#include "postgres.h"
#include "access/genam.h"
#include "access/htup_details.h"
#include "access/table.h"
#include "catalog/pg_class.h"
#include "catalog/pg_tablespace.h"
#include "miscadmin.h"
#include "utils/builtins.h"
#include "utils/catcache.h"
#include "utils/fmgroids.h"
#include "utils/hsearch.h"
#include "utils/inval.h"
#include "utils/rel.h"
#include "utils/relfilenumbermap.h"
#include "utils/relmapper.h"

Include dependency graph for relfilenumbermap.c:

Data Structures
struct	RelfilenumberMapKey

struct	RelfilenumberMapEntry

Functions
static void	RelfilenumberMapInvalidateCallback (Datum arg, Oid relid)

static void	InitializeRelfilenumberMap (void)

Oid	RelidByRelfilenumber (Oid reltablespace, RelFileNumber relfilenumber)

Variables
static HTAB *	RelfilenumberMapHash = NULL

static ScanKeyData	relfilenumber_skey [2]

Function Documentation

◆ InitializeRelfilenumberMap()

static void InitializeRelfilenumberMap ( void )

static

Definition at line 88 of file relfilenumbermap.c.

 {
     HASHCTL     ctl;
     int         i;
  
     /* Make sure we've initialized CacheMemoryContext. */
     if (CacheMemoryContext == NULL)
         CreateCacheMemoryContext();
  
     /* build skey */
     MemSet(&relfilenumber_skey, 0, sizeof(relfilenumber_skey));
  
     for (i = 0; i < 2; i++)
     {
         fmgr_info_cxt(F_OIDEQ,
                       &relfilenumber_skey[i].sk_func,
                       CacheMemoryContext);
         relfilenumber_skey[i].sk_strategy = BTEqualStrategyNumber;
         relfilenumber_skey[i].sk_subtype = InvalidOid;
         relfilenumber_skey[i].sk_collation = InvalidOid;
     }
  
     relfilenumber_skey[0].sk_attno = Anum_pg_class_reltablespace;
     relfilenumber_skey[1].sk_attno = Anum_pg_class_relfilenode;
  
     /*
      * Only create the RelfilenumberMapHash now, so we don't end up partially
      * initialized when fmgr_info_cxt() above ERRORs out with an out of memory
      * error.
      */
     ctl.keysize = sizeof(RelfilenumberMapKey);
     ctl.entrysize = sizeof(RelfilenumberMapEntry);
     ctl.hcxt = CacheMemoryContext;
  
     RelfilenumberMapHash =
         hash_create("RelfilenumberMap cache", 64, &ctl,
                     HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
  
     /* Watch for invalidation events. */
     CacheRegisterRelcacheCallback(RelfilenumberMapInvalidateCallback,
                                   (Datum) 0);
 }

References BTEqualStrategyNumber, CacheMemoryContext, CacheRegisterRelcacheCallback(), CreateCacheMemoryContext(), HASHCTL::entrysize, fmgr_info_cxt(), HASH_BLOBS, HASH_CONTEXT, hash_create(), HASH_ELEM, HASHCTL::hcxt, i, InvalidOid, HASHCTL::keysize, MemSet, relfilenumber_skey, RelfilenumberMapHash, RelfilenumberMapInvalidateCallback(), ScanKeyData::sk_attno, ScanKeyData::sk_collation, ScanKeyData::sk_strategy, and ScanKeyData::sk_subtype.

Referenced by RelidByRelfilenumber().

◆ RelfilenumberMapInvalidateCallback()

static void RelfilenumberMapInvalidateCallback	(	Datum	arg,
		Oid	relid
	)

static

Definition at line 54 of file relfilenumbermap.c.

