/*
* PrepareToInvalidateCacheTuple()
*
* This is part of a rather subtle chain of events, so pay attention:
*
* When a tuple is inserted or deleted, it cannot be flushed from the
* catcaches immediately, for reasons explained at the top of cache/inval.c.
* Instead we have to add entry(s) for the tuple to a list of pending tuple
* invalidations that will be done at the end of the command or transaction.
*
* The lists of tuples that need to be flushed are kept by inval.c. This
* routine is a helper routine for inval.c. Given a tuple belonging to
* the specified relation, find all catcaches it could be in, compute the
* correct hash value for each such catcache, and call the specified function
* to record the cache id, hash value, and tuple ItemPointer in inval.c's
* lists. CatalogCacheIdInvalidate will be called later, if appropriate,
* using the recorded information.
*
* Note that it is irrelevant whether the given tuple is actually loaded
* into the catcache at the moment. Even if it's not there now, it might
* be by the end of the command, or there might be a matching negative entry
* to flush --- or other backends' caches might have such entries --- so
* we have to make list entries to flush it later.
*
* Also note that it's not an error if there are no catcaches for the
* specified relation. inval.c doesn't know exactly which rels have
* catcaches --- it will call this routine for any tuple that's in a
* system relation.
*/
void
PrepareToInvalidateCacheTuple(Relation relation,
HeapTuple tuple,
void (*function) (int, uint32, ItemPointer, Oid))
{
CatCache *ccp;
Oid reloid;
CACHE1_elog(DEBUG2, "PrepareToInvalidateCacheTuple: called");
/*
* sanity checks
*/
Assert(RelationIsValid(relation));
Assert(HeapTupleIsValid(tuple));
Assert(PointerIsValid(function));
Assert(CacheHdr != NULL);
reloid = RelationGetRelid(relation);
/* ----------------
* for each cache
* if the cache contains tuples from the specified relation
* compute the tuple's hash value in this cache,
* and call the passed function to register the information.
* ----------------
*/
for (ccp = CacheHdr->ch_caches; ccp; ccp = ccp->cc_next)
{
/* Just in case cache hasn't finished initialization yet... */
if (ccp->cc_tupdesc == NULL)
CatalogCacheInitializeCache(ccp);
if (ccp->cc_reloid != reloid)
continue;
(*function) (ccp->id,
CatalogCacheComputeTupleHashValue(ccp, tuple),
&tuple->t_self,
ccp->cc_relisshared ? (Oid) 0 : MyDatabaseId);
}
}
/*
* SearchCatCacheList
*
* Generate a list of all tuples matching a partial key (that is,
* a key specifying just the first K of the cache's N key columns).
*
* The caller must not modify the list object or the pointed-to tuples,
* and must call ReleaseCatCacheList() when done with the list.
*/
CatCList *
SearchCatCacheList(CatCache *cache,
int nkeys,
Datum v1,
Datum v2,
Datum v3,
Datum v4)
{
ScanKeyData cur_skey[CATCACHE_MAXKEYS];
uint32 lHashValue;
Dlelem *elt;
CatCList *cl;
CatCTup *ct;
List *volatile ctlist;
ListCell *ctlist_item;
int nmembers;
bool ordered;
HeapTuple ntp;
MemoryContext oldcxt;
int i;
/*
* one-time startup overhead for each cache
*/
if (cache->cc_tupdesc == NULL)
CatalogCacheInitializeCache(cache);
Assert(nkeys > 0 && nkeys < cache->cc_nkeys);
#ifdef CATCACHE_STATS
cache->cc_lsearches++;
#endif
/*
* initialize the search key information
*/
memcpy(cur_skey, cache->cc_skey, sizeof(cur_skey));
cur_skey[0].sk_argument = v1;
cur_skey[1].sk_argument = v2;
cur_skey[2].sk_argument = v3;
cur_skey[3].sk_argument = v4;
/*
* compute a hash value of the given keys for faster search. We don't
* presently divide the CatCList items into buckets, but this still lets
* us skip non-matching items quickly most of the time.
