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/*-------------------------------------------------------------------------
*
* locks.c--
*
* Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/rewrite/Attic/locks.c,v 1.9 1998/02/26 04:35:15 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h" /* for oid defs */
#include "utils/elog.h" /* for elog */
#include "nodes/pg_list.h" /* lisp support package */
#include "nodes/parsenodes.h"
#include "nodes/primnodes.h" /* Var node def */
#include "utils/syscache.h" /* for SearchSysCache */
#include "rewrite/locks.h" /* for rewrite specific lock defns */
/*
* ThisLockWasTriggered
*
* walk the tree, if there we find a varnode,
* we check the varattno against the attnum
* if we find at least one such match, we return true
* otherwise, we return false
*/
static bool
nodeThisLockWasTriggered(Node *node, int varno, AttrNumber attnum,
int sublevels_up)
{
if (node == NULL)
return FALSE;
switch (nodeTag(node))
{
case T_Var:
{
Var *var = (Var *) node;
if (varno == var->varno &&
(attnum == var->varattno || attnum == -1))
return TRUE;
}
break;
case T_Expr:
{
Expr *expr = (Expr *) node;
return nodeThisLockWasTriggered((Node *) expr->args, varno,
attnum, sublevels_up);
}
break;
case T_TargetEntry:
{
TargetEntry *tle = (TargetEntry *) node;
return nodeThisLockWasTriggered(tle->expr, varno, attnum,
sublevels_up);
}
break;
case T_Aggreg:
{
Aggreg *agg = (Aggreg *) node;
return nodeThisLockWasTriggered(agg->target, varno, attnum,
sublevels_up);
}
break;
case T_List:
{
List *l;
foreach(l, (List *) node)
{
if (nodeThisLockWasTriggered(lfirst(l), varno, attnum,
sublevels_up))
return TRUE;
}
return FALSE;
}
break;
case T_SubLink:
{
SubLink *sublink = (SubLink *) node;
Query *query = (Query *) sublink->subselect;
return nodeThisLockWasTriggered(query->qual, varno, attnum,
sublevels_up + 1);
}
break;
default:
break;
}
return (FALSE);
}
/*
* thisLockWasTriggered -
* walk the tree, if there we find a varnode, we check the varattno
* against the attnum if we find at least one such match, we return true
* otherwise, we return false
*/
static bool
thisLockWasTriggered(int varno,
AttrNumber attnum,
Query *parsetree)
{
if (nodeThisLockWasTriggered(parsetree->qual, varno, attnum, 0))
return true;
if (nodeThisLockWasTriggered((Node *) parsetree->targetList, varno, attnum, 0))
return true;
return false;
}
/*
* matchLocks -
* match the list of locks and returns the matching rules
*/
List *
matchLocks(CmdType event,
RuleLock *rulelocks,
int varno,
Query *parsetree)
{
List *real_locks = NIL;
int nlocks;
int i;
Assert(rulelocks != NULL); /* we get called iff there is some lock */
Assert(parsetree != NULL);
if (parsetree->commandType != CMD_SELECT)
{
if (parsetree->resultRelation != varno)
{
return (NULL);
}
}
nlocks = rulelocks->numLocks;
for (i = 0; i < nlocks; i++)
{
RewriteRule *oneLock = rulelocks->rules[i];
if (oneLock->event == event)
{
if (parsetree->commandType != CMD_SELECT ||
thisLockWasTriggered(varno,
oneLock->attrno,
parsetree))
{
real_locks = lappend(real_locks, oneLock);
}
}
}
return (real_locks);
}
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