#include "utils/resowner_private.h"
#include "utils/syscache.h"
+/*
+ * If a catcache invalidation is processed while we are in the middle of
+ * creating a catcache entry (or list), it might apply to the entry we're
+ * creating, making it invalid before it's been inserted to the catcache. To
+ * catch such cases, we have a stack of "create-in-progress" entries. Cache
+ * invalidation marks any matching entries in the stack as dead, in addition
+ * to the actual CatCTup and CatCList entries.
+ */
+typedef struct CatCInProgress
+{
+ CatCache *cache; /* cache that the entry belongs to */
+ uint32 hash_value; /* hash of the entry; ignored for lists */
+ bool list; /* is it a list entry? */
+ bool dead; /* set when the entry is invalidated */
+ struct CatCInProgress *next;
+} CatCInProgress;
+
+static CatCInProgress *catcache_in_progress_stack = NULL;
/* #define CACHEDEBUG */ /* turns DEBUG elogs on */
static void CatCacheRemoveCTup(CatCache *cache, CatCTup *ct);
static void CatCacheRemoveCList(CatCache *cache, CatCList *cl);
static void CatalogCacheInitializeCache(CatCache *cache);
-static CatCTup *CatalogCacheCreateEntry(CatCache *cache,
- HeapTuple ntp, SysScanDesc scandesc,
+static CatCTup *CatalogCacheCreateEntry(CatCache *cache, HeapTuple ntp,
Datum *arguments,
uint32 hashValue, Index hashIndex);
/* could be multiple matches, so keep looking! */
}
}
+
+ /* Also invalidate any entries that are being built */
+ for (CatCInProgress *e = catcache_in_progress_stack; e != NULL; e = e->next)
+ {
+ if (e->cache == cache)
+ {
+ if (e->list || e->hash_value == hashValue)
+ e->dead = true;
+ }
+ }
}
/* ----------------------------------------------------------------
*
* This is not very efficient if the target cache is nearly empty.
* However, it shouldn't need to be efficient; we don't invoke it often.
+ *
+ * If 'debug_discard' is true, we are being called as part of
+ * debug_discard_caches. In that case, the cache is not reset for
+ * correctness, but just to get more testing of cache invalidation. We skip
+ * resetting in-progress build entries in that case, or we'd never make any
+ * progress.
*/
static void
-ResetCatalogCache(CatCache *cache)
+ResetCatalogCache(CatCache *cache, bool debug_discard)
{
dlist_mutable_iter iter;
int i;
#endif
}
}
+
+ /* Also invalidate any entries that are being built */
+ if (!debug_discard)
+ {
+ for (CatCInProgress *e = catcache_in_progress_stack; e != NULL; e = e->next)
+ {
+ if (e->cache == cache)
+ e->dead = true;
+ }
+ }
}
/*
*/
void
ResetCatalogCaches(void)
+{
+ ResetCatalogCachesExt(false);
+}
+
+void
+ResetCatalogCachesExt(bool debug_discard)
{
slist_iter iter;
{
CatCache *cache = slist_container(CatCache, cc_next, iter.cur);
- ResetCatalogCache(cache);
+ ResetCatalogCache(cache, debug_discard);
}
CACHE_elog(DEBUG2, "end of ResetCatalogCaches call");
if (cache->cc_reloid == catId)
{
/* Yes, so flush all its contents */
- ResetCatalogCache(cache);
+ ResetCatalogCache(cache, false);
/* Tell inval.c to call syscache callbacks for this cache */
CallSyscacheCallbacks(cache->id, 0);
while (HeapTupleIsValid(ntp = systable_getnext(scandesc)))
{
- ct = CatalogCacheCreateEntry(cache, ntp, scandesc, NULL,
+ ct = CatalogCacheCreateEntry(cache, ntp, NULL,
hashValue, hashIndex);
/* upon failure, we must start the scan over */
if (ct == NULL)
if (IsBootstrapProcessingMode())
return NULL;
- ct = CatalogCacheCreateEntry(cache, NULL, NULL, arguments,
+ ct = CatalogCacheCreateEntry(cache, NULL, arguments,
hashValue, hashIndex);
/* Creating a negative cache entry shouldn't fail */
HeapTuple ntp;
MemoryContext oldcxt;
int i;
+ CatCInProgress *save_in_progress;
+ CatCInProgress in_progress_ent;
/*
* one-time startup overhead for each cache
ctlist = NIL;
+ /*
+ * Cache invalidation can happen while we're building the list.