*/
lHashValue = CatalogCacheComputeHashValue(cache, nkeys, cur_skey);
/*
* scan the items until we find a match or exhaust our list
*/
for (elt = DLGetHead(&cache->cc_lists);
elt;
elt = DLGetSucc(elt))
{
bool res;
cl = (CatCList *) DLE_VAL(elt);
if (cl->dead)
continue; /* ignore dead entries */
if (cl->hash_value != lHashValue)
continue; /* quickly skip entry if wrong hash val */
/*
* see if the cached list matches our key.
*/
if (cl->nkeys != nkeys)
continue;
HeapKeyTest(&cl->tuple,
cache->cc_tupdesc,
nkeys,
cur_skey,
res);
if (!res)
continue;
/*
* We found a matching list. Move the list to the front of the
* cache's list-of-lists, to speed subsequent searches. (We do not
* move the members to the fronts of their hashbucket lists, however,
* since there's no point in that unless they are searched for
* individually.)
*/
DLMoveToFront(&cl->cache_elem);
/* Bump the list's refcount and return it */
ResourceOwnerEnlargeCatCacheListRefs(CurrentResourceOwner);
cl->refcount++;
ResourceOwnerRememberCatCacheListRef(CurrentResourceOwner, cl);
CACHE2_elog(DEBUG2, "SearchCatCacheList(%s): found list",
cache->cc_relname);
#ifdef CATCACHE_STATS
cache->cc_lhits++;
#endif
return cl;
}
/*
* List was not found in cache, so we have to build it by reading the
* relation. For each matching tuple found in the relation, use an
* existing cache entry if possible, else build a new one.
*
* We have to bump the member refcounts temporarily to ensure they won't
* get dropped from the cache while loading other members. We use a PG_TRY
* block to ensure we can undo those refcounts if we get an error before
* we finish constructing the CatCList.
*/
ResourceOwnerEnlargeCatCacheListRefs(CurrentResourceOwner);
ctlist = NIL;
PG_TRY();
{
Relation relation;
SysScanDesc scandesc;
relation = heap_open(cache->cc_reloid, AccessShareLock);
scandesc = systable_beginscan(relation,
cache->cc_indexoid,
IndexScanOK(cache, cur_skey),
SnapshotNow,
nkeys,
cur_skey);
/* The list will be ordered iff we are doing an index scan */
ordered = (scandesc->irel != NULL);
while (HeapTupleIsValid(ntp = systable_getnext(scandesc)))
{
uint32 hashValue;
Index hashIndex;
/*
* See if there's an entry for this tuple already.
*/
ct = NULL;
hashValue = CatalogCacheComputeTupleHashValue(cache, ntp);
hashIndex = HASH_INDEX(hashValue, cache->cc_nbuckets);
for (elt = DLGetHead(&cache->cc_bucket[hashIndex]);
elt;
elt = DLGetSucc(elt))
{
ct = (CatCTup *) DLE_VAL(elt);
if (ct->dead || ct->negative)
continue; /* ignore dead and negative entries */
if (ct->hash_value != hashValue)
continue; /* quickly skip entry if wrong hash val */
if (!ItemPointerEquals(&(ct->tuple.t_self), &(ntp->t_self)))
continue; /* not same tuple */
/*
* Found a match, but can't use it if it belongs to another
* list already
*/
if (ct->c_list)
continue;
break; /* A-OK */
}
if (elt == NULL)
{
/* We didn't find a usable entry, so make a new one */
ct = CatalogCacheCreateEntry(cache, ntp,
hashValue, hashIndex,
false);
}
/* Careful here: add entry to ctlist, then bump its refcount */
/* This way leaves state correct if lappend runs out of memory */
ctlist = lappend(ctlist, ct);
ct->refcount++;
}
systable_endscan(scandesc);
heap_close(relation, AccessShareLock);
/*
* Now we can build the CatCList entry. First we need a dummy tuple
* containing the key values...
