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, 37 insertions, 36 deletions

diff --git a/src/backend/executor/execQual.c b/src/backend/executor/execQual.c
index d44f580be02..93088489647 100644
--- a/src/backend/executor/execQual.c
+++ b/src/backend/executor/execQual.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.159 2004/05/10 22:44:43 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.160 2004/05/26 04:41:15 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -217,7 +217,7 @@ ExecEvalArrayRef(ArrayRefExprState *astate,
 	ArrayType  *array_source;
 	ArrayType  *resultArray;
 	bool		isAssignment = (arrayRef->refassgnexpr != NULL);
-	List	   *elt;
+	ListCell   *l;
 	int			i = 0,
 				j = 0;
 	IntArray	upper,
@@ -258,9 +258,9 @@ ExecEvalArrayRef(ArrayRefExprState *astate,
 		array_source = NULL;
 	}
 
-	foreach(elt, astate->refupperindexpr)
+	foreach(l, astate->refupperindexpr)
 	{
-		ExprState  *eltstate = (ExprState *) lfirst(elt);
+		ExprState  *eltstate = (ExprState *) lfirst(l);
 
 		if (i >= MAXDIM)
 			ereport(ERROR,
@@ -284,9 +284,9 @@ ExecEvalArrayRef(ArrayRefExprState *astate,
 
 	if (astate->reflowerindexpr != NIL)
 	{
-		foreach(elt, astate->reflowerindexpr)
+		foreach(l, astate->reflowerindexpr)
 		{
-			ExprState  *eltstate = (ExprState *) lfirst(elt);
+			ExprState  *eltstate = (ExprState *) lfirst(l);
 
 			if (j >= MAXDIM)
 				ereport(ERROR,
@@ -798,7 +798,7 @@ ExecEvalFuncArgs(FunctionCallInfo fcinfo,
 {
 	ExprDoneCond argIsDone;
 	int			i;
-	List	   *arg;
+	ListCell   *arg;
 
 	argIsDone = ExprSingleResult;		/* default assumption */
 
@@ -1070,7 +1070,7 @@ ExecMakeFunctionResultNoSets(FuncExprState *fcache,
 							 bool *isNull,
 							 ExprDoneCond *isDone)
 {
-	List	   *arg;
+	ListCell   *arg;
 	Datum		result;
 	FunctionCallInfoData fcinfo;
 	int			i;
@@ -1703,7 +1703,7 @@ static Datum
 ExecEvalNot(BoolExprState *notclause, ExprContext *econtext,
 			bool *isNull, ExprDoneCond *isDone)
 {
-	ExprState  *clause = lfirst(notclause->args);
+	ExprState  *clause = linitial(notclause->args);
 	Datum		expr_value;
 
 	if (isDone)
@@ -1734,7 +1734,7 @@ ExecEvalOr(BoolExprState *orExpr, ExprContext *econtext,
 		   bool *isNull, ExprDoneCond *isDone)
 {
 	List	   *clauses = orExpr->args;
-	List	   *clause;
+	ListCell   *clause;
 	bool		AnyNull;
 
 	if (isDone)
@@ -1786,7 +1786,7 @@ ExecEvalAnd(BoolExprState *andExpr, ExprContext *econtext,
 			bool *isNull, ExprDoneCond *isDone)
 {
 	List	   *clauses = andExpr->args;
-	List	   *clause;
+	ListCell   *clause;
 	bool		AnyNull;
 
 	if (isDone)
@@ -1802,6 +1802,7 @@ ExecEvalAnd(BoolExprState *andExpr, ExprContext *econtext,
 	 * when you interpret NULL as "don't know", using the same sort of
 	 * reasoning as for OR, above.
 	 */
+
 	foreach(clause, clauses)
 	{
 		ExprState  *clausestate = (ExprState *) lfirst(clause);
@@ -1838,7 +1839,7 @@ ExecEvalCase(CaseExprState *caseExpr, ExprContext *econtext,
 			 bool *isNull, ExprDoneCond *isDone)
 {
 	List	   *clauses = caseExpr->args;
-	List	   *clause;
+	ListCell   *clause;
 	Datum		save_datum;
 	bool		save_isNull;
 
@@ -1938,7 +1939,7 @@ ExecEvalArray(ArrayExprState *astate, ExprContext *econtext,
 {
 	ArrayExpr  *arrayExpr = (ArrayExpr *) astate->xprstate.expr;
 	ArrayType  *result;
-	List	   *element;
+	ListCell   *element;
 	Oid			element_type = arrayExpr->element_typeid;
 	int			ndims = 0;
 	int			dims[MAXDIM];
@@ -2118,7 +2119,7 @@ ExecEvalRow(RowExprState *rstate,
 	Datum	   *values;
 	char	   *nulls;
 	int			nargs;
-	List	   *arg;
+	ListCell   *arg;
 	int			i;
 
