1 /*------------------------------------------------------------------------- 2 * 3 * catcache.h 4 * Low-level catalog cache definitions. 5 * 6 * NOTE: every catalog cache must have a corresponding unique index on 7 * the system table that it caches --- ie, the index must match the keys 8 * used to do lookups in this cache. All cache fetches are done with 9 * indexscans (under normal conditions). The index should be unique to 10 * guarantee that there can only be one matching row for a key combination. 11 * 12 * 13 * Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group 14 * Portions Copyright (c) 1994, Regents of the University of California 15 * 16 * src/include/utils/catcache.h 17 * 18 *------------------------------------------------------------------------- 19 */ 20 #ifndef CATCACHE_H 21 #define CATCACHE_H 22 23 #include "access/htup.h" 24 #include "access/skey.h" 25 #include "lib/ilist.h" 26 #include "utils/relcache.h" 27 28 /* 29 * struct catctup: individual tuple in the cache. 30 * struct catclist: list of tuples matching a partial key. 31 * struct catcache: information for managing a cache. 32 * struct catcacheheader: information for managing all the caches. 33 */ 34 35 #define CATCACHE_MAXKEYS 4 36 37 typedef struct catcache 38 { 39 int id; /* cache identifier --- see syscache.h */ 40 slist_node cc_next; /* list link */ 41 const char *cc_relname; /* name of relation the tuples come from */ 42 Oid cc_reloid; /* OID of relation the tuples come from */ 43 Oid cc_indexoid; /* OID of index matching cache keys */ 44 bool cc_relisshared; /* is relation shared across databases? */ 45 TupleDesc cc_tupdesc; /* tuple descriptor (copied from reldesc) */ 46 int cc_ntup; /* # of tuples currently in this cache */ 47 int cc_nbuckets; /* # of hash buckets in this cache */ 48 int cc_nkeys; /* # of keys (1..CATCACHE_MAXKEYS) */ 49 int cc_key[CATCACHE_MAXKEYS]; /* AttrNumber of each key */ 50 PGFunction cc_hashfunc[CATCACHE_MAXKEYS]; /* hash function for each key */ 51 ScanKeyData cc_skey[CATCACHE_MAXKEYS]; /* precomputed key info for 52 * heap scans */ 53 bool cc_isname[CATCACHE_MAXKEYS]; /* flag "name" key columns */ 54 dlist_head cc_lists; /* list of CatCList structs */ 55 #ifdef CATCACHE_STATS 56 long cc_searches; /* total # searches against this cache */ 57 long cc_hits; /* # of matches against existing entry */ 58 long cc_neg_hits; /* # of matches against negative entry */ 59 long cc_newloads; /* # of successful loads of new entry */ 60 61 /* 62 * cc_searches - (cc_hits + cc_neg_hits + cc_newloads) is number of failed 63 * searches, each of which will result in loading a negative entry 64 */ 65 long cc_invals; /* # of entries invalidated from cache */ 66 long cc_lsearches; /* total # list-searches */ 67 long cc_lhits; /* # of matches against existing lists */ 68 #endif 69 dlist_head *cc_bucket; /* hash buckets */ 70 } CatCache; 71 72 73 typedef struct catctup 74 { 75 int ct_magic; /* for identifying CatCTup entries */ 76 #define CT_MAGIC 0x57261502 77 CatCache *my_cache; /* link to owning catcache */ 78 79 /* 80 * Each tuple in a cache is a member of a dlist that stores the elements 81 * of its hash bucket. We keep each dlist in LRU order to speed repeated 82 * lookups. 83 */ 84 dlist_node cache_elem; /* list member of per-bucket list */ 85 86 /* 87 * The tuple may also be a member of at most one CatCList. (If a single 88 * catcache is list-searched with varying numbers of keys, we may have to 89 * make multiple entries for the same tuple because of this restriction. 90 * Currently, that's not expected to be common, so we accept the potential 91 * inefficiency.) 92 */ 93 struct catclist *c_list; /* containing CatCList, or NULL if none */ 94 95 /* 96 * A tuple marked "dead" must not be returned by subsequent searches. 97 * However, it won't be physically deleted from the cache until its 98 * refcount goes to zero. (If it's a member of a CatCList, the list's 99 * refcount must go to zero, too; also, remember to mark the list dead at 100 * the same time the tuple is marked.) 