132 : : /*
1133 : : * If removing the directory fails, the worst thing that will happen is
1134 : : * that the user won't be able to create a new slot with the same name
1135 : : * until the next server restart. We warn about it, but that's all.
1136 : : */
1137 [ - + ]: 623 : if (!rmtree(tmppath, true))
1138 [ # # ]: 0 : ereport(WARNING,
1139 : : (errmsg("could not remove directory \"%s\"", tmppath)));
1140 : :
1141 : : /*
1142 : : * Drop the statistics entry for the replication slot. Do this while
1143 : : * holding ReplicationSlotAllocationLock so that we don't drop a
1144 : : * statistics entry for another slot with the same name just created in
1145 : : * another session.
1146 : : */
1147 [ + + ]: 623 : if (SlotIsLogical(slot))
1148 : 451 : pgstat_drop_replslot(slot);
1149 : :
1150 : : /*
1151 : : * We release this at the very end, so that nobody starts trying to create
1152 : : * a slot while we're still cleaning up the detritus of the old one.
1153 : : */
1154 : 623 : LWLockRelease(ReplicationSlotAllocationLock);
1155 : 623 : }
1156 : :
1157 : : /*
1158 : : * Serialize the currently acquired slot's state from memory to disk, thereby
1159 : : * guaranteeing the current state will survive a crash.
1160 : : */
1161 : : void
1162 : 1516 : ReplicationSlotSave(void)
1163 : : {
1164 : : char path[MAXPGPATH];
1165 : :
1166 : : Assert(MyReplicationSlot != NULL);
1167 : :
1168 : 1516 : sprintf(path, "%s/%s", PG_REPLSLOT_DIR, NameStr(MyReplicationSlot->data.name));
1169 : 1516 : SaveSlotToPath(MyReplicationSlot, path, ERROR);
1170 : 1516 : }
1171 : :
1172 : : /*
1173 : : * Signal that it would be useful if the currently acquired slot would be
1174 : : * flushed out to disk.
1175 : : *
1176 : : * Note that the actual flush to disk can be delayed for a long time, if
1177 : : * required for correctness explicitly do a ReplicationSlotSave().
1178 : : */
1179 : : void
1180 : 42747 : ReplicationSlotMarkDirty(void)
1181 : : {
1182 : 42747 : ReplicationSlot *slot = MyReplicationSlot;
1183 : :
1184 : : Assert(MyReplicationSlot != NULL);
1185 : :
1186 : 42747 : SpinLockAcquire(&slot->mutex);
1187 : 42747 : MyReplicationSlot->just_dirtied = true;
1188 : 42747 : MyReplicationSlot->dirty = true;
1189 : 42747 : SpinLockRelease(&slot->mutex);
1190 : 42747 : }
1191 : :
1192 : : /*
1193 : : * Convert a slot that's marked as RS_EPHEMERAL or RS_TEMPORARY to a
1194 : : * RS_PERSISTENT slot, guaranteeing it will be there after an eventual crash.
1195 : : */
1196 : : void
1197 : 498 : ReplicationSlotPersist(void)
1198 : : {
1199 : 498 : ReplicationSlot *slot = MyReplicationSlot;
1200 : :
1201 : : Assert(slot != NULL);
1202 : : Assert(slot->data.persistency != RS_PERSISTENT);
1203 : :
1204 : 498 : SpinLockAcquire(&slot->mutex);
1205 : 498 : slot->data.persistency = RS_PERSISTENT;
1206 : 498 : SpinLockRelease(&slot->mutex);
1207 : :
1208 : 498 : ReplicationSlotMarkDirty();
1209 : 498 : ReplicationSlotSave();
1210 : 498 : }
1211 : :
1212 : : /*
1213 : : * Compute the oldest xmin across all slots and store it in the ProcArray.
1214 : : *
1215 : : * If already_locked is true, both the ReplicationSlotControlLock and the
1216 : : * ProcArrayLock have already been acquired exclusively. It is crucial that the
1217 : : * caller first acquires the ReplicationSlotControlLock, followed by the
1218 : : * ProcArrayLock, to prevent any undetectable deadlocks since this function
1219 : : * acquires them in that order.
1220 : : */
1221 : : void
1222 : 2662 : ReplicationSlotsComputeRequiredXmin(bool already_locked)
1223 : : {
1224 : : int i;
1225 : 2662 : TransactionId agg_xmin = InvalidTransactionId;
1226 : 2662 : TransactionId agg_catalog_xmin = InvalidTransactionId;
1227 : :
1228 : : Assert(ReplicationSlotCtl != NULL);
1229 : : Assert(!already_locked ||
1230 : : (LWLockHeldByMeInMode(ReplicationSlotControlLock, LW_EXCLUSIVE) &&
1231 : : LWLockHeldByMeInMode(ProcArrayLock, LW_EXCLUSIVE)));
1232 : :
1233 : : /*
1234 : : * Hold the ReplicationSlotControlLock until after updating the slot xmin
1235 : : * values, so no backend updates the initial xmin for newly created slot
1236 : : * concurrently. A shared lock is used here to minimize lock contention,
1237 : : * especially when many slots exist and advancements occur frequently.
1238 : : * This is safe since an exclusive lock is taken during initial slot xmin
1239 : : * update in slot creation.
1240 : : *
1241 : : * One might think that we can hold the ProcArrayLock exclusively and
1242 : : * update the slot xmin values, but it could increase lock contention on
1243 : : * the ProcArrayLock, which is not great since this function can be called
1244 : : * at non-negligible frequency.
1245 : : *
1246 : : * Concurrent invocation of this function may cause the computed slot xmin
1247 : : * to regress. However, this is harmless because tuples prior to the most
1248 : : * recent xmin are no longer useful once advancement occurs (see
1249 : : * LogicalConfirmReceivedLocation where the slot's xmin value is flushed
1250 : : * before updating the effective_xmin). Thus, such regression merely
1251 : : * prevents VACUUM from prematurely removing tuples without causing the
1252 : : * early deletion of required data.
1253 : : */
1254 [ + + ]: 2662 : if (!already_locked)
1255 : 2139 : LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
1256 : :
1257 [ + + ]: 40443 : for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
1258 : : {
1259 : 37781 : ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
1260 : : TransactionId effective_xmin;
1261 : : TransactionId effective_catalog_xmin;
1262 : : bool invalidated;
1263 : :
1264 [ + + ]: 37781 : if (!s->in_use)
1265 : 35238 : continue;
1266 : :
1267 : 2543 : SpinLockAcquire(&s->mutex);
1268 : 2543 : effective_xmin = s->effective_xmin;
1269 : 2543 : effective_catalog_xmin = s->effective_catalog_xmin;
1270 : 2543 : invalidated = s->data.invalidated != RS_INVAL_NONE;
1271 : 2543 : SpinLockRelease(&s->mutex);
1272 : :
1273 : : /* invalidated slots need not apply */
1274 [ + + ]: 2543 : if (invalidated)
1275 : 26 : continue;
1276 : :
1277 : : /* check the data xmin */
1278 [ + + + + ]: 2517 : if (TransactionIdIsValid(effective_xmin) &&
1279 [ - + ]: 6 : (!TransactionIdIsValid(agg_xmin) ||
1280 : 6 : TransactionIdPrecedes(effective_xmin, agg_xmin)))
1281 : 363 : agg_xmin = effective_xmin;
1282 : :
1283 : : /* check the catalog xmin */
1284 [ + + + + ]: 2517 : if (TransactionIdIsValid(effective_catalog_xmin) &&
1285 [ + + ]: 1049 : (!TransactionIdIsValid(agg_catalog_xmin) ||
1286 : 1049 : TransactionIdPrecedes(effective_catalog_xmin, agg_catalog_xmin)))
1287 : 1310 : agg_catalog_xmin = effective_catalog_xmin;
1288 : : }
1289 : :
1290 : 2662 : ProcArraySetReplicationSlotXmin(agg_xmin, agg_catalog_xmin, already_locked);
1291 : :
1292 [ + + ]: 2662 : if (!already_locked)
1293 : 2139 : LWLockRelease(ReplicationSlotControlLock);
1294 : 2662 : }
1295 : :
1296 : : /*
1297 : : * Compute the oldest restart LSN across all slots and inform xlog module.
1298 : : *
1299 : : * Note: while max_slot_wal_keep_size is theoretically relevant for this
1300 : : * purpose, we don't try to account for that, because this module doesn't
1301 : : * know what to compare against.
1302 : : */
1303 : : void
1304 : 43805 : ReplicationSlotsComputeRequiredLSN(void)
1305 : : {
1306 : : int i;
1307 : 43805 : XLogRecPtr min_required = InvalidXLogRecPtr;
1308 : :
1309 : : Assert(ReplicationSlotCtl != NULL);
1310 : :
1311 : 43805 : LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
1312 [ + + ]: 696577 : for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
1313 : : {
1314 : 652772 : ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
1315 : : XLogRecPtr restart_lsn;
1316 : : XLogRecPtr last_saved_restart_lsn;
1317 : : bool invalidated;
1318 : : ReplicationSlotPersistency persistency;
1319 : :
1320 [ + + ]: 652772 : if (!s->in_use)
1321 : 608443 : continue;
1322 : :
1323 : 44329 : SpinLockAcquire(&s->mutex);
1324 : 44329 : persistency = s->data.persistency;
1325 : 44329 : restart_lsn = s->data.restart_lsn;
1326 : 44329 : invalidated = s->data.invalidated != RS_INVAL_NONE;
1327 : 44329 : last_saved_restart_lsn = s->last_saved_restart_lsn;
1328 : 44329 : SpinLockRelease(&s->mutex);
1329 : :
1330 : : /* invalidated slots need not apply */
1331 [ + + ]: 44329 : if (invalidated)
1332 : 27 : continue;
1333 : :
1334 : : /*
1335 : : * For persistent slot use last_saved_restart_lsn to compute the
1336 : : * oldest LSN for removal of WAL segments. The segments between
1337 : : * last_saved_restart_lsn and restart_lsn might be needed by a
1338 : : * persistent slot in the case of database crash. Non-persistent
1339 : : * slots can't survive the database crash, so we don't care about
1340 : : * last_saved_restart_lsn for them.
1341 : : */
1342 [ + + ]: 44302 : if (persistency == RS_PERSISTENT)
1343 : : {
1344 [ + + + + ]: 43298 : if (XLogRecPtrIsValid(last_saved_restart_lsn) &&
1345 : : restart_lsn > last_saved_restart_lsn)
1346 : : {
1347 : 40115 : restart_lsn = last_saved_restart_lsn;
1348 : : }
1349 : : }
1350 : :
1351 [ + + + + ]: 44302 : if (XLogRecPtrIsValid(restart_lsn) &&
1352 [ + + ]: 1693 : (!XLogRecPtrIsValid(min_required) ||
1353 : : restart_lsn < min_required))
1354 : 42786 : min_required = restart_lsn;
1355 : : }
1356 : 43805 : LWLockRelease(ReplicationSlotControlLock);
1357 : :
1358 : 43805 : XLogSetReplicationSlotMinimumLSN(min_required);
1359 : 43805 : }
1360 : :
1361 : : /*
1362 : : * Compute the oldest WAL LSN required by *logical* decoding slots..
1363 : : *
1364 : : * Returns InvalidXLogRecPtr if logical decoding is disabled or no logical
1365 : : * slots exist.
1366 : : *
1367 : : * NB: this returns a value >= ReplicationSlotsComputeRequiredLSN(), since it
1368 : : * ignores physical replication slots.
1369 : : *
1370 : : * The results aren't required frequently, so we don't maintain a precomputed
1371 : : * value like we do for ComputeRequiredLSN() and ComputeRequiredXmin().
