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Tom Lane bd272cace6 Mega-commit to make heap_open/heap_openr/heap_close take an
additional argument specifying the kind of lock to acquire/release (or
'NoLock' to do no lock processing).  Ensure that all relations are locked
with some appropriate lock level before being examined --- this ensures
that relevant shared-inval messages have been processed and should prevent
problems caused by concurrent VACUUM.  Fix several bugs having to do with
mismatched increment/decrement of relation ref count and mismatched
heap_open/close (which amounts to the same thing).  A bogus ref count on
a relation doesn't matter much *unless* a SI Inval message happens to
arrive at the wrong time, which is probably why we got away with this
sloppiness for so long.  Repair missing grab of AccessExclusiveLock in
DROP TABLE, ALTER/RENAME TABLE, etc, as noted by Hiroshi.
Recommend 'make clean all' after pulling this update; I modified the
Relation struct layout slightly.
Will post further discussion to pghackers list shortly.
1999-09-18 19:08:25 +00:00

1160 lines
29 KiB
C

/*-------------------------------------------------------------------------
*
* catcache.c
* System catalog cache for tuples matching a key.
*
* Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/cache/catcache.c,v 1.49 1999/09/18 19:07:55 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/genam.h"
#include "access/heapam.h"
#include "access/valid.h"
#include "catalog/pg_type.h"
#include "miscadmin.h"
#include "utils/builtins.h"
#include "utils/catcache.h"
static void CatCacheRemoveCTup(CatCache *cache, Dlelem *e);
static Index CatalogCacheComputeHashIndex(struct catcache * cacheInP);
static Index CatalogCacheComputeTupleHashIndex(struct catcache * cacheInOutP,
Relation relation, HeapTuple tuple);
static void CatalogCacheInitializeCache(struct catcache * cache,
Relation relation);
static long comphash(long l, char *v);
/* ----------------
* variables, macros and other stuff
*
* note CCSIZE allocates 51 buckets .. one was already allocated in
* the catcache structure.
* ----------------
*/
#ifdef CACHEDEBUG
#define CACHE1_elog(a,b) elog(a,b)
#define CACHE2_elog(a,b,c) elog(a,b,c)
#define CACHE3_elog(a,b,c,d) elog(a,b,c,d)
#define CACHE4_elog(a,b,c,d,e) elog(a,b,c,d,e)
#define CACHE5_elog(a,b,c,d,e,f) elog(a,b,c,d,e,f)
#define CACHE6_elog(a,b,c,d,e,f,g) elog(a,b,c,d,e,f,g)
#else
#define CACHE1_elog(a,b)
#define CACHE2_elog(a,b,c)
#define CACHE3_elog(a,b,c,d)
#define CACHE4_elog(a,b,c,d,e)
#define CACHE5_elog(a,b,c,d,e,f)
#define CACHE6_elog(a,b,c,d,e,f,g)
#endif
static CatCache *Caches = NULL; /* head of list of caches */
GlobalMemory CacheCxt; /* context in which caches are allocated */
/* CacheCxt is global because relcache uses it too. */
/* ----------------
* EQPROC is used in CatalogCacheInitializeCache
* XXX this should be replaced by catalog lookups soon
* ----------------
*/
static long eqproc[] = {
F_BOOLEQ, 0l, F_CHAREQ, F_NAMEEQ, 0l,
F_INT2EQ, F_KEYFIRSTEQ, F_INT4EQ, 0l, F_TEXTEQ,
F_OIDEQ, 0l, 0l, 0l, F_OID8EQ
};
#define EQPROC(SYSTEMTYPEOID) eqproc[(SYSTEMTYPEOID)-16]
/* ----------------------------------------------------------------
* internal support functions
* ----------------------------------------------------------------
*/
/* --------------------------------
* CatalogCacheInitializeCache
* --------------------------------
*/
#ifdef CACHEDEBUG
#define CatalogCacheInitializeCache_DEBUG1 \
do { \
elog(DEBUG, "CatalogCacheInitializeCache: cache @%08lx", cache); \
if (relation) \
elog(DEBUG, "CatalogCacheInitializeCache: called w/relation(inval)"); \
