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.
2025-11-07 19:06:32 +03:00 · 2004-05-26 04:41:50 +00:00
parent 18d0d10563
commit d0b4399d81
125 changed files with 3639 additions and 3038 deletions
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -16,7 +16,7 @@
 *
 *
 * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepjointree.c,v 1.17 2004/05/10 22:44:45 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepjointree.c,v 1.18 2004/05/26 04:41:26 neilc Exp $
 *
 *-------------------------------------------------------------------------
 */
@@ -97,11 +97,11 @@ pull_up_IN_clauses(Query *parse, Node *node)
 	if (and_clause(node))
 	{
 		List	   *newclauses = NIL;
-		List	   *oldclauses;
+		ListCell   *l;

-		foreach(oldclauses, ((BoolExpr *) node)->args)
+		foreach(l, ((BoolExpr *) node)->args)
 		{
-			Node	   *oldclause = lfirst(oldclauses);
+			Node	   *oldclause = (Node *) lfirst(l);

 			newclauses = lappend(newclauses,
 								 pull_up_IN_clauses(parse,
@@ -162,7 +162,7 @@ pull_up_subqueries(Query *parse, Node *jtnode, bool below_outer_join)
 		{
 			int			rtoffset;
 			List	   *subtlist;
-			List	   *rt;
+			ListCell   *rt;

 			/*
 			 * Need a modifiable copy of the subquery to hack on.  Even if
@@ -314,7 +314,7 @@ pull_up_subqueries(Query *parse, Node *jtnode, bool below_outer_join)
 	else if (IsA(jtnode, FromExpr))
 	{
 		FromExpr   *f = (FromExpr *) jtnode;
-		List	   *l;
+		ListCell   *l;

 		foreach(l, f->fromlist)
 			lfirst(l) = pull_up_subqueries(parse, lfirst(l),
@@ -447,7 +447,7 @@ is_simple_subquery(Query *subquery)
 static bool
 has_nullable_targetlist(Query *subquery)
 {
-	List	   *l;
+	ListCell   *l;

 	foreach(l, subquery->targetList)
 	{
@@ -488,7 +488,7 @@ resolvenew_in_jointree(Node *jtnode, int varno,
 	else if (IsA(jtnode, FromExpr))
 	{
 		FromExpr   *f = (FromExpr *) jtnode;
-		List	   *l;
+		ListCell   *l;

 		foreach(l, f->fromlist)
 			resolvenew_in_jointree(lfirst(l), varno, rte, subtlist);
@@ -588,7 +588,7 @@ reduce_outer_joins_pass1(Node *jtnode)
 	else if (IsA(jtnode, FromExpr))
 	{
 		FromExpr   *f = (FromExpr *) jtnode;
-		List	   *l;
+		ListCell   *l;

 		foreach(l, f->fromlist)
 		{
@@ -653,8 +653,8 @@ reduce_outer_joins_pass2(Node *jtnode,
 	else if (IsA(jtnode, FromExpr))
 	{
 		FromExpr   *f = (FromExpr *) jtnode;
-		List	   *l;
-		List	   *s;
+		ListCell   *l;
+		ListCell   *s;
 		Relids		pass_nonnullable;

 		/* Scan quals to see if we can add any nonnullability constraints */
@@ -662,15 +662,14 @@ reduce_outer_joins_pass2(Node *jtnode,
 		pass_nonnullable = bms_add_members(pass_nonnullable,
 										   nonnullable_rels);
 		/* And recurse --- but only into interesting subtrees */
-		s = state->sub_states;
-		foreach(l, f->fromlist)
+		Assert(length(f->fromlist) == length(state->sub_states));
+		forboth(l, f->fromlist, s, state->sub_states)
 		{
 			reduce_outer_joins_state *sub_state = lfirst(s);

 			if (sub_state->contains_outer)
 				reduce_outer_joins_pass2(lfirst(l), sub_state, parse,
 										 pass_nonnullable);
-			s = lnext(s);
 		}
 		bms_free(pass_nonnullable);
 	}
@@ -679,7 +678,7 @@ reduce_outer_joins_pass2(Node *jtnode,
 		JoinExpr   *j = (JoinExpr *) jtnode;
 		int			rtindex = j->rtindex;
 		JoinType	jointype = j->jointype;
-		reduce_outer_joins_state *left_state = lfirst(state->sub_states);
+		reduce_outer_joins_state *left_state = linitial(state->sub_states);
 		reduce_outer_joins_state *right_state = lsecond(state->sub_states);