1372 : : */
1373 : : XLogRecPtr
1374 : 3898 : ReplicationSlotsComputeLogicalRestartLSN(void)
1375 : : {
1376 : 3898 : XLogRecPtr result = InvalidXLogRecPtr;
1377 : : int i;
1378 : :
1379 [ - + ]: 3898 : if (max_replication_slots + max_repack_replication_slots <= 0)
1380 : 0 : return InvalidXLogRecPtr;
1381 : :
1382 : 3898 : LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
1383 : :
1384 [ + + ]: 61806 : for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
1385 : : {
1386 : : ReplicationSlot *s;
1387 : : XLogRecPtr restart_lsn;
1388 : : XLogRecPtr last_saved_restart_lsn;
1389 : : bool invalidated;
1390 : : ReplicationSlotPersistency persistency;
1391 : :
1392 : 57908 : s = &ReplicationSlotCtl->replication_slots[i];
1393 : :
1394 : : /* cannot change while ReplicationSlotCtlLock is held */
1395 [ + + ]: 57908 : if (!s->in_use)
1396 : 57072 : continue;
1397 : :
1398 : : /* we're only interested in logical slots */
1399 [ + + ]: 836 : if (!SlotIsLogical(s))
1400 : 568 : continue;
1401 : :
1402 : : /* read once, it's ok if it increases while we're checking */
1403 : 268 : SpinLockAcquire(&s->mutex);
1404 : 268 : persistency = s->data.persistency;
1405 : 268 : restart_lsn = s->data.restart_lsn;
1406 : 268 : invalidated = s->data.invalidated != RS_INVAL_NONE;
1407 : 268 : last_saved_restart_lsn = s->last_saved_restart_lsn;
1408 : 268 : SpinLockRelease(&s->mutex);
1409 : :
1410 : : /* invalidated slots need not apply */
1411 [ + + ]: 268 : if (invalidated)
1412 : 10 : continue;
1413 : :
1414 : : /*
1415 : : * For persistent slot use last_saved_restart_lsn to compute the
1416 : : * oldest LSN for removal of WAL segments. The segments between
1417 : : * last_saved_restart_lsn and restart_lsn might be needed by a
1418 : : * persistent slot in the case of database crash. Non-persistent
1419 : : * slots can't survive the database crash, so we don't care about
1420 : : * last_saved_restart_lsn for them.
1421 : : */
1422 [ + + ]: 258 : if (persistency == RS_PERSISTENT)
1423 : : {
1424 [ + - - + ]: 256 : if (XLogRecPtrIsValid(last_saved_restart_lsn) &&
1425 : : restart_lsn > last_saved_restart_lsn)
1426 : : {
1427 : 0 : restart_lsn = last_saved_restart_lsn;
1428 : : }
1429 : : }
1430 : :
1431 [ - + ]: 258 : if (!XLogRecPtrIsValid(restart_lsn))
1432 : 0 : continue;
1433 : :
1434 [ + + + + ]: 258 : if (!XLogRecPtrIsValid(result) ||
1435 : : restart_lsn < result)
1436 : 202 : result = restart_lsn;
1437 : : }
1438 : :
1439 : 3898 : LWLockRelease(ReplicationSlotControlLock);
1440 : :
1441 : 3898 : return result;
1442 : : }
1443 : :
1444 : : /*
1445 : : * ReplicationSlotsCountDBSlots -- count the number of slots that refer to the
1446 : : * passed database oid.
1447 : : *
1448 : : * Returns true if there are any slots referencing the database. *nslots will
1449 : : * be set to the absolute number of slots in the database, *nactive to ones
1450 : : * currently active.
1451 : : */
1452 : : bool
1453 : 54 : ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
1454 : : {
1455 : : int i;
1456 : :
1457 : 54 : *nslots = *nactive = 0;
1458 : :
1459 [ - + ]: 54 : if (max_replication_slots + max_repack_replication_slots <= 0)
1460 : 0 : return false;
1461 : :
1462 : 54 : LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
1463 [ + + ]: 837 : for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
1464 : : {
1465 : : ReplicationSlot *s;
1466 : :
1467 : 783 : s = &ReplicationSlotCtl->replication_slots[i];
1468 : :
1469 : : /* cannot change while ReplicationSlotCtlLock is held */
1470 [ + + ]: 783 : if (!s->in_use)
1471 : 762 : continue;
1472 : :
1473 : : /* only logical slots are database specific, skip */
1474 [ + + ]: 21 : if (!SlotIsLogical(s))
1475 : 10 : continue;
1476 : :
1477 : : /* not our database, skip */
1478 [ + + ]: 11 : if (s->data.database != dboid)
1479 : 8 : continue;
1480 : :
1481 : : /* NB: intentionally counting invalidated slots */
1482 : :
1483 : : /* count slots with spinlock held */
1484 : 3 : SpinLockAcquire(&s->mutex);
1485 : 3 : (*nslots)++;
1486 [ + + ]: 3 : if (s->active_proc != INVALID_PROC_NUMBER)
1487 : 1 : (*nactive)++;
1488 : 3 : SpinLockRelease(&s->mutex);
1489 : : }
1490 : 54 : LWLockRelease(ReplicationSlotControlLock);
1491 : :
1492 [ + + ]: 54 : if (*nslots > 0)
1493 : 3 : return true;
1494 : 51 : return false;
1495 : : }
1496 : :
1497 : : /*
1498 : : * ReplicationSlotsDropDBSlots -- Drop all db-specific slots relating to the
1499 : : * passed database oid. The caller should hold an exclusive lock on the
1500 : : * pg_database oid for the database to prevent creation of new slots on the db
1501 : : * or replay from existing slots.
1502 : : *
1503 : : * Another session that concurrently acquires an existing slot on the target DB
1504 : : * (most likely to drop it) may cause this function to ERROR. If that happens
1505 : : * it may have dropped some but not all slots.
1506 : : *
1507 : : * This routine isn't as efficient as it could be - but we don't drop
1508 : : * databases often, especially databases with lots of slots.
1509 : : *
1510 : : * If the last logical slot in the cluster is dropped, request to disable
1511 : : * logical decoding.
1512 : : */
1513 : : void
1514 : 68 : ReplicationSlotsDropDBSlots(Oid dboid)
1515 : : {
1516 : : int i;
1517 : : bool found_valid_logicalslot;
1518 : 68 : bool dropped = false;
1519 : :
1520 [ + - ]: 68 : if (max_replication_slots + max_repack_replication_slots <= 0)
1521 : 0 : return;
1522 : :
1523 : 68 : restart:
1524 : 73 : found_valid_logicalslot = false;
1525 : 73 : LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
1526 [ + + ]: 1053 : for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
1527 : : {
1528 : : ReplicationSlot *s;
1529 : : char *slotname;
1530 : : ProcNumber active_proc;
1531 : :
1532 : 985 : s = &ReplicationSlotCtl->replication_slots[i];
1533 : :
1534 : : /* cannot change while ReplicationSlotCtlLock is held */
1535 [ + + ]: 985 : if (!s->in_use)
1536 : 955 : continue;
1537 : :
1538 : : /* only logical slots are database specific, skip */
1539 [ + + ]: 30 : if (!SlotIsLogical(s))
1540 : 11 : continue;
1541 : :
1542 : : /*
1543 : : * Check logical slots on other databases too so we can disable
1544 : : * logical decoding only if no slots in the cluster.
1545 : : */
1546 : 19 : SpinLockAcquire(&s->mutex);
1547 : 19 : found_valid_logicalslot |= (s->data.invalidated == RS_INVAL_NONE);
1548 : 19 : SpinLockRelease(&s->mutex);
1549 : :
1550 : : /* not our database, skip */
1551 [ + + ]: 19 : if (s->data.database != dboid)
1552 : 14 : continue;
1553 : :
1554 : : /* NB: intentionally including invalidated slots to drop */
1555 : :
1556 : : /* acquire slot, so ReplicationSlotDropAcquired can be reused */
1557 : 5 : SpinLockAcquire(&s->mutex);
1558 : : /* can't change while ReplicationSlotControlLock is held */
1559 : 5 : slotname = NameStr(s->data.name);
1560 : 5 : active_proc = s->active_proc;
1561 [ + - ]: 5 : if (active_proc == INVALID_PROC_NUMBER)
1562 : : {
1563 : 5 : MyReplicationSlot = s;
1564 : 5 : s->active_proc = MyProcNumber;
1565 : : }
1566 : 5 : SpinLockRelease(&s->mutex);
1567 : :
1568 : : /*
1569 : : * Even though we hold an exclusive lock on the database object a
1570 : : * logical slot for that DB can still be active, e.g. if it's
1571 : : * concurrently being dropped by a backend connected to another DB.
1572 : : *
1573 : : * That's fairly unlikely in practice, so we'll just bail out.
1574 : : *
1575 : : * The slot sync worker holds a shared lock on the database before
1576 : : * operating on synced logical slots to avoid conflict with the drop
1577 : : * happening here. The persistent synced slots are thus safe but there
1578 : : * is a possibility that the slot sync worker has created a temporary
1579 : : * slot (which stays active even on release) and we are trying to drop
1580 : : * that here. In practice, the chances of hitting this scenario are
1581 : : * less as during slot synchronization, the temporary slot is
1582 : : * immediately converted to persistent and thus is safe due to the
1583 : : * shared lock taken on the database. So, we'll just bail out in such
1584 : : * a case.
1585 : : *
1586 : : * XXX: We can consider shutting down the slot sync worker before
1587 : : * trying to drop synced temporary slots here.
1588 : : */
1589 [ - + ]: 5 : if (active_proc != INVALID_PROC_NUMBER)
1590 [ # # ]: 0 : ereport(ERROR,
1591 : : (errcode(ERRCODE_OBJECT_IN_USE),
1592 : : errmsg("replication slot \"%s\" is active for PID %d",
1593 : : slotname, GetPGProcByNumber(active_proc)->pid)));
1594 : :
1595 : : /*
1596 : : * To avoid duplicating ReplicationSlotDropAcquired() and to avoid
1597 : : * holding ReplicationSlotControlLock over filesystem operations,
1598 : : * release ReplicationSlotControlLock and use
1599 : : * ReplicationSlotDropAcquired.
1600 : : *
1601 : : * As that means the set of slots could change, restart scan from the
1602 : : * beginning each time we release the lock.
1603 : : */
1604 : 5 : LWLockRelease(ReplicationSlotControlLock);
1605 : 5 : ReplicationSlotDropAcquired(false);
1606 : 5 : dropped = true;
1607 : 5 : goto restart;
1608 : : }
1609 : 68 : LWLockRelease(ReplicationSlotControlLock);
1610 : :
1611 [ + + - + ]: 68 : if (dropped && !found_valid_logicalslot)
1612 : 0 : RequestDisableLogicalDecoding();
1613 : : }
1614 : :
1615 : : /*
1616 : : * Returns true if there is at least one in-use valid logical replication slot.
1617 : : */
1618 : : bool
1619 : 508 : CheckLogicalSlotExists(void)
1620 : : {
1621 : 508 : bool found = false;
1622 : :
1623 [ - + ]: 508 : if (max_replication_slots + max_repack_replication_slots <= 0)
1624 : 0 : return false;
1625 : :
1626 : 508 : LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
1627 [ + + ]: 7975 : for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
1628 : : {
1629 : : ReplicationSlot *s;
1630 : : bool invalidated;
1631 : :
1632 : 7475 : s = &ReplicationSlotCtl->replication_slots[i];
1633 : :
1634 : : /* cannot change while ReplicationSlotCtlLock is held */
1635 [ + + ]: 7475 : if (!s->in_use)
1636 : 7444 : continue;
1637 : :
1638 [ + + ]: 31 : if (SlotIsPhysical(s))
1639 : 20 : continue;
1640 : :
1641 : 11 : SpinLockAcquire(&s->mutex);
1642 : 11 : invalidated = s->data.invalidated != RS_INVAL_NONE;
1643 : 11 : SpinLockRelease(&s->mutex);
1644 : :
1645 [ + + ]: 11 : if (invalidated)
1646 : 3 : continue;
1647 : :
1648 : 8 : found = true;
1649 : 8 : break;
1650 : : }
1651 : 508 : LWLockRelease(ReplicationSlotControlLock);
1652 : :
1653 : 508 : return found;
1654 : : }
1655 : :
1656 : : /*
1657 : : * Check whether the server's configuration supports using replication
1658 : : * slots.
1659 : : */
1660 : : void
1661 : 1942 : CheckSlotRequirements(bool repack)
1662 : : {
1663 : : /*
1664 : : * NB: Adding a new requirement likely means that RestoreSlotFromDisk()
1665 : : * needs the same check.
1666 : : */
1667 : :
1668 [ + + - + ]: 1942 : if (!repack && max_replication_slots == 0)
1669 [ # # ]: 0 : ereport(ERROR,
1670 : : errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
1671 : : errmsg("replication slots can only be used if \"%s\" > 0",
1672 : : "max_replication_slots"));
1673 : :
1674 [ + + - + ]: 1942 : if (repack && max_repack_replication_slots == 0)
1675 [ # # ]: 0 : ereport(ERROR,
1676 : : errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
1677 : : errmsg("REPACK can only be used if \"%s\" > 0",
1678 : : "max_repack_replication_slots"));
1679 : :
1680 [ - + ]: 1942 : if (wal_level < WAL_LEVEL_REPLICA)
1681 [ # # ]: 0 : ereport(ERROR,
1682 : : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
1683 : : errmsg("replication slots can only be used if \"wal_level\" >= \"replica\"")));
1684 : 1942 : }
1685 : :
1686 : : /*
1687 : : * Check whether the user has privilege to use replication slots.