else \
elog(DEBUG, "CatalogCacheInitializeCache: called w/relname %s", \
cache->cc_relname) \
} while(0)
#define CatalogCacheInitializeCache_DEBUG2 \
do { \
if (cache->cc_key[i] > 0) { \
elog(DEBUG, "CatalogCacheInitializeCache: load %d/%d w/%d, %d", \
i+1, cache->cc_nkeys, cache->cc_key[i], \
relation->rd_att->attrs[cache->cc_key[i] - 1]->attlen); \
} else { \
elog(DEBUG, "CatalogCacheInitializeCache: load %d/%d w/%d", \
i+1, cache->cc_nkeys, cache->cc_key[i]); \
} \
} while(0)
#else
#define CatalogCacheInitializeCache_DEBUG1
#define CatalogCacheInitializeCache_DEBUG2
#endif
static void
CatalogCacheInitializeCache(struct catcache * cache,
Relation relation)
{
MemoryContext oldcxt;
short didopen = 0;
short i;
TupleDesc tupdesc;
CatalogCacheInitializeCache_DEBUG1;
/* ----------------
* first switch to the cache context so our allocations
* do not vanish at the end of a transaction
* ----------------
*/
if (!CacheCxt)
CacheCxt = CreateGlobalMemory("Cache");
oldcxt = MemoryContextSwitchTo((MemoryContext) CacheCxt);
/* ----------------
* If no relation was passed we must open it to get access to
* its fields. If one of the other caches has already opened
* it we use heap_open() instead of heap_openr().
* XXX is that really worth the trouble of checking?
* ----------------
*/
if (!RelationIsValid(relation))
{
struct catcache *cp;
/* ----------------
* scan the caches to see if any other cache has opened the relation
* ----------------
*/
for (cp = Caches; cp; cp = cp->cc_next)
{
if (strncmp(cp->cc_relname, cache->cc_relname, NAMEDATALEN) == 0)
{
if (cp->relationId != InvalidOid)
break;
}
}
/* ----------------
* open the relation by name or by id
* ----------------
*/
if (cp)
relation = heap_open(cp->relationId, NoLock);
else
relation = heap_openr(cache->cc_relname, NoLock);
didopen = 1;
}
/* ----------------
* initialize the cache's relation id
* ----------------
*/
Assert(RelationIsValid(relation));
cache->relationId = RelationGetRelid(relation);
tupdesc = cache->cc_tupdesc = RelationGetDescr(relation);
CACHE3_elog(DEBUG, "CatalogCacheInitializeCache: relid %u, %d keys",
cache->relationId, cache->cc_nkeys);
/* ----------------
* initialize cache's key information
* ----------------
*/
for (i = 0; i < cache->cc_nkeys; ++i)
{
CatalogCacheInitializeCache_DEBUG2;
if (cache->cc_key[i] > 0)
{
/*
* Yoiks. The implementation of the hashing code and the
* implementation of int28's are at loggerheads. The right
* thing to do is to throw out the implementation of int28's
* altogether; until that happens, we do the right thing here
* to guarantee that the hash key generator doesn't try to
* dereference an int2 by mistake.
*/
if (tupdesc->attrs[cache->cc_key[i] - 1]->atttypid == INT28OID)
cache->cc_klen[i] = sizeof(short);
else
cache->cc_klen[i] = tupdesc->attrs[cache->cc_key[i] - 1]->attlen;
cache->cc_skey[i].sk_procedure = EQPROC(tupdesc->attrs[cache->cc_key[i] - 1]->atttypid);
fmgr_info(cache->cc_skey[i].sk_procedure,
&cache->cc_skey[i].sk_func);
cache->cc_skey[i].sk_nargs = cache->cc_skey[i].sk_func.fn_nargs;
CACHE5_elog(DEBUG, "CatalogCacheInit %s %d %d %x",
&relation->rd_rel->relname,
i,
tupdesc->attrs[cache->cc_key[i] - 1]->attlen,
cache);
}
}
/* ----------------
* close the relation if we opened it
* ----------------
*/
if (didopen)
heap_close(relation, NoLock);
/* ----------------
* initialize index information for the cache. this
* should only be done once per cache.
* ----------------
*/
if (cache->cc_indname != NULL && cache->indexId == InvalidOid)
{
if (RelationGetForm(relation)->relhasindex)
{
/*
* If the index doesn't exist we are in trouble.