 		/* Can we simplify this join? */
@@ -798,7 +797,7 @@ find_nonnullable_rels(Node *node, bool top_level)
 	}
 	else if (IsA(node, List))
 	{
-		List	   *l;
+		ListCell   *l;

 		foreach(l, (List *) node)
 		{
@@ -898,7 +897,7 @@ simplify_jointree(Query *parse, Node *jtnode)
 	{
 		FromExpr   *f = (FromExpr *) jtnode;
 		List	   *newlist = NIL;
-		List	   *l;
+		ListCell   *l;

 		foreach(l, f->fromlist)
 		{
@@ -918,7 +917,16 @@ simplify_jointree(Query *parse, Node *jtnode)
 				 */
 				FromExpr   *subf = (FromExpr *) child;
 				int			childlen = length(subf->fromlist);
-				int			myothers = length(newlist) + length(lnext(l));
+				int			myothers;
+				ListCell   *l2;
+
+				/*
+				 * XXX: This is a quick hack, not sure of the proper
+				 * fix.
+				 */
+				myothers = length(newlist);
+				for_each_cell(l2, lnext(l))
+					myothers++;

 				if (childlen <= 1 ||
 					(childlen + myothers) <= from_collapse_limit)
@@ -1022,7 +1030,7 @@ simplify_jointree(Query *parse, Node *jtnode)
 static void
 fix_in_clause_relids(List *in_info_list, int varno, Relids subrelids)
 {
-	List	   *l;
+	ListCell   *l;

 	foreach(l, in_info_list)
 	{
@@ -1060,7 +1068,7 @@ get_relids_in_jointree(Node *jtnode)
 	else if (IsA(jtnode, FromExpr))
 	{
 		FromExpr   *f = (FromExpr *) jtnode;
-		List	   *l;
+		ListCell   *l;

 		foreach(l, f->fromlist)
 		{
@@ -1119,7 +1127,7 @@ find_jointree_node_for_rel(Node *jtnode, int relid)
 	else if (IsA(jtnode, FromExpr))
 	{
 		FromExpr   *f = (FromExpr *) jtnode;
-		List	   *l;
+		ListCell   *l;

 		foreach(l, f->fromlist)
 		{
--- a/src/backend/optimizer/prep/prepqual.c
+++ b/src/backend/optimizer/prep/prepqual.c
@@ -8,7 +8,7 @@
 *
 *
 * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepqual.c,v 1.41 2003/12/30 21:49:19 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepqual.c,v 1.42 2004/05/26 04:41:26 neilc Exp $
 *
 *-------------------------------------------------------------------------
 */
@@ -144,7 +144,7 @@ flatten_andors_mutator(Node *node, void *context)
 static void
 flatten_andors_and_walker(FastList *out_list, List *andlist)
 {
-	List	   *arg;
+	ListCell   *arg;

 	foreach(arg, andlist)
 	{
@@ -160,7 +160,7 @@ flatten_andors_and_walker(FastList *out_list, List *andlist)
 static void
 flatten_andors_or_walker(FastList *out_list, List *orlist)
 {
-	List	   *arg;
+	ListCell   *arg;

 	foreach(arg, orlist)
 	{
@@ -193,7 +193,7 @@ pull_ands(List *andlist)
 static void
 pull_ands_walker(FastList *out_list, List *andlist)
 {
-	List	   *arg;
+	ListCell   *arg;

 	foreach(arg, andlist)
 	{
@@ -226,7 +226,7 @@ pull_ors(List *orlist)
 static void
 pull_ors_walker(FastList *out_list, List *orlist)
 {
-	List	   *arg;
+	ListCell   *arg;

 	foreach(arg, orlist)
 	{
@@ -258,7 +258,7 @@ find_nots(Expr *qual)
 	if (and_clause((Node *) qual))
 	{
 		FastList	t_list;
-		List	   *temp;
+		ListCell   *temp;

 		FastListInit(&t_list);
 		foreach(temp, ((BoolExpr *) qual)->args)
@@ -268,7 +268,7 @@ find_nots(Expr *qual)
 	else if (or_clause((Node *) qual))
 	{
 		FastList	t_list;
-		List	   *temp;
+		ListCell   *temp;

 		FastListInit(&t_list);
 		foreach(temp, ((BoolExpr *) qual)->args)
@@ -324,7 +324,7 @@ push_nots(Expr *qual)
 		 *--------------------
 		 */
 		FastList	t_list;
-		List	   *temp;
+		ListCell   *temp;

 		FastListInit(&t_list);
 		foreach(temp, ((BoolExpr *) qual)->args)
@@ -334,7 +334,7 @@ push_nots(Expr *qual)
 	else if (or_clause((Node *) qual))
 	{
 		FastList	t_list;
-		List	   *temp;
+		ListCell   *temp;