*/
ntp = build_dummy_tuple(cache, nkeys, cur_skey);
oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
nmembers = list_length(ctlist);
cl = (CatCList *)
palloc(sizeof(CatCList) + nmembers * sizeof(CatCTup *));
heap_copytuple_with_tuple(ntp, &cl->tuple);
MemoryContextSwitchTo(oldcxt);
heap_freetuple(ntp);
/*
* We are now past the last thing that could trigger an elog before we
* have finished building the CatCList and remembering it in the
* resource owner. So it's OK to fall out of the PG_TRY, and indeed
* we'd better do so before we start marking the members as belonging
* to the list.
*/
}
PG_CATCH();
{
foreach(ctlist_item, ctlist)
{
ct = (CatCTup *) lfirst(ctlist_item);
Assert(ct->c_list == NULL);
Assert(ct->refcount > 0);
ct->refcount--;
if (
#ifndef CATCACHE_FORCE_RELEASE
ct->dead &&
#endif
ct->refcount == 0 &&
(ct->c_list == NULL || ct->c_list->refcount == 0))
CatCacheRemoveCTup(cache, ct);
}
PG_RE_THROW();
}
/*
* SearchCatCacheList
*
* Generate a list of all tuples matching a partial key (that is,
* a key specifying just the first K of the cache's N key columns).
*
* The caller must not modify the list object or the pointed-to tuples,
* and must call ReleaseCatCacheList() when done with the list.
*/
CatCList *
SearchCatCacheList(CatCache *cache,
int nkeys,
Datum v1,
Datum v2,
Datum v3,
Datum v4)
{
ScanKeyData cur_skey[4];
uint32 lHashValue;
Dlelem *elt;
CatCList *cl;
CatCTup *ct;
List *ctlist;
int nmembers;
Relation relation;
SysScanDesc scandesc;
bool ordered;
HeapTuple ntp;
MemoryContext oldcxt;
int i;
/*
* one-time startup overhead for each cache
*/
if (cache->cc_tupdesc == NULL)
CatalogCacheInitializeCache(cache);
Assert(nkeys > 0 && nkeys < cache->cc_nkeys);
#ifdef CATCACHE_STATS
cache->cc_lsearches++;
#endif
/*
* initialize the search key information
*/
memcpy(cur_skey, cache->cc_skey, sizeof(cur_skey));
cur_skey[0].sk_argument = v1;
cur_skey[1].sk_argument = v2;
cur_skey[2].sk_argument = v3;
cur_skey[3].sk_argument = v4;
/*
* compute a hash value of the given keys for faster search. We don't
* presently divide the CatCList items into buckets, but this still
* lets us skip non-matching items quickly most of the time.
*/
lHashValue = CatalogCacheComputeHashValue(cache, nkeys, cur_skey);
/*
* scan the items until we find a match or exhaust our list
*/
for (elt = DLGetHead(&cache->cc_lists);
elt;
elt = DLGetSucc(elt))
{
bool res;
cl = (CatCList *) DLE_VAL(elt);
if (cl->dead)
continue; /* ignore dead entries */
if (cl->hash_value != lHashValue)
continue; /* quickly skip entry if wrong hash val */
/*
* see if the cached list matches our key.
*/
if (cl->nkeys != nkeys)
continue;
HeapKeyTest(&cl->tuple,
cache->cc_tupdesc,
nkeys,
cur_skey,
res);
if (!res)
continue;
/*
* we found a matching list: move each of its members to the front
* of the global LRU list. Also move the list itself to the front
* of the cache's list-of-lists, to speed subsequent searches. (We
* do not move the members to the fronts of their hashbucket
* lists, however, since there's no point in that unless they are
* searched for individually.) Also bump the members' refcounts.