*/
relation = index_openr(cache->cc_indname);
Assert(relation);
cache->indexId = RelationGetRelid(relation);
index_close(relation);
}
else
cache->cc_indname = NULL;
}
/* ----------------
* return to the proper memory context
* ----------------
*/
MemoryContextSwitchTo(oldcxt);
}
/* --------------------------------
* CatalogCacheSetId
*
* XXX temporary function
* --------------------------------
*/
#ifdef NOT_USED
void
CatalogCacheSetId(CatCache *cacheInOutP, int id)
{
Assert(id == InvalidCatalogCacheId || id >= 0);
cacheInOutP->id = id;
}
#endif
/* ----------------
* comphash
* Compute a hash value, somehow.
*
* XXX explain algorithm here.
*
* l is length of the attribute value, v
* v is the attribute value ("Datum")
* ----------------
*/
static long
comphash(long l, char *v)
{
long i;
NameData n;
CACHE3_elog(DEBUG, "comphash (%d,%x)", l, v);
switch (l)
{
case 1:
case 2:
case 4:
return (long) v;
}
if (l == NAMEDATALEN)
{
/*
* if it's a name, make sure that the values are null-padded.
*
* Note that this other fixed-length types can also have the same
* typelen so this may break them - XXX
*/
namestrcpy(&n, v);
v = n.data;
}
else if (l < 0)
l = VARSIZE(v);
i = 0;
while (l--)
i += *v++;
return i;
}
/* --------------------------------
* CatalogCacheComputeHashIndex
* --------------------------------
*/
static Index
CatalogCacheComputeHashIndex(struct catcache * cacheInP)
{
Index hashIndex;
hashIndex = 0x0;
CACHE6_elog(DEBUG, "CatalogCacheComputeHashIndex %s %d %d %d %x",
cacheInP->cc_relname,
cacheInP->cc_nkeys,
cacheInP->cc_klen[0],
cacheInP->cc_klen[1],
cacheInP);
switch (cacheInP->cc_nkeys)
{
case 4:
hashIndex ^= comphash(cacheInP->cc_klen[3],
(char *) cacheInP->cc_skey[3].sk_argument) << 9;
/* FALLTHROUGH */
case 3:
hashIndex ^= comphash(cacheInP->cc_klen[2],
(char *) cacheInP->cc_skey[2].sk_argument) << 6;
/* FALLTHROUGH */
case 2:
hashIndex ^= comphash(cacheInP->cc_klen[1],
(char *) cacheInP->cc_skey[1].sk_argument) << 3;
/* FALLTHROUGH */
case 1:
hashIndex ^= comphash(cacheInP->cc_klen[0],
(char *) cacheInP->cc_skey[0].sk_argument);
break;
default:
elog(FATAL, "CCComputeHashIndex: %d cc_nkeys", cacheInP->cc_nkeys);
break;
}
hashIndex %= cacheInP->cc_size;
return hashIndex;
}
/* --------------------------------
* CatalogCacheComputeTupleHashIndex
* --------------------------------
*/
static Index
CatalogCacheComputeTupleHashIndex(struct catcache * cacheInOutP,
Relation relation,
HeapTuple tuple)
{
bool isNull = '\0';
if (cacheInOutP->relationId == InvalidOid)
CatalogCacheInitializeCache(cacheInOutP, relation);
switch (cacheInOutP->cc_nkeys)
{
case 4:
cacheInOutP->cc_skey[3].sk_argument =
(cacheInOutP->cc_key[3] == ObjectIdAttributeNumber)
? (Datum) tuple->t_data->t_oid
: fastgetattr(tuple,
cacheInOutP->cc_key[3],
RelationGetDescr(relation),
&isNull);
Assert(!isNull);
/* FALLTHROUGH */
case 3:
cacheInOutP->cc_skey[2].sk_argument =
(cacheInOutP->cc_key[2] == ObjectIdAttributeNumber)
? (Datum) tuple->t_data->t_oid
: fastgetattr(tuple,
cacheInOutP->cc_key[2],
RelationGetDescr(relation),
&isNull);
Assert(!isNull);
/* FALLTHROUGH */
case 2:
cacheInOutP->cc_skey[1].sk_argument =
(cacheInOutP->cc_key[1] == ObjectIdAttributeNumber)
? (Datum) tuple->t_data->t_oid
: fastgetattr(tuple,
cacheInOutP->cc_key[1],
RelationGetDescr(relation),
&isNull);
Assert(!isNull);
/* FALLTHROUGH */
case 1:
cacheInOutP->cc_skey[0].sk_argument =
(cacheInOutP->cc_key[0] == ObjectIdAttributeNumber)
? (Datum) tuple->t_data->t_oid
: fastgetattr(tuple,
cacheInOutP->cc_key[0],
RelationGetDescr(relation),
&isNull);
Assert(!isNull);
break;
default:
elog(FATAL, "CCComputeTupleHashIndex: %d cc_nkeys",
cacheInOutP->cc_nkeys
);
break;
}
return CatalogCacheComputeHashIndex(cacheInOutP);