 		FastListInit(&t_list);
 		foreach(temp, ((BoolExpr *) qual)->args)
@@ -398,7 +398,7 @@ find_duplicate_ors(Expr *qual)
 	if (or_clause((Node *) qual))
 	{
 		List	   *orlist = NIL;
-		List	   *temp;
+		ListCell   *temp;

 		/* Recurse */
 		foreach(temp, ((BoolExpr *) qual)->args)
@@ -412,7 +412,7 @@ find_duplicate_ors(Expr *qual)
 	else if (and_clause((Node *) qual))
 	{
 		List	   *andlist = NIL;
-		List	   *temp;
+		ListCell   *temp;

 		/* Recurse */
 		foreach(temp, ((BoolExpr *) qual)->args)
@@ -441,13 +441,12 @@ process_duplicate_ors(List *orlist)
 	int			num_subclauses = 0;
 	List	   *winners;
 	List	   *neworlist;
-	List	   *temp;
-	List	   *temp2;
+	ListCell   *temp;

 	if (orlist == NIL)
 		return NULL;			/* probably can't happen */
-	if (lnext(orlist) == NIL)
-		return lfirst(orlist);	/* single-expression OR (can this happen?) */
+	if (length(orlist) == 1)	/* single-expression OR (can this happen?) */
+		return linitial(orlist);

 	/*
 	 * Choose the shortest AND clause as the reference list --- obviously,
@@ -457,7 +456,7 @@ process_duplicate_ors(List *orlist)
 	 */
 	foreach(temp, orlist)
 	{
-		Expr	   *clause = lfirst(temp);
+		Expr	   *clause = (Expr *) lfirst(temp);

 		if (and_clause((Node *) clause))
 		{
@@ -489,12 +488,13 @@ process_duplicate_ors(List *orlist)
 	winners = NIL;
 	foreach(temp, reference)
 	{
-		Expr	   *refclause = lfirst(temp);
+		Expr	   *refclause = (Expr *) lfirst(temp);
 		bool		win = true;
+		ListCell   *temp2;

 		foreach(temp2, orlist)
 		{
-			Expr	   *clause = lfirst(temp2);
+			Expr	   *clause = (Expr *) lfirst(temp2);

 			if (and_clause((Node *) clause))
 			{
@@ -537,7 +537,7 @@ process_duplicate_ors(List *orlist)
 	neworlist = NIL;
 	foreach(temp, orlist)
 	{
-		Expr	   *clause = lfirst(temp);
+		Expr	   *clause = (Expr *) lfirst(temp);

 		if (and_clause((Node *) clause))
 		{
@@ -546,8 +546,8 @@ process_duplicate_ors(List *orlist)
 			subclauses = set_difference(subclauses, winners);
 			if (subclauses != NIL)
 			{
-				if (lnext(subclauses) == NIL)
-					neworlist = lappend(neworlist, lfirst(subclauses));
+				if (length(subclauses) == 1)
+					neworlist = lappend(neworlist, linitial(subclauses));
 				else
 					neworlist = lappend(neworlist, make_andclause(subclauses));
 			}
@@ -577,8 +577,8 @@ process_duplicate_ors(List *orlist)
 	 */
 	if (neworlist != NIL)
 	{
-		if (lnext(neworlist) == NIL)
-			winners = lappend(winners, lfirst(neworlist));
+		if (length(neworlist) == 1)
+			winners = lappend(winners, linitial(neworlist));
 		else
 			winners = lappend(winners, make_orclause(pull_ors(neworlist)));
 	}
@@ -587,8 +587,8 @@ process_duplicate_ors(List *orlist)
 	 * And return the constructed AND clause, again being wary of a single
 	 * element and AND/OR flatness.
 	 */
-	if (lnext(winners) == NIL)
-		return (Expr *) lfirst(winners);
+	if (length(winners) == 1)
+		return (Expr *) linitial(winners);
 	else
 		return make_andclause(pull_ands(winners));
 }
--- a/src/backend/optimizer/prep/preptlist.c
+++ b/src/backend/optimizer/prep/preptlist.c
@@ -15,7 +15,7 @@
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/preptlist.c,v 1.66 2003/11/29 19:51:51 pgsql Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/preptlist.c,v 1.67 2004/05/26 04:41:26 neilc Exp $
 *
 *-------------------------------------------------------------------------
 */
@@ -122,10 +122,13 @@ expand_targetlist(List *tlist, int command_type,
 				  Index result_relation, List *range_table)
 {
 	List	   *new_tlist = NIL;
+	ListCell   *tlist_item;
 	Relation	rel;
 	int			attrno,
 				numattrs;

