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, 50 insertions, 53 deletions

diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 1b4c9d47809..efa7dd77122 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.169 2004/04/25 18:23:56 neilc Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.170 2004/05/26 04:41:24 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -263,7 +263,7 @@ build_relation_tlist(RelOptInfo *rel)
 {
 	FastList	tlist;
 	int			resdomno = 1;
-	List	   *v;
+	ListCell   *v;
 
 	FastListInit(&tlist);
 	foreach(v, FastListValue(&rel->reltargetlist))
@@ -415,7 +415,7 @@ create_append_plan(Query *root, AppendPath *best_path)
 	Append	   *plan;
 	List	   *tlist = build_relation_tlist(best_path->path.parent);
 	List	   *subplans = NIL;
-	List	   *subpaths;
+	ListCell   *subpaths;
 
 	foreach(subpaths, best_path->subpaths)
 	{
@@ -505,7 +505,7 @@ create_unique_plan(Query *root, UniquePath *best_path)
 	List	   *newtlist;
 	int			nextresno;
 	bool		newitems;
-	List	   *l;
+	ListCell   *l;
 
 	subplan = create_plan(root, best_path->subpath);
 
@@ -544,7 +544,7 @@ create_unique_plan(Query *root, UniquePath *best_path)
 			break;
 		}
 	}
-	if (l == NIL)				/* fell out of loop? */
+	if (l == NULL)				/* fell out of loop? */
 		elog(ERROR, "could not find UniquePath in in_info_list");
 
 	/* set up to record positions of unique columns */
@@ -702,7 +702,7 @@ create_indexscan_plan(Query *root,
 	List	   *indxsubtype;
 	List	   *indxlossy;
 	FastList	indexids;
-	List	   *i;
+	ListCell   *l;
 	IndexScan  *scan_plan;
 
 	/* it should be a base rel... */
@@ -727,7 +727,7 @@ create_indexscan_plan(Query *root,
 		 */
 		Assert(length(best_path->indexclauses) == 1);
 		scan_clauses = set_ptrUnion(scan_clauses,
-									(List *) lfirst(best_path->indexclauses));
+									(List *) linitial(best_path->indexclauses));
 	}
 
 	/* Reduce RestrictInfo list to bare expressions */
@@ -738,9 +738,9 @@ create_indexscan_plan(Query *root,
 
 	/* Build list of index OIDs */
 	FastListInit(&indexids);
-	foreach(i, best_path->indexinfo)
+	foreach(l, best_path->indexinfo)
 	{
-		IndexOptInfo *index = (IndexOptInfo *) lfirst(i);
+		IndexOptInfo *index = (IndexOptInfo *) lfirst(l);
 
 		FastAppendo(&indexids, index->indexoid);
 	}
@@ -750,9 +750,9 @@ create_indexscan_plan(Query *root,
 	 * executor as indxqualorig
 	 */
 	stripped_indxquals = NIL;
-	foreach(i, indxquals)
+	foreach(l, indxquals)
 	{
-		List   *andlist = (List *) lfirst(i);
+		List   *andlist = (List *) lfirst(l);
 
 		stripped_indxquals = lappend(stripped_indxquals,
 									 get_actual_clauses(andlist));
@@ -785,7 +785,7 @@ create_indexscan_plan(Query *root,
 		 * behavior.
 		 */
 		Assert(stripped_indxquals != NIL);
-		qpqual = set_difference(scan_clauses, lfirst(stripped_indxquals));
+		qpqual = set_difference(scan_clauses, linitial(stripped_indxquals));
 	}
 
 	/*
@@ -955,7 +955,7 @@ create_nestloop_plan(Query *root,
 			joinrestrictclauses =
 				select_nonredundant_join_clauses(root,
 												 joinrestrictclauses,
-												 lfirst(indexclauses),
+												 linitial(indexclauses),
 												 best_path->jointype);
 		}
 	}
@@ -1182,17 +1182,17 @@ fix_indxqual_references(List *indexquals, IndexPath *index_path,
 {
 	Relids		baserelids = index_path->path.parent->relids;
 	int			baserelid = index_path->path.parent->relid;
-	List	   *ixinfo = index_path->indexinfo;
-	List	   *i;
+	List	   *index_info = index_path->indexinfo;
+	ListCell   *iq, *ii;
 
 	*fixed_indexquals = NIL;
 	*indxstrategy = NIL;
 	*indxsubtype = NIL;
 	*indxlossy = NIL;
-	foreach(i, indexquals)
+	forboth(iq, indexquals, ii, index_info)
 	{
-		List	   *indexqual = lfirst(i);
-		IndexOptInfo *index = (IndexOptInfo *) lfirst(ixinfo);
+		List	   *indexqual = (List *) lfirst(iq);
+		IndexOptInfo *index = (IndexOptInfo *) lfirst(ii);
 		List	   *fixed_qual;
 		List	   *strategy;
 		List	   *subtype;
@@ -1204,8 +1204,6 @@ fix_indxqual_references(List *indexquals, IndexPath *index_path,
 		*indxstrategy = lappend(*indxstrategy, strategy);
 		*indxsubtype = lappend(*indxsubtype, subtype);
 		*indxlossy = lappend(*indxlossy, lossy);
-
-		ixinfo = lnext(ixinfo);
 	}
 }
 