1688 : : */
1689 : : void
1690 : 608 : CheckSlotPermissions(void)
1691 : : {
1692 [ + + ]: 608 : if (!has_rolreplication(GetUserId()))
1693 [ + - ]: 5 : ereport(ERROR,
1694 : : (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
1695 : : errmsg("permission denied to use replication slots"),
1696 : : errdetail("Only roles with the %s attribute may use replication slots.",
1697 : : "REPLICATION")));
1698 : 603 : }
1699 : :
1700 : : /*
1701 : : * Reserve WAL for the currently active slot.
1702 : : *
1703 : : * Compute and set restart_lsn in a manner that's appropriate for the type of
1704 : : * the slot and concurrency safe.
1705 : : */
1706 : : void
1707 : 674 : ReplicationSlotReserveWal(void)
1708 : : {
1709 : 674 : ReplicationSlot *slot = MyReplicationSlot;
1710 : : XLogSegNo segno;
1711 : : XLogRecPtr restart_lsn;
1712 : :
1713 : : Assert(slot != NULL);
1714 : : Assert(!XLogRecPtrIsValid(slot->data.restart_lsn));
1715 : : Assert(!XLogRecPtrIsValid(slot->last_saved_restart_lsn));
1716 : :
1717 : : /*
1718 : : * The replication slot mechanism is used to prevent the removal of
1719 : : * required WAL.
1720 : : *
1721 : : * Acquire an exclusive lock to prevent the checkpoint process from
1722 : : * concurrently computing the minimum slot LSN (see
1723 : : * CheckPointReplicationSlots). This ensures that the WAL reserved for
1724 : : * replication cannot be removed during a checkpoint.
1725 : : *
1726 : : * The mechanism is reliable because if WAL reservation occurs first, the
1727 : : * checkpoint must wait for the restart_lsn update before determining the
1728 : : * minimum non-removable LSN. On the other hand, if the checkpoint happens
1729 : : * first, subsequent WAL reservations will select positions at or beyond
1730 : : * the redo pointer of that checkpoint.
1731 : : */
1732 : 674 : LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
1733 : :
1734 : : /*
1735 : : * For logical slots log a standby snapshot and start logical decoding at
1736 : : * exactly that position. That allows the slot to start up more quickly.
1737 : : * But on a standby we cannot do WAL writes, so just use the replay
1738 : : * pointer; effectively, an attempt to create a logical slot on standby
1739 : : * will cause it to wait for an xl_running_xact record to be logged
1740 : : * independently on the primary, so that a snapshot can be built using the
1741 : : * record.
1742 : : *
1743 : : * None of this is needed (or indeed helpful) for physical slots as
1744 : : * they'll start replay at the last logged checkpoint anyway. Instead,
1745 : : * return the location of the last redo LSN, where a base backup has to
1746 : : * start replay at.
1747 : : */
1748 [ + + ]: 674 : if (SlotIsPhysical(slot))
1749 : 170 : restart_lsn = GetRedoRecPtr();
1750 [ + + ]: 504 : else if (RecoveryInProgress())
1751 : 28 : restart_lsn = GetXLogReplayRecPtr(NULL);
1752 : : else
1753 : 476 : restart_lsn = GetXLogInsertRecPtr();
1754 : :
1755 : 674 : SpinLockAcquire(&slot->mutex);
1756 : 674 : slot->data.restart_lsn = restart_lsn;
1757 : 674 : SpinLockRelease(&slot->mutex);
1758 : :
1759 : : /* prevent WAL removal as fast as possible */
1760 : 674 : ReplicationSlotsComputeRequiredLSN();
1761 : :
1762 : : /* Checkpoint shouldn't remove the required WAL. */
1763 : 674 : XLByteToSeg(slot->data.restart_lsn, segno, wal_segment_size);
1764 [ - + ]: 674 : if (XLogGetLastRemovedSegno() >= segno)
1765 [ # # ]: 0 : elog(ERROR, "WAL required by replication slot %s has been removed concurrently",
1766 : : NameStr(slot->data.name));
1767 : :
1768 : 674 : LWLockRelease(ReplicationSlotAllocationLock);
1769 : :
1770 [ + + + + ]: 674 : if (!RecoveryInProgress() && SlotIsLogical(slot))
1771 : : {
1772 : : XLogRecPtr flushptr;
1773 : :
1774 : : /* make sure we have enough information to start */
1775 : 476 : flushptr = LogStandbySnapshot();
1776 : :
1777 : : /* and make sure it's fsynced to disk */
1778 : 476 : XLogFlush(flushptr);
1779 : : }
1780 : 674 : }
1781 : :
1782 : : /*
1783 : : * Report that replication slot needs to be invalidated
1784 : : */
1785 : : static void
1786 : 23 : ReportSlotInvalidation(ReplicationSlotInvalidationCause cause,
1787 : : bool terminating,
1788 : : int pid,
1789 : : NameData slotname,
1790 : : XLogRecPtr restart_lsn,
1791 : : XLogRecPtr oldestLSN,
1792 : : TransactionId snapshotConflictHorizon,
1793 : : long slot_idle_seconds)
1794 : : {
1795 : : StringInfoData err_detail;
1796 : : StringInfoData err_hint;
1797 : :
1798 : 23 : initStringInfo(&err_detail);
1799 : 23 : initStringInfo(&err_hint);
1800 : :
1801 [ + + + - : 23 : switch (cause)
- ]
1802 : : {
1803 : 7 : case RS_INVAL_WAL_REMOVED:
1804 : : {
1805 : 7 : uint64 ex = oldestLSN - restart_lsn;
1806 : :
1807 : 7 : appendStringInfo(&err_detail,
1808 : 7 : ngettext("The slot's restart_lsn %X/%08X exceeds the limit by %" PRIu64 " byte.",
1809 : : "The slot's restart_lsn %X/%08X exceeds the limit by %" PRIu64 " bytes.",
1810 : : ex),
1811 : 7 : LSN_FORMAT_ARGS(restart_lsn),
1812 : : ex);
1813 : : /* translator: %s is a GUC variable name */
1814 : 7 : appendStringInfo(&err_hint, _("You might need to increase \"%s\"."),
1815 : : "max_slot_wal_keep_size");
1816 : 7 : break;
1817 : : }
1818 : 12 : case RS_INVAL_HORIZON:
1819 : 12 : appendStringInfo(&err_detail, _("The slot conflicted with xid horizon %u."),
1820 : : snapshotConflictHorizon);
1821 : 12 : break;
1822 : :
1823 : 4 : case RS_INVAL_WAL_LEVEL:
1824 : 4 : appendStringInfoString(&err_detail, _("Logical decoding on standby requires the primary server to either set \"wal_level\" >= \"logical\" or have at least one logical slot when \"wal_level\" = \"replica\"."));
1825 : 4 : break;
1826 : :
1827 : 0 : case RS_INVAL_IDLE_TIMEOUT:
1828 : : {
1829 : : /* translator: %s is a GUC variable name */
1830 : 0 : appendStringInfo(&err_detail, _("The slot's idle time of %lds exceeds the configured \"%s\" duration of %ds."),
1831 : : slot_idle_seconds, "idle_replication_slot_timeout",
1832 : : idle_replication_slot_timeout_secs);
1833 : : /* translator: %s is a GUC variable name */
1834 : 0 : appendStringInfo(&err_hint, _("You might need to increase \"%s\"."),
1835 : : "idle_replication_slot_timeout");
1836 : 0 : break;
1837 : : }
1838 : : case RS_INVAL_NONE:
1839 : : pg_unreachable();
1840 : : }
1841 : :
1842 [ + - + + : 23 : ereport(LOG,
+ + ]
1843 : : terminating ?
1844 : : errmsg("terminating process %d to release replication slot \"%s\"",
1845 : : pid, NameStr(slotname)) :
1846 : : errmsg("invalidating obsolete replication slot \"%s\"",
1847 : : NameStr(slotname)),
1848 : : errdetail_internal("%s", err_detail.data),
1849 : : err_hint.len ? errhint("%s", err_hint.data) : 0);
1850 : :
1851 : 23 : pfree(err_detail.data);
1852 : 23 : pfree(err_hint.data);
1853 : 23 : }
1854 : :
1855 : : /*
1856 : : * Can we invalidate an idle replication slot?
1857 : : *
1858 : : * Idle timeout invalidation is allowed only when:
1859 : : *
1860 : : * 1. Idle timeout is set
1861 : : * 2. Slot has reserved WAL
1862 : : * 3. Slot is inactive
1863 : : * 4. The slot is not being synced from the primary while the server is in
1864 : : * recovery. This is because synced slots are always considered to be
1865 : : * inactive because they don't perform logical decoding to produce changes.
1866 : : */
1867 : : static inline bool
1868 : 395 : CanInvalidateIdleSlot(ReplicationSlot *s)
1869 : : {
1870 : 395 : return (idle_replication_slot_timeout_secs != 0 &&
1871 [ # # ]: 0 : XLogRecPtrIsValid(s->data.restart_lsn) &&
1872 [ - + - - ]: 395 : s->inactive_since > 0 &&
1873 [ # # # # ]: 0 : !(RecoveryInProgress() && s->data.synced));
1874 : : }
1875 : :
1876 : : /*
1877 : : * DetermineSlotInvalidationCause - Determine the cause for which a slot
1878 : : * becomes invalid among the given possible causes.
1879 : : *
1880 : : * This function sequentially checks all possible invalidation causes and
1881 : : * returns the first one for which the slot is eligible for invalidation.
1882 : : */
1883 : : static ReplicationSlotInvalidationCause
1884 : 430 : DetermineSlotInvalidationCause(uint32 possible_causes, ReplicationSlot *s,
1885 : : XLogRecPtr oldestLSN, Oid dboid,
1886 : : TransactionId snapshotConflictHorizon,
1887 : : TimestampTz *inactive_since, TimestampTz now)
1888 : : {
1889 : : Assert(possible_causes != RS_INVAL_NONE);
1890 : :
1891 [ + + ]: 430 : if (possible_causes & RS_INVAL_WAL_REMOVED)
1892 : : {
1893 : 402 : XLogRecPtr restart_lsn = s->data.restart_lsn;
1894 : :
1895 [ + + + + ]: 402 : if (XLogRecPtrIsValid(restart_lsn) &&
1896 : : restart_lsn < oldestLSN)
1897 : 7 : return RS_INVAL_WAL_REMOVED;
1898 : : }
1899 : :
1900 [ + + ]: 423 : if (possible_causes & RS_INVAL_HORIZON)
1901 : : {
1902 : : /* invalid DB oid signals a shared relation */
1903 [ + - + + ]: 24 : if (SlotIsLogical(s) &&
1904 [ + - ]: 19 : (dboid == InvalidOid || dboid == s->data.database))
1905 : : {
1906 : 24 : TransactionId effective_xmin = s->effective_xmin;
1907 : 24 : TransactionId catalog_effective_xmin = s->effective_catalog_xmin;
1908 : :
1909 [ - + - - ]: 24 : if (TransactionIdIsValid(effective_xmin) &&
1910 : 0 : TransactionIdPrecedesOrEquals(effective_xmin,
1911 : : snapshotConflictHorizon))
1912 : 0 : return RS_INVAL_HORIZON;
1913 [ + - + + ]: 48 : else if (TransactionIdIsValid(catalog_effective_xmin) &&
1914 : 24 : TransactionIdPrecedesOrEquals(catalog_effective_xmin,
1915 : : snapshotConflictHorizon))
1916 : 12 : return RS_INVAL_HORIZON;
1917 : : }
1918 : : }
1919 : :
1920 [ + + ]: 411 : if (possible_causes & RS_INVAL_WAL_LEVEL)
1921 : : {
1922 [ + - ]: 4 : if (SlotIsLogical(s))
1923 : 4 : return RS_INVAL_WAL_LEVEL;
1924 : : }
1925 : :
1926 [ + + ]: 407 : if (possible_causes & RS_INVAL_IDLE_TIMEOUT)
1927 : : {
1928 : : Assert(now > 0);
1929 : :
1930 [ - + ]: 395 : if (CanInvalidateIdleSlot(s))
1931 : : {
1932 : : /*
1933 : : * Simulate the invalidation due to idle_timeout to test the
1934 : : * timeout behavior promptly, without waiting for it to trigger
1935 : : * naturally.
1936 : : */
1937 : : #ifdef USE_INJECTION_POINTS
1938 [ # # ]: 0 : if (IS_INJECTION_POINT_ATTACHED("slot-timeout-inval"))
1939 : : {
1940 : 0 : *inactive_since = 0; /* since the beginning of time */
1941 : 0 : return RS_INVAL_IDLE_TIMEOUT;
1942 : : }
1943 : : #endif
1944 : :
1945 : : /*
1946 : : * Check if the slot needs to be invalidated due to
1947 : : * idle_replication_slot_timeout GUC.