+	tlist_item = list_head(tlist);
+
 	/*
 	 * The rewriter should have already ensured that the TLEs are in
 	 * correct order; but we have to insert TLEs for any missing
@@ -143,15 +146,15 @@ expand_targetlist(List *tlist, int command_type,
 		Form_pg_attribute att_tup = rel->rd_att->attrs[attrno - 1];
 		TargetEntry *new_tle = NULL;

-		if (tlist != NIL)
+		if (tlist_item != NULL)
 		{
-			TargetEntry *old_tle = (TargetEntry *) lfirst(tlist);
+			TargetEntry *old_tle = (TargetEntry *) lfirst(tlist_item);
 			Resdom	   *resdom = old_tle->resdom;

 			if (!resdom->resjunk && resdom->resno == attrno)
 			{
 				new_tle = old_tle;
-				tlist = lnext(tlist);
+				tlist_item = lnext(tlist_item);
 			}
 		}

@@ -259,9 +262,9 @@ expand_targetlist(List *tlist, int command_type,
 	 * an UPDATE in a table with dropped columns, or an inheritance child
 	 * table with extra columns.)
 	 */
-	while (tlist)
+	while (tlist_item)
 	{
-		TargetEntry *old_tle = (TargetEntry *) lfirst(tlist);
+		TargetEntry *old_tle = (TargetEntry *) lfirst(tlist_item);
 		Resdom	   *resdom = old_tle->resdom;

 		if (!resdom->resjunk)
@@ -275,7 +278,7 @@ expand_targetlist(List *tlist, int command_type,
 		}
 		new_tlist = lappend(new_tlist, old_tle);
 		attrno++;
-		tlist = lnext(tlist);
+		tlist_item = lnext(tlist_item);
 	}

 	heap_close(rel, AccessShareLock);
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -14,7 +14,7 @@
 *
 *
 * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.110 2004/05/11 22:43:55 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.111 2004/05/26 04:41:26 neilc Exp $
 *
 *-------------------------------------------------------------------------
 */
@@ -420,15 +420,19 @@ generate_setop_tlist(List *colTypes, int flag,
 {
 	List	   *tlist = NIL;
 	int			resno = 1;
-	List	   *i;
+	ListCell   *i,
+			   *j,
+			   *k;
 	Resdom	   *resdom;
 	Node	   *expr;

+	j = list_head(input_tlist);
+	k = list_head(refnames_tlist);
 	foreach(i, colTypes)
 	{
 		Oid			colType = lfirsto(i);
-		TargetEntry *inputtle = (TargetEntry *) lfirst(input_tlist);
-		TargetEntry *reftle = (TargetEntry *) lfirst(refnames_tlist);
+		TargetEntry *inputtle = (TargetEntry *) lfirst(j);
+		TargetEntry *reftle = (TargetEntry *) lfirst(k);
 		int32		colTypmod;

 		Assert(inputtle->resdom->resno == resno);
@@ -476,8 +480,8 @@ generate_setop_tlist(List *colTypes, int flag,
 							pstrdup(reftle->resdom->resname),
 							false);
 		tlist = lappend(tlist, makeTargetEntry(resdom, (Expr *) expr));
-		input_tlist = lnext(input_tlist);
-		refnames_tlist = lnext(refnames_tlist);
+		j = lnext(j);
+		k = lnext(k);
 	}

 	if (flag >= 0)
@@ -518,11 +522,12 @@ generate_append_tlist(List *colTypes, bool flag,
 {
 	List	   *tlist = NIL;
 	int			resno = 1;
-	List	   *curColType;
+	ListCell   *curColType;
+	ListCell   *ref_tl_item;
 	int			colindex;
 	Resdom	   *resdom;
 	Node	   *expr;
-	List	   *planl;
+	ListCell   *planl;
 	int32	   *colTypmods;

 	/*
@@ -536,9 +541,9 @@ generate_append_tlist(List *colTypes, bool flag,
 	foreach(planl, input_plans)
 	{
 		Plan	   *subplan = (Plan *) lfirst(planl);
-		List	   *subtlist;
+		ListCell   *subtlist;