@@ -1232,15 +1230,15 @@ fix_indxqual_sublist(List *indexqual,
 					 List **subtype,
 					 List **lossy)
 {
-	List	   *i;
+	ListCell   *l;
 
 	*fixed_quals = NIL;
 	*strategy = NIL;
 	*subtype = NIL;
 	*lossy = NIL;
-	foreach(i, indexqual)
+	foreach(l, indexqual)
 	{
-		RestrictInfo *rinfo = (RestrictInfo *) lfirst(i);
+		RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
 		OpExpr	   *clause;
 		OpExpr	   *newclause;
 		Oid			opclass;
@@ -1250,8 +1248,7 @@ fix_indxqual_sublist(List *indexqual,
 
 		Assert(IsA(rinfo, RestrictInfo));
 		clause = (OpExpr *) rinfo->clause;
-		if (!IsA(clause, OpExpr) ||
-			length(clause->args) != 2)
+		if (!IsA(clause, OpExpr) || length(clause->args) != 2)
 			elog(ERROR, "indexqual clause is not binary opclause");
 
 		/*
@@ -1275,7 +1272,7 @@ fix_indxqual_sublist(List *indexqual,
 		 * Now, determine which index attribute this is, change the
 		 * indexkey operand as needed, and get the index opclass.
 		 */
-		lfirst(newclause->args) = fix_indxqual_operand(lfirst(newclause->args),
+		linitial(newclause->args) = fix_indxqual_operand(linitial(newclause->args),
 													   baserelid,
 													   index,
 													   &opclass);
@@ -1309,7 +1306,7 @@ fix_indxqual_operand(Node *node, int baserelid, IndexOptInfo *index,
 	 */
 	Var		   *result;
 	int			pos;
-	List	   *indexprs;
+	ListCell   *indexpr_item;
 
 	/*
 	 * Remove any binary-compatible relabeling of the indexkey
@@ -1340,29 +1337,29 @@ fix_indxqual_operand(Node *node, int baserelid, IndexOptInfo *index,
 	}
 
 	/* Try to match against index expressions */
-	indexprs = index->indexprs;
+	indexpr_item = list_head(index->indexprs);
 	for (pos = 0; pos < index->ncolumns; pos++)
 	{
 		if (index->indexkeys[pos] == 0)
 		{
 			Node	   *indexkey;
 
-			if (indexprs == NIL)
+			if (indexpr_item == NULL)
 				elog(ERROR, "too few entries in indexprs list");
-			indexkey = (Node *) lfirst(indexprs);
+			indexkey = (Node *) lfirst(indexpr_item);
 			if (indexkey && IsA(indexkey, RelabelType))
 				indexkey = (Node *) ((RelabelType *) indexkey)->arg;
 			if (equal(node, indexkey))
 			{
 				/* Found a match */
 				result = makeVar(baserelid, pos + 1,
-								 exprType(lfirst(indexprs)), -1,
+								 exprType(lfirst(indexpr_item)), -1,
 								 0);
 				/* return the correct opclass, too */
 				*opclass = index->classlist[pos];
 				return (Node *) result;
 			}
-			indexprs = lnext(indexprs);
+			indexpr_item = lnext(indexpr_item);
 		}
 	}
 
@@ -1383,11 +1380,11 @@ static List *
 get_switched_clauses(List *clauses, Relids outerrelids)
 {
 	List	   *t_list = NIL;
-	List	   *i;
+	ListCell   *l;
 
-	foreach(i, clauses)
+	foreach(l, clauses)
 	{
-		RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(i);
+		RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(l);
 		OpExpr	   *clause = (OpExpr *) restrictinfo->clause;
 
 		Assert(is_opclause(clause));
@@ -1432,7 +1429,7 @@ order_qual_clauses(Query *root, List *clauses)
 {
 	FastList	nosubplans;
 	FastList	withsubplans;
-	List	   *l;
+	ListCell   *l;
 
 	/* No need to work hard if the query is subselect-free */
 	if (!root->hasSubLinks)
@@ -1442,7 +1439,7 @@ order_qual_clauses(Query *root, List *clauses)
 	FastListInit(&withsubplans);
 	foreach(l, clauses)
 	{
-		Node	   *clause = lfirst(l);
+		Node	   *clause = (Node *) lfirst(l);
 
 		if (contain_subplans(clause))
 			FastAppend(&withsubplans, clause);
@@ -1632,7 +1629,7 @@ make_append(List *appendplans, bool isTarget, List *tlist)
 {
 	Append	   *node = makeNode(Append);
 	Plan	   *plan = &node->plan;
-	List	   *subnode;
+	ListCell   *subnode;
 