1948 : : */
1949 [ # # ]: 0 : if (TimestampDifferenceExceedsSeconds(s->inactive_since, now,
1950 : : idle_replication_slot_timeout_secs))
1951 : : {
1952 : 0 : *inactive_since = s->inactive_since;
1953 : 0 : return RS_INVAL_IDLE_TIMEOUT;
1954 : : }
1955 : : }
1956 : : }
1957 : :
1958 : 407 : return RS_INVAL_NONE;
1959 : : }
1960 : :
1961 : : /*
1962 : : * Helper for InvalidateObsoleteReplicationSlots
1963 : : *
1964 : : * Acquires the given slot and mark it invalid, if necessary and possible.
1965 : : *
1966 : : * Returns true if the slot was invalidated.
1967 : : *
1968 : : * Set *released_lock_out if ReplicationSlotControlLock was released in the
1969 : : * interim (and in that case we're not holding the lock at return, otherwise
1970 : : * we are).
1971 : : *
1972 : : * This is inherently racy, because we release the LWLock
1973 : : * for syscalls, so caller must restart if we return true.
1974 : : */
1975 : : static bool
1976 : 469 : InvalidatePossiblyObsoleteSlot(uint32 possible_causes,
1977 : : ReplicationSlot *s,
1978 : : XLogRecPtr oldestLSN,
1979 : : Oid dboid, TransactionId snapshotConflictHorizon,
1980 : : bool *released_lock_out)
1981 : : {
1982 : 469 : int last_signaled_pid = 0;
1983 : 469 : bool released_lock = false;
1984 : 469 : bool invalidated = false;
1985 : 469 : TimestampTz inactive_since = 0;
1986 : :
1987 : : for (;;)
1988 : 7 : {
1989 : : XLogRecPtr restart_lsn;
1990 : : NameData slotname;
1991 : : ProcNumber active_proc;
1992 : 476 : int active_pid = 0;
1993 : 476 : ReplicationSlotInvalidationCause invalidation_cause = RS_INVAL_NONE;
1994 : 476 : TimestampTz now = 0;
1995 : 476 : long slot_idle_secs = 0;
1996 : :
1997 : : Assert(LWLockHeldByMeInMode(ReplicationSlotControlLock, LW_SHARED));
1998 : :
1999 [ - + ]: 476 : if (!s->in_use)
2000 : : {
2001 [ # # ]: 0 : if (released_lock)
2002 : 0 : LWLockRelease(ReplicationSlotControlLock);
2003 : 0 : break;
2004 : : }
2005 : :
2006 [ + + ]: 476 : if (possible_causes & RS_INVAL_IDLE_TIMEOUT)
2007 : : {
2008 : : /*
2009 : : * Assign the current time here to avoid system call overhead
2010 : : * while holding the spinlock in subsequent code.
2011 : : */
2012 : 416 : now = GetCurrentTimestamp();
2013 : : }
2014 : :
2015 : : /*
2016 : : * Check if the slot needs to be invalidated. If it needs to be
2017 : : * invalidated, and is not currently acquired, acquire it and mark it
2018 : : * as having been invalidated. We do this with the spinlock held to
2019 : : * avoid race conditions -- for example the restart_lsn could move
2020 : : * forward, or the slot could be dropped.
2021 : : */
2022 : 476 : SpinLockAcquire(&s->mutex);
2023 : :
2024 : 476 : restart_lsn = s->data.restart_lsn;
2025 : :
2026 : : /* we do nothing if the slot is already invalid */
2027 [ + + ]: 476 : if (s->data.invalidated == RS_INVAL_NONE)
2028 : 430 : invalidation_cause = DetermineSlotInvalidationCause(possible_causes,
2029 : : s, oldestLSN,
2030 : : dboid,
2031 : : snapshotConflictHorizon,
2032 : : &inactive_since,
2033 : : now);
2034 : :
2035 : : /* if there's no invalidation, we're done */
2036 [ + + ]: 476 : if (invalidation_cause == RS_INVAL_NONE)
2037 : : {
2038 : 453 : SpinLockRelease(&s->mutex);
2039 [ - + ]: 453 : if (released_lock)
2040 : 0 : LWLockRelease(ReplicationSlotControlLock);
2041 : 453 : break;
2042 : : }
2043 : :
2044 : 23 : slotname = s->data.name;
2045 : 23 : active_proc = s->active_proc;
2046 : :
2047 : : /*
2048 : : * If the slot can be acquired, do so and mark it invalidated
2049 : : * immediately. Otherwise we'll signal the owning process, below, and
2050 : : * retry.
2051 : : *
2052 : : * Note: Unlike other slot attributes, slot's inactive_since can't be
2053 : : * changed until the acquired slot is released or the owning process
2054 : : * is terminated. So, the inactive slot can only be invalidated
2055 : : * immediately without being terminated.
2056 : : */
2057 [ + + ]: 23 : if (active_proc == INVALID_PROC_NUMBER)
2058 : : {
2059 : 16 : MyReplicationSlot = s;
2060 : 16 : s->active_proc = MyProcNumber;
2061 : 16 : s->data.invalidated = invalidation_cause;
2062 : :
2063 : : /*
2064 : : * XXX: We should consider not overwriting restart_lsn and instead
2065 : : * just rely on .invalidated.
2066 : : */
2067 [ + + ]: 16 : if (invalidation_cause == RS_INVAL_WAL_REMOVED)
2068 : : {
2069 : 5 : s->data.restart_lsn = InvalidXLogRecPtr;
2070 : 5 : s->last_saved_restart_lsn = InvalidXLogRecPtr;
2071 : : }
2072 : :
2073 : : /* Let caller know */
2074 : 16 : invalidated = true;
2075 : : }
2076 : : else
2077 : : {
2078 : 7 : active_pid = GetPGProcByNumber(active_proc)->pid;
2079 : : Assert(active_pid != 0);
2080 : : }
2081 : :
2082 : 23 : SpinLockRelease(&s->mutex);
2083 : :
2084 : : /*
2085 : : * Calculate the idle time duration of the slot if slot is marked
2086 : : * invalidated with RS_INVAL_IDLE_TIMEOUT.
2087 : : */
2088 [ - + ]: 23 : if (invalidation_cause == RS_INVAL_IDLE_TIMEOUT)
2089 : : {
2090 : : int slot_idle_usecs;
2091 : :
2092 : 0 : TimestampDifference(inactive_since, now, &slot_idle_secs,
2093 : : &slot_idle_usecs);
2094 : : }
2095 : :
2096 [ + + ]: 23 : if (active_proc != INVALID_PROC_NUMBER)
2097 : : {
2098 : : /*
2099 : : * Prepare the sleep on the slot's condition variable before
2100 : : * releasing the lock, to close a possible race condition if the
2101 : : * slot is released before the sleep below.
2102 : : */
2103 : 7 : ConditionVariablePrepareToSleep(&s->active_cv);
2104 : :
2105 : 7 : LWLockRelease(ReplicationSlotControlLock);
2106 : 7 : released_lock = true;
2107 : :
2108 : : /*
2109 : : * Signal to terminate the process that owns the slot, if we
2110 : : * haven't already signalled it. (Avoidance of repeated
2111 : : * signalling is the only reason for there to be a loop in this
2112 : : * routine; otherwise we could rely on caller's restart loop.)
2113 : : *
2114 : : * There is the race condition that other process may own the slot
2115 : : * after its current owner process is terminated and before this
2116 : : * process owns it. To handle that, we signal only if the PID of
2117 : : * the owning process has changed from the previous time. (This
2118 : : * logic assumes that the same PID is not reused very quickly.)
2119 : : */
2120 [ + - ]: 7 : if (last_signaled_pid != active_pid)
2121 : : {
2122 : 7 : ReportSlotInvalidation(invalidation_cause, true, active_pid,
2123 : : slotname, restart_lsn,
2124 : : oldestLSN, snapshotConflictHorizon,
2125 : : slot_idle_secs);
2126 : :
2127 [ + + ]: 7 : if (MyBackendType == B_STARTUP)
2128 : 5 : (void) SignalRecoveryConflict(GetPGProcByNumber(active_proc),
2129 : : active_pid,
2130 : : RECOVERY_CONFLICT_LOGICALSLOT);
2131 : : else
2132 : 2 : (void) kill(active_pid, SIGTERM);
2133 : :
2134 : 7 : last_signaled_pid = active_pid;
2135 : : }
2136 : :
2137 : : /* Wait until the slot is released. */
2138 : 7 : ConditionVariableSleep(&s->active_cv,
2139 : : WAIT_EVENT_REPLICATION_SLOT_DROP);
2140 : :
2141 : : /*
2142 : : * Re-acquire lock and start over; we expect to invalidate the
2143 : : * slot next time (unless another process acquires the slot in the
2144 : : * meantime).
2145 : : *
2146 : : * Note: It is possible for a slot to advance its restart_lsn or
2147 : : * xmin values sufficiently between when we release the mutex and
2148 : : * when we recheck, moving from a conflicting state to a non
2149 : : * conflicting state. This is intentional and safe: if the slot
2150 : : * has caught up while we're busy here, the resources we were
2151 : : * concerned about (WAL segments or tuples) have not yet been
2152 : : * removed, and there's no reason to invalidate the slot.
2153 : : */
2154 : 7 : LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
2155 : 7 : continue;
2156 : : }
2157 : : else
2158 : : {
2159 : : /*
2160 : : * We hold the slot now and have already invalidated it; flush it
2161 : : * to ensure that state persists.
2162 : : *
2163 : : * Don't want to hold ReplicationSlotControlLock across file
2164 : : * system operations, so release it now but be sure to tell caller
2165 : : * to restart from scratch.
2166 : : */
2167 : 16 : LWLockRelease(ReplicationSlotControlLock);
2168 : 16 : released_lock = true;
2169 : :
2170 : : /* Make sure the invalidated state persists across server restart */
2171 : 16 : ReplicationSlotMarkDirty();
2172 : 16 : ReplicationSlotSave();
2173 : 16 : ReplicationSlotRelease();
2174 : :
2175 : 16 : ReportSlotInvalidation(invalidation_cause, false, active_pid,
2176 : : slotname, restart_lsn,
2177 : : oldestLSN, snapshotConflictHorizon,
2178 : : slot_idle_secs);
2179 : :
2180 : : /* done with this slot for now */
2181 : 16 : break;
2182 : : }
2183 : : }
2184 : :
2185 : : Assert(released_lock == !LWLockHeldByMe(ReplicationSlotControlLock));
2186 : :
2187 : 469 : *released_lock_out = released_lock;
2188 : 469 : return invalidated;
2189 : : }
2190 : :
2191 : : /*
2192 : : * Invalidate slots that require resources about to be removed.
2193 : : *
2194 : : * Returns true when any slot have got invalidated.
2195 : : *
2196 : : * Whether a slot needs to be invalidated depends on the invalidation cause.
2197 : : * A slot is invalidated if it:
2198 : : * - RS_INVAL_WAL_REMOVED: requires a LSN older than the given segment
2199 : : * - RS_INVAL_HORIZON: requires a snapshot <= the given horizon in the given
2200 : : * db; dboid may be InvalidOid for shared relations
2201 : : * - RS_INVAL_WAL_LEVEL: is a logical slot and effective_wal_level is not
2202 : : * logical.
2203 : : * - RS_INVAL_IDLE_TIMEOUT: has been idle longer than the configured
2204 : : * "idle_replication_slot_timeout" duration.
2205 : : *
2206 : : * Note: This function attempts to invalidate the slot for multiple possible
2207 : : * causes in a single pass, minimizing redundant iterations. The "cause"
2208 : : * parameter can be a MASK representing one or more of the defined causes.
2209 : : *
2210 : : * If it invalidates the last logical slot in the cluster, it requests to
2211 : : * disable logical decoding.
2212 : : *
2213 : : * NB - this runs as part of checkpoint, so avoid raising errors if possible.
