/* * Rebuild the event trigger cache. */ static void BuildEventTriggerCache(void) { HASHCTL ctl; HTAB *cache; MemoryContext oldcontext; Relation rel; Relation irel; SysScanDesc scan; if (EventTriggerCacheContext != NULL) { /* * Free up any memory already allocated in EventTriggerCacheContext. * This can happen either because a previous rebuild failed, or * because an invalidation happened before the rebuild was complete. */ MemoryContextResetAndDeleteChildren(EventTriggerCacheContext); } else { /* * This is our first time attempting to build the cache, so we need * to set up the memory context and register a syscache callback to * capture future invalidation events. */ if (CacheMemoryContext == NULL) CreateCacheMemoryContext(); EventTriggerCacheContext = AllocSetContextCreate(CacheMemoryContext, "EventTriggerCache", ALLOCSET_DEFAULT_MINSIZE, ALLOCSET_DEFAULT_INITSIZE, ALLOCSET_DEFAULT_MAXSIZE); CacheRegisterSyscacheCallback(EVENTTRIGGEROID, InvalidateEventCacheCallback, (Datum) 0); } /* Switch to correct memory context. */ oldcontext = MemoryContextSwitchTo(EventTriggerCacheContext); /* Prevent the memory context from being nuked while we're rebuilding. */ EventTriggerCacheState = ETCS_REBUILD_STARTED; /* Create new hash table. */ MemSet(&ctl, 0, sizeof(ctl)); ctl.keysize = sizeof(EventTriggerEvent); ctl.entrysize = sizeof(EventTriggerCacheEntry); ctl.hash = tag_hash; ctl.hcxt = EventTriggerCacheContext; cache = hash_create("Event Trigger Cache", 32, &ctl, HASH_ELEM | HASH_FUNCTION | HASH_CONTEXT); /* * Prepare to scan pg_event_trigger in name order. We use an MVCC * snapshot to avoid getting inconsistent results if the table is * being concurrently updated. */ rel = relation_open(EventTriggerRelationId, AccessShareLock); irel = index_open(EventTriggerNameIndexId, AccessShareLock); scan = systable_beginscan_ordered(rel, irel, GetLatestSnapshot(), 0, NULL); /* * Build a cache item for each pg_event_trigger tuple, and append each * one to the appropriate cache entry. */ for (;;) { HeapTuple tup; Form_pg_event_trigger form; char *evtevent; EventTriggerEvent event; EventTriggerCacheItem *item; Datum evttags; bool evttags_isnull; EventTriggerCacheEntry *entry; bool found; /* Get next tuple. */ tup = systable_getnext_ordered(scan, ForwardScanDirection); if (!HeapTupleIsValid(tup)) break; /* Skip trigger if disabled. */ form = (Form_pg_event_trigger) GETSTRUCT(tup); if (form->evtenabled == TRIGGER_DISABLED) continue; /* Decode event name. */ evtevent = NameStr(form->evtevent); if (strcmp(evtevent, "ddl_command_start") == 0) event = EVT_DDLCommandStart; else continue; /* Allocate new cache item. */ item = palloc0(sizeof(EventTriggerCacheItem)); item->fnoid = form->evtfoid; item->enabled = form->evtenabled; /* Decode and sort tags array. */ evttags = heap_getattr(tup, Anum_pg_event_trigger_evttags, RelationGetDescr(rel), &evttags_isnull); if (!evttags_isnull) { item->ntags = DecodeTextArrayToCString(evttags, &item->tag); qsort(item->tag, item->ntags, sizeof(char *), pg_qsort_strcmp); } /* Add to cache entry. */ entry = hash_search(cache, &event, HASH_ENTER, &found); if (found) entry->triggerlist = lappend(entry->triggerlist, item); else entry->triggerlist = list_make1(item); } /* Done with pg_event_trigger scan. */ systable_endscan_ordered(scan); index_close(irel, AccessShareLock); relation_close(rel, AccessShareLock); /* Restore previous memory context. */ MemoryContextSwitchTo(oldcontext); /* Install new cache. */ EventTriggerCache = cache; /* * If the cache has been invalidated since we entered this routine, we * still use and return the cache we just finished constructing, to avoid * infinite loops, but we leave the cache marked stale so that we'll * rebuild it again on next access. Otherwise, we mark the cache valid. */ if (EventTriggerCacheState == ETCS_REBUILD_STARTED) EventTriggerCacheState = ETCS_VALID; }