 {
     HASH_SEQ_STATUS status;
     RelfilenumberMapEntry *entry;
  
     /* callback only gets registered after creating the hash */
     Assert(RelfilenumberMapHash != NULL);
  
     hash_seq_init(&status, RelfilenumberMapHash);
     while ((entry = (RelfilenumberMapEntry *) hash_seq_search(&status)) != NULL)
     {
         /*
          * If relid is InvalidOid, signaling a complete reset, we must remove
          * all entries, otherwise just remove the specific relation's entry.
          * Always remove negative cache entries.
          */
         if (relid == InvalidOid ||  /* complete reset */
             entry->relid == InvalidOid ||   /* negative cache entry */
             entry->relid == relid)  /* individual flushed relation */
         {
             if (hash_search(RelfilenumberMapHash,
                             &entry->key,
                             HASH_REMOVE,
                             NULL) == NULL)
                 elog(ERROR, "hash table corrupted");
         }
     }
 }

References Assert(), elog(), ERROR, HASH_REMOVE, hash_search(), hash_seq_init(), hash_seq_search(), InvalidOid, RelfilenumberMapEntry::key, RelfilenumberMapHash, and RelfilenumberMapEntry::relid.

Referenced by InitializeRelfilenumberMap().

◆ RelidByRelfilenumber()

Oid RelidByRelfilenumber	(	Oid	reltablespace,
		RelFileNumber	relfilenumber
	)

Definition at line 138 of file relfilenumbermap.c.

 {
     RelfilenumberMapKey key;
     RelfilenumberMapEntry *entry;
     bool        found;
     SysScanDesc scandesc;
     Relation    relation;
     HeapTuple   ntp;
     ScanKeyData skey[2];
     Oid         relid;
  
     if (RelfilenumberMapHash == NULL)
         InitializeRelfilenumberMap();
  
     /* pg_class will show 0 when the value is actually MyDatabaseTableSpace */
     if (reltablespace == MyDatabaseTableSpace)
         reltablespace = 0;
  
     MemSet(&key, 0, sizeof(key));
     key.reltablespace = reltablespace;
     key.relfilenumber = relfilenumber;
  
     /*
      * Check cache and return entry if one is found. Even if no target
      * relation can be found later on we store the negative match and return a
      * InvalidOid from cache. That's not really necessary for performance
      * since querying invalid values isn't supposed to be a frequent thing,
      * but it's basically free.
      */
     entry = hash_search(RelfilenumberMapHash, &key, HASH_FIND, &found);
  
     if (found)
         return entry->relid;
  
     /* ok, no previous cache entry, do it the hard way */
  
     /* initialize empty/negative cache entry before doing the actual lookups */
     relid = InvalidOid;
  
     if (reltablespace == GLOBALTABLESPACE_OID)
     {
         /*
          * Ok, shared table, check relmapper.
          */
         relid = RelationMapFilenumberToOid(relfilenumber, true);
     }
     else
     {
         /*
          * Not a shared table, could either be a plain relation or a
          * non-shared, nailed one, like e.g. pg_class.
          */
  
         /* check for plain relations by looking in pg_class */
         relation = table_open(RelationRelationId, AccessShareLock);
  
         /* copy scankey to local copy, it will be modified during the scan */
         memcpy(skey, relfilenumber_skey, sizeof(skey));
  
         /* set scan arguments */
         skey[0].sk_argument = ObjectIdGetDatum(reltablespace);
         skey[1].sk_argument = ObjectIdGetDatum(relfilenumber);
  
         scandesc = systable_beginscan(relation,
                                       ClassTblspcRelfilenodeIndexId,
                                       true,
                                       NULL,
                                       2,
                                       skey);
  
         found = false;
  
         while (HeapTupleIsValid(ntp = systable_getnext(scandesc)))
         {
             Form_pg_class classform = (Form_pg_class) GETSTRUCT(ntp);
  
             if (found)
                 elog(ERROR,
                      "unexpected duplicate for tablespace %u, relfilenumber %u",
                      reltablespace, relfilenumber);
             found = true;
  
             Assert(classform->reltablespace == reltablespace);
             Assert(classform->relfilenode == relfilenumber);
             relid = classform->oid;
         }
  
         systable_endscan(scandesc);
         table_close(relation, AccessShareLock);
  
         /* check for tables that are mapped but not shared */
         if (!found)
             relid = RelationMapFilenumberToOid(relfilenumber, false);
     }
  
     /*
      * Only enter entry into cache now, our opening of pg_class could have
      * caused cache invalidations to be executed which would have deleted a
      * new entry if we had entered it above.
      */
     entry = hash_search(RelfilenumberMapHash, &key, HASH_ENTER, &found);
     if (found)
         elog(ERROR, "corrupted hashtable");
     entry->relid = relid;
  
     return relid;
 }