*/
for (i = 0; i < cl->n_members; i++)
{
cl->members[i]->refcount++;
DLMoveToFront(&cl->members[i]->lrulist_elem);
}
DLMoveToFront(&cl->cache_elem);
/* Bump the list's refcount and return it */
cl->refcount++;
CACHE2_elog(DEBUG2, "SearchCatCacheList(%s): found list",
cache->cc_relname);
#ifdef CATCACHE_STATS
cache->cc_lhits++;
#endif
return cl;
}
/*
* List was not found in cache, so we have to build it by reading the
* relation. For each matching tuple found in the relation, use an
* existing cache entry if possible, else build a new one.
*/
relation = heap_open(cache->cc_reloid, AccessShareLock);
scandesc = systable_beginscan(relation,
cache->cc_indname,
true,
SnapshotNow,
nkeys,
cur_skey);
/* The list will be ordered iff we are doing an index scan */
ordered = (scandesc->irel != NULL);
ctlist = NIL;
nmembers = 0;
while (HeapTupleIsValid(ntp = systable_getnext(scandesc)))
{
uint32 hashValue;
Index hashIndex;
/*
* See if there's an entry for this tuple already.
*/
ct = NULL;
hashValue = CatalogCacheComputeTupleHashValue(cache, ntp);
hashIndex = HASH_INDEX(hashValue, cache->cc_nbuckets);
for (elt = DLGetHead(&cache->cc_bucket[hashIndex]);
elt;
elt = DLGetSucc(elt))
{
ct = (CatCTup *) DLE_VAL(elt);
if (ct->dead || ct->negative)
continue; /* ignore dead and negative entries */
if (ct->hash_value != hashValue)
continue; /* quickly skip entry if wrong hash val */
if (!ItemPointerEquals(&(ct->tuple.t_self), &(ntp->t_self)))
continue; /* not same tuple */
/*
* Found a match, but can't use it if it belongs to another
* list already
*/
if (ct->c_list)
continue;
/* Found a match, so bump its refcount and move to front */
ct->refcount++;
DLMoveToFront(&ct->lrulist_elem);
break;
}
if (elt == NULL)
{
/* We didn't find a usable entry, so make a new one */
ct = CatalogCacheCreateEntry(cache, ntp,
hashValue, hashIndex,
false);
}
ctlist = lcons(ct, ctlist);
nmembers++;
}
systable_endscan(scandesc);
heap_close(relation, AccessShareLock);
/*
* Now we can build the CatCList entry. First we need a dummy tuple
* containing the key values...
*/
ntp = build_dummy_tuple(cache, nkeys, cur_skey);
oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
cl = (CatCList *) palloc(sizeof(CatCList) + nmembers * sizeof(CatCTup *));
heap_copytuple_with_tuple(ntp, &cl->tuple);
MemoryContextSwitchTo(oldcxt);
heap_freetuple(ntp);
cl->cl_magic = CL_MAGIC;
cl->my_cache = cache;
DLInitElem(&cl->cache_elem, (void *) cl);
cl->refcount = 1; /* count this first reference */
cl->dead = false;
cl->ordered = ordered;
cl->nkeys = nkeys;
cl->hash_value = lHashValue;
cl->n_members = nmembers;
/* The list is backwards because we built it with lcons */
for (i = nmembers; --i >= 0;)
{
cl->members[i] = ct = (CatCTup *) lfirst(ctlist);
Assert(ct->c_list == NULL);
ct->c_list = cl;
/* mark list dead if any members already dead */
if (ct->dead)
cl->dead = true;
ctlist = lnext(ctlist);
}
DLAddHead(&cache->cc_lists, &cl->cache_elem);
CACHE3_elog(DEBUG2, "SearchCatCacheList(%s): made list of %d members",
cache->cc_relname, nmembers);
return cl;
}
