Reimplement the linked list data structure used throughout the backend.

In the past, we used a 'Lispy' linked list implementation: a "list" was
merely a pointer to the head node of the list. The problem with that
design is that it makes lappend() and length() linear time. This patch
fixes that problem (and others) by maintaining a count of the list
length and a pointer to the tail node along with each head node pointer.
A "list" is now a pointer to a structure containing some meta-data
about the list; the head and tail pointers in that structure refer
to ListCell structures that maintain the actual linked list of nodes.

The function names of the list API have also been changed to, I hope,
be more logically consistent. By default, the old function names are
still available; they will be disabled-by-default once the rest of
the tree has been updated to use the new API names.

3 files changed, 27 insertions, 25 deletions

diff --git a/src/backend/rewrite/rewriteDefine.c b/src/backend/rewrite/rewriteDefine.c
index 1cd340f978a..685eebc577f 100644
--- a/src/backend/rewrite/rewriteDefine.c
+++ b/src/backend/rewrite/rewriteDefine.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/rewrite/rewriteDefine.c,v 1.94 2004/05/18 22:49:51 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/rewrite/rewriteDefine.c,v 1.95 2004/05/26 04:41:33 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -167,7 +167,7 @@ InsertRule(char *rulname,
 	if (event_qual != NULL)
 	{
 		/* Find query containing OLD/NEW rtable entries */
-		Query	   *qry = (Query *) lfirst(action);
+		Query	   *qry = (Query *) linitial(action);
 
 		qry = getInsertSelectQuery(qry, NULL);
 		recordDependencyOnExpr(&myself, event_qual, qry->rtable,
@@ -193,7 +193,7 @@ DefineQueryRewrite(RuleStmt *stmt)
 	Oid			ruleId;
 	int			event_attno;
 	Oid			event_attype;
-	List	   *l;
+	ListCell   *l;
 	Query	   *query;
 	AclResult	aclresult;
 	bool		RelisBecomingView = false;
@@ -245,7 +245,7 @@ DefineQueryRewrite(RuleStmt *stmt)
 	 */
 	if (event_type == CMD_SELECT)
 	{
-		List	   *tllist;
+		ListCell	   *tllist;
 		int			i;
 
 		/*
@@ -268,7 +268,7 @@ DefineQueryRewrite(RuleStmt *stmt)
 		/*
 		 * ... the one action must be a SELECT, ...
 		 */
-		query = (Query *) lfirst(action);
+		query = (Query *) linitial(action);
 		if (!is_instead || query->commandType != CMD_SELECT)
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
@@ -509,7 +509,7 @@ DefineQueryRewrite(RuleStmt *stmt)
 static void
 setRuleCheckAsUser_Query(Query *qry, AclId userid)
 {
-	List	   *l;
+	ListCell   *l;
 
 	/* Set all the RTEs in this query node */
 	foreach(l, qry->rtable)
diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
index 3b898b973d8..9ac665449ce 100644
--- a/src/backend/rewrite/rewriteHandler.c
+++ b/src/backend/rewrite/rewriteHandler.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/rewrite/rewriteHandler.c,v 1.135 2004/05/10 22:44:46 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/rewrite/rewriteHandler.c,v 1.136 2004/05/26 04:41:33 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -238,13 +238,13 @@ static List *
 adjustJoinTreeList(Query *parsetree, bool removert, int rt_index)
 {
 	List	   *newjointree = copyObject(parsetree->jointree->fromlist);
-	List	   *jjt;
+	ListCell   *l;
 
 	if (removert)
 	{
-		foreach(jjt, newjointree)
+		foreach(l, newjointree)
 		{
-			RangeTblRef *rtr = lfirst(jjt);
+			RangeTblRef *rtr = lfirst(l);
 
 			if (IsA(rtr, RangeTblRef) &&
 				rtr->rtindex == rt_index)
@@ -295,7 +295,7 @@ rewriteTargetList(Query *parsetree, Relation target_relation)
 	List	   *new_tlist = NIL;
 	int			attrno,
 				numattrs;
-	List	   *temp;
+	ListCell   *temp;
 
 	/*
 	 * Scan the tuple description in the relation's relcache entry to make
@@ -627,7 +627,7 @@ ApplyRetrieveRule(Query *parsetree,
 	 * Make a modifiable copy of the view query, and recursively expand
 	 * any view references inside it.
 	 */
-	rule_action = copyObject(lfirst(rule->actions));
+	rule_action = copyObject(linitial(rule->actions));
 
 	rule_action = fireRIRrules(rule_action, activeRIRs);
 
