Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * spccache.c
4 : * Tablespace cache management.
5 : *
6 : * We cache the parsed version of spcoptions for each tablespace to avoid
7 : * needing to reparse on every lookup. Right now, there doesn't appear to
8 : * be a measurable performance gain from doing this, but that might change
9 : * in the future as we add more options.
10 : *
11 : * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
12 : * Portions Copyright (c) 1994, Regents of the University of California
13 : *
14 : * IDENTIFICATION
15 : * src/backend/utils/cache/spccache.c
16 : *
17 : *-------------------------------------------------------------------------
18 : */
19 : #include "postgres.h"
20 :
21 : #include "access/reloptions.h"
22 : #include "catalog/pg_tablespace.h"
23 : #include "commands/tablespace.h"
24 : #include "miscadmin.h"
25 : #include "optimizer/cost.h"
26 : #include "storage/bufmgr.h"
27 : #include "utils/catcache.h"
28 : #include "utils/hsearch.h"
29 : #include "utils/inval.h"
30 : #include "utils/spccache.h"
31 : #include "utils/syscache.h"
32 :
33 :
34 : /* Hash table for information about each tablespace */
35 : static HTAB *TableSpaceCacheHash = NULL;
36 :
37 : typedef struct
38 : {
39 : Oid oid; /* lookup key - must be first */
40 : TableSpaceOpts *opts; /* options, or NULL if none */
41 : } TableSpaceCacheEntry;
42 :
43 :
44 : /*
45 : * InvalidateTableSpaceCacheCallback
46 : * Flush all cache entries when pg_tablespace is updated.
47 : *
48 : * When pg_tablespace is updated, we must flush the cache entry at least
49 : * for that tablespace. Currently, we just flush them all. This is quick
50 : * and easy and doesn't cost much, since there shouldn't be terribly many
51 : * tablespaces, nor do we expect them to be frequently modified.
52 : */
53 : static void
54 28 : InvalidateTableSpaceCacheCallback(Datum arg, int cacheid, uint32 hashvalue)
55 : {
56 : HASH_SEQ_STATUS status;
57 : TableSpaceCacheEntry *spc;
58 :
59 28 : hash_seq_init(&status, TableSpaceCacheHash);
60 28 : while ((spc = (TableSpaceCacheEntry *) hash_seq_search(&status)) != NULL)
61 : {
62 28 : if (spc->opts)
63 0 : pfree(spc->opts);
64 28 : if (hash_search(TableSpaceCacheHash,
65 28 : (void *) &spc->oid,
66 : HASH_REMOVE,
67 : NULL) == NULL)
68 0 : elog(ERROR, "hash table corrupted");
69 : }
70 28 : }
71 :
72 : /*
73 : * InitializeTableSpaceCache
74 : * Initialize the tablespace cache.
75 : */
76 : static void
77 217 : InitializeTableSpaceCache(void)
78 : {
79 : HASHCTL ctl;
80 :
81 : /* Initialize the hash table. */
82 217 : MemSet(&ctl, 0, sizeof(ctl));
83 217 : ctl.keysize = sizeof(Oid);
84 217 : ctl.entrysize = sizeof(TableSpaceCacheEntry);
85 217 : TableSpaceCacheHash =
86 217 : hash_create("TableSpace cache", 16, &ctl,
87 : HASH_ELEM | HASH_BLOBS);
88 :
89 : /* Make sure we've initialized CacheMemoryContext. */
90 217 : if (!CacheMemoryContext)
91 0 : CreateCacheMemoryContext();
92 :
93 : /* Watch for invalidation events. */
94 217 : CacheRegisterSyscacheCallback(TABLESPACEOID,
95 : InvalidateTableSpaceCacheCallback,
96 : (Datum) 0);
97 217 : }
98 :
99 : /*
100 : * get_tablespace
101 : * Fetch TableSpaceCacheEntry structure for a specified table OID.
102 : *
103 : * Pointers returned by this function should not be stored, since a cache
104 : * flush will invalidate them.
105 : */
106 : static TableSpaceCacheEntry *
107 76590 : get_tablespace(Oid spcid)
108 : {
109 : TableSpaceCacheEntry *spc;
110 : HeapTuple tp;
111 : TableSpaceOpts *opts;
112 :
113 : /*
114 : * Since spcid is always from a pg_class tuple, InvalidOid implies the
115 : * default.
