* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/access/gist/gistscan.c,v 1.62 2006/03/05 15:58:20 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/access/gist/gistscan.c,v 1.63 2006/04/03 13:44:33 teodor Exp $
*
*-------------------------------------------------------------------------
*/
#include "utils/memutils.h"
#include "utils/resowner.h"
-/* routines defined and used here */
-static void gistregscan(IndexScanDesc scan);
-static void gistdropscan(IndexScanDesc scan);
-static void gistadjone(IndexScanDesc scan, int op, BlockNumber blkno,
- OffsetNumber offnum, XLogRecPtr newlsn, XLogRecPtr oldlsn);
-static void adjustiptr(IndexScanDesc scan, ItemPointer iptr, GISTSearchStack *stk,
- int op, BlockNumber blkno, OffsetNumber offnum, XLogRecPtr newlsn, XLogRecPtr oldlsn);
static void gistfreestack(GISTSearchStack *s);
-/*
- * Whenever we start a GiST scan in a backend, we register it in
- * private space. Then if the GiST index gets updated, we check all
- * registered scans and adjust them if the tuple they point at got
- * moved by the update. We only need to do this in private space,
- * because when we update an GiST we have a write lock on the tree, so
- * no other process can have any locks at all on it. A single
- * transaction can have write and read locks on the same object, so
- * that's why we need to handle this case.
- */
-typedef struct GISTScanListData
-{
- IndexScanDesc gsl_scan;
- ResourceOwner gsl_owner;
- struct GISTScanListData *gsl_next;
-} GISTScanListData;
-
-typedef GISTScanListData *GISTScanList;
-
-/* pointer to list of local scans on GiSTs */
-static GISTScanList GISTScans = NULL;
-
Datum
gistbeginscan(PG_FUNCTION_ARGS)
{
IndexScanDesc scan;
scan = RelationGetIndexScan(r, nkeys, key);
- gistregscan(scan);
PG_RETURN_POINTER(scan);
}
pfree(scan->opaque);
}
-
- gistdropscan(scan);
-
PG_RETURN_VOID();
}
-static void
-gistregscan(IndexScanDesc scan)
-{
- GISTScanList l;
-
- l = (GISTScanList) palloc(sizeof(GISTScanListData));
- l->gsl_scan = scan;
- l->gsl_owner = CurrentResourceOwner;
- l->gsl_next = GISTScans;
- GISTScans = l;
-}
-
-static void
-gistdropscan(IndexScanDesc scan)
-{
- GISTScanList l;
- GISTScanList prev;
-
- prev = NULL;
-
- for (l = GISTScans; l != NULL && l->gsl_scan != scan; l = l->gsl_next)
- prev = l;
-
- if (l == NULL)
- elog(ERROR, "GiST scan list corrupted -- could not find 0x%p",
- (void *) scan);
-
- if (prev == NULL)
- GISTScans = l->gsl_next;
- else
- prev->gsl_next = l->gsl_next;
-
- pfree(l);
-}
-
-/*
- * ReleaseResources_gist() --- clean up gist subsystem resources.
- *
- * This is here because it needs to touch this module's static var GISTScans.
- */
-void
-ReleaseResources_gist(void)
-{
- GISTScanList l;
- GISTScanList prev;
- GISTScanList next;
-
- /*
- * Note: this should be a no-op during normal query shutdown. However, in
- * an abort situation ExecutorEnd is not called and so there may be open
- * index scans to clean up.
- */
- prev = NULL;
-
- for (l = GISTScans; l != NULL; l = next)
- {
- next = l->gsl_next;
- if (l->gsl_owner == CurrentResourceOwner)
- {
- if (prev == NULL)
- GISTScans = next;
- else
- prev->gsl_next = next;
-
- pfree(l);
- /* prev does not change */
- }
- else
- prev = l;
- }
-}
-
-void
-gistadjscans(Relation rel, int op, BlockNumber blkno, OffsetNumber offnum, XLogRecPtr newlsn, XLogRecPtr oldlsn)
-{
- GISTScanList l;
- Oid relid;
-
- if (XLogRecPtrIsInvalid(newlsn) || XLogRecPtrIsInvalid(oldlsn))
- return;
-
- relid = RelationGetRelid(rel);
- for (l = GISTScans; l != NULL; l = l->gsl_next)
- {
- if (l->gsl_scan->indexRelation->rd_id == relid)
- gistadjone(l->gsl_scan, op, blkno, offnum, newlsn, oldlsn);
- }
-}
-
-/*
- * gistadjone() -- adjust one scan for update.
- *
- * By here, the scan passed in is on a modified relation. Op tells
- * us what the modification is, and blkno and offind tell us what
- * block and offset index were affected. This routine checks the
- * current and marked positions, and the current and marked stacks,
- * to see if any stored location needs to be changed because of the
- * update. If so, we make the change here.
- */
-static void
-gistadjone(IndexScanDesc scan,
- int op,
- BlockNumber blkno,
- OffsetNumber offnum, XLogRecPtr newlsn, XLogRecPtr oldlsn)
-{
- GISTScanOpaque so = (GISTScanOpaque) scan->opaque;
-
- adjustiptr(scan, &(scan->currentItemData), so->stack, op, blkno, offnum, newlsn, oldlsn);
- adjustiptr(scan, &(scan->currentMarkData), so->markstk, op, blkno, offnum, newlsn, oldlsn);
-}
-
-/*
- * adjustiptr() -- adjust current and marked item pointers in the scan
- *
- * Depending on the type of update and the place it happened, we
- * need to do nothing, to back up one record, or to start over on
- * the same page.
- */
-static void
-adjustiptr(IndexScanDesc scan,
- ItemPointer iptr, GISTSearchStack *stk,
- int op,
- BlockNumber blkno,
- OffsetNumber offnum, XLogRecPtr newlsn, XLogRecPtr oldlsn)
-{
- OffsetNumber curoff;
- GISTScanOpaque so;
-
- if (ItemPointerIsValid(iptr))
- {
- if (ItemPointerGetBlockNumber(iptr) == blkno)
- {
- curoff = ItemPointerGetOffsetNumber(iptr);
- so = (GISTScanOpaque) scan->opaque;
-
- switch (op)
- {
- case GISTOP_DEL:
- /* back up one if we need to */
- if (curoff >= offnum && XLByteEQ(stk->lsn, oldlsn)) /* the same vesrion of
- * page */
- {
- if (curoff > FirstOffsetNumber)
- {
- /* just adjust the item pointer */
- ItemPointerSet(iptr, blkno, OffsetNumberPrev(curoff));
- }
- else
- {
- /*
- * remember that we're before the current tuple
- */
- ItemPointerSet(iptr, blkno, FirstOffsetNumber);
- if (iptr == &(scan->currentItemData))
- so->flags |= GS_CURBEFORE;
- else
- so->flags |= GS_MRKBEFORE;
- }
- stk->lsn = newlsn;
- }
- break;
- default:
- elog(ERROR, "unrecognized GiST scan adjust operation: %d",
- op);
- }
- }
- }
-}
-
static void
gistfreestack(GISTSearchStack *s)
-{
+{
while (s != NULL)
{
GISTSearchStack *p = s->next;
-
pfree(s);
s = p;
}
}
+
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