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spccache.c
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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) 1996-2021, 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/optimizer.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 */
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
55 {
58 
59  hash_seq_init(&status, TableSpaceCacheHash);
60  while ((spc = (TableSpaceCacheEntry *) hash_seq_search(&status)) != NULL)
61  {
62  if (spc->opts)
63  pfree(spc->opts);
64  if (hash_search(TableSpaceCacheHash,
65  (void *) &spc->oid,
67  NULL) == NULL)
68  elog(ERROR, "hash table corrupted");
69  }
70 }
71 
72 /*
73  * InitializeTableSpaceCache
74  * Initialize the tablespace cache.
75  */
76 static void
78 {
79  HASHCTL ctl;
80 
81  /* Initialize the hash table. */
82  ctl.keysize = sizeof(Oid);
83  ctl.entrysize = sizeof(TableSpaceCacheEntry);
84  TableSpaceCacheHash =
85  hash_create("TableSpace cache", 16, &ctl,
87 
88  /* Make sure we've initialized CacheMemoryContext. */
89  if (!CacheMemoryContext)
91 
92  /* Watch for invalidation events. */
95  (Datum) 0);
96 }
97 
98 /*
99  * get_tablespace
100  * Fetch TableSpaceCacheEntry structure for a specified table OID.
101  *
102  * Pointers returned by this function should not be stored, since a cache
103  * flush will invalidate them.
104  */
105 static TableSpaceCacheEntry *
107 {
109  HeapTuple tp;
111 
112  /*
113  * Since spcid is always from a pg_class tuple, InvalidOid implies the
114  * default.
115  */
116  if (spcid == InvalidOid)
117  spcid = MyDatabaseTableSpace;
118 
119  /* Find existing cache entry, if any. */
120  if (!TableSpaceCacheHash)
122  spc = (TableSpaceCacheEntry *) hash_search(TableSpaceCacheHash,
123  (void *) &spcid,
124  HASH_FIND,
125  NULL);
126  if (spc)
127  return spc;
128 
129  /*
130  * Not found in TableSpace cache. Check catcache. If we don't find a
131  * valid HeapTuple, it must mean someone has managed to request tablespace
132  * details for a non-existent tablespace. We'll just treat that case as
133  * if no options were specified.
134  */
136  if (!HeapTupleIsValid(tp))
137  opts = NULL;
138  else
139  {
140  Datum datum;
141  bool isNull;
142 
144  tp,
145  Anum_pg_tablespace_spcoptions,
146  &isNull);
147  if (isNull)
148  opts = NULL;
149  else
150  {
151  bytea *bytea_opts = tablespace_reloptions(datum, false);
152 
153  opts = MemoryContextAlloc(CacheMemoryContext, VARSIZE(bytea_opts));
154  memcpy(opts, bytea_opts, VARSIZE(bytea_opts));
155  }
156  ReleaseSysCache(tp);
157  }
158 
159  /*
160  * Now create the cache entry. It's important to do this only after
161  * reading the pg_tablespace entry, since doing so could cause a cache
162  * flush.
163  */
164  spc = (TableSpaceCacheEntry *) hash_search(TableSpaceCacheHash,
165  (void *) &spcid,
166  HASH_ENTER,
167  NULL);
168  spc->opts = opts;
169  return spc;
170 }
171 
172 /*
173  * get_tablespace_page_costs
174  * Return random and/or sequential page costs for a given tablespace.
175  *
176  * This value is not locked by the transaction, so this value may
177  * be changed while a SELECT that has used these values for planning
178  * is still executing.
179  */
180 void
182  double *spc_random_page_cost,
183  double *spc_seq_page_cost)
184 {
185  TableSpaceCacheEntry *spc = get_tablespace(spcid);
186 
187  Assert(spc != NULL);
188 
189  if (spc_random_page_cost)
190  {
191  if (!spc->opts || spc->opts->random_page_cost < 0)
192  *spc_random_page_cost = random_page_cost;
193  else
194  *spc_random_page_cost = spc->opts->random_page_cost;
195  }
196 
197  if (spc_seq_page_cost)
198  {
199  if (!spc->opts || spc->opts->seq_page_cost < 0)
200  *spc_seq_page_cost = seq_page_cost;
201  else
202  *spc_seq_page_cost = spc->opts->seq_page_cost;
203  }
204 }
205 
206 /*
207  * get_tablespace_io_concurrency
208  *
209  * This value is not locked by the transaction, so this value may
210  * be changed while a SELECT that has used these values for planning
211  * is still executing.