2214 : : */
2215 : : bool
2216 : 1975 : InvalidateObsoleteReplicationSlots(uint32 possible_causes,
2217 : : XLogSegNo oldestSegno, Oid dboid,
2218 : : TransactionId snapshotConflictHorizon)
2219 : : {
2220 : : XLogRecPtr oldestLSN;
2221 : 1975 : bool invalidated = false;
2222 : 1975 : bool invalidated_logical = false;
2223 : : bool found_valid_logicalslot;
2224 : :
2225 : : Assert(!(possible_causes & RS_INVAL_HORIZON) || TransactionIdIsValid(snapshotConflictHorizon));
2226 : : Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
2227 : : Assert(possible_causes != RS_INVAL_NONE);
2228 : :
2229 [ + + - + ]: 1975 : if (max_replication_slots == 0 && max_repack_replication_slots == 0)
2230 : 0 : return invalidated;
2231 : :
2232 : 1975 : XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
2233 : :
2234 : 1991 : restart:
2235 : 1991 : found_valid_logicalslot = false;
2236 : 1991 : LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
2237 [ + + ]: 31250 : for (int i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
2238 : : {
2239 : 29275 : ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
2240 : 29275 : bool released_lock = false;
2241 : :
2242 [ + + ]: 29275 : if (!s->in_use)
2243 : 28806 : continue;
2244 : :
2245 : : /* Prevent invalidation of logical slots during binary upgrade */
2246 [ + + + + ]: 478 : if (SlotIsLogical(s) && IsBinaryUpgrade)
2247 : : {
2248 : 9 : SpinLockAcquire(&s->mutex);
2249 : 9 : found_valid_logicalslot |= (s->data.invalidated == RS_INVAL_NONE);
2250 : 9 : SpinLockRelease(&s->mutex);
2251 : :
2252 : 9 : continue;
2253 : : }
2254 : :
2255 [ + + ]: 469 : if (InvalidatePossiblyObsoleteSlot(possible_causes, s, oldestLSN,
2256 : : dboid, snapshotConflictHorizon,
2257 : : &released_lock))
2258 : : {
2259 : : Assert(released_lock);
2260 : :
2261 : : /* Remember we have invalidated a physical or logical slot */
2262 : 16 : invalidated = true;
2263 : :
2264 : : /*
2265 : : * Additionally, remember we have invalidated a logical slot as we
2266 : : * can request disabling logical decoding later.
2267 : : */
2268 [ + + ]: 16 : if (SlotIsLogical(s))
2269 : 13 : invalidated_logical = true;
2270 : : }
2271 : : else
2272 : : {
2273 : : /*
2274 : : * We need to check if the slot is invalidated here since
2275 : : * InvalidatePossiblyObsoleteSlot() returns false also if the slot
2276 : : * is already invalidated.
2277 : : */
2278 : 453 : SpinLockAcquire(&s->mutex);
2279 : 906 : found_valid_logicalslot |=
2280 [ + + + + ]: 453 : (SlotIsLogical(s) && (s->data.invalidated == RS_INVAL_NONE));
2281 : 453 : SpinLockRelease(&s->mutex);
2282 : : }
2283 : :
2284 : : /* if the lock was released, start from scratch */
2285 [ + + ]: 469 : if (released_lock)
2286 : 16 : goto restart;
2287 : : }
2288 : 1975 : LWLockRelease(ReplicationSlotControlLock);
2289 : :
2290 : : /*
2291 : : * If any slots have been invalidated, recalculate the resource limits.
2292 : : */
2293 [ + + ]: 1975 : if (invalidated)
2294 : : {
2295 : 11 : ReplicationSlotsComputeRequiredXmin(false);
2296 : 11 : ReplicationSlotsComputeRequiredLSN();
2297 : : }
2298 : :
2299 : : /*
2300 : : * Request the checkpointer to disable logical decoding if no valid
2301 : : * logical slots remain. If called by the checkpointer during a
2302 : : * checkpoint, only the request is initiated; actual deactivation is
2303 : : * deferred until after the checkpoint completes.
2304 : : */
2305 [ + + + - ]: 1975 : if (invalidated_logical && !found_valid_logicalslot)
2306 : 8 : RequestDisableLogicalDecoding();
2307 : :
2308 : 1975 : return invalidated;
2309 : : }
2310 : :
2311 : : /*
2312 : : * Flush all replication slots to disk.
2313 : : *
2314 : : * It is convenient to flush dirty replication slots at the time of checkpoint.
2315 : : * Additionally, in case of a shutdown checkpoint, we also identify the slots
2316 : : * for which the confirmed_flush LSN has been updated since the last time it
2317 : : * was saved and flush them.
2318 : : */
2319 : : void
2320 : 1949 : CheckPointReplicationSlots(bool is_shutdown)
2321 : : {
2322 : : int i;
2323 : 1949 : bool last_saved_restart_lsn_updated = false;
2324 : :
2325 [ + + ]: 1949 : elog(DEBUG1, "performing replication slot checkpoint");
2326 : :
2327 : : /*
2328 : : * Prevent any slot from being created/dropped while we're active. As we
2329 : : * explicitly do *not* want to block iterating over replication_slots or
2330 : : * acquiring a slot we cannot take the control lock - but that's OK,
2331 : : * because holding ReplicationSlotAllocationLock is strictly stronger, and
2332 : : * enough to guarantee that nobody can change the in_use bits on us.
2333 : : *
2334 : : * Additionally, acquiring the Allocation lock is necessary to serialize
2335 : : * the slot flush process with concurrent slot WAL reservation. This
2336 : : * ensures that the WAL position being reserved is either flushed to disk
2337 : : * or is beyond or equal to the redo pointer of the current checkpoint
2338 : : * (See ReplicationSlotReserveWal for details).
2339 : : */
2340 : 1949 : LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
2341 : :
2342 [ + + ]: 30903 : for (i = 0; i < max_replication_slots + max_repack_replication_slots; i++)
2343 : : {
2344 : 28954 : ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
2345 : : char path[MAXPGPATH];
2346 : :
2347 [ + + ]: 28954 : if (!s->in_use)
2348 : 28536 : continue;
2349 : :
2350 : : /* save the slot to disk, locking is handled in SaveSlotToPath() */
2351 : 418 : sprintf(path, "%s/%s", PG_REPLSLOT_DIR, NameStr(s->data.name));
2352 : :
2353 : : /*
2354 : : * Slot's data is not flushed each time the confirmed_flush LSN is
2355 : : * updated as that could lead to frequent writes. However, we decide
2356 : : * to force a flush of all logical slot's data at the time of shutdown
2357 : : * if the confirmed_flush LSN is changed since we last flushed it to
2358 : : * disk. This helps in avoiding an unnecessary retreat of the
2359 : : * confirmed_flush LSN after restart.
2360 : : */
2361 [ + + + + ]: 418 : if (is_shutdown && SlotIsLogical(s))
2362 : : {
2363 : 98 : SpinLockAcquire(&s->mutex);
2364 : :
2365 [ + + ]: 98 : if (s->data.invalidated == RS_INVAL_NONE &&
2366 [ + + ]: 97 : s->data.confirmed_flush > s->last_saved_confirmed_flush)
2367 : : {
2368 : 42 : s->just_dirtied = true;
2369 : 42 : s->dirty = true;
2370 : : }
2371 : 98 : SpinLockRelease(&s->mutex);
2372 : : }
2373 : :
2374 : : /*
2375 : : * Track if we're going to update slot's last_saved_restart_lsn. We
2376 : : * need this to know if we need to recompute the required LSN.
2377 : : */
2378 [ + + ]: 418 : if (s->last_saved_restart_lsn != s->data.restart_lsn)
2379 : 218 : last_saved_restart_lsn_updated = true;
2380 : :
2381 : 418 : SaveSlotToPath(s, path, LOG);
2382 : : }
2383 : 1949 : LWLockRelease(ReplicationSlotAllocationLock);
2384 : :
2385 : : /*
2386 : : * Recompute the required LSN if SaveSlotToPath() updated
2387 : : * last_saved_restart_lsn for any slot.
2388 : : */
2389 [ + + ]: 1949 : if (last_saved_restart_lsn_updated)
2390 : 218 : ReplicationSlotsComputeRequiredLSN();
2391 : 1949 : }
2392 : :
2393 : : /*
2394 : : * Load all replication slots from disk into memory at server startup. This
2395 : : * needs to be run before we start crash recovery.
2396 : : */
2397 : : void
2398 : 1088 : StartupReplicationSlots(void)
2399 : : {
2400 : : DIR *replication_dir;
2401 : : struct dirent *replication_de;
2402 : :
2403 [ + + ]: 1088 : elog(DEBUG1, "starting up replication slots");
2404 : :
2405 : : /* restore all slots by iterating over all on-disk entries */
2406 : 1088 : replication_dir = AllocateDir(PG_REPLSLOT_DIR);
2407 [ + + ]: 3387 : while ((replication_de = ReadDir(replication_dir, PG_REPLSLOT_DIR)) != NULL)
2408 : : {
2409 : : char path[MAXPGPATH + sizeof(PG_REPLSLOT_DIR)];
2410 : : PGFileType de_type;
2411 : :
2412 [ + + ]: 2301 : if (strcmp(replication_de->d_name, ".") == 0 ||
2413 [ + + ]: 1215 : strcmp(replication_de->d_name, "..") == 0)
2414 : 2172 : continue;
2415 : :
2416 : 129 : snprintf(path, sizeof(path), "%s/%s", PG_REPLSLOT_DIR, replication_de->d_name);
2417 : 129 : de_type = get_dirent_type(path, replication_de, false, DEBUG1);
2418 : :
2419 : : /* we're only creating directories here, skip if it's not our's */
2420 [ + - - + ]: 129 : if (de_type != PGFILETYPE_ERROR && de_type != PGFILETYPE_DIR)
2421 : 0 : continue;
2422 : :
2423 : : /* we crashed while a slot was being setup or deleted, clean up */
2424 [ - + ]: 129 : if (pg_str_endswith(replication_de->d_name, ".tmp"))
2425 : : {
2426 [ # # ]: 0 : if (!rmtree(path, true))
2427 : : {
2428 [ # # ]: 0 : ereport(WARNING,
2429 : : (errmsg("could not remove directory \"%s\"",
2430 : : path)));
2431 : 0 : continue;
2432 : : }
2433 : 0 : fsync_fname(PG_REPLSLOT_DIR, true);
2434 : 0 : continue;
2435 : : }
2436 : :
2437 : : /* looks like a slot in a normal state, restore */
2438 : 129 : RestoreSlotFromDisk(replication_de->d_name);
2439 : : }
2440 : 1086 : FreeDir(replication_dir);
2441 : :
2442 : : /* currently no slots exist, we're done. */
2443 [ - + ]: 1086 : if (max_replication_slots + max_repack_replication_slots <= 0)
2444 : 0 : return;
2445 : :
2446 : : /* Now that we have recovered all the data, compute replication xmin */
2447 : 1086 : ReplicationSlotsComputeRequiredXmin(false);
2448 : 1086 : ReplicationSlotsComputeRequiredLSN();
2449 : : }
2450 : :
2451 : : /* ----
2452 : : * Manipulation of on-disk state of replication slots
2453 : : *
2454 : : * NB: none of the routines below should take any notice whether a slot is the
2455 : : * current one or not, that's all handled a layer above.
2456 : : * ----
2457 : : */
2458 : : static void
2459 : 728 : CreateSlotOnDisk(ReplicationSlot *slot)
2460 : : {
2461 : : char tmppath[MAXPGPATH];
2462 : : char path[MAXPGPATH];
2463 : : struct stat st;
2464 : :
2465 : : /*
2466 : : * No need to take out the io_in_progress_lock, nobody else can see this
2467 : : * slot yet, so nobody else will write. We're reusing SaveSlotToPath which
2468 : : * takes out the lock, if we'd take the lock here, we'd deadlock.
2469 : : */
2470 : :
2471 : 728 : sprintf(path, "%s/%s", PG_REPLSLOT_DIR, NameStr(slot->data.name));
2472 : 728 : sprintf(tmppath, "%s/%s.tmp", PG_REPLSLOT_DIR, NameStr(slot->data.name));
2473 : :
2474 : : /*
2475 : : * It's just barely possible that some previous effort to create or drop a
2476 : : * slot with this name left a temp directory lying around. If that seems
2477 : : * to be the case, try to remove it. If the rmtree() fails, we'll error
2478 : : * out at the MakePGDirectory() below, so we don't bother checking
2479 : : * success.
2480 : : */
2481 [ - + - - ]: 728 : if (stat(tmppath, &st) == 0 && S_ISDIR(st.st_mode))
2482 : 0 : rmtree(tmppath, true);
2483 : :
2484 : : /* Create and fsync the temporary slot directory. */
2485 [ - + ]: 728 : if (MakePGDirectory(tmppath) < 0)
2486 [ # # ]: 0 : ereport(ERROR,
2487 : : (errcode_for_file_access(),
2488 : : errmsg("could not create directory \"%s\": %m",
2489 : : tmppath)));
2490 : 728 : fsync_fname(tmppath, true);
2491 : :
2492 : : /* Write the actual state file. */
2493 : 728 : slot->dirty = true; /* signal that we really need to write */
2494 : 728 : SaveSlotToPath(slot, tmppath, ERROR);
2495 : :
2496 : : /* Rename the directory into place. */
2497 [ - + ]: 728 : if (rename(tmppath, path) != 0)
2498 [ # # ]: 0 : ereport(ERROR,
2499 : : (errcode_for_file_access(),
2500 : : errmsg("could not rename file \"%s\" to \"%s\": %m",
2501 : : tmppath, path)));
2502 : :
2503 : : /*
2504 : : * If we'd now fail - really unlikely - we wouldn't know whether this slot
2505 : : * would persist after an OS crash or not - so, force a restart. The
2506 : : * restart would try to fsync this again till it works.