/* * Rebuild the event trigger cache. */ static void BuildEventTriggerCache(void) { HASHCTL ctl; HTAB *cache; MemoryContext oldcontext; Relation rel; Relation irel; SysScanDesc scan; if (EventTriggerCacheContext != NULL) { /* * The cache has been previously built, and subsequently invalidated, * and now we're trying to rebuild it. Normally, there won't be * anything in the context at this point, because the invalidation * will have already reset it. But if the previous attempt to rebuild * the cache failed, then there might be some junk lying around * that we want to reclaim. */ MemoryContextReset(EventTriggerCacheContext); } else { /* * This is our first time attempting to build the cache, so we need * to set up the memory context and register a syscache callback to * capture future invalidation events. */ if (CacheMemoryContext == NULL) CreateCacheMemoryContext(); EventTriggerCacheContext = AllocSetContextCreate(CacheMemoryContext, "EventTriggerCache", ALLOCSET_DEFAULT_MINSIZE, ALLOCSET_DEFAULT_INITSIZE, ALLOCSET_DEFAULT_MAXSIZE); CacheRegisterSyscacheCallback(EVENTTRIGGEROID, InvalidateEventCacheCallback, (Datum) 0); } /* Switch to correct memory context. */ oldcontext = MemoryContextSwitchTo(EventTriggerCacheContext); /* * Create a new hash table, but don't assign it to the global variable * until it accurately represents the state of the catalogs, so that * if we fail midway through this we won't end up with incorrect cache * contents. */ MemSet(&ctl, 0, sizeof(ctl)); ctl.keysize = sizeof(EventTriggerEvent); ctl.entrysize = sizeof(EventTriggerCacheEntry); ctl.hash = tag_hash; cache = hash_create("Event Trigger Cache", 32, &ctl, HASH_ELEM | HASH_FUNCTION); /* * Prepare to scan pg_event_trigger in name order. We use an MVCC * snapshot to avoid getting inconsistent results if the table is * being concurrently updated. */ rel = relation_open(EventTriggerRelationId, AccessShareLock); irel = index_open(EventTriggerNameIndexId, AccessShareLock); scan = systable_beginscan_ordered(rel, irel, GetLatestSnapshot(), 0, NULL); /* * Build a cache item for each pg_event_trigger tuple, and append each * one to the appropriate cache entry. */ for (;;) { HeapTuple tup; Form_pg_event_trigger form; char *evtevent; EventTriggerEvent event; EventTriggerCacheItem *item; Datum evttags; bool evttags_isnull; EventTriggerCacheEntry *entry; bool found; /* Get next tuple. */ tup = systable_getnext_ordered(scan, ForwardScanDirection); if (!HeapTupleIsValid(tup)) break; /* Skip trigger if disabled. */ form = (Form_pg_event_trigger) GETSTRUCT(tup); if (form->evtenabled == TRIGGER_DISABLED) continue; /* Decode event name. */ evtevent = NameStr(form->evtevent); if (strcmp(evtevent, "ddl_command_start") == 0) event = EVT_DDLCommandStart; else continue; /* Allocate new cache item. */ item = palloc0(sizeof(EventTriggerCacheItem)); item->fnoid = form->evtfoid; item->enabled = form->evtenabled; /* Decode and sort tags array. */ evttags = heap_getattr(tup, Anum_pg_event_trigger_evttags, RelationGetDescr(rel), &evttags_isnull); if (!evttags_isnull) { item->ntags = DecodeTextArrayToCString(evttags, &item->tag); qsort(item->tag, item->ntags, sizeof(char *), pg_qsort_strcmp); } /* Add to cache entry. */ entry = hash_search(cache, &event, HASH_ENTER, &found); if (found) entry->triggerlist = lappend(entry->triggerlist, item); else entry->triggerlist = list_make1(item); } /* Done with pg_event_trigger scan. */ systable_endscan_ordered(scan); index_close(irel, AccessShareLock); relation_close(rel, AccessShareLock); /* Restore previous memory context. */ MemoryContextSwitchTo(oldcontext); /* Cache is now valid. */ EventTriggerCache = cache; }