+ * CatalogCacheCreateEntry() handles concurrent invalidation of individual
+ * tuples, but it's also possible that a new entry is concurrently added
+ * that should be part of the list we're building. Register an
+ * "in-progress" entry that will receive the invalidation, until we have
+ * built the final list entry.
+ */
+ save_in_progress = catcache_in_progress_stack;
+ in_progress_ent.next = catcache_in_progress_stack;
+ in_progress_ent.cache = cache;
+ in_progress_ent.hash_value = lHashValue;
+ in_progress_ent.list = true;
+ in_progress_ent.dead = false;
+ catcache_in_progress_stack = &in_progress_ent;
+
PG_TRY();
{
ScanKeyData cur_skey[CATCACHE_MAXKEYS];
Relation relation;
SysScanDesc scandesc;
- bool stale;
relation = table_open(cache->cc_reloid, AccessShareLock);
+ /*
+ * Scan the table for matching entries. If an invalidation arrives
+ * mid-build, we will loop back here to retry.
+ */
do
{
/*
- * Ok, need to make a lookup in the relation, copy the scankey and
- * fill out any per-call fields. (We must re-do this when
- * retrying, because systable_beginscan scribbles on the scankey.)
+ * If we are retrying, release refcounts on any items created on
+ * the previous iteration. We dare not try to free them if
+ * they're now unreferenced, since an error while doing that would
+ * result in the PG_CATCH below doing extra refcount decrements.
+ * Besides, we'll likely re-adopt those items in the next
+ * iteration, so it's not worth complicating matters to try to get
+ * rid of them.
+ */
+ foreach(ctlist_item, ctlist)
+ {
+ ct = (CatCTup *) lfirst(ctlist_item);
+ Assert(ct->c_list == NULL);
+ Assert(ct->refcount > 0);
+ ct->refcount--;
+ }
+ /* Reset ctlist in preparation for new try */
+ ctlist = NIL;
+ in_progress_ent.dead = false;
+
+ /*
+ * Copy the scankey and fill out any per-call fields. (We must
+ * re-do this when retrying, because systable_beginscan scribbles
+ * on the scankey.)
*/
memcpy(cur_skey, cache->cc_skey, sizeof(ScanKeyData) * cache->cc_nkeys);
cur_skey[0].sk_argument = v1;
/* The list will be ordered iff we are doing an index scan */
ordered = (scandesc->irel != NULL);
- stale = false;
-
- while (HeapTupleIsValid(ntp = systable_getnext(scandesc)))
+ while (HeapTupleIsValid(ntp = systable_getnext(scandesc)) &&
+ !in_progress_ent.dead)
{
uint32 hashValue;
Index hashIndex;
if (!found)
{
/* We didn't find a usable entry, so make a new one */
- ct = CatalogCacheCreateEntry(cache, ntp, scandesc, NULL,
+ ct = CatalogCacheCreateEntry(cache, ntp, NULL,
hashValue, hashIndex);
+
/* upon failure, we must start the scan over */
if (ct == NULL)
{
- /*
- * Release refcounts on any items we already had. We
- * dare not try to free them if they're now
- * unreferenced, since an error while doing that would
- * result in the PG_CATCH below doing extra refcount
- * decrements. Besides, we'll likely re-adopt those
- * items in the next iteration, so it's not worth
- * complicating matters to try to get rid of them.
- */
- foreach(ctlist_item, ctlist)
- {
- ct = (CatCTup *) lfirst(ctlist_item);
- Assert(ct->c_list == NULL);
- Assert(ct->refcount > 0);
- ct->refcount--;
- }
- /* Reset ctlist in preparation for new try */
- ctlist = NIL;
- stale = true;
+ in_progress_ent.dead = true;
break;
}
}
}
systable_endscan(scandesc);
- } while (stale);
+ } while (in_progress_ent.dead);
table_close(relation, AccessShareLock);
}
PG_CATCH();
{
+ Assert(catcache_in_progress_stack == &in_progress_ent);
+ catcache_in_progress_stack = save_in_progress;
+
foreach(ctlist_item, ctlist)
{
ct = (CatCTup *) lfirst(ctlist_item);
PG_RE_THROW();
}
PG_END_TRY();
+ Assert(catcache_in_progress_stack == &in_progress_ent);
+ catcache_in_progress_stack = save_in_progress;
cl->cl_magic = CL_MAGIC;
cl->my_cache = cache;
}
-/*
- * equalTuple
- * Are these tuples memcmp()-equal?
