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/*-------------------------------------------------------------------------
*
* catcache.h
* Low-level catalog cache definitions.
*
* NOTE: every catalog cache must have a corresponding unique index on
* the system table that it caches --- ie, the index must match the keys
* used to do lookups in this cache. All cache fetches are done with
* indexscans (under normal conditions). The index should be unique to
* guarantee that there can only be one matching row for a key combination.
*
*
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: catcache.h,v 1.41 2002/03/26 19:16:56 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef CATCACHE_H
#define CATCACHE_H
#include "access/htup.h"
#include "lib/dllist.h"
/*
* struct catctup: individual tuple in the cache.
* struct catcache: information for managing a cache.
* struct catcacheheader: information for managing all the caches.
*/
typedef struct catcache
{
int id; /* cache identifier --- see syscache.h */
struct catcache *cc_next; /* link to next catcache */
const char *cc_relname; /* name of relation the tuples come from */
const char *cc_indname; /* name of index matching cache keys */
Oid cc_reloid; /* OID of relation the tuples come from */
bool cc_relisshared; /* is relation shared? */
TupleDesc cc_tupdesc; /* tuple descriptor (copied from reldesc) */
int cc_reloidattr; /* AttrNumber of relation OID attr, or 0 */
int cc_ntup; /* # of tuples currently in this cache */
int cc_nbuckets; /* # of hash buckets in this cache */
int cc_nkeys; /* # of keys (1..4) */
int cc_key[4]; /* AttrNumber of each key */
PGFunction cc_hashfunc[4]; /* hash function to use for each key */
ScanKeyData cc_skey[4]; /* precomputed key info for heap scans */
bool cc_isname[4]; /* flag key columns that are NAMEs */
#ifdef CATCACHE_STATS
long cc_searches; /* total # searches against this cache */
long cc_hits; /* # of matches against existing entry */
long cc_neg_hits; /* # of matches against negative entry */
long cc_newloads; /* # of successful loads of new entry */
/*
* cc_searches - (cc_hits + cc_neg_hits + cc_newloads) is number of
* failed searches, each of which will result in loading a negative entry
*/
long cc_invals; /* # of entries invalidated from cache */
long cc_discards; /* # of entries discarded due to overflow */
#endif
Dllist cc_bucket[1]; /* hash buckets --- VARIABLE LENGTH ARRAY */
} CatCache; /* VARIABLE LENGTH STRUCT */
typedef struct catctup
{
int ct_magic; /* for Assert checks */
#define CT_MAGIC 0x57261502
CatCache *my_cache; /* link to owning catcache */
/*
* Each tuple in a cache is a member of two lists: one lists all the
* elements in all the caches in LRU order, and the other lists just
* the elements in one hashbucket of one cache, also in LRU order.
*
* A tuple marked "dead" must not be returned by subsequent searches.
* However, it won't be physically deleted from the cache until its
* refcount goes to zero.
*
* A negative cache entry is an assertion that there is no tuple
* matching a particular key. This is just as useful as a normal entry
* so far as avoiding catalog searches is concerned. Management of
* positive and negative entries is identical.
*/
Dlelem lrulist_elem; /* list member of global LRU list */
Dlelem cache_elem; /* list member of per-bucket list */
int refcount; /* number of active references */
bool dead; /* dead but not yet removed? */
bool negative; /* negative cache entry? */
uint32 hash_value; /* hash value for this tuple's keys */
HeapTupleData tuple; /* tuple management header */
} CatCTup;
typedef struct catcacheheader
{
CatCache *ch_caches; /* head of list of CatCache structs */
int ch_ntup; /* # of tuples in all caches */
int ch_maxtup; /* max # of tuples allowed (LRU) */
Dllist ch_lrulist; /* overall LRU list, most recent first */
} CatCacheHeader;
/* this extern duplicates utils/memutils.h... */
extern MemoryContext CacheMemoryContext;
extern void CreateCacheMemoryContext(void);
extern void AtEOXact_CatCache(bool isCommit);
extern CatCache *InitCatCache(int id, const char *relname, const char *indname,
int reloidattr,
int nkeys, const int *key);
extern void InitCatCachePhase2(CatCache *cache);
extern HeapTuple SearchCatCache(CatCache *cache,
Datum v1, Datum v2,
Datum v3, Datum v4);
extern void ReleaseCatCache(HeapTuple tuple);
extern void ResetCatalogCaches(void);
extern void CatalogCacheFlushRelation(Oid relId);
extern void CatalogCacheIdInvalidate(int cacheId, uint32 hashValue,
ItemPointer pointer);
extern void PrepareToInvalidateCacheTuple(Relation relation,
HeapTuple tuple,
void (*function) (int, uint32, ItemPointer, Oid));
#endif /* CATCACHE_H */
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