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.

1 files changed, 23 insertions, 23 deletions

diff --git a/src/backend/optimizer/util/relnode.c b/src/backend/optimizer/util/relnode.c
index d6853ca819d..8969b2d6185 100644
--- a/src/backend/optimizer/util/relnode.c
+++ b/src/backend/optimizer/util/relnode.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/relnode.c,v 1.56 2004/04/25 18:23:56 neilc Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/relnode.c,v 1.57 2004/05/26 04:41:27 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -47,21 +47,21 @@ static void subbuild_joinrel_joinlist(RelOptInfo *joinrel,
 void
 build_base_rel(Query *root, int relid)
 {
-	List	   *rels;
+	ListCell   *l;
 	RelOptInfo *rel;
 
 	/* Rel should not exist already */
-	foreach(rels, root->base_rel_list)
+	foreach(l, root->base_rel_list)
 	{
-		rel = (RelOptInfo *) lfirst(rels);
+		rel = (RelOptInfo *) lfirst(l);
 		if (relid == rel->relid)
 			elog(ERROR, "rel already exists");
 	}
 
 	/* It should not exist as an "other" rel, either */
-	foreach(rels, root->other_rel_list)
+	foreach(l, root->other_rel_list)
 	{
-		rel = (RelOptInfo *) lfirst(rels);
+		rel = (RelOptInfo *) lfirst(l);
 		if (relid == rel->relid)
 			elog(ERROR, "rel already exists as \"other\" rel");
 	}
@@ -82,21 +82,21 @@ build_base_rel(Query *root, int relid)
 RelOptInfo *
 build_other_rel(Query *root, int relid)
 {
-	List	   *rels;
+	ListCell   *l;
 	RelOptInfo *rel;
 
 	/* Already made? */
-	foreach(rels, root->other_rel_list)
+	foreach(l, root->other_rel_list)
 	{
-		rel = (RelOptInfo *) lfirst(rels);
+		rel = (RelOptInfo *) lfirst(l);
 		if (relid == rel->relid)
 			return rel;
 	}
 
 	/* It should not exist as a base rel */
-	foreach(rels, root->base_rel_list)
+	foreach(l, root->base_rel_list)
 	{
-		rel = (RelOptInfo *) lfirst(rels);
+		rel = (RelOptInfo *) lfirst(l);
 		if (relid == rel->relid)
 			elog(ERROR, "rel already exists as base rel");
 	}
@@ -187,19 +187,19 @@ make_base_rel(Query *root, int relid)
 RelOptInfo *
 find_base_rel(Query *root, int relid)
 {
-	List	   *rels;
+	ListCell   *l;
 	RelOptInfo *rel;
 
-	foreach(rels, root->base_rel_list)
+	foreach(l, root->base_rel_list)
 	{
-		rel = (RelOptInfo *) lfirst(rels);
+		rel = (RelOptInfo *) lfirst(l);
 		if (relid == rel->relid)
 			return rel;
 	}
 
-	foreach(rels, root->other_rel_list)
+	foreach(l, root->other_rel_list)
 	{
-		rel = (RelOptInfo *) lfirst(rels);
+		rel = (RelOptInfo *) lfirst(l);
 		if (relid == rel->relid)
 			return rel;
 	}
@@ -217,11 +217,11 @@ find_base_rel(Query *root, int relid)
 RelOptInfo *
 find_join_rel(Query *root, Relids relids)
 {
-	List	   *joinrels;
+	ListCell   *l;
 
-	foreach(joinrels, root->join_rel_list)
+	foreach(l, root->join_rel_list)
 	{
-		RelOptInfo *rel = (RelOptInfo *) lfirst(joinrels);
+		RelOptInfo *rel = (RelOptInfo *) lfirst(l);
 
 		if (bms_equal(rel->relids, relids))
 			return rel;
@@ -363,8 +363,7 @@ static void
 build_joinrel_tlist(Query *root, RelOptInfo *joinrel)
 {
 	Relids		relids = joinrel->relids;
-	List	   *rels;
-	List	   *vars;
+	ListCell   *rels;
 
 	FastListInit(&joinrel->reltargetlist);
 	joinrel->width = 0;
@@ -372,6 +371,7 @@ build_joinrel_tlist(Query *root, RelOptInfo *joinrel)
 	foreach(rels, root->base_rel_list)
 	{
 		RelOptInfo *baserel = (RelOptInfo *) lfirst(rels);
+		ListCell   *vars;
 
 		if (!bms_is_member(baserel->relid, relids))
 			continue;
@@ -481,7 +481,7 @@ subbuild_joinrel_restrictlist(RelOptInfo *joinrel,
 							  List *joininfo_list)
 {
 	List	   *restrictlist = NIL;
-	List	   *xjoininfo;
+	ListCell   *xjoininfo;
 
 	foreach(xjoininfo, joininfo_list)
 	{
@@ -515,7 +515,7 @@ static void
 subbuild_joinrel_joinlist(RelOptInfo *joinrel,
 						  List *joininfo_list)
 {
-	List	   *xjoininfo;
+	ListCell   *xjoininfo;
 
 	foreach(xjoininfo, joininfo_list)
 	{