2507 : : */
2508 : 728 : START_CRIT_SECTION();
2509 : :
2510 : 728 : fsync_fname(path, true);
2511 : 728 : fsync_fname(PG_REPLSLOT_DIR, true);
2512 : :
2513 : 728 : END_CRIT_SECTION();
2514 : 728 : }
2515 : :
2516 : : /*
2517 : : * Shared functionality between saving and creating a replication slot.
2518 : : */
2519 : : static void
2520 : 2662 : SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel)
2521 : : {
2522 : : char tmppath[MAXPGPATH];
2523 : : char path[MAXPGPATH];
2524 : : int fd;
2525 : : ReplicationSlotOnDisk cp;
2526 : : bool was_dirty;
2527 : :
2528 : : /* first check whether there's something to write out */
2529 : 2662 : SpinLockAcquire(&slot->mutex);
2530 : 2662 : was_dirty = slot->dirty;
2531 : 2662 : slot->just_dirtied = false;
2532 : 2662 : SpinLockRelease(&slot->mutex);
2533 : :
2534 : : /* and don't do anything if there's nothing to write */
2535 [ + + ]: 2662 : if (!was_dirty)
2536 : 147 : return;
2537 : :
2538 : 2515 : LWLockAcquire(&slot->io_in_progress_lock, LW_EXCLUSIVE);
2539 : :
2540 : : /* silence valgrind :( */
2541 : 2515 : memset(&cp, 0, sizeof(ReplicationSlotOnDisk));
2542 : :
2543 : 2515 : sprintf(tmppath, "%s/state.tmp", dir);
2544 : 2515 : sprintf(path, "%s/state", dir);
2545 : :
2546 : 2515 : fd = OpenTransientFile(tmppath, O_CREAT | O_EXCL | O_WRONLY | PG_BINARY);
2547 [ - + ]: 2515 : if (fd < 0)
2548 : : {
2549 : : /*
2550 : : * If not an ERROR, then release the lock before returning. In case
2551 : : * of an ERROR, the error recovery path automatically releases the
2552 : : * lock, but no harm in explicitly releasing even in that case. Note
2553 : : * that LWLockRelease() could affect errno.
2554 : : */
2555 : 0 : int save_errno = errno;
2556 : :
2557 : 0 : LWLockRelease(&slot->io_in_progress_lock);
2558 : 0 : errno = save_errno;
2559 [ # # ]: 0 : ereport(elevel,
2560 : : (errcode_for_file_access(),
2561 : : errmsg("could not create file \"%s\": %m",
2562 : : tmppath)));
2563 : 0 : return;
2564 : : }
2565 : :
2566 : 2515 : cp.magic = SLOT_MAGIC;
2567 : 2515 : INIT_CRC32C(cp.checksum);
2568 : 2515 : cp.version = SLOT_VERSION;
2569 : 2515 : cp.length = ReplicationSlotOnDiskV2Size;
2570 : :
2571 : 2515 : SpinLockAcquire(&slot->mutex);
2572 : :
2573 : 2515 : memcpy(&cp.slotdata, &slot->data, sizeof(ReplicationSlotPersistentData));
2574 : :
2575 : 2515 : SpinLockRelease(&slot->mutex);
2576 : :
2577 : 2515 : COMP_CRC32C(cp.checksum,
2578 : : (char *) (&cp) + ReplicationSlotOnDiskNotChecksummedSize,
2579 : : ReplicationSlotOnDiskChecksummedSize);
2580 : 2515 : FIN_CRC32C(cp.checksum);
2581 : :
2582 : 2515 : errno = 0;
2583 : 2515 : pgstat_report_wait_start(WAIT_EVENT_REPLICATION_SLOT_WRITE);
2584 [ - + ]: 2515 : if ((write(fd, &cp, sizeof(cp))) != sizeof(cp))
2585 : : {
2586 : 0 : int save_errno = errno;
2587 : :
2588 : 0 : pgstat_report_wait_end();
2589 : 0 : CloseTransientFile(fd);
2590 : 0 : unlink(tmppath);
2591 : 0 : LWLockRelease(&slot->io_in_progress_lock);
2592 : :
2593 : : /* if write didn't set errno, assume problem is no disk space */
2594 [ # # ]: 0 : errno = save_errno ? save_errno : ENOSPC;
2595 [ # # ]: 0 : ereport(elevel,
2596 : : (errcode_for_file_access(),
2597 : : errmsg("could not write to file \"%s\": %m",
2598 : : tmppath)));
2599 : 0 : return;
2600 : : }
2601 : 2515 : pgstat_report_wait_end();
2602 : :
2603 : : /* fsync the temporary file */
2604 : 2515 : pgstat_report_wait_start(WAIT_EVENT_REPLICATION_SLOT_SYNC);
2605 [ - + ]: 2515 : if (pg_fsync(fd) != 0)
2606 : : {
2607 : 0 : int save_errno = errno;
2608 : :
2609 : 0 : pgstat_report_wait_end();
2610 : 0 : CloseTransientFile(fd);
2611 : 0 : unlink(tmppath);
2612 : 0 : LWLockRelease(&slot->io_in_progress_lock);
2613 : :
2614 : 0 : errno = save_errno;
2615 [ # # ]: 0 : ereport(elevel,
2616 : : (errcode_for_file_access(),
2617 : : errmsg("could not fsync file \"%s\": %m",
2618 : : tmppath)));
2619 : 0 : return;
2620 : : }
2621 : 2515 : pgstat_report_wait_end();
2622 : :
2623 [ - + ]: 2515 : if (CloseTransientFile(fd) != 0)
2624 : : {
2625 : 0 : int save_errno = errno;
2626 : :
2627 : 0 : unlink(tmppath);
2628 : 0 : LWLockRelease(&slot->io_in_progress_lock);
2629 : :
2630 : 0 : errno = save_errno;
2631 [ # # ]: 0 : ereport(elevel,
2632 : : (errcode_for_file_access(),
2633 : : errmsg("could not close file \"%s\": %m",
2634 : : tmppath)));
2635 : 0 : return;
2636 : : }
2637 : :
2638 : : /* rename to permanent file, fsync file and directory */
2639 [ - + ]: 2515 : if (rename(tmppath, path) != 0)
2640 : : {
2641 : 0 : int save_errno = errno;
2642 : :
2643 : 0 : unlink(tmppath);
2644 : 0 : LWLockRelease(&slot->io_in_progress_lock);
2645 : :
2646 : 0 : errno = save_errno;
2647 [ # # ]: 0 : ereport(elevel,
2648 : : (errcode_for_file_access(),
2649 : : errmsg("could not rename file \"%s\" to \"%s\": %m",
2650 : : tmppath, path)));
2651 : 0 : return;
2652 : : }
2653 : :
2654 : : /*
2655 : : * Check CreateSlotOnDisk() for the reasoning of using a critical section.
2656 : : */
2657 : 2515 : START_CRIT_SECTION();
2658 : :
2659 : 2515 : fsync_fname(path, false);
2660 : 2515 : fsync_fname(dir, true);
2661 : 2515 : fsync_fname(PG_REPLSLOT_DIR, true);
2662 : :
2663 : 2515 : END_CRIT_SECTION();
2664 : :
2665 : : /*
2666 : : * Successfully wrote, unset dirty bit, unless somebody dirtied again
2667 : : * already and remember the confirmed_flush LSN value.
2668 : : */
2669 : 2515 : SpinLockAcquire(&slot->mutex);
2670 [ + + ]: 2515 : if (!slot->just_dirtied)
2671 : 2489 : slot->dirty = false;
2672 : 2515 : slot->last_saved_confirmed_flush = cp.slotdata.confirmed_flush;
2673 : 2515 : slot->last_saved_restart_lsn = cp.slotdata.restart_lsn;
2674 : 2515 : SpinLockRelease(&slot->mutex);
2675 : :
2676 : 2515 : LWLockRelease(&slot->io_in_progress_lock);
2677 : : }
2678 : :
2679 : : /*
2680 : : * Load a single slot from disk into memory.
2681 : : */
2682 : : static void
2683 : 129 : RestoreSlotFromDisk(const char *name)
2684 : : {
2685 : : ReplicationSlotOnDisk cp;
2686 : : int i;
2687 : : char slotdir[MAXPGPATH + sizeof(PG_REPLSLOT_DIR)];
2688 : : char path[MAXPGPATH + sizeof(PG_REPLSLOT_DIR) + 10];
2689 : : int fd;
2690 : 129 : bool restored = false;
2691 : : int readBytes;
2692 : : pg_crc32c checksum;
2693 : 129 : TimestampTz now = 0;
2694 : :
2695 : : /* no need to lock here, no concurrent access allowed yet */
2696 : :
2697 : : /* delete temp file if it exists */
2698 : 129 : sprintf(slotdir, "%s/%s", PG_REPLSLOT_DIR, name);
2699 : 129 : sprintf(path, "%s/state.tmp", slotdir);
2700 [ + - - + ]: 129 : if (unlink(path) < 0 && errno != ENOENT)
2701 [ # # ]: 0 : ereport(PANIC,
2702 : : (errcode_for_file_access(),
2703 : : errmsg("could not remove file \"%s\": %m", path)));
2704 : :
2705 : 129 : sprintf(path, "%s/state", slotdir);
2706 : :
2707 [ + + ]: 129 : elog(DEBUG1, "restoring replication slot from \"%s\"", path);
2708 : :
2709 : : /* on some operating systems fsyncing a file requires O_RDWR */
2710 : 129 : fd = OpenTransientFile(path, O_RDWR | PG_BINARY);
2711 : :
2712 : : /*
2713 : : * We do not need to handle this as we are rename()ing the directory into
2714 : : * place only after we fsync()ed the state file.
2715 : : */
2716 [ - + ]: 129 : if (fd < 0)
2717 [ # # ]: 0 : ereport(PANIC,
2718 : : (errcode_for_file_access(),
2719 : : errmsg("could not open file \"%s\": %m", path)));
2720 : :
2721 : : /*
2722 : : * Sync state file before we're reading from it. We might have crashed
2723 : : * while it wasn't synced yet and we shouldn't continue on that basis.