}
/* --------------------------------
* CatCacheRemoveCTup
* --------------------------------
*/
static void
CatCacheRemoveCTup(CatCache *cache, Dlelem *elt)
{
CatCTup *ct;
CatCTup *other_ct;
Dlelem *other_elt;
if (elt)
ct = (CatCTup *) DLE_VAL(elt);
else
return;
other_elt = ct->ct_node;
other_ct = (CatCTup *) DLE_VAL(other_elt);
DLRemove(other_elt);
DLFreeElem(other_elt);
free(other_ct);
DLRemove(elt);
DLFreeElem(elt);
free(ct);
--cache->cc_ntup;
}
/* --------------------------------
* CatalogCacheIdInvalidate()
*
* Invalidate a tuple given a cache id. In this case the id should always
* be found (whether the cache has opened its relation or not). Of course,
* if the cache has yet to open its relation, there will be no tuples so
* no problem.
* --------------------------------
*/
void
CatalogCacheIdInvalidate(int cacheId, /* XXX */
Index hashIndex,
ItemPointer pointer)
{
CatCache *ccp;
CatCTup *ct;
Dlelem *elt;
MemoryContext oldcxt;
/* ----------------
* sanity checks
* ----------------
*/
Assert(hashIndex < NCCBUCK);
Assert(ItemPointerIsValid(pointer));
CACHE1_elog(DEBUG, "CatalogCacheIdInvalidate: called");
/* ----------------
* switch to the cache context for our memory allocations
* ----------------
*/
if (!CacheCxt)
CacheCxt = CreateGlobalMemory("Cache");
oldcxt = MemoryContextSwitchTo((MemoryContext) CacheCxt);
/* ----------------
* inspect every cache that could contain the tuple
* ----------------
*/
for (ccp = Caches; ccp; ccp = ccp->cc_next)
{
if (cacheId != ccp->id)
continue;
/* ----------------
* inspect the hash bucket until we find a match or exhaust
* ----------------
*/
for (elt = DLGetHead(ccp->cc_cache[hashIndex]);
elt;
elt = DLGetSucc(elt))
{
ct = (CatCTup *) DLE_VAL(elt);
if (ItemPointerEquals(pointer, &ct->ct_tup->t_self))
break;
}
/* ----------------
* if we found a matching tuple, invalidate it.
* ----------------
*/
if (elt)
{
CatCacheRemoveCTup(ccp, elt);
CACHE1_elog(DEBUG, "CatalogCacheIdInvalidate: invalidated");
}
if (cacheId != InvalidCatalogCacheId)
break;
}
/* ----------------
* return to the proper memory context
* ----------------
*/
MemoryContextSwitchTo(oldcxt);
/* sendpm('I', "Invalidated tuple"); */
}
/* ----------------------------------------------------------------
* public functions
*
* ResetSystemCache
* InitIndexedSysCache
* InitSysCache
* SearchSysCache
* RelationInvalidateCatalogCacheTuple
* ----------------------------------------------------------------
*/
/* --------------------------------
* ResetSystemCache
* --------------------------------
*/
void
ResetSystemCache()
{
MemoryContext oldcxt;
struct catcache *cache;
CACHE1_elog(DEBUG, "ResetSystemCache called");
/* ----------------
* first switch to the cache context so our allocations
* do not vanish at the end of a transaction
* ----------------
*/
if (!CacheCxt)
CacheCxt = CreateGlobalMemory("Cache");
oldcxt = MemoryContextSwitchTo((MemoryContext) CacheCxt);
/* ----------------
* here we purge the contents of all the caches
*
* for each system cache
* for each hash bucket
* for each tuple in hash bucket
* remove the tuple
* ----------------
*/
for (cache = Caches; PointerIsValid(cache); cache = cache->cc_next)
{
int hash;
for (hash = 0; hash < NCCBUCK; hash += 1)
{
Dlelem *elt,
*nextelt;
for (elt = DLGetHead(cache->cc_cache[hash]); elt; elt = nextelt)
{
nextelt = DLGetSucc(elt);
CatCacheRemoveCTup(cache, elt);
if (cache->cc_ntup < 0)
elog(NOTICE,
"ResetSystemCache: cc_ntup<0 (software error)");
}
}
cache->cc_ntup = 0; /* in case of WARN error above */
cache->busy = false; /* to recover from recursive-use error */
}
CACHE1_elog(DEBUG, "end of ResetSystemCache call");
/* ----------------
* back to the old context before we return...
