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catcache.h
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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) 1996-2017, 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 */
39 typedef uint32 (*CCHashFN) (Datum datum);
40 
41 /* function computing equality of two datums */
42 typedef bool (*CCFastEqualFN) (Datum a, Datum b);
43 
44 typedef 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 
86 typedef 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  */
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  */
157 typedef 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  */
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 
182 typedef struct catcacheheader
183 {
184  slist_head ch_caches; /* head of list of CatCache structs */
185  int ch_ntup; /* # of tuples in all caches */
187 
188 
189 /* this extern duplicates utils/memutils.h... */
191 
192 extern void CreateCacheMemoryContext(void);
193 
194 extern CatCache *InitCatCache(int id, Oid reloid, Oid indexoid,
195  int nkeys, const int *key,
196  int nbuckets);
197 extern void InitCatCachePhase2(CatCache *cache, bool touch_index);
198 
199 extern HeapTuple SearchCatCache(CatCache *cache,
200  Datum v1, Datum v2, Datum v3, Datum v4);
201 extern HeapTuple SearchCatCache1(CatCache *cache,
202  Datum v1);
203 extern HeapTuple SearchCatCache2(CatCache *cache,
204  Datum v1, Datum v2);
205 extern HeapTuple SearchCatCache3(CatCache *cache,
206  Datum v1, Datum v2, Datum v3);
207 extern HeapTuple SearchCatCache4(CatCache *cache,
208  Datum v1, Datum v2, Datum v3, Datum v4);
209 extern void ReleaseCatCache(HeapTuple tuple);
210 
211 extern uint32 GetCatCacheHashValue(CatCache *cache,
212  Datum v1, Datum v2,
213  Datum v3, Datum v4);
214 
215 extern CatCList *SearchCatCacheList(CatCache *cache, int nkeys,
216  Datum v1, Datum v2,
217  Datum v3, Datum v4);
218 extern void ReleaseCatCacheList(CatCList *list);
219 
220 extern void ResetCatalogCaches(void);
221 extern void CatalogCacheFlushCatalog(Oid catId);
222 extern void CatCacheInvalidate(CatCache *cache, uint32 hashValue);
223 extern void PrepareToInvalidateCacheTuple(Relation relation,
224  HeapTuple tuple,
225  HeapTuple newtuple,
226  void (*function) (int, uint32, Oid));
227 
228 extern void PrintCatCacheLeakWarning(HeapTuple tuple);
230 
231 #endif /* CATCACHE_H */
int cc_keyno[CATCACHE_MAXKEYS]
Definition: catcache.h:53
int n_members
Definition: catcache.h:176
uint32 hash_value
Definition: catcache.h:162
uint32 hash_value
Definition: catcache.h:91
CatCache * my_cache
Definition: catcache.h:132
void CreateCacheMemoryContext(void)
Definition: catcache.c:636
CCHashFN cc_hashfunc[CATCACHE_MAXKEYS]
Definition: catcache.h:50
struct catclist CatCList
dlist_head * cc_bucket
Definition: catcache.h:49
void CatCacheInvalidate(CatCache *cache, uint32 hashValue)
Definition: catcache.c:568
struct catcacheheader CatCacheHeader
void ReleaseCatCache(HeapTuple tuple)
Definition: catcache.c:1458
HeapTuple SearchCatCache1(CatCache *cache, Datum v1)
Definition: catcache.c:1182
slist_node cc_next
Definition: catcache.h:61
int id
Definition: catcache.h:46
struct catcache CatCache
int cl_magic
Definition: catcache.h:159
void InitCatCachePhase2(CatCache *cache, bool touch_index)
Definition: catcache.c:1050
bool dead
Definition: catcache.h:173
uint32 GetCatCacheHashValue(CatCache *cache, Datum v1, Datum v2, Datum v3, Datum v4)
Definition: catcache.c:1490
unsigned int Oid
Definition: postgres_ext.h:31
dlist_head cc_lists
Definition: catcache.h:54
HeapTuple SearchCatCache(CatCache *cache, Datum v1, Datum v2, Datum v3, Datum v4)
Definition: catcache.c:1165
bool cc_relisshared
Definition: catcache.h:60
short nkeys
Definition: catcache.h:175
#define PGDLLIMPORT
Definition: c.h:1050
char bool
Definition: c.h:247
struct catclist * c_list
Definition: catcache.h:130
Oid cc_indexoid
Definition: catcache.h:59
#define CATCACHE_MAXKEYS
Definition: catcache.h:35
Oid cc_reloid
Definition: catcache.h:58
int cc_nkeys
Definition: catcache.h:56
struct catctup CatCTup
TupleDesc cc_tupdesc
Definition: catcache.h:48
int cc_ntup
Definition: catcache.h:55
unsigned int uint32
Definition: c.h:296
dlist_node cache_elem
Definition: catcache.h:164
PGDLLIMPORT MemoryContext CacheMemoryContext
Definition: mcxt.c:46
uintptr_t Datum
Definition: postgres.h:372
CatCache * my_cache
Definition: catcache.h:177
slist_head ch_caches
Definition: catcache.h:184
CatCache * InitCatCache(int id, Oid reloid, Oid indexoid, int nkeys, const int *key, int nbuckets)
Definition: catcache.c:779
HeapTuple SearchCatCache3(CatCache *cache, Datum v1, Datum v2, Datum v3)
Definition: catcache.c:1198
int cc_nbuckets
Definition: catcache.h:47
CCFastEqualFN cc_fastequal[CATCACHE_MAXKEYS]
Definition: catcache.h:51
uint32(* CCHashFN)(Datum datum)
Definition: catcache.h:39
int refcount
Definition: catcache.h:118
HeapTuple SearchCatCache4(CatCache *cache, Datum v1, Datum v2, Datum v3, Datum v4)
Definition: catcache.c:1206
const char * cc_relname
Definition: catcache.h:57
dlist_node cache_elem
Definition: catcache.h:104
void CatalogCacheFlushCatalog(Oid catId)
Definition: catcache.c:735
bool negative
Definition: catcache.h:120
bool ordered
Definition: catcache.h:174
void PrintCatCacheLeakWarning(HeapTuple tuple)
Definition: catcache.c:2094
void ResetCatalogCaches(void)
Definition: catcache.c:705
CatCList * SearchCatCacheList(CatCache *cache, int nkeys, Datum v1, Datum v2, Datum v3, Datum v4)
Definition: catcache.c:1519
void PrintCatCacheListLeakWarning(CatCList *list)
Definition: catcache.c:2110
HeapTupleData tuple
Definition: catcache.h:121
HeapTuple SearchCatCache2(CatCache *cache, Datum v1, Datum v2)
Definition: catcache.c:1190
int refcount
Definition: catcache.h:172
ScanKeyData cc_skey[CATCACHE_MAXKEYS]
Definition: catcache.h:62
bool(* CCFastEqualFN)(Datum a, Datum b)
Definition: catcache.h:42
int ct_magic
Definition: catcache.h:88
bool dead
Definition: catcache.h:119
void ReleaseCatCacheList(CatCList *list)
Definition: catcache.c:1795
void PrepareToInvalidateCacheTuple(Relation relation, HeapTuple tuple, HeapTuple newtuple, void(*function)(int, uint32, Oid))
Definition: catcache.c:2030