2724 : : */
2725 : 129 : pgstat_report_wait_start(WAIT_EVENT_REPLICATION_SLOT_RESTORE_SYNC);
2726 [ - + ]: 129 : if (pg_fsync(fd) != 0)
2727 [ # # ]: 0 : ereport(PANIC,
2728 : : (errcode_for_file_access(),
2729 : : errmsg("could not fsync file \"%s\": %m",
2730 : : path)));
2731 : 129 : pgstat_report_wait_end();
2732 : :
2733 : : /* Also sync the parent directory */
2734 : 129 : START_CRIT_SECTION();
2735 : 129 : fsync_fname(slotdir, true);
2736 : 129 : END_CRIT_SECTION();
2737 : :
2738 : : /* read part of statefile that's guaranteed to be version independent */
2739 : 129 : pgstat_report_wait_start(WAIT_EVENT_REPLICATION_SLOT_READ);
2740 : 129 : readBytes = read(fd, &cp, ReplicationSlotOnDiskConstantSize);
2741 : 129 : pgstat_report_wait_end();
2742 [ - + ]: 129 : if (readBytes != ReplicationSlotOnDiskConstantSize)
2743 : : {
2744 [ # # ]: 0 : if (readBytes < 0)
2745 [ # # ]: 0 : ereport(PANIC,
2746 : : (errcode_for_file_access(),
2747 : : errmsg("could not read file \"%s\": %m", path)));
2748 : : else
2749 [ # # ]: 0 : ereport(PANIC,
2750 : : (errcode(ERRCODE_DATA_CORRUPTED),
2751 : : errmsg("could not read file \"%s\": read %d of %zu",
2752 : : path, readBytes,
2753 : : (Size) ReplicationSlotOnDiskConstantSize)));
2754 : : }
2755 : :
2756 : : /* verify magic */
2757 [ - + ]: 129 : if (cp.magic != SLOT_MAGIC)
2758 [ # # ]: 0 : ereport(PANIC,
2759 : : (errcode(ERRCODE_DATA_CORRUPTED),
2760 : : errmsg("replication slot file \"%s\" has wrong magic number: %u instead of %u",
2761 : : path, cp.magic, SLOT_MAGIC)));
2762 : :
2763 : : /* verify version */
2764 [ - + ]: 129 : if (cp.version != SLOT_VERSION)
2765 [ # # ]: 0 : ereport(PANIC,
2766 : : (errcode(ERRCODE_DATA_CORRUPTED),
2767 : : errmsg("replication slot file \"%s\" has unsupported version %u",
2768 : : path, cp.version)));
2769 : :
2770 : : /* boundary check on length */
2771 [ - + ]: 129 : if (cp.length != ReplicationSlotOnDiskV2Size)
2772 [ # # ]: 0 : ereport(PANIC,
2773 : : (errcode(ERRCODE_DATA_CORRUPTED),
2774 : : errmsg("replication slot file \"%s\" has corrupted length %u",
2775 : : path, cp.length)));
2776 : :
2777 : : /* Now that we know the size, read the entire file */
2778 : 129 : pgstat_report_wait_start(WAIT_EVENT_REPLICATION_SLOT_READ);
2779 : 258 : readBytes = read(fd,
2780 : : (char *) &cp + ReplicationSlotOnDiskConstantSize,
2781 : 129 : cp.length);
2782 : 129 : pgstat_report_wait_end();
2783 [ - + ]: 129 : if (readBytes != cp.length)
2784 : : {
2785 [ # # ]: 0 : if (readBytes < 0)
2786 [ # # ]: 0 : ereport(PANIC,
2787 : : (errcode_for_file_access(),
2788 : : errmsg("could not read file \"%s\": %m", path)));
2789 : : else
2790 [ # # ]: 0 : ereport(PANIC,
2791 : : (errcode(ERRCODE_DATA_CORRUPTED),
2792 : : errmsg("could not read file \"%s\": read %d of %zu",
2793 : : path, readBytes, (Size) cp.length)));
2794 : : }
2795 : :
2796 [ - + ]: 129 : if (CloseTransientFile(fd) != 0)
2797 [ # # ]: 0 : ereport(PANIC,
2798 : : (errcode_for_file_access(),
2799 : : errmsg("could not close file \"%s\": %m", path)));
2800 : :
2801 : : /* now verify the CRC */
2802 : 129 : INIT_CRC32C(checksum);
2803 : 129 : COMP_CRC32C(checksum,
2804 : : (char *) &cp + ReplicationSlotOnDiskNotChecksummedSize,
2805 : : ReplicationSlotOnDiskChecksummedSize);
2806 : 129 : FIN_CRC32C(checksum);
2807 : :
2808 [ - + ]: 129 : if (!EQ_CRC32C(checksum, cp.checksum))
2809 [ # # ]: 0 : ereport(PANIC,
2810 : : (errmsg("checksum mismatch for replication slot file \"%s\": is %u, should be %u",
2811 : : path, checksum, cp.checksum)));
2812 : :
2813 : : /*
2814 : : * If we crashed with an ephemeral slot active, don't restore but delete
2815 : : * it.
2816 : : */
2817 [ - + ]: 129 : if (cp.slotdata.persistency != RS_PERSISTENT)
2818 : : {
2819 [ # # ]: 0 : if (!rmtree(slotdir, true))
2820 : : {
2821 [ # # ]: 0 : ereport(WARNING,
2822 : : (errmsg("could not remove directory \"%s\"",
2823 : : slotdir)));
2824 : : }
2825 : 0 : fsync_fname(PG_REPLSLOT_DIR, true);
2826 : 0 : return;
2827 : : }
2828 : :
2829 : : /*
2830 : : * Verify that requirements for the specific slot type are met. That's
2831 : : * important because if these aren't met we're not guaranteed to retain
2832 : : * all the necessary resources for the slot.
2833 : : *
2834 : : * NB: We have to do so *after* the above checks for ephemeral slots,
2835 : : * because otherwise a slot that shouldn't exist anymore could prevent
2836 : : * restarts.
2837 : : *
2838 : : * NB: Changing the requirements here also requires adapting
2839 : : * CheckSlotRequirements() and CheckLogicalDecodingRequirements().
2840 : : */
2841 [ + + ]: 129 : if (cp.slotdata.database != InvalidOid)
2842 : : {
2843 [ + + ]: 90 : if (wal_level < WAL_LEVEL_REPLICA)
2844 [ + - ]: 1 : ereport(FATAL,
2845 : : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
2846 : : errmsg("logical replication slot \"%s\" exists, but \"wal_level\" < \"replica\"",
2847 : : NameStr(cp.slotdata.name)),
2848 : : errhint("Change \"wal_level\" to be \"replica\" or higher.")));
2849 : :
2850 : : /*
2851 : : * In standby mode, the hot standby must be enabled. This check is
2852 : : * necessary to ensure logical slots are invalidated when they become
2853 : : * incompatible due to insufficient wal_level. Otherwise, if the
2854 : : * primary reduces effective_wal_level < logical while hot standby is
2855 : : * disabled, primary disable logical decoding while hot standby is
2856 : : * disabled, logical slots would remain valid even after promotion.
2857 : : */
2858 [ + + + + ]: 89 : if (StandbyMode && !EnableHotStandby)
2859 [ + - ]: 1 : ereport(FATAL,
2860 : : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
2861 : : errmsg("logical replication slot \"%s\" exists on the standby, but \"hot_standby\" = \"off\"",
2862 : : NameStr(cp.slotdata.name)),
2863 : : errhint("Change \"hot_standby\" to be \"on\".")));
2864 : : }
2865 [ - + ]: 39 : else if (wal_level < WAL_LEVEL_REPLICA)
2866 [ # # ]: 0 : ereport(FATAL,
2867 : : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
2868 : : errmsg("physical replication slot \"%s\" exists, but \"wal_level\" < \"replica\"",
2869 : : NameStr(cp.slotdata.name)),
2870 : : errhint("Change \"wal_level\" to be \"replica\" or higher.")));
2871 : :
2872 : : /*
2873 : : * Nothing can be active yet, don't lock anything. Note we iterate up to
2874 : : * max_replication_slots instead of adding max_repack_replication_slots as
2875 : : * in all other places, because we must enforce the GUC value in case
2876 : : * there were more slots before the shutdown than what it is set up to
2877 : : * now.
2878 : : */
2879 [ + - ]: 188 : for (i = 0; i < max_replication_slots; i++)
2880 : : {
2881 : : ReplicationSlot *slot;
2882 : :
2883 : 188 : slot = &ReplicationSlotCtl->replication_slots[i];
2884 : :
2885 [ + + ]: 188 : if (slot->in_use)
2886 : 61 : continue;
2887 : :
2888 : : /* restore the entire set of persistent data */
2889 : 127 : memcpy(&slot->data, &cp.slotdata,
2890 : : sizeof(ReplicationSlotPersistentData));
2891 : :
2892 : : /* initialize in memory state */
2893 : 127 : slot->effective_xmin = cp.slotdata.xmin;
2894 : 127 : slot->effective_catalog_xmin = cp.slotdata.catalog_xmin;
2895 : 127 : slot->last_saved_confirmed_flush = cp.slotdata.confirmed_flush;
2896 : 127 : slot->last_saved_restart_lsn = cp.slotdata.restart_lsn;
2897 : :
2898 : 127 : slot->candidate_catalog_xmin = InvalidTransactionId;
2899 : 127 : slot->candidate_xmin_lsn = InvalidXLogRecPtr;
2900 : 127 : slot->candidate_restart_lsn = InvalidXLogRecPtr;
2901 : 127 : slot->candidate_restart_valid = InvalidXLogRecPtr;
2902 : :
2903 : 127 : slot->in_use = true;
2904 : 127 : slot->active_proc = INVALID_PROC_NUMBER;
2905 : :
2906 : : /*
2907 : : * Set the time since the slot has become inactive after loading the
2908 : : * slot from the disk into memory. Whoever acquires the slot i.e.
2909 : : * makes the slot active will reset it. Use the same inactive_since
2910 : : * time for all the slots.
2911 : : */
2912 [ + - ]: 127 : if (now == 0)
2913 : 127 : now = GetCurrentTimestamp();
2914 : :
2915 : 127 : ReplicationSlotSetInactiveSince(slot, now, false);
2916 : :
2917 : 127 : restored = true;
2918 : 127 : break;
2919 : : }
2920 : :
2921 [ - + ]: 127 : if (!restored)
2922 [ # # ]: 0 : ereport(FATAL,
2923 : : (errmsg("too many replication slots active before shutdown"),
2924 : : errhint("Increase \"max_replication_slots\" and try again.")));
2925 : : }
2926 : :
2927 : : /*
2928 : : * Maps an invalidation reason for a replication slot to
2929 : : * ReplicationSlotInvalidationCause.
2930 : : */
2931 : : ReplicationSlotInvalidationCause
2932 : 0 : GetSlotInvalidationCause(const char *cause_name)
2933 : : {
2934 : : Assert(cause_name);
2935 : :
2936 : : /* Search lookup table for the cause having this name */
2937 [ # # ]: 0 : for (int i = 0; i <= RS_INVAL_MAX_CAUSES; i++)
2938 : : {
2939 [ # # ]: 0 : if (strcmp(SlotInvalidationCauses[i].cause_name, cause_name) == 0)
2940 : 0 : return SlotInvalidationCauses[i].cause;
2941 : : }
2942 : :
2943 : : Assert(false);
2944 : 0 : return RS_INVAL_NONE; /* to keep compiler quiet */
2945 : : }
2946 : :
2947 : : /*
2948 : : * Maps a ReplicationSlotInvalidationCause to the invalidation
2949 : : * reason for a replication slot.
2950 : : */
2951 : : const char *
2952 : 45 : GetSlotInvalidationCauseName(ReplicationSlotInvalidationCause cause)
2953 : : {
2954 : : /* Search lookup table for the name of this cause */
2955 [ + - ]: 146 : for (int i = 0; i <= RS_INVAL_MAX_CAUSES; i++)
2956 : : {
2957 [ + + ]: 146 : if (SlotInvalidationCauses[i].cause == cause)
2958 : 45 : return SlotInvalidationCauses[i].cause_name;
2959 : : }
2960 : :
2961 : : Assert(false);
2962 : 0 : return "none"; /* to keep compiler quiet */
2963 : : }
2964 : :
2965 : : /*
2966 : : * A helper function to validate slots specified in GUC synchronized_standby_slots.
2967 : : *
2968 : : * The rawname will be parsed, and the result will be saved into *elemlist.
2969 : : */
2970 : : static bool
2971 : 28 : validate_sync_standby_slots(char *rawname, List **elemlist)
2972 : : {
2973 : : /* Verify syntax and parse string into a list of identifiers */
2974 [ - + ]: 28 : if (!SplitIdentifierString(rawname, ',', elemlist))
2975 : : {
2976 : 0 : GUC_check_errdetail("List syntax is invalid.");
2977 : 0 : return false;
2978 : : }
2979 : :
2980 : : /* Iterate the list to validate each slot name */
2981 [ + - + + : 80 : foreach_ptr(char, name, *elemlist)
+ + ]
2982 : : {
2983 : : int err_code;
2984 : 28 : char *err_msg = NULL;
2985 : 28 : char *err_hint = NULL;
2986 : :
2987 [ + + ]: 28 : if (!ReplicationSlotValidateNameInternal(name, false, &err_code,
2988 : : &err_msg, &err_hint))
2989 : : {
2990 : 2 : GUC_check_errcode(err_code);
2991 : 2 : GUC_check_errdetail("%s", err_msg);
2992 [ + - ]: 2 : if (err_hint != NULL)
2993 : 2 : GUC_check_errhint("%s", err_hint);
2994 : 2 : return false;
2995 : : }
2996 : : }
2997 : :
2998 : 26 : return true;
2999 : : }
3000 : :
3001 : : /*
3002 : : * GUC check_hook for synchronized_standby_slots
3003 : : */
3004 : : bool
3005 : 1332 : check_synchronized_standby_slots(char **newval, void **extra, GucSource source)
3006 : : {
3007 : : char *rawname;
3008 : : char *ptr;
3009 : : List *elemlist;
3010 : : int size;
3011 : : bool ok;
3012 : : SyncStandbySlotsConfigData *config;
3013 : :
3014 [ + + ]: 1332 : if ((*newval)[0] == '\0')
3015 : 1304 : return true;
3016 : :
3017 : : /* Need a modifiable copy of the GUC string */
3018 : 28 : rawname = pstrdup(*newval);
3019 : :
3020 : : /* Now verify if the specified slots exist and have correct type */
3021 : 28 : ok = validate_sync_standby_slots(rawname, &elemlist);
3022 : :
3023 [ + + - + ]: 28 : if (!ok || elemlist == NIL)
3024 : : {
3025 : 2 : pfree(rawname);
3026 : 2 : list_free(elemlist);
3027 : 2 : return ok;
3028 : : }
3029 : :
3030 : : /* Compute the size required for the SyncStandbySlotsConfigData struct */
3031 : 26 : size = offsetof(SyncStandbySlotsConfigData, slot_names);
3032 [ + - + + : 78 : foreach_ptr(char, slot_name, elemlist)
+ + ]
3033 : 26 : size += strlen(slot_name) + 1;
3034 : :
3035 : : /* GUC extra value must be guc_malloc'd, not palloc'd */
3036 : 26 : config = (SyncStandbySlotsConfigData *) guc_malloc(LOG, size);
3037 [ - + ]: 26 : if (!config)
3038 : 0 : return false;
3039 : :
3040 : : /* Transform the data into SyncStandbySlotsConfigData */
3041 : 26 : config->nslotnames = list_length(elemlist);
3042 : :
3043 : 26 : ptr = config->slot_names;
3044 [ + - + + : 78 : foreach_ptr(char, slot_name, elemlist)
+ + ]
3045 : : {
3046 : 26 : strcpy(ptr, slot_name);
3047 : 26 : ptr += strlen(slot_name) + 1;
3048 : : }
3049 : :
3050 : 26 : *extra = config;
3051 : :
3052 : 26 : pfree(rawname);
3053 : 26 : list_free(elemlist);
3054 : 26 : return true;
3055 : : }
3056 : :
3057 : : /*
3058 : : * GUC assign_hook for synchronized_standby_slots
3059 : : */
3060 : : void
3061 : 1329 : assign_synchronized_standby_slots(const char *newval, void *extra)
3062 : : {
3063 : : /*
3064 : : * The standby slots may have changed, so we must recompute the oldest
3065 : : * LSN.
