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) 1996-2019, 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
38/* function computing a datum's hash */
39typedef uint32 (*CCHashFN) (Datum datum);
40
41/* function computing equality of two datums */
42typedef bool (*CCFastEqualFN) (Datum a, Datum b);
43
44typedef struct catcache
45{
46 int id; /* cache identifier --- see syscache.h */
47 int cc_nbuckets; /* # of hash buckets in this cache */
48 TupleDesc cc_tupdesc; /* tuple descriptor (copied from reldesc) */
49 dlist_head *cc_bucket; /* hash buckets */
50 CCHashFN cc_hashfunc[CATCACHE_MAXKEYS]; /* hash function for each key */
51 CCFastEqualFN cc_fastequal[CATCACHE_MAXKEYS]; /* fast equal function for
52 * each key */
53 int cc_keyno[CATCACHE_MAXKEYS]; /* AttrNumber of each key */
54 dlist_head cc_lists; /* list of CatCList structs */
55 int cc_ntup; /* # of tuples currently in this cache */
56 int cc_nkeys; /* # of keys (1..CATCACHE_MAXKEYS) */
57 const char *cc_relname; /* name of relation the tuples come from */
58 Oid cc_reloid; /* OID of relation the tuples come from */
59 Oid cc_indexoid; /* OID of index matching cache keys */
60 bool cc_relisshared; /* is relation shared across databases? */
61 slist_node cc_next; /* list link */
62 ScanKeyData cc_skey[CATCACHE_MAXKEYS]; /* precomputed key info for heap
63 * scans */
64
65 /*
66 * Keep these at the end, so that compiling catcache.c with CATCACHE_STATS
67 * doesn't break ABI for other modules
68 */
69#ifdef CATCACHE_STATS
70 long cc_searches; /* total # searches against this cache */
71 long cc_hits; /* # of matches against existing entry */
72 long cc_neg_hits; /* # of matches against negative entry */
73 long cc_newloads; /* # of successful loads of new entry */
74
75 /*
76 * cc_searches - (cc_hits + cc_neg_hits + cc_newloads) is number of failed
77 * searches, each of which will result in loading a negative entry
78 */
79 long cc_invals; /* # of entries invalidated from cache */
80 long cc_lsearches; /* total # list-searches */
81 long cc_lhits; /* # of matches against existing lists */
82#endif
83} CatCache;
84
85
86typedef struct catctup
87{
88 int ct_magic; /* for identifying CatCTup entries */
89#define CT_MAGIC 0x57261502
90
91 uint32 hash_value; /* hash value for this tuple's keys */
92
93 /*
94 * Lookup keys for the entry. By-reference datums point into the tuple for
95 * positive cache entries, and are separately allocated for negative ones.
96 */
97 Datum keys[CATCACHE_MAXKEYS];
98
99 /*
100 * Each tuple in a cache is a member of a dlist that stores the elements
101 * of its hash bucket. We keep each dlist in LRU order to speed repeated
102 * lookups.
103 */
104 dlist_node cache_elem; /* list member of per-bucket list */
105
106 /*
107 * A tuple marked "dead" must not be returned by subsequent searches.
108 * However, it won't be physically deleted from the cache until its
109 * refcount goes to zero. (If it's a member of a CatCList, the list's
110 * refcount must go to zero, too; also, remember to mark the list dead at
111 * the same time the tuple is marked.)
112 *
113 * A negative cache entry is an assertion that there is no tuple matching
114 * a particular key. This is just as useful as a normal entry so far as
115 * avoiding catalog searches is concerned. Management of positive and
116 * negative entries is identical.
117 */
118 int refcount; /* number of active references */
119 bool dead; /* dead but not yet removed? */
120 bool negative; /* negative cache entry? */
121 HeapTupleData tuple; /* tuple management header */
122
123 /*
124 * The tuple may also be a member of at most one CatCList. (If a single
125 * catcache is list-searched with varying numbers of keys, we may have to
126 * make multiple entries for the same tuple because of this restriction.
127 * Currently, that's not expected to be common, so we accept the potential
128 * inefficiency.)
