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Diffstat (limited to 'src/include/utils/catcache.h')
| -rw-r--r-- | src/include/utils/catcache.h | 231 |
1 files changed, 231 insertions, 0 deletions
diff --git a/src/include/utils/catcache.h b/src/include/utils/catcache.h new file mode 100644 index 0000000..f4aa316 --- /dev/null +++ b/src/include/utils/catcache.h @@ -0,0 +1,231 @@ +/*------------------------------------------------------------------------- + * + * 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) 1996-2020, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * src/include/utils/catcache.h + * + *------------------------------------------------------------------------- + */ +#ifndef CATCACHE_H +#define CATCACHE_H + +#include "access/htup.h" +#include "access/skey.h" +#include "lib/ilist.h" +#include "utils/relcache.h" + +/* + * struct catctup: individual tuple in the cache. + * struct catclist: list of tuples matching a partial key. + * struct catcache: information for managing a cache. + * struct catcacheheader: information for managing all the caches. + */ + +#define CATCACHE_MAXKEYS 4 + + +/* function computing a datum's hash */ +typedef uint32 (*CCHashFN) (Datum datum); + +/* function computing equality of two datums */ +typedef bool (*CCFastEqualFN) (Datum a, Datum b); + +typedef struct catcache +{ + int id; /* cache identifier --- see syscache.h */ + int cc_nbuckets; /* # of hash buckets in this cache */ + TupleDesc cc_tupdesc; /* tuple descriptor (copied from reldesc) */ + dlist_head *cc_bucket; /* hash buckets */ + CCHashFN cc_hashfunc[CATCACHE_MAXKEYS]; /* hash function for each key */ + CCFastEqualFN cc_fastequal[CATCACHE_MAXKEYS]; /* fast equal function for + * each key */ + int cc_keyno[CATCACHE_MAXKEYS]; /* AttrNumber of each key */ + dlist_head cc_lists; /* list of CatCList structs */ + int cc_ntup; /* # of tuples currently in this cache */ + int cc_nkeys; /* # of keys (1..CATCACHE_MAXKEYS) */ + const char *cc_relname; /* name of relation the tuples come from */ + Oid cc_reloid; /* OID of relation the tuples come from */ + Oid cc_indexoid; /* OID of index matching cache keys */ + bool cc_relisshared; /* is relation shared across databases? */ + slist_node cc_next; /* list link */ + ScanKeyData cc_skey[CATCACHE_MAXKEYS]; /* precomputed key info for heap + * scans */ + + /* + * Keep these at the end, so that compiling catcache.c with CATCACHE_STATS + * doesn't break ABI for other modules + */ +#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_lsearches; /* total # list-searches */ + long cc_lhits; /* # of matches against existing lists */ +#endif +} CatCache; + + +typedef struct catctup +{ + int ct_magic; /* for identifying CatCTup entries */ +#define CT_MAGIC 0x57261502 + + uint32 hash_value; /* hash value for this tuple's keys */ + + /* + * Lookup keys for the entry. By-reference datums point into the tuple for + * positive cache entries, and are separately allocated for negative ones. + */ + Datum keys[CATCACHE_MAXKEYS]; + + /* + * Each tuple in a cache is a member of a dlist that stores the elements + * of its hash bucket. We keep each dlist in LRU order to speed repeated + * lookups. + */ + dlist_node cache_elem; /* list member of per-bucket list */ + + /* + * 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. (If it's a member of a CatCList, the list's + * refcount must go to zero, too; also, remember to mark the list dead at + * the same time the tuple is marked.) + * + * 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. + */ + int refcount; /* number of active references */ + bool dead; /* dead but not yet removed? */ + bool negative; /* negative cache entry? */ + HeapTupleData tuple; /* tuple management header */ + + /* + * The tuple may also be a member of at most one CatCList. (If a