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, 39 insertions, 39 deletions

diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index 4dabbf50dac..0727bfb6f2c 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.170 2004/05/10 22:44:45 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/clauses.c,v 1.171 2004/05/26 04:41:27 neilc Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -114,7 +114,7 @@ get_leftop(Expr *clause)
 	OpExpr	   *expr = (OpExpr *) clause;
 
 	if (expr->args != NIL)
-		return lfirst(expr->args);
+		return linitial(expr->args);
 	else
 		return NULL;
 }
@@ -130,8 +130,8 @@ get_rightop(Expr *clause)
 {
 	OpExpr	   *expr = (OpExpr *) clause;
 
-	if (expr->args != NIL && lnext(expr->args) != NIL)
-		return lfirst(lnext(expr->args));
+	if (list_length(expr->args) >= 2)
+		return lsecond(expr->args);
 	else
 		return NULL;
 }
@@ -176,7 +176,7 @@ make_notclause(Expr *notclause)
 Expr *
 get_notclausearg(Expr *notclause)
 {
-	return lfirst(((BoolExpr *) notclause)->args);
+	return linitial(((BoolExpr *) notclause)->args);
 }
 
 /*****************************************************************************
@@ -278,8 +278,8 @@ make_ands_explicit(List *andclauses)
 {
 	if (andclauses == NIL)
 		return (Expr *) makeBoolConst(true, false);
-	else if (lnext(andclauses) == NIL)
-		return (Expr *) lfirst(andclauses);
+	else if (length(andclauses) == 1)
+		return (Expr *) linitial(andclauses);
 	else
 		return make_andclause(andclauses);
 }
@@ -595,7 +595,7 @@ contain_mutable_functions_walker(Node *node, void *context)
 	if (IsA(node, SubLink))
 	{
 		SubLink    *sublink = (SubLink *) node;
-		List	   *opid;
+		ListCell   *opid;
 
 		foreach(opid, sublink->operOids)
 		{
@@ -678,7 +678,7 @@ contain_volatile_functions_walker(Node *node, void *context)
 	if (IsA(node, SubLink))
 	{
 		SubLink    *sublink = (SubLink *) node;
-		List	   *opid;
+		ListCell   *opid;
 
 		foreach(opid, sublink->operOids)
 		{
@@ -848,7 +848,7 @@ pull_constant_clauses(List *quals, List **constantQual)
 {
 	FastList	constqual,
 				restqual;
-	List	   *q;
+	ListCell   *q;
 
 	FastListInit(&constqual);
 	FastListInit(&restqual);
@@ -882,7 +882,7 @@ pull_constant_clauses(List *quals, List **constantQual)
 bool
 has_distinct_on_clause(Query *query)
 {
-	List	   *targetList;
+	ListCell   *l;
 
 	/* Is there a DISTINCT clause at all? */
 	if (query->distinctClause == NIL)
@@ -901,9 +901,9 @@ has_distinct_on_clause(Query *query)
 	 * This code assumes that the DISTINCT list is valid, ie, all its entries
 	 * match some entry of the tlist.
 	 */
-	foreach(targetList, query->targetList)
+	foreach(l, query->targetList)
 	{
-		TargetEntry *tle = (TargetEntry *) lfirst(targetList);
+		TargetEntry *tle = (TargetEntry *) lfirst(l);
 
 		if (tle->resdom->ressortgroupref == 0)
 		{
@@ -998,8 +998,8 @@ CommuteClause(OpExpr *clause)
 	clause->opfuncid = InvalidOid;
 	/* opresulttype and opretset are assumed not to change */
 
-	temp = lfirst(clause->args);
-	lfirst(clause->args) = lsecond(clause->args);
+	temp = linitial(clause->args);
+	linitial(clause->args) = lsecond(clause->args);
 	lsecond(clause->args) = temp;
 }
 
@@ -1162,7 +1162,7 @@ eval_const_expressions_mutator(Node *node, List *active_fns)
 	{
 		DistinctExpr *expr = (DistinctExpr *) node;
 		List	   *args;
-		List	   *arg;
+		ListCell   *arg;
 		bool		has_null_input = false;
 		bool		all_null_input = true;
 		bool		has_nonconst_input = false;
@@ -1281,8 +1281,8 @@ eval_const_expressions_mutator(Node *node, List *active_fns)
 					if (newargs == NIL)
 						return makeBoolConst(false, false);
 					/* If only one nonconst-or-NULL input, it's the result */
-					if (lnext(newargs) == NIL)
-						return (Node *) lfirst(newargs);
+					if (length(newargs) == 1)
+						return (Node *) linitial(newargs);
 					/* Else we still need an OR node */
 					return (Node *) make_orclause(newargs);
 				}
@@ -1302,16 +1302,16 @@ eval_const_expressions_mutator(Node *node, List *active_fns)
 					if (newargs == NIL)
 						return makeBoolConst(true, false);
 					/* If only one nonconst-or-NULL input, it's the result */
-					if (lnext(newargs) == NIL)
-						return (Node *) lfirst(newargs);
+					if (length(newargs) == 1)
+						return (Node *) linitial(newargs);
 					/* Else we still need an AND node */
 					return (Node *) make_andclause(newargs);
 				}
 			case NOT_EXPR:
 				Assert(length(args) == 1);
-				if (IsA(lfirst(args), Const))
+				if (IsA(linitial(args), Const))
 				{
-					Const *const_input = (Const *) lfirst(args);
+					Const *const_input = (Const *) linitial(args);
 