@@ -687,7 +687,7 @@ static void
 markQueryForUpdate(Query *qry, bool skipOldNew)
 {
 	Index		rti = 0;
-	List	   *l;
+	ListCell   *l;
 
 	foreach(l, qry->rtable)
 	{
@@ -865,7 +865,7 @@ fireRIRrules(Query *parsetree, List *activeRIRs)
 		if (locks != NIL)
 		{
 			List	   *newActiveRIRs;
-			List	   *l;
+			ListCell   *l;
 
 			if (oidMember(RelationGetRelid(rel), activeRIRs))
 				ereport(ERROR,
@@ -995,15 +995,15 @@ fireRules(Query *parsetree,
 		  Query **qual_product)
 {
 	List	   *results = NIL;
-	List	   *i;
+	ListCell   *l;
 
-	foreach(i, locks)
+	foreach(l, locks)
 	{
-		RewriteRule *rule_lock = (RewriteRule *) lfirst(i);
+		RewriteRule *rule_lock = (RewriteRule *) lfirst(l);
 		Node	   *event_qual = rule_lock->qual;
 		List	   *actions = rule_lock->actions;
 		QuerySource qsrc;
-		List	   *r;
+		ListCell   *r;
 
 		/* Determine correct QuerySource value for actions */
 		if (rule_lock->isInstead)
@@ -1143,8 +1143,8 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 			 */
 			if (product_queries != NIL)
 			{
-				List	   *n;
-				rewrite_event *rev;
+				ListCell	   *n;
+				rewrite_event  *rev;
 
 				foreach(n, rewrite_events)
 				{
@@ -1225,7 +1225,7 @@ QueryRewrite(Query *parsetree)
 {
 	List	   *querylist;
 	List	   *results = NIL;
-	List	   *l;
+	ListCell   *l;
 	CmdType		origCmdType;
 	bool		foundOriginalQuery;
 	Query	   *lastInstead;
diff --git a/src/backend/rewrite/rewriteManip.c b/src/backend/rewrite/rewriteManip.c
index 45b60715966..4079230c0b1 100644
--- a/src/backend/rewrite/rewriteManip.c
+++ b/src/backend/rewrite/rewriteManip.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/rewrite/rewriteManip.c,v 1.82 2004/05/10 22:44:46 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/rewrite/rewriteManip.c,v 1.83 2004/05/26 04:41:33 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -216,7 +216,6 @@ OffsetVarNodes(Node *node, int offset, int sublevels_up)
 	if (node && IsA(node, Query))
 	{
 		Query	   *qry = (Query *) node;
-		List	   *l;
 
 		/*
 		 * If we are starting at a Query, and sublevels_up is zero, then
@@ -227,6 +226,8 @@ OffsetVarNodes(Node *node, int offset, int sublevels_up)
 		 */
 		if (sublevels_up == 0)
 		{
+			ListCell   *l;
+
 			if (qry->resultRelation)
 				qry->resultRelation += offset;
 			foreach(l, qry->rowMarks)
@@ -356,7 +357,6 @@ ChangeVarNodes(Node *node, int rt_index, int new_index, int sublevels_up)
 	if (node && IsA(node, Query))
 	{
 		Query	   *qry = (Query *) node;
-		List	   *l;
 
 		/*
 		 * If we are starting at a Query, and sublevels_up is zero, then
@@ -367,6 +367,8 @@ ChangeVarNodes(Node *node, int rt_index, int new_index, int sublevels_up)
 		 */
 		if (sublevels_up == 0)
 		{
+			ListCell   *l;
+
 			if (qry->resultRelation == rt_index)
 				qry->resultRelation = new_index;
 			foreach(l, qry->rowMarks)
@@ -678,7 +680,7 @@ getInsertSelectQuery(Query *parsetree, Query ***subquery_ptr)
 	Assert(parsetree->jointree && IsA(parsetree->jointree, FromExpr));
 	if (length(parsetree->jointree->fromlist) != 1)
 		elog(ERROR, "expected to find SELECT subquery");
-	rtr = (RangeTblRef *) lfirst(parsetree->jointree->fromlist);
+	rtr = (RangeTblRef *) linitial(parsetree->jointree->fromlist);
 	Assert(IsA(rtr, RangeTblRef));
 	selectrte = rt_fetch(rtr->rtindex, parsetree->rtable);
 	selectquery = selectrte->subquery;