129 */
130 struct catclist *c_list; /* containing CatCList, or NULL if none */
131
132 CatCache *my_cache; /* link to owning catcache */
133 /* properly aligned tuple data follows, unless a negative entry */
134} CatCTup;
135
136
137/*
138 * A CatCList describes the result of a partial search, ie, a search using
139 * only the first K key columns of an N-key cache. We store the keys used
140 * into the keys attribute to represent the stored key set. The CatCList
141 * object contains links to cache entries for all the table rows satisfying
142 * the partial key. (Note: none of these will be negative cache entries.)
143 *
144 * A CatCList is only a member of a per-cache list; we do not currently
145 * divide them into hash buckets.
146 *
147 * A list marked "dead" must not be returned by subsequent searches.
148 * However, it won't be physically deleted from the cache until its
149 * refcount goes to zero. (A list should be marked dead if any of its
150 * member entries are dead.)
151 *
152 * If "ordered" is true then the member tuples appear in the order of the
153 * cache's underlying index. This will be true in normal operation, but
154 * might not be true during bootstrap or recovery operations. (namespace.c
155 * is able to save some cycles when it is true.)
156 */
157typedef struct catclist
158{
159 int cl_magic; /* for identifying CatCList entries */
160#define CL_MAGIC 0x52765103
161
162 uint32 hash_value; /* hash value for lookup keys */
163
164 dlist_node cache_elem; /* list member of per-catcache list */
165
166 /*
167 * Lookup keys for the entry, with the first nkeys elements being valid.
168 * All by-reference are separately allocated.
169 */
170 Datum keys[CATCACHE_MAXKEYS];
171
172 int refcount; /* number of active references */
173 bool dead; /* dead but not yet removed? */
174 bool ordered; /* members listed in index order? */
175 short nkeys; /* number of lookup keys specified */
176 int n_members; /* number of member tuples */
177 CatCache *my_cache; /* link to owning catcache */
178 CatCTup *members[FLEXIBLE_ARRAY_MEMBER]; /* members */
179} CatCList;
180
181
182typedef struct catcacheheader
183{
184 slist_head ch_caches; /* head of list of CatCache structs */
185 int ch_ntup; /* # of tuples in all caches */
186} CatCacheHeader;
187
188
189/* this extern duplicates utils/memutils.h... */
190extern PGDLLIMPORT MemoryContext CacheMemoryContext;
191
192extern void CreateCacheMemoryContext(void);
193
194extern CatCache *InitCatCache(int id, Oid reloid, Oid indexoid,
195 int nkeys, const int *key,
196 int nbuckets);
197extern void InitCatCachePhase2(CatCache *cache, bool touch_index);
198
199extern HeapTuple SearchCatCache(CatCache *cache,
200 Datum v1, Datum v2, Datum v3, Datum v4);
201extern HeapTuple SearchCatCache1(CatCache *cache,
202 Datum v1);
203extern HeapTuple SearchCatCache2(CatCache *cache,
204 Datum v1, Datum v2);
205extern HeapTuple SearchCatCache3(CatCache *cache,
206 Datum v1, Datum v2, Datum v3);
207extern HeapTuple SearchCatCache4(CatCache *cache,
208 Datum v1, Datum v2, Datum v3, Datum v4);
209extern void ReleaseCatCache(HeapTuple tuple);
210
211extern uint32 GetCatCacheHashValue(CatCache *cache,
212 Datum v1, Datum v2,
213 Datum v3, Datum v4);
214
215extern CatCList *SearchCatCacheList(CatCache *cache, int nkeys,
216 Datum v1, Datum v2,
217 Datum v3);
218extern void ReleaseCatCacheList(CatCList *list);
219
220extern void ResetCatalogCaches(void);
221extern void CatalogCacheFlushCatalog(Oid catId);
222extern void CatCacheInvalidate(CatCache *cache, uint32 hashValue);
223extern void PrepareToInvalidateCacheTuple(Relation relation,
224 HeapTuple tuple,
225 HeapTuple newtuple,
226 void (*function) (int, uint32, Oid));
227
228extern void PrintCatCacheLeakWarning(HeapTuple tuple);
229extern void PrintCatCacheListLeakWarning(CatCList *list);
230
231#endif /* CATCACHE_H */
232