 					/* NOT NULL => NULL */
 					if (const_input->constisnull)
@@ -1320,13 +1320,13 @@ eval_const_expressions_mutator(Node *node, List *active_fns)
 					return makeBoolConst(!DatumGetBool(const_input->constvalue),
 										 false);
 				}
-				else if (not_clause((Node *) lfirst(args)))
+				else if (not_clause((Node *) linitial(args)))
 				{
 					/* Cancel NOT/NOT */
-					return (Node *) get_notclausearg((Expr *) lfirst(args));
+					return (Node *) get_notclausearg((Expr *) linitial(args));
 				}
 				/* Else we still need a NOT node */
-				return (Node *) make_notclause((Expr *) lfirst(args));
+				return (Node *) make_notclause((Expr *) linitial(args));
 			default:
 				elog(ERROR, "unrecognized boolop: %d",
 					 (int) expr->boolop);
@@ -1414,7 +1414,7 @@ eval_const_expressions_mutator(Node *node, List *active_fns)
 		FastList	newargs;
 		Node	   *defresult;
 		Const	   *const_input;
-		List	   *arg;
+		ListCell   *arg;
 
 		/* Simplify the test expression, if any */
 		newarg = eval_const_expressions_mutator((Node *) caseexpr->arg,
@@ -1480,7 +1480,7 @@ eval_const_expressions_mutator(Node *node, List *active_fns)
 		ArrayExpr  *newarray;
 		bool		all_const = true;
 		FastList	newelems;
-		List	   *element;
+		ListCell   *element;
 
 		FastListInit(&newelems);
 		foreach(element, arrayexpr->elements)
@@ -1511,7 +1511,7 @@ eval_const_expressions_mutator(Node *node, List *active_fns)
 		CoalesceExpr *coalesceexpr = (CoalesceExpr *) node;
 		CoalesceExpr *newcoalesce;
 		FastList	newargs;
-		List	   *arg;
+		ListCell   *arg;
 
 		FastListInit(&newargs);
 		foreach(arg, coalesceexpr->args)
@@ -1614,7 +1614,7 @@ static List *
 simplify_or_arguments(List *args, bool *haveNull, bool *forceTrue)
 {
 	List	   *newargs = NIL;
-	List	   *larg;
+	ListCell   *larg;
 
 	foreach(larg, args)
 	{
@@ -1675,7 +1675,7 @@ static List *
 simplify_and_arguments(List *args, bool *haveNull, bool *forceFalse)
 {
 	List	   *newargs = NIL;
-	List	   *larg;
+	ListCell   *larg;
 
 	foreach(larg, args)
 	{
@@ -1774,7 +1774,7 @@ evaluate_function(Oid funcid, Oid result_type, List *args,
 	Form_pg_proc funcform = (Form_pg_proc) GETSTRUCT(func_tuple);
 	bool		has_nonconst_input = false;
 	bool		has_null_input = false;
-	List	   *arg;
+	ListCell   *arg;
 	FuncExpr   *newexpr;
 
 	/*
@@ -1870,7 +1870,7 @@ inline_function(Oid funcid, Oid result_type, List *args,
 	Query	   *querytree;
 	Node	   *newexpr;
 	int		   *usecounts;
-	List	   *arg;
+	ListCell   *arg;
 	int			i;
 
 	/*
@@ -1946,13 +1946,13 @@ inline_function(Oid funcid, Oid result_type, List *args,
 	if (length(raw_parsetree_list) != 1)
 		goto fail;
 
-	querytree_list = parse_analyze(lfirst(raw_parsetree_list),
+	querytree_list = parse_analyze(linitial(raw_parsetree_list),
 								   argtypes, funcform->pronargs);
 
 	if (length(querytree_list) != 1)
 		goto fail;
 
-	querytree = (Query *) lfirst(querytree_list);
+	querytree = (Query *) linitial(querytree_list);
 
 	/*
 	 * The single command must be a simple "SELECT expression".
@@ -1976,7 +1976,7 @@ inline_function(Oid funcid, Oid result_type, List *args,
 		length(querytree->targetList) != 1)
 		goto fail;
 
-	newexpr = (Node *) ((TargetEntry *) lfirst(querytree->targetList))->expr;
+	newexpr = (Node *) ((TargetEntry *) linitial(querytree->targetList))->expr;
 
 	/*
 	 * If the function has any arguments declared as polymorphic types,
@@ -2330,7 +2330,7 @@ expression_tree_walker(Node *node,
 					   bool (*walker) (),
 					   void *context)
 {
-	List	   *temp;
+	ListCell   *temp;
 
 	/*
 	 * The walker has already visited the current node, and so we need
@@ -2576,7 +2576,7 @@ query_tree_walker(Query *query,
 				  void *context,
 				  int flags)
 {
-	List	   *rt;
+	ListCell   *rt;
 
 	Assert(query != NULL && IsA(query, Query));
 
@@ -2972,7 +2972,7 @@ expression_tree_mutator(Node *node,
 				 * elements!
 				 */
 				FastList	resultlist;
-				List	   *temp;
+				ListCell   *temp;
 
 				FastListInit(&resultlist);
 				foreach(temp, (List *) node)
@@ -3064,7 +3064,7 @@ query_tree_mutator(Query *query,
 				   int flags)
 {
 	FastList	newrt;
-	List	   *rt;
+	ListCell   *rt;
 
 	Assert(query != NULL && IsA(query, Query));