101 * 102 * A negative cache entry is an assertion that there is no tuple matching 103 * a particular key. This is just as useful as a normal entry so far as 104 * avoiding catalog searches is concerned. Management of positive and 105 * negative entries is identical. 106 */ 107 int refcount; /* number of active references */ 108 bool dead; /* dead but not yet removed? */ 109 bool negative; /* negative cache entry? */ 110 uint32 hash_value; /* hash value for this tuple's keys */ 111 HeapTupleData tuple; /* tuple management header */ 112 } CatCTup; 113 114 115 typedef struct catclist 116 { 117 int cl_magic; /* for identifying CatCList entries */ 118 #define CL_MAGIC 0x52765103 119 CatCache *my_cache; /* link to owning catcache */ 120 121 /* 122 * A CatCList describes the result of a partial search, ie, a search using 123 * only the first K key columns of an N-key cache. We form the keys used 124 * into a tuple (with other attributes NULL) to represent the stored key 125 * set. The CatCList object contains links to cache entries for all the 126 * table rows satisfying the partial key. (Note: none of these will be 127 * negative cache entries.) 128 * 129 * A CatCList is only a member of a per-cache list; we do not currently 130 * divide them into hash buckets. 131 * 132 * A list marked "dead" must not be returned by subsequent searches. 133 * However, it won't be physically deleted from the cache until its 134 * refcount goes to zero. (A list should be marked dead if any of its 135 * member entries are dead.) 136 * 137 * If "ordered" is true then the member tuples appear in the order of the 138 * cache's underlying index. This will be true in normal operation, but 139 * might not be true during bootstrap or recovery operations. (namespace.c 140 * is able to save some cycles when it is true.) 141 */ 142 dlist_node cache_elem; /* list member of per-catcache list */ 143 int refcount; /* number of active references */ 144 bool dead; /* dead but not yet removed? */ 145 bool ordered; /* members listed in index order? */ 146 short nkeys; /* number of lookup keys specified */ 147 uint32 hash_value; /* hash value for lookup keys */ 148 HeapTupleData tuple; /* header for tuple holding keys */ 149 int n_members; /* number of member tuples */ 150 CatCTup *members[FLEXIBLE_ARRAY_MEMBER]; /* members */ 151 } CatCList; 152 153 154 typedef struct catcacheheader 155 { 156 slist_head ch_caches; /* head of list of CatCache structs */ 157 int ch_ntup; /* # of tuples in all caches */ 158 } CatCacheHeader; 159 160 161 /* this extern duplicates utils/memutils.h... */ 162 extern PGDLLIMPORT MemoryContext CacheMemoryContext; 163 164 extern void CreateCacheMemoryContext(void); 165 166 extern CatCache *InitCatCache(int id, Oid reloid, Oid indexoid, 167 int nkeys, const int *key, 168 int nbuckets); 169 extern void InitCatCachePhase2(CatCache *cache, bool touch_index); 170 171 extern HeapTuple SearchCatCache(CatCache *cache, 172 Datum v1, Datum v2, 173 Datum v3, Datum v4); 174 extern void ReleaseCatCache(HeapTuple tuple); 175 176 extern uint32 GetCatCacheHashValue(CatCache *cache, 177 Datum v1, Datum v2, 178 Datum v3, Datum v4); 179 180 extern CatCList *SearchCatCacheList(CatCache *cache, int nkeys, 181 Datum v1, Datum v2, 182 Datum v3, Datum v4); 183 extern void ReleaseCatCacheList(CatCList *list); 184 185 extern void ResetCatalogCaches(void); 186 extern void CatalogCacheFlushCatalog(Oid catId); 187 extern void CatCacheInvalidate(CatCache *cache, uint32 hashValue); 188 extern void PrepareToInvalidateCacheTuple(Relation relation, 189 HeapTuple tuple, 190 HeapTuple newtuple, 191 void (*function) (int, uint32, Oid)); 192 193 extern void PrintCatCacheLeakWarning(HeapTuple tuple); 194 extern void PrintCatCacheListLeakWarning(CatCList *list); 195 196 #endif /* CATCACHE_H */ 197