135 lines
2.7 KiB
C
135 lines
2.7 KiB
C
/*-------------------------------------------------------------------------
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*
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* hashscan.c
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* manage scans on hash tables
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*
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* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/access/hash/hashscan.c,v 1.40 2006/03/05 15:58:20 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "access/hash.h"
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#include "utils/resowner.h"
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typedef struct HashScanListData
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{
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IndexScanDesc hashsl_scan;
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ResourceOwner hashsl_owner;
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struct HashScanListData *hashsl_next;
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} HashScanListData;
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typedef HashScanListData *HashScanList;
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static HashScanList HashScans = NULL;
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/*
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* ReleaseResources_hash() --- clean up hash subsystem resources.
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*
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* This is here because it needs to touch this module's static var HashScans.
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*/
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void
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ReleaseResources_hash(void)
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{
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HashScanList l;
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HashScanList prev;
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HashScanList next;
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/*
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* Note: this should be a no-op during normal query shutdown. However, in
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* an abort situation ExecutorEnd is not called and so there may be open
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* index scans to clean up.
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*/
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prev = NULL;
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for (l = HashScans; l != NULL; l = next)
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{
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next = l->hashsl_next;
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if (l->hashsl_owner == CurrentResourceOwner)
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{
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if (prev == NULL)
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HashScans = next;
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else
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prev->hashsl_next = next;
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pfree(l);
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/* prev does not change */
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}
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else
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prev = l;
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}
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}
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/*
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* _Hash_regscan() -- register a new scan.
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*/
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void
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_hash_regscan(IndexScanDesc scan)
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{
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HashScanList new_el;
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new_el = (HashScanList) palloc(sizeof(HashScanListData));
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new_el->hashsl_scan = scan;
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new_el->hashsl_owner = CurrentResourceOwner;
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new_el->hashsl_next = HashScans;
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HashScans = new_el;
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}
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/*
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* _hash_dropscan() -- drop a scan from the scan list
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*/
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void
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_hash_dropscan(IndexScanDesc scan)
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{
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HashScanList chk,
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last;
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last = NULL;
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for (chk = HashScans;
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chk != NULL && chk->hashsl_scan != scan;
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chk = chk->hashsl_next)
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last = chk;
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if (chk == NULL)
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elog(ERROR, "hash scan list trashed; can't find 0x%p", (void *) scan);
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if (last == NULL)
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HashScans = chk->hashsl_next;
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else
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last->hashsl_next = chk->hashsl_next;
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pfree(chk);
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}
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/*
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* Is there an active scan in this bucket?
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*/
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bool
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_hash_has_active_scan(Relation rel, Bucket bucket)
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{
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Oid relid = RelationGetRelid(rel);
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HashScanList l;
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for (l = HashScans; l != NULL; l = l->hashsl_next)
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{
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if (relid == l->hashsl_scan->indexRelation->rd_id)
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{
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HashScanOpaque so = (HashScanOpaque) l->hashsl_scan->opaque;
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if (so->hashso_bucket_valid &&
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so->hashso_bucket == bucket)
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return true;
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}
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}
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return false;
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}
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