3066 : : */
3067 : 1329 : ss_oldest_flush_lsn = InvalidXLogRecPtr;
3068 : :
3069 : 1329 : synchronized_standby_slots_config = (SyncStandbySlotsConfigData *) extra;
3070 : 1329 : }
3071 : :
3072 : : /*
3073 : : * Check if the passed slot_name is specified in the synchronized_standby_slots GUC.
3074 : : */
3075 : : bool
3076 : 40735 : SlotExistsInSyncStandbySlots(const char *slot_name)
3077 : : {
3078 : : const char *standby_slot_name;
3079 : :
3080 : : /* Return false if there is no value in synchronized_standby_slots */
3081 [ + + ]: 40735 : if (synchronized_standby_slots_config == NULL)
3082 : 40720 : return false;
3083 : :
3084 : : /*
3085 : : * XXX: We are not expecting this list to be long so a linear search
3086 : : * shouldn't hurt but if that turns out not to be true then we can cache
3087 : : * this information for each WalSender as well.
3088 : : */
3089 : 15 : standby_slot_name = synchronized_standby_slots_config->slot_names;
3090 [ + + ]: 22 : for (int i = 0; i < synchronized_standby_slots_config->nslotnames; i++)
3091 : : {
3092 [ + + ]: 15 : if (strcmp(standby_slot_name, slot_name) == 0)
3093 : 8 : return true;
3094 : :
3095 : 7 : standby_slot_name += strlen(standby_slot_name) + 1;
3096 : : }
3097 : :
3098 : 7 : return false;
3099 : : }
3100 : :
3101 : : /*
3102 : : * Return true if the slots specified in synchronized_standby_slots have caught up to
3103 : : * the given WAL location, false otherwise.
3104 : : *
3105 : : * The elevel parameter specifies the error level used for logging messages
3106 : : * related to slots that do not exist, are invalidated, or are inactive.
3107 : : */
3108 : : bool
3109 : 2790 : StandbySlotsHaveCaughtup(XLogRecPtr wait_for_lsn, int elevel)
3110 : : {
3111 : : const char *name;
3112 : 2790 : int caught_up_slot_num = 0;
3113 : 2790 : XLogRecPtr min_restart_lsn = InvalidXLogRecPtr;
3114 : :
3115 : : /*
3116 : : * Don't need to wait for the standbys to catch up if there is no value in
3117 : : * synchronized_standby_slots.
3118 : : */
3119 [ + + ]: 2790 : if (synchronized_standby_slots_config == NULL)
3120 : 2756 : return true;
3121 : :
3122 : : /*
3123 : : * Don't need to wait for the standbys to catch up if we are on a standby
3124 : : * server, since we do not support syncing slots to cascading standbys.
3125 : : */
3126 [ - + ]: 34 : if (RecoveryInProgress())
3127 : 0 : return true;
3128 : :
3129 : : /*
3130 : : * Don't need to wait for the standbys to catch up if they are already
3131 : : * beyond the specified WAL location.
3132 : : */
3133 [ + + ]: 34 : if (XLogRecPtrIsValid(ss_oldest_flush_lsn) &&
3134 [ + + ]: 18 : ss_oldest_flush_lsn >= wait_for_lsn)
3135 : 9 : return true;
3136 : :
3137 : : /*
3138 : : * To prevent concurrent slot dropping and creation while filtering the
3139 : : * slots, take the ReplicationSlotControlLock outside of the loop.
3140 : : */
3141 : 25 : LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
3142 : :
3143 : 25 : name = synchronized_standby_slots_config->slot_names;
3144 [ + + ]: 33 : for (int i = 0; i < synchronized_standby_slots_config->nslotnames; i++)
3145 : : {
3146 : : XLogRecPtr restart_lsn;
3147 : : bool invalidated;
3148 : : bool inactive;
3149 : : ReplicationSlot *slot;
3150 : :
3151 : 25 : slot = SearchNamedReplicationSlot(name, false);
3152 : :
3153 : : /*
3154 : : * If a slot name provided in synchronized_standby_slots does not
3155 : : * exist, report a message and exit the loop.
3156 : : */
3157 [ - + ]: 25 : if (!slot)
3158 : : {
3159 [ # # ]: 0 : ereport(elevel,
3160 : : errcode(ERRCODE_INVALID_PARAMETER_VALUE),
3161 : : errmsg("replication slot \"%s\" specified in parameter \"%s\" does not exist",
3162 : : name, "synchronized_standby_slots"),
3163 : : errdetail("Logical replication is waiting on the standby associated with replication slot \"%s\".",
3164 : : name),
3165 : : errhint("Create the replication slot \"%s\" or amend parameter \"%s\".",
3166 : : name, "synchronized_standby_slots"));
3167 : 0 : break;
3168 : : }
3169 : :
3170 : : /* Same as above: if a slot is not physical, exit the loop. */
3171 [ - + ]: 25 : if (SlotIsLogical(slot))
3172 : : {
3173 [ # # ]: 0 : ereport(elevel,
3174 : : errcode(ERRCODE_INVALID_PARAMETER_VALUE),
3175 : : errmsg("cannot specify logical replication slot \"%s\" in parameter \"%s\"",
3176 : : name, "synchronized_standby_slots"),
3177 : : errdetail("Logical replication is waiting for correction on replication slot \"%s\".",
3178 : : name),
3179 : : errhint("Remove the logical replication slot \"%s\" from parameter \"%s\".",
3180 : : name, "synchronized_standby_slots"));
3181 : 0 : break;
3182 : : }
3183 : :
3184 : 25 : SpinLockAcquire(&slot->mutex);
3185 : 25 : restart_lsn = slot->data.restart_lsn;
3186 : 25 : invalidated = slot->data.invalidated != RS_INVAL_NONE;
3187 : 25 : inactive = slot->active_proc == INVALID_PROC_NUMBER;
3188 : 25 : SpinLockRelease(&slot->mutex);
3189 : :
3190 [ - + ]: 25 : if (invalidated)
3191 : : {
3192 : : /* Specified physical slot has been invalidated */
3193 [ # # ]: 0 : ereport(elevel,
3194 : : errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
3195 : : errmsg("physical replication slot \"%s\" specified in parameter \"%s\" has been invalidated",
3196 : : name, "synchronized_standby_slots"),
3197 : : errdetail("Logical replication is waiting on the standby associated with replication slot \"%s\".",
3198 : : name),
3199 : : errhint("Drop and recreate the replication slot \"%s\", or amend parameter \"%s\".",
3200 : : name, "synchronized_standby_slots"));
3201 : 0 : break;
3202 : : }
3203 : :
3204 [ + + + + ]: 25 : if (!XLogRecPtrIsValid(restart_lsn) || restart_lsn < wait_for_lsn)
3205 : : {
3206 : : /* Log a message if no active_pid for this physical slot */
3207 [ + + ]: 17 : if (inactive)
3208 [ + - ]: 13 : ereport(elevel,
3209 : : errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
3210 : : errmsg("replication slot \"%s\" specified in parameter \"%s\" does not have active_pid",
3211 : : name, "synchronized_standby_slots"),
3212 : : errdetail("Logical replication is waiting on the standby associated with replication slot \"%s\".",
3213 : : name),
3214 : : errhint("Start the standby associated with the replication slot \"%s\", or amend parameter \"%s\".",
3215 : : name, "synchronized_standby_slots"));
3216 : :
3217 : : /* Continue if the current slot hasn't caught up. */
3218 : 16 : break;
3219 : : }
3220 : :
3221 : : Assert(restart_lsn >= wait_for_lsn);
3222 : :
3223 [ - + - - ]: 8 : if (!XLogRecPtrIsValid(min_restart_lsn) ||
3224 : : min_restart_lsn > restart_lsn)
3225 : 8 : min_restart_lsn = restart_lsn;
3226 : :
3227 : 8 : caught_up_slot_num++;
3228 : :
3229 : 8 : name += strlen(name) + 1;
3230 : : }
3231 : :
3232 : 24 : LWLockRelease(ReplicationSlotControlLock);
3233 : :
3234 : : /*
3235 : : * Return false if not all the standbys have caught up to the specified
3236 : : * WAL location.
3237 : : */
3238 [ + + ]: 24 : if (caught_up_slot_num != synchronized_standby_slots_config->nslotnames)
3239 : 16 : return false;
3240 : :
3241 : : /* The ss_oldest_flush_lsn must not retreat. */
3242 : : Assert(!XLogRecPtrIsValid(ss_oldest_flush_lsn) ||
3243 : : min_restart_lsn >= ss_oldest_flush_lsn);
3244 : :
3245 : 8 : ss_oldest_flush_lsn = min_restart_lsn;
3246 : :
3247 : 8 : return true;
3248 : : }
3249 : :
3250 : : /*
3251 : : * Wait for physical standbys to confirm receiving the given lsn.
3252 : : *
3253 : : * Used by logical decoding SQL functions. It waits for physical standbys
3254 : : * corresponding to the physical slots specified in the synchronized_standby_slots GUC.
3255 : : */
3256 : : void
3257 : 236 : WaitForStandbyConfirmation(XLogRecPtr wait_for_lsn)
3258 : : {
3259 : : /*
3260 : : * Don't need to wait for the standby to catch up if the current acquired
3261 : : * slot is not a logical failover slot, or there is no value in
3262 : : * synchronized_standby_slots.
3263 : : */
3264 [ + + + + ]: 236 : if (!MyReplicationSlot->data.failover || !synchronized_standby_slots_config)
3265 : 235 : return;
3266 : :
3267 : 1 : ConditionVariablePrepareToSleep(&WalSndCtl->wal_confirm_rcv_cv);
3268 : :
3269 : : for (;;)
3270 : : {
3271 [ - + ]: 2 : CHECK_FOR_INTERRUPTS();
3272 : :
3273 [ + + ]: 2 : if (ConfigReloadPending)
3274 : : {
3275 : 1 : ConfigReloadPending = false;
3276 : 1 : ProcessConfigFile(PGC_SIGHUP);
3277 : : }
3278 : :
3279 : : /* Exit if done waiting for every slot. */
3280 [ + + ]: 2 : if (StandbySlotsHaveCaughtup(wait_for_lsn, WARNING))
3281 : 1 : break;
3282 : :
3283 : : /*
3284 : : * Wait for the slots in the synchronized_standby_slots to catch up,
3285 : : * but use a timeout (1s) so we can also check if the
3286 : : * synchronized_standby_slots has been changed.
3287 : : */
3288 : 1 : ConditionVariableTimedSleep(&WalSndCtl->wal_confirm_rcv_cv, 1000,
3289 : : WAIT_EVENT_WAIT_FOR_STANDBY_CONFIRMATION);
3290 : : }
3291 : :
3292 : 1 : ConditionVariableCancelSleep();
3293 : : }
|