* ----------------
*/
MemoryContextSwitchTo(oldcxt);
}
/* --------------------------------
* SystemCacheRelationFlushed
*
* This is called by RelationFlushRelation() to clear out cached information
* about a relation being dropped. (This could be a DROP TABLE command,
* or a temp table being dropped at end of transaction, or a table created
* during the current transaction that is being dropped because of abort.)
* Remove all cache entries relevant to the specified relation OID.
*
* A special case occurs when relId is itself one of the cacheable system
* tables --- although those'll never be dropped, they can get flushed from
* the relcache (VACUUM causes this, for example). In that case we need to
* force the next SearchSysCache() call to reinitialize the cache itself,
* because we have info (such as cc_tupdesc) that is pointing at the about-
* to-be-deleted relcache entry.
* --------------------------------
*/
void
SystemCacheRelationFlushed(Oid relId)
{
struct catcache *cache;
/*
* XXX Ideally we'd search the caches and just zap entries that actually
* refer to the indicated relation. For now, we take the brute-force
* approach: just flush the caches entirely.
*/
ResetSystemCache();
/*
* If relcache is dropping a system relation's cache entry, mark the
* associated cache structures invalid, so we can rebuild them from
* scratch (not just repopulate them) next time they are used.
*/
for (cache = Caches; PointerIsValid(cache); cache = cache->cc_next)
{
if (cache->relationId == relId)
cache->relationId = InvalidOid;
}
}
/* --------------------------------
* InitIndexedSysCache
*
* This allocates and initializes a cache for a system catalog relation.
* Actually, the cache is only partially initialized to avoid opening the
* relation. The relation will be opened and the rest of the cache
* structure initialized on the first access.
* --------------------------------
*/
#ifdef CACHEDEBUG
#define InitSysCache_DEBUG1 \
do { \
elog(DEBUG, "InitSysCache: rid=%u id=%d nkeys=%d size=%d\n", \
cp->relationId, cp->id, cp->cc_nkeys, cp->cc_size); \
for (i = 0; i < nkeys; i += 1) \
{ \
elog(DEBUG, "InitSysCache: key=%d len=%d skey=[%d %d %d %d]\n", \
cp->cc_key[i], cp->cc_klen[i], \
cp->cc_skey[i].sk_flags, \
cp->cc_skey[i].sk_attno, \
cp->cc_skey[i].sk_procedure, \
cp->cc_skey[i].sk_argument); \
} \
} while(0)
#else
#define InitSysCache_DEBUG1
#endif
CatCache *
InitSysCache(char *relname,
char *iname,
int id,
int nkeys,
int *key,
HeapTuple (*iScanfuncP) ())
{
CatCache *cp;
int i;
MemoryContext oldcxt;
char *indname;
indname = (iname) ? iname : NULL;
/* ----------------
* first switch to the cache context so our allocations
* do not vanish at the end of a transaction
* ----------------
*/
if (!CacheCxt)
CacheCxt = CreateGlobalMemory("Cache");
oldcxt = MemoryContextSwitchTo((MemoryContext) CacheCxt);
/* ----------------
* allocate a new cache structure
* ----------------
*/
cp = (CatCache *) palloc(sizeof(CatCache));
MemSet((char *) cp, 0, sizeof(CatCache));
/* ----------------
* initialize the cache buckets (each bucket is a list header)
* and the LRU tuple list
* ----------------
*/
{
/*
* We can only do this optimization because the number of hash
* buckets never changes. Without it, we call malloc() too much.