-		curColType = colTypes;
+		curColType = list_head(colTypes);
 		colindex = 0;
 		foreach(subtlist, subplan->targetlist)
 		{
@@ -546,11 +551,11 @@ generate_append_tlist(List *colTypes, bool flag,

 			if (subtle->resdom->resjunk)
 				continue;
-			Assert(curColType != NIL);
-			if (subtle->resdom->restype == lfirsto(curColType))
+			Assert(curColType != NULL);
+			if (subtle->resdom->restype == lfirst_oid(curColType))
 			{
 				/* If first subplan, copy the typmod; else compare */
-				if (planl == input_plans)
+				if (planl == list_head(input_plans))
 					colTypmods[colindex] = subtle->resdom->restypmod;
 				else if (subtle->resdom->restypmod != colTypmods[colindex])
 					colTypmods[colindex] = -1;
@@ -563,18 +568,18 @@ generate_append_tlist(List *colTypes, bool flag,
 			curColType = lnext(curColType);
 			colindex++;
 		}
-		Assert(curColType == NIL);
+		Assert(curColType == NULL);
 	}

 	/*
 	 * Now we can build the tlist for the Append.
 	 */
 	colindex = 0;
-	foreach(curColType, colTypes)
+	forboth(curColType, colTypes, ref_tl_item, refnames_tlist)
 	{
 		Oid			colType = lfirsto(curColType);
 		int32		colTypmod = colTypmods[colindex++];
-		TargetEntry *reftle = (TargetEntry *) lfirst(refnames_tlist);
+		TargetEntry *reftle = (TargetEntry *) lfirst(ref_tl_item);

 		Assert(reftle->resdom->resno == resno);
 		Assert(!reftle->resdom->resjunk);
@@ -589,7 +594,6 @@ generate_append_tlist(List *colTypes, bool flag,
 							pstrdup(reftle->resdom->resname),
 							false);
 		tlist = lappend(tlist, makeTargetEntry(resdom, (Expr *) expr));
-		refnames_tlist = lnext(refnames_tlist);
 	}

 	if (flag)
@@ -623,11 +627,12 @@ generate_append_tlist(List *colTypes, bool flag,
 static bool
 tlist_same_datatypes(List *tlist, List *colTypes, bool junkOK)
 {
-	List	   *i;
+	ListCell   *l;
+	ListCell   *curColType = list_head(colTypes);

-	foreach(i, tlist)
+	foreach(l, tlist)
 	{
-		TargetEntry *tle = (TargetEntry *) lfirst(i);
+		TargetEntry *tle = (TargetEntry *) lfirst(l);

 		if (tle->resdom->resjunk)
 		{
@@ -636,14 +641,14 @@ tlist_same_datatypes(List *tlist, List *colTypes, bool junkOK)
 		}
 		else
 		{
-			if (colTypes == NIL)
+			if (curColType == NULL)
 				return false;
-			if (tle->resdom->restype != lfirsto(colTypes))
+			if (tle->resdom->restype != lfirst_oid(curColType))
 				return false;
-			colTypes = lnext(colTypes);
+			curColType = lnext(curColType);
 		}
 	}
-	if (colTypes != NIL)
+	if (curColType != NULL)
 		return false;
 	return true;
 }
@@ -667,10 +672,10 @@ find_all_inheritors(Oid parentrel)
 	 */
 	while (unexamined_relids != NIL)
 	{
-		Oid			currentrel = lfirsto(unexamined_relids);
+		Oid			currentrel = linitial_oid(unexamined_relids);
 		List	   *currentchildren;

-		unexamined_relids = lnext(unexamined_relids);
+		unexamined_relids = list_delete_first(unexamined_relids);
 		examined_relids = lappendo(examined_relids, currentrel);
 		currentchildren = find_inheritance_children(currentrel);

@@ -719,7 +724,7 @@ expand_inherited_rtentry(Query *parse, Index rti, bool dup_parent)
 	Oid			parentOID;
 	List	   *inhOIDs;
 	List	   *inhRTIs;
-	List	   *l;
+	ListCell   *l;

 	/* Does RT entry allow inheritance? */
 	if (!rte->inh)
@@ -739,7 +744,7 @@ expand_inherited_rtentry(Query *parse, Index rti, bool dup_parent)
 	 * case.  This could happen despite above has_subclass() check, if
 	 * table once had a child but no longer does.
 	 */
-	if (lnext(inhOIDs) == NIL)
+	if (length(inhOIDs) < 2)
 		return NIL;
 	/* OK, it's an inheritance set; expand it */
 	if (dup_parent)
@@ -1020,7 +1025,7 @@ static List *
 adjust_inherited_tlist(List *tlist, Oid old_relid, Oid new_relid)
 {
 	bool		changed_it = false;
-	List	   *tl;
+	ListCell   *tl;
 	List	   *new_tlist;
 	bool		more;
 	int			attrno;