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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) 1996-2000, PostgreSQL, Inc
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: catcache.h,v 1.30 2001/01/05 22:54:37 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef CATCACHE_H
#define CATCACHE_H
/* #define CACHEDEBUG */ /* turns DEBUG elogs on */
#include "access/htup.h"
#include "lib/dllist.h"
/*
* struct catctup: individual tuple in the cache.
* struct catcache: information for managing a cache.
*/
typedef struct catctup
{
int ct_magic; /* for Assert checks */
#define CT_MAGIC 0x57261502
/*
* Each tuple in a cache is a member of two lists: one lists all the
* elements in that cache in LRU order, and the other lists just the
* elements in one hashbucket, 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.
*/
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? */
HeapTupleData tuple; /* tuple management header */
} CatCTup;
/* voodoo constants */
#define NCCBUCK 500 /* CatCache buckets */
#define MAXTUP 500 /* Maximum # of tuples stored per cache */
typedef struct catcache
{
int id; /* cache identifier --- see syscache.h */
struct catcache *cc_next; /* link to next catcache */
char *cc_relname; /* name of relation the tuples come from */
char *cc_indname; /* name of index matching cache keys */
TupleDesc cc_tupdesc; /* tuple descriptor (copied from reldesc) */
short cc_ntup; /* # of tuples in this cache */
short cc_maxtup; /* max # of tuples allowed (LRU) */
short cc_size; /* # of hash buckets in this cache */
short cc_nkeys; /* number of keys (1..4) */
short 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 */
Dllist cc_lrulist; /* overall LRU list, most recent first */
Dllist cc_cache[NCCBUCK]; /* hash buckets */
} CatCache;
#define InvalidCatalogCacheId (-1)
/* this extern duplicates utils/memutils.h... */
extern MemoryContext CacheMemoryContext;
extern void CreateCacheMemoryContext(void);
extern void AtEOXact_CatCache(bool isCommit);
extern CatCache *InitCatCache(int id, char *relname, char *indname,
int nkeys, int *key);
extern HeapTuple SearchCatCache(CatCache *cache,
Datum v1, Datum v2,
Datum v3, Datum v4);
extern void ReleaseCatCache(HeapTuple tuple);
extern void ResetSystemCache(void);
extern void SystemCacheRelationFlushed(Oid relId);
extern void CatalogCacheIdInvalidate(int cacheId, Index hashIndex,
ItemPointer pointer);
extern void PrepareToInvalidateCacheTuple(Relation relation,
HeapTuple tuple,
void (*function) (int, Index, ItemPointer));
#endif /* CATCACHE_H */
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