212  */
213 int
215 {
216  TableSpaceCacheEntry *spc = get_tablespace(spcid);
217 
218  if (!spc->opts || spc->opts->effective_io_concurrency < 0)
220  else
221  return spc->opts->effective_io_concurrency;
222 }
223 
224 /*
225  * get_tablespace_maintenance_io_concurrency
226  */
227 int
229 {
230  TableSpaceCacheEntry *spc = get_tablespace(spcid);
231 
232  if (!spc->opts || spc->opts->maintenance_io_concurrency < 0)
234  else
235  return spc->opts->maintenance_io_concurrency;
236 }
int maintenance_io_concurrency
Definition: tablespace.h:43
int maintenance_io_concurrency
Definition: bufmgr.c:150
#define HASH_ELEM
Definition: hsearch.h:95
#define VARSIZE(PTR)
Definition: postgres.h:316
static TableSpaceCacheEntry * get_tablespace(Oid spcid)
Definition: spccache.c:106
float8 random_page_cost
Definition: tablespace.h:40
Size entrysize
Definition: hsearch.h:76
bytea * tablespace_reloptions(Datum reloptions, bool validate)
Definition: reloptions.c:2080
int get_tablespace_io_concurrency(Oid spcid)
Definition: spccache.c:214
TableSpaceOpts * opts
Definition: spccache.c:40
void * hash_search(HTAB *hashp, const void *keyPtr, HASHACTION action, bool *foundPtr)
Definition: dynahash.c:954
unsigned int Oid
Definition: postgres_ext.h:31
int effective_io_concurrency
Definition: bufmgr.c:143
Oid MyDatabaseTableSpace
Definition: globals.c:90
float8 seq_page_cost
Definition: tablespace.h:41
Definition: dynahash.c:219
double random_page_cost
Definition: costsize.c:120
int get_tablespace_maintenance_io_concurrency(Oid spcid)
Definition: spccache.c:228
void pfree(void *pointer)
Definition: mcxt.c:1169
#define ObjectIdGetDatum(X)
Definition: postgres.h:551
#define ERROR
Definition: elog.h:46
static HTAB * TableSpaceCacheHash
Definition: spccache.c:35
HTAB * hash_create(const char *tabname, long nelem, const HASHCTL *info, int flags)
Definition: dynahash.c:349
unsigned int uint32
Definition: c.h:441
void get_tablespace_page_costs(Oid spcid, double *spc_random_page_cost, double *spc_seq_page_cost)
Definition: spccache.c:181
static AmcheckOptions opts
Definition: pg_amcheck.c:110
HeapTuple SearchSysCache1(int cacheId, Datum key1)
Definition: syscache.c:1127
#define HASH_BLOBS
Definition: hsearch.h:97
void CacheRegisterSyscacheCallback(int cacheid, SyscacheCallbackFunction func, Datum arg)
Definition: inval.c:1498
uintptr_t Datum
Definition: postgres.h:411
void ReleaseSysCache(HeapTuple tuple)
Definition: syscache.c:1175
Datum SysCacheGetAttr(int cacheId, HeapTuple tup, AttrNumber attributeNumber, bool *isNull)
Definition: syscache.c:1388
Size keysize
Definition: hsearch.h:75
static void InvalidateTableSpaceCacheCallback(Datum arg, int cacheid, uint32 hashvalue)
Definition: spccache.c:54
#define InvalidOid
Definition: postgres_ext.h:36
#define HeapTupleIsValid(tuple)
Definition: htup.h:78
#define Assert(condition)
Definition: c.h:804
void CreateCacheMemoryContext(void)
Definition: catcache.c:620
void * hash_seq_search(HASH_SEQ_STATUS *status)
Definition: dynahash.c:1436
void hash_seq_init(HASH_SEQ_STATUS *status, HTAB *hashp)
Definition: dynahash.c:1426
void * MemoryContextAlloc(MemoryContext context, Size size)
Definition: mcxt.c:863
static void InitializeTableSpaceCache(void)
Definition: spccache.c:77
#define elog(elevel,...)
Definition: elog.h:232
void * arg
Definition: c.h:621
static void static void status(const char *fmt,...) pg_attribute_printf(1
Definition: pg_regress.c:227
double seq_page_cost
Definition: costsize.c:119
int effective_io_concurrency
Definition: tablespace.h:42
MemoryContext CacheMemoryContext
Definition: mcxt.c:51