* We could move this to dllist.c, but the way we do this is not
* dynamic/portabl, so why allow other routines to use it.
*/
Dllist *cache_begin = malloc((NCCBUCK + 1) * sizeof(Dllist));
for (i = 0; i <= NCCBUCK; ++i)
{
cp->cc_cache[i] = &cache_begin[i];
cp->cc_cache[i]->dll_head = 0;
cp->cc_cache[i]->dll_tail = 0;
}
}
cp->cc_lrulist = DLNewList();
/* ----------------
* Caches is the pointer to the head of the list of all the
* system caches. here we add the new cache to the top of the list.
* ----------------
*/
cp->cc_next = Caches; /* list of caches (single link) */
Caches = cp;
/* ----------------
* initialize the cache's relation information for the relation
* corresponding to this cache and initialize some of the the new
* cache's other internal fields.
* ----------------
*/
cp->relationId = InvalidOid;
cp->indexId = InvalidOid;
cp->cc_relname = relname;
cp->cc_indname = indname;
cp->cc_tupdesc = (TupleDesc) NULL;
cp->id = id;
cp->busy = false;
cp->cc_maxtup = MAXTUP;
cp->cc_size = NCCBUCK;
cp->cc_nkeys = nkeys;
cp->cc_iscanfunc = iScanfuncP;
/* ----------------
* initialize the cache's key information
* ----------------
*/
for (i = 0; i < nkeys; ++i)
{
cp->cc_key[i] = key[i];
if (!key[i])
elog(FATAL, "InitSysCache: called with 0 key[%d]", i);
if (key[i] < 0)
{
if (key[i] != ObjectIdAttributeNumber)
elog(FATAL, "InitSysCache: called with %d key[%d]", key[i], i);
else
{
cp->cc_klen[i] = sizeof(Oid);
/*
* ScanKeyEntryData and struct skey are equivalent. It
* looks like a move was made to obsolete struct skey, but
* it didn't reach this file. Someday we should clean up
* this code and consolidate to ScanKeyEntry - mer 10 Nov
* 1991
*/
ScanKeyEntryInitialize(&cp->cc_skey[i],
(bits16) 0,
(AttrNumber) key[i],
(RegProcedure) F_OIDEQ,
(Datum) 0);
continue;
}
}
cp->cc_skey[i].sk_attno = key[i];
}
/* ----------------
* all done. new cache is initialized. print some debugging
* information, if appropriate.
* ----------------
*/
InitSysCache_DEBUG1;
/* ----------------
* back to the old context before we return...
* ----------------
*/
MemoryContextSwitchTo(oldcxt);
return cp;
}
/* --------------------------------
* SearchSysCache
*
* This call searches a system cache for a tuple, opening the relation
* if necessary (the first access to a particular cache).
* --------------------------------
*/
HeapTuple
SearchSysCache(struct catcache * cache,
Datum v1,
Datum v2,
Datum v3,
Datum v4)
{
unsigned hash;
CatCTup *ct = NULL;
CatCTup *nct;
CatCTup *nct2;
Dlelem *elt;
HeapTuple ntp = 0;
Relation relation;
MemoryContext oldcxt;
/* ----------------
* sanity checks
* ----------------
*/
if (cache->relationId == InvalidOid)
CatalogCacheInitializeCache(cache, NULL);
/* ----------------
* initialize the search key information
* ----------------
*/
cache->cc_skey[0].sk_argument = v1;
cache->cc_skey[1].sk_argument = v2;
cache->cc_skey[2].sk_argument = v3;
cache->cc_skey[3].sk_argument = v4;
/* ----------------
* find the hash bucket in which to look for the tuple
* ----------------
*/
hash = CatalogCacheComputeHashIndex(cache);
/* ----------------
* scan the hash bucket until we find a match or exhaust our tuples
* ----------------
*/
for (elt = DLGetHead(cache->cc_cache[hash]);
elt;
elt = DLGetSucc(elt))
{
bool res;
ct = (CatCTup *) DLE_VAL(elt);
/* ----------------
* see if the cached tuple matches our key.