- */
-static bool
-equalTuple(HeapTuple a, HeapTuple b)
-{
- uint32 alen;
- uint32 blen;
-
- alen = a->t_len;
- blen = b->t_len;
- return (alen == blen &&
- memcmp((char *) a->t_data,
- (char *) b->t_data, blen) == 0);
-}
-
/*
* CatalogCacheCreateEntry
* Create a new CatCTup entry, copying the given HeapTuple and other
*
* To create a normal cache entry, ntp must be the HeapTuple just fetched
* from scandesc, and "arguments" is not used. To create a negative cache
- * entry, pass NULL for ntp and scandesc; then "arguments" is the cache
- * keys to use. In either case, hashValue/hashIndex are the hash values
- * computed from the cache keys.
+ * entry, pass NULL for ntp; then "arguments" is the cache keys to use.
+ * In either case, hashValue/hashIndex are the hash values computed from
+ * the cache keys.
*
* Returns NULL if we attempt to detoast the tuple and observe that it
* became stale. (This cannot happen for a negative entry.) Caller must
* retry the tuple lookup in that case.
*/
static CatCTup *
-CatalogCacheCreateEntry(CatCache *cache, HeapTuple ntp, SysScanDesc scandesc,
- Datum *arguments,
+CatalogCacheCreateEntry(CatCache *cache, HeapTuple ntp, Datum *arguments,
uint32 hashValue, Index hashIndex)
{
CatCTup *ct;
- HeapTuple dtp;
MemoryContext oldcxt;
if (ntp)
{
int i;
+ HeapTuple dtp = NULL;
/*
- * The visibility recheck below essentially never fails during our
- * regression tests, and there's no easy way to force it to fail for
- * testing purposes. To ensure we have test coverage for the retry
- * paths in our callers, make debug builds randomly fail about 0.1% of
- * the times through this code path, even when there's no toasted
- * fields.
+ * The invalidation of the in-progress entry essentially never happens
+ * during our regression tests, and there's no easy way to force it to
+ * fail for testing purposes. To ensure we have test coverage for the
+ * retry paths in our callers, make debug builds randomly fail about
+ * 0.1% of the times through this code path, even when there's no
+ * toasted fields.
*/
#ifdef USE_ASSERT_CHECKING
if (random() <= (MAX_RANDOM_VALUE / 1000))
*/
if (HeapTupleHasExternal(ntp))
{
- bool need_cmp = IsInplaceUpdateOid(cache->cc_reloid);
- HeapTuple before = NULL;
- bool matches = true;
-
- if (need_cmp)
- before = heap_copytuple(ntp);
- dtp = toast_flatten_tuple(ntp, cache->cc_tupdesc);
+ CatCInProgress *save_in_progress;
+ CatCInProgress in_progress_ent;
/*
* The tuple could become stale while we are doing toast table
- * access (since AcceptInvalidationMessages can run then).
- * equalTuple() detects staleness from inplace updates, while
- * systable_recheck_tuple() detects staleness from normal updates.
- *
- * While this equalTuple() follows the usual rule of reading with
- * a pin and no buffer lock, it warrants suspicion since an
- * inplace update could appear at any moment. It's safe because
- * the inplace update sends an invalidation that can't reorder
- * before the inplace heap change. If the heap change reaches
- * this process just after equalTuple() looks, we've not missed
- * its inval.
+ * access (since AcceptInvalidationMessages can run then). The
+ * invalidation will mark our in-progress entry as dead.
*/
- if (need_cmp)
+ save_in_progress = catcache_in_progress_stack;
+ in_progress_ent.next = catcache_in_progress_stack;
+ in_progress_ent.cache = cache;
+ in_progress_ent.hash_value = hashValue;
+ in_progress_ent.list = false;
+ in_progress_ent.dead = false;
+ catcache_in_progress_stack = &in_progress_ent;
+
+ PG_TRY();
{
- matches = equalTuple(before, ntp);
- heap_freetuple(before);
+ dtp = toast_flatten_tuple(ntp, cache->cc_tupdesc);
}
- if (!matches || !systable_recheck_tuple(scandesc, ntp))
+ PG_FINALLY();
+ {
+ Assert(catcache_in_progress_stack == &in_progress_ent);
+ catcache_in_progress_stack = save_in_progress;
+ }
+ PG_END_TRY();
+
+ if (in_progress_ent.dead)
{
heap_freetuple(dtp);
return NULL;
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