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, 12 insertions, 13 deletions

diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 84b2aa82805..b8fe70e9350 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/setrefs.c,v 1.101 2004/05/11 13:15:15 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/setrefs.c,v 1.102 2004/05/26 04:41:24 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -84,7 +84,7 @@ static void set_sa_opfuncid(ScalarArrayOpExpr *opexpr);
 void
 set_plan_references(Plan *plan, List *rtable)
 {
-	List	   *pl;
+	ListCell *l;
 
 	if (plan == NULL)
 		return;
@@ -213,15 +213,14 @@ set_plan_references(Plan *plan, List *rtable)
 			fix_expr_references(plan, ((Result *) plan)->resconstantqual);
 			break;
 		case T_Append:
-
 			/*
 			 * Append, like Sort et al, doesn't actually evaluate its
-			 * targetlist or quals, and we haven't bothered to give it its
-			 * own tlist copy.	So, don't fix targetlist/qual. But do
-			 * recurse into child plans.
+			 * targetlist or quals, and we haven't bothered to give it
+			 * its own tlist copy. So, don't fix targetlist/qual. But
+			 * do recurse into child plans.
 			 */
-			foreach(pl, ((Append *) plan)->appendplans)
-				set_plan_references((Plan *) lfirst(pl), rtable);
+			foreach(l, ((Append *) plan)->appendplans)
+				set_plan_references((Plan *) lfirst(l), rtable);
 			break;
 		default:
 			elog(ERROR, "unrecognized node type: %d",
@@ -242,9 +241,9 @@ set_plan_references(Plan *plan, List *rtable)
 	set_plan_references(plan->lefttree, rtable);
 	set_plan_references(plan->righttree, rtable);
 
-	foreach(pl, plan->initPlan)
+	foreach(l, plan->initPlan)
 	{
-		SubPlan    *sp = (SubPlan *) lfirst(pl);
+		SubPlan    *sp = (SubPlan *) lfirst(l);
 
 		Assert(IsA(sp, SubPlan));
 		set_plan_references(sp->plan, sp->rtable);
@@ -440,8 +439,8 @@ set_uppernode_references(Plan *plan, Index subvarno)
 {
 	Plan	   *subplan = plan->lefttree;
 	List	   *subplan_targetlist,
-			   *output_targetlist,
-			   *l;
+			   *output_targetlist;
+	ListCell   *l;
 	bool		tlist_has_non_vars;
 
 	if (subplan != NULL)
@@ -483,7 +482,7 @@ set_uppernode_references(Plan *plan, Index subvarno)
 static bool
 targetlist_has_non_vars(List *tlist)
 {
-	List	   *l;
+	ListCell   *l;
 
 	foreach(l, tlist)
 	{