* (should we be worried about time ranges? -cim 10/2/90)
* ----------------
*/
HeapKeyTest(ct->ct_tup,
cache->cc_tupdesc,
cache->cc_nkeys,
cache->cc_skey,
res);
if (res)
break;
}
/* ----------------
* if we found a tuple in the cache, move it to the top of the
* lru list, and return it. We also move it to the front of the
* list for its hashbucket, in order to speed subsequent searches.
* (The most frequently accessed elements in any hashbucket will
* tend to be near the front of the hashbucket's list.)
* ----------------
*/
if (elt)
{
Dlelem *old_lru_elt = ((CatCTup *) DLE_VAL(elt))->ct_node;
DLMoveToFront(old_lru_elt);
DLMoveToFront(elt);
#ifdef CACHEDEBUG
relation = heap_open(cache->relationId, NoLock);
CACHE3_elog(DEBUG, "SearchSysCache(%s): found in bucket %d",
RelationGetRelationName(relation), hash);
heap_close(relation, NoLock);
#endif /* CACHEDEBUG */
return ct->ct_tup;
}
/* ----------------
* Tuple was not found in cache, so we have to try and
* retrieve it directly from the relation. If it's found,
* we add it to the cache.
*
* To guard against possible infinite recursion, we mark this cache
* "busy" while trying to load a new entry for it. It is OK to
* recursively invoke SearchSysCache for a different cache, but
* a recursive call for the same cache will error out. (We could
* store the specific key(s) being looked for, and consider only
* a recursive request for the same key to be an error, but this
* simple scheme is sufficient for now.)
* ----------------
*/
if (cache->busy)
{
elog(ERROR, "SearchSysCache: recursive use of cache %d", cache->id);
}
cache->busy = true;
/* ----------------
* open the relation associated with the cache
* ----------------
*/
relation = heap_open(cache->relationId, AccessShareLock);
CACHE2_elog(DEBUG, "SearchSysCache(%s)",
RelationGetRelationName(relation));
/* ----------------
* Switch to the cache memory context.
* ----------------
*/
if (!CacheCxt)
CacheCxt = CreateGlobalMemory("Cache");
oldcxt = MemoryContextSwitchTo((MemoryContext) CacheCxt);
/* ----------------
* Scan the relation to find the tuple. If there's an index, and
* if this isn't bootstrap (initdb) time, use the index.
* ----------------
*/
CACHE2_elog(DEBUG, "SearchSysCache: performing scan (override==%d)",
heapisoverride());
if ((RelationGetForm(relation))->relhasindex
&& !IsBootstrapProcessingMode())
{
/* ----------
* Switch back to old memory context so memory not freed
* in the scan function will go away at transaction end.
* wieck - 10/18/1996
* ----------
*/
MemoryContextSwitchTo(oldcxt);
Assert(cache->cc_iscanfunc);
switch (cache->cc_nkeys)
{
case 4:
ntp = cache->cc_iscanfunc(relation, v1, v2, v3, v4);
break;
case 3:
ntp = cache->cc_iscanfunc(relation, v1, v2, v3);
break;
case 2:
ntp = cache->cc_iscanfunc(relation, v1, v2);
break;
case 1:
ntp = cache->cc_iscanfunc(relation, v1);
break;
}
/* ----------
* Back to Cache context. If we got a tuple copy it
* into our context.
* wieck - 10/18/1996
* ----------
*/
MemoryContextSwitchTo((MemoryContext) CacheCxt);
if (HeapTupleIsValid(ntp))
ntp = heap_copytuple(ntp);
}
else
{
HeapScanDesc sd;
/* ----------
* As above do the lookup in the callers memory
* context.
* wieck - 10/18/1996
* ----------
*/
MemoryContextSwitchTo(oldcxt);
sd = heap_beginscan(relation, 0, SnapshotNow,
cache->cc_nkeys, cache->cc_skey);
ntp = heap_getnext(sd, 0);
MemoryContextSwitchTo((MemoryContext) CacheCxt);
if (HeapTupleIsValid(ntp))
{
CACHE1_elog(DEBUG, "SearchSysCache: found tuple");
ntp = heap_copytuple(ntp);
}
MemoryContextSwitchTo(oldcxt);
heap_endscan(sd);
MemoryContextSwitchTo((MemoryContext) CacheCxt);
}
cache->busy = false;
/* ----------------
* scan is complete. if tup is valid, we copy it and add the copy to
* the cache.