 	/*
 	 * Compute cost as sum of subplan costs.  We charge nothing extra for
@@ -1647,7 +1644,7 @@ make_append(List *appendplans, bool isTarget, List *tlist)
 	{
 		Plan	   *subplan = (Plan *) lfirst(subnode);
 
-		if (subnode == appendplans)		/* first node? */
+		if (subnode == list_head(appendplans))		/* first node? */
 			plan->startup_cost = subplan->startup_cost;
 		plan->total_cost += subplan->total_cost;
 		plan->plan_rows += subplan->plan_rows;
@@ -1837,7 +1834,7 @@ static Sort *
 make_sort_from_pathkeys(Query *root, Plan *lefttree, List *pathkeys)
 {
 	List	   *tlist = lefttree->targetlist;
-	List	   *i;
+	ListCell   *i;
 	int			numsortkeys;
 	AttrNumber *sortColIdx;
 	Oid		   *sortOperators;
@@ -1854,7 +1851,7 @@ make_sort_from_pathkeys(Query *root, Plan *lefttree, List *pathkeys)
 		List	   *keysublist = (List *) lfirst(i);
 		PathKeyItem *pathkey = NULL;
 		Resdom	   *resdom = NULL;
-		List	   *j;
+		ListCell   *j;
 
 		/*
 		 * We can sort by any one of the sort key items listed in this
@@ -1870,7 +1867,7 @@ make_sort_from_pathkeys(Query *root, Plan *lefttree, List *pathkeys)
 		 */
 		foreach(j, keysublist)
 		{
-			pathkey = lfirst(j);
+			pathkey = (PathKeyItem *) lfirst(j);
 			Assert(IsA(pathkey, PathKeyItem));
 			resdom = tlist_member(pathkey->key, tlist);
 			if (resdom)
@@ -1881,10 +1878,10 @@ make_sort_from_pathkeys(Query *root, Plan *lefttree, List *pathkeys)
 			/* No matching Var; look for a computable expression */
 			foreach(j, keysublist)
 			{
-				List   *exprvars;
-				List   *k;
+				List		*exprvars;
+				ListCell	*k;
 
-				pathkey = lfirst(j);
+				pathkey = (PathKeyItem *) lfirst(j);
 				exprvars = pull_var_clause(pathkey->key, false);
 				foreach(k, exprvars)
 				{
@@ -1948,7 +1945,7 @@ Sort *
 make_sort_from_sortclauses(Query *root, List *sortcls, Plan *lefttree)
 {
 	List	   *sub_tlist = lefttree->targetlist;
-	List	   *i;
+	ListCell   *l;
 	int			numsortkeys;
 	AttrNumber *sortColIdx;
 	Oid		   *sortOperators;
@@ -1960,9 +1957,9 @@ make_sort_from_sortclauses(Query *root, List *sortcls, Plan *lefttree)
 
 	numsortkeys = 0;
 
-	foreach(i, sortcls)
+	foreach(l, sortcls)
 	{
-		SortClause *sortcl = (SortClause *) lfirst(i);
+		SortClause *sortcl = (SortClause *) lfirst(l);
 		TargetEntry *tle = get_sortgroupclause_tle(sortcl, sub_tlist);
 
 		/*
@@ -2001,7 +1998,7 @@ make_sort_from_groupcols(Query *root,
 {
 	List	   *sub_tlist = lefttree->targetlist;
 	int			grpno = 0;
-	List	   *i;
+	ListCell   *l;
 	int			numsortkeys;
 	AttrNumber *sortColIdx;
 	Oid		   *sortOperators;
@@ -2013,9 +2010,9 @@ make_sort_from_groupcols(Query *root,
 
 	numsortkeys = 0;
 
-	foreach(i, groupcls)
+	foreach(l, groupcls)
 	{
-		GroupClause *grpcl = (GroupClause *) lfirst(i);
+		GroupClause *grpcl = (GroupClause *) lfirst(l);
 		TargetEntry *tle = get_tle_by_resno(sub_tlist, grpColIdx[grpno]);
 
 		/*
@@ -2213,7 +2210,7 @@ make_unique(Plan *lefttree, List *distinctList)
 	int			numCols = length(distinctList);
 	int			keyno = 0;
 	AttrNumber *uniqColIdx;
-	List	   *slitem;
+	ListCell   *slitem;
 
 	copy_plan_costsize(plan, lefttree);
 
@@ -2270,7 +2267,7 @@ make_setop(SetOpCmd cmd, Plan *lefttree,
 	int			numCols = length(distinctList);
 	int			keyno = 0;
 	AttrNumber *dupColIdx;
-	List	   *slitem;
+	ListCell   *slitem;
 
 	copy_plan_costsize(plan, lefttree);