single + * catcache is list-searched with varying numbers of keys, we may have to + * make multiple entries for the same tuple because of this restriction. + * Currently, that's not expected to be common, so we accept the potential + * inefficiency.) + */ + struct catclist *c_list; /* containing CatCList, or NULL if none */ + + CatCache *my_cache; /* link to owning catcache */ + /* properly aligned tuple data follows, unless a negative entry */ +} CatCTup; + + +/* + * A CatCList describes the result of a partial search, ie, a search using + * only the first K key columns of an N-key cache. We store the keys used + * into the keys attribute to represent the stored key set. The CatCList + * object contains links to cache entries for all the table rows satisfying + * the partial key. (Note: none of these will be negative cache entries.) + * + * A CatCList is only a member of a per-cache list; we do not currently + * divide them into hash buckets. + * + * A list 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 list should be marked dead if any of its + * member entries are dead.) + * + * If "ordered" is true then the member tuples appear in the order of the + * cache's underlying index. This will be true in normal operation, but + * might not be true during bootstrap or recovery operations. (namespace.c + * is able to save some cycles when it is true.) + */ +typedef struct catclist +{ + int cl_magic; /* for identifying CatCList entries */ +#define CL_MAGIC 0x52765103 + + uint32 hash_value; /* hash value for lookup keys */ + + dlist_node cache_elem; /* list member of per-catcache list */ + + /* + * Lookup keys for the entry, with the first nkeys elements being valid. + * All by-reference are separately allocated. + */ + Datum keys[CATCACHE_MAXKEYS]; + + int refcount; /* number of active references */ + bool dead; /* dead but not yet removed? */ + bool ordered; /* members listed in index order? */ + short nkeys; /* number of lookup keys specified */ + int n_members; /* number of member tuples */ + CatCache *my_cache; /* link to owning catcache */ + CatCTup *members[FLEXIBLE_ARRAY_MEMBER]; /* members */ +} CatCList; + + +typedef struct catcacheheader +{ + slist_head ch_caches; /* head of list of CatCache structs */ + int ch_ntup; /* # of tuples in all caches */ +} CatCacheHeader; + + +/* this extern duplicates utils/memutils.h... */ +extern PGDLLIMPORT MemoryContext CacheMemoryContext; + +extern void CreateCacheMemoryContext(void); + +extern CatCache *InitCatCache(int id, Oid reloid, Oid indexoid, + int nkeys, const int *key, + int nbuckets); +extern void InitCatCachePhase2(CatCache *cache, bool touch_index); + +extern HeapTuple SearchCatCache(CatCache *cache, + Datum v1, Datum v2, Datum v3, Datum v4); +extern HeapTuple SearchCatCache1(CatCache *cache, + Datum v1); +extern HeapTuple SearchCatCache2(CatCache *cache, + Datum v1, Datum v2); +extern HeapTuple SearchCatCache3(CatCache *cache, + Datum v1, Datum v2, Datum v3); +extern HeapTuple SearchCatCache4(CatCache *cache, + Datum v1, Datum v2, Datum v3, Datum v4); +extern void ReleaseCatCache(HeapTuple tuple); + +extern uint32 GetCatCacheHashValue(CatCache *cache, + Datum v1, Datum v2, + Datum v3, Datum v4); + +extern CatCList *SearchCatCacheList(CatCache *cache, int nkeys, + Datum v1, Datum v2, + Datum v3); +extern void ReleaseCatCacheList(CatCList *list); + +extern void ResetCatalogCaches(void); +extern void CatalogCacheFlushCatalog(Oid catId); +extern void CatCacheInvalidate(CatCache *cache, uint32 hashValue); +extern void PrepareToInvalidateCacheTuple(Relation relation, + HeapTuple tuple, + HeapTuple newtuple, + void (*function) (int, uint32, Oid)); + +extern void PrintCatCacheLeakWarning(HeapTuple tuple); +extern void PrintCatCacheListLeakWarning(CatCList *list); + +#endif /* CATCACHE_H */ |