* ----------------
*/
if (HeapTupleIsValid(ntp))
{
/* ----------------
* allocate a new cache tuple holder, store the pointer
* to the heap tuple there and initialize the list pointers.
* ----------------
*/
Dlelem *lru_elt;
/*
* this is a little cumbersome here because we want the Dlelem's
* in both doubly linked lists to point to one another. That makes
* it easier to remove something from both the cache bucket and
* the lru list at the same time
*/
nct = (CatCTup *) malloc(sizeof(CatCTup));
nct->ct_tup = ntp;
elt = DLNewElem(nct);
nct2 = (CatCTup *) malloc(sizeof(CatCTup));
nct2->ct_tup = ntp;
lru_elt = DLNewElem(nct2);
nct2->ct_node = elt;
nct->ct_node = lru_elt;
DLAddHead(cache->cc_lrulist, lru_elt);
DLAddHead(cache->cc_cache[hash], elt);
/* ----------------
* If we've exceeded the desired size of this cache,
* throw away the least recently used entry.
* ----------------
*/
if (++cache->cc_ntup > cache->cc_maxtup)
{
CatCTup *ct;
elt = DLGetTail(cache->cc_lrulist);
ct = (CatCTup *) DLE_VAL(elt);
if (ct != nct) /* shouldn't be possible, but be safe... */
{
CACHE2_elog(DEBUG, "SearchSysCache(%s): Overflow, LRU removal",
RelationGetRelationName(relation));
CatCacheRemoveCTup(cache, elt);
}
}
CACHE4_elog(DEBUG, "SearchSysCache(%s): Contains %d/%d tuples",
RelationGetRelationName(relation),
cache->cc_ntup, cache->cc_maxtup);
CACHE3_elog(DEBUG, "SearchSysCache(%s): put in bucket %d",
RelationGetRelationName(relation), hash);
}
/* ----------------
* close the relation, switch back to the original memory context
* and return the tuple we found (or NULL)
* ----------------
*/
heap_close(relation, AccessShareLock);
MemoryContextSwitchTo(oldcxt);
return ntp;
}
/* --------------------------------
* RelationInvalidateCatalogCacheTuple()
*
* Invalidate a tuple from a specific relation. This call determines the
* cache in question and calls CatalogCacheIdInvalidate(). It is -ok-
* if the relation cannot be found, it simply means this backend has yet
* to open it.
* --------------------------------
*/
void
RelationInvalidateCatalogCacheTuple(Relation relation,
HeapTuple tuple,
void (*function) (int, Index, ItemPointer))
{
struct catcache *ccp;
MemoryContext oldcxt;
Oid relationId;
/* ----------------
* sanity checks
* ----------------
*/
Assert(RelationIsValid(relation));
Assert(HeapTupleIsValid(tuple));
Assert(PointerIsValid(function));
CACHE1_elog(DEBUG, "RelationInvalidateCatalogCacheTuple: called");
/* ----------------
* switch to the cache memory context
* ----------------
*/
if (!CacheCxt)
CacheCxt = CreateGlobalMemory("Cache");
oldcxt = MemoryContextSwitchTo((MemoryContext) CacheCxt);
/* ----------------
* for each cache
* if the cache contains tuples from the specified relation
* call the invalidation function on the tuples
* in the proper hash bucket
* ----------------
*/
relationId = RelationGetRelid(relation);
for (ccp = Caches; ccp; ccp = ccp->cc_next)
{
if (relationId != ccp->relationId)
continue;
#ifdef NOT_USED
/* OPT inline simplification of CatalogCacheIdInvalidate */
if (!PointerIsValid(function))
function = CatalogCacheIdInvalidate;
#endif
(*function) (ccp->id,
CatalogCacheComputeTupleHashIndex(ccp, relation, tuple),
&tuple->t_self);
}
/* ----------------
* return to the proper memory context
* ----------------
*/
MemoryContextSwitchTo(oldcxt);
/* sendpm('I', "Invalidated tuple"); */
}