116 : */
117 76590 : if (spcid == InvalidOid)
118 73478 : spcid = MyDatabaseTableSpace;
119 :
120 : /* Find existing cache entry, if any. */
121 76590 : if (!TableSpaceCacheHash)
122 217 : InitializeTableSpaceCache();
123 76590 : spc = (TableSpaceCacheEntry *) hash_search(TableSpaceCacheHash,
124 : (void *) &spcid,
125 : HASH_FIND,
126 : NULL);
127 76590 : if (spc)
128 76324 : return spc;
129 :
130 : /*
131 : * Not found in TableSpace cache. Check catcache. If we don't find a
132 : * valid HeapTuple, it must mean someone has managed to request tablespace
133 : * details for a non-existent tablespace. We'll just treat that case as
134 : * if no options were specified.
135 : */
136 266 : tp = SearchSysCache1(TABLESPACEOID, ObjectIdGetDatum(spcid));
137 266 : if (!HeapTupleIsValid(tp))
138 0 : opts = NULL;
139 : else
140 : {
141 : Datum datum;
142 : bool isNull;
143 :
144 266 : datum = SysCacheGetAttr(TABLESPACEOID,
145 : tp,
146 : Anum_pg_tablespace_spcoptions,
147 : &isNull);
148 266 : if (isNull)
149 266 : opts = NULL;
150 : else
151 : {
152 0 : bytea *bytea_opts = tablespace_reloptions(datum, false);
153 :
154 0 : opts = MemoryContextAlloc(CacheMemoryContext, VARSIZE(bytea_opts));
155 0 : memcpy(opts, bytea_opts, VARSIZE(bytea_opts));
156 : }
157 266 : ReleaseSysCache(tp);
158 : }
159 :
160 : /*
161 : * Now create the cache entry. It's important to do this only after
162 : * reading the pg_tablespace entry, since doing so could cause a cache
163 : * flush.
164 : */
165 266 : spc = (TableSpaceCacheEntry *) hash_search(TableSpaceCacheHash,
166 : (void *) &spcid,
167 : HASH_ENTER,
168 : NULL);
169 266 : spc->opts = opts;
170 266 : return spc;
171 : }
172 :
173 : /*
174 : * get_tablespace_page_costs
175 : * Return random and/or sequential page costs for a given tablespace.
176 : *
177 : * This value is not locked by the transaction, so this value may
178 : * be changed while a SELECT that has used these values for planning
179 : * is still executing.
180 : */
181 : void
182 74864 : get_tablespace_page_costs(Oid spcid,
183 : double *spc_random_page_cost,
184 : double *spc_seq_page_cost)
185 : {
186 74864 : TableSpaceCacheEntry *spc = get_tablespace(spcid);
187 :
188 74864 : Assert(spc != NULL);
189 :
190 74864 : if (spc_random_page_cost)
191 : {
192 58705 : if (!spc->opts || spc->opts->random_page_cost < 0)
193 58705 : *spc_random_page_cost = random_page_cost;
194 : else
195 0 : *spc_random_page_cost = spc->opts->random_page_cost;
196 : }
197 :
198 74864 : if (spc_seq_page_cost)
199 : {
200 53844 : if (!spc->opts || spc->opts->seq_page_cost < 0)
201 53844 : *spc_seq_page_cost = seq_page_cost;
202 : else
203 0 : *spc_seq_page_cost = spc->opts->seq_page_cost;
204 : }
205 74864 : }
206 :
207 : /*
208 : * get_tablespace_io_concurrency
209 : *
210 : * This value is not locked by the transaction, so this value may
211 : * be changed while a SELECT that has used these values for planning
212 : * is still executing.
213 : */
214 : int
215 1726 : get_tablespace_io_concurrency(Oid spcid)
216 : {
217 1726 : TableSpaceCacheEntry *spc = get_tablespace(spcid);
218 :
219 1726 : if (!spc->opts || spc->opts->effective_io_concurrency < 0)
220 1726 : return effective_io_concurrency;
221 : else
222 0 : return spc->opts->effective_io_concurrency;
223 : }
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