 	/* Set default values for result flags: non-null, not a set result */
@@ -2161,7 +2162,7 @@ static Datum
 ExecEvalCoalesce(CoalesceExprState *coalesceExpr, ExprContext *econtext,
 				 bool *isNull, ExprDoneCond *isDone)
 {
-	List	   *arg;
+	ListCell   *arg;
 
 	if (isDone)
 		*isDone = ExprSingleResult;
@@ -2390,7 +2391,7 @@ ExecEvalCoerceToDomain(CoerceToDomainState *cstate, ExprContext *econtext,
 {
 	CoerceToDomain *ctest = (CoerceToDomain *) cstate->xprstate.expr;
 	Datum		result;
-	List	   *l;
+	ListCell   *l;
 
 	result = ExecEvalExpr(cstate->arg, econtext, isNull, isDone);
 
@@ -2826,14 +2827,14 @@ ExecInitExpr(Expr *node, PlanState *parent)
 				CaseExpr   *caseexpr = (CaseExpr *) node;
 				CaseExprState *cstate = makeNode(CaseExprState);
 				FastList	outlist;
-				List	   *inlist;
+				ListCell   *l;
 
 				cstate->xprstate.evalfunc = (ExprStateEvalFunc) ExecEvalCase;
 				cstate->arg = ExecInitExpr(caseexpr->arg, parent);
 				FastListInit(&outlist);
-				foreach(inlist, caseexpr->args)
+				foreach(l, caseexpr->args)
 				{
-					CaseWhen   *when = (CaseWhen *) lfirst(inlist);
+					CaseWhen   *when = (CaseWhen *) lfirst(l);
 					CaseWhenState *wstate = makeNode(CaseWhenState);
 
 					Assert(IsA(when, CaseWhen));
@@ -2853,13 +2854,13 @@ ExecInitExpr(Expr *node, PlanState *parent)
 				ArrayExpr  *arrayexpr = (ArrayExpr *) node;
 				ArrayExprState *astate = makeNode(ArrayExprState);
 				FastList	outlist;
-				List	   *inlist;
+				ListCell   *l;
 
 				astate->xprstate.evalfunc = (ExprStateEvalFunc) ExecEvalArray;
 				FastListInit(&outlist);
-				foreach(inlist, arrayexpr->elements)
+				foreach(l, arrayexpr->elements)
 				{
-					Expr	   *e = (Expr *) lfirst(inlist);
+					Expr	   *e = (Expr *) lfirst(l);
 					ExprState  *estate;
 
 					estate = ExecInitExpr(e, parent);
@@ -2879,13 +2880,13 @@ ExecInitExpr(Expr *node, PlanState *parent)
 				RowExpr	   *rowexpr = (RowExpr *) node;
 				RowExprState *rstate = makeNode(RowExprState);
 				List	   *outlist;
-				List	   *inlist;
+				ListCell   *l;
 
 				rstate->xprstate.evalfunc = (ExprStateEvalFunc) ExecEvalRow;
 				outlist = NIL;
-				foreach(inlist, rowexpr->args)
+				foreach(l, rowexpr->args)
 				{
-					Expr	   *e = (Expr *) lfirst(inlist);
+					Expr	   *e = (Expr *) lfirst(l);
 					ExprState  *estate;
 
 					estate = ExecInitExpr(e, parent);
@@ -2912,13 +2913,13 @@ ExecInitExpr(Expr *node, PlanState *parent)
 				CoalesceExpr *coalesceexpr = (CoalesceExpr *) node;
 				CoalesceExprState *cstate = makeNode(CoalesceExprState);
 				FastList	outlist;
-				List	   *inlist;
+				ListCell   *l;
 
 				cstate->xprstate.evalfunc = (ExprStateEvalFunc) ExecEvalCoalesce;
 				FastListInit(&outlist);
-				foreach(inlist, coalesceexpr->args)
+				foreach(l, coalesceexpr->args)
 				{
-					Expr	   *e = (Expr *) lfirst(inlist);
+					Expr	   *e = (Expr *) lfirst(l);
 					ExprState  *estate;
 
 					estate = ExecInitExpr(e, parent);
@@ -2984,13 +2985,13 @@ ExecInitExpr(Expr *node, PlanState *parent)
 		case T_List:
 			{
 				FastList	outlist;
-				List	   *inlist;
+				ListCell   *l;
 
 				FastListInit(&outlist);
-				foreach(inlist, (List *) node)
+				foreach(l, (List *) node)
 				{
 					FastAppend(&outlist,
-							   ExecInitExpr((Expr *) lfirst(inlist),
+							   ExecInitExpr((Expr *) lfirst(l),
 											parent));
 				}
 				/* Don't fall through to the "common" code below */
@@ -3101,7 +3102,7 @@ ExecQual(List *qual, ExprContext *econtext, bool resultForNull)
 {
 	bool		result;
 	MemoryContext oldContext;
-	List	   *qlist;
+	ListCell   *l;
 
 	/*
 	 * debugging stuff
@@ -3131,9 +3132,9 @@ ExecQual(List *qual, ExprContext *econtext, bool resultForNull)
 	 */
 	result = true;
 
-	foreach(qlist, qual)
+	foreach(l, qual)
 	{
-		ExprState  *clause = (ExprState *) lfirst(qlist);
+		ExprState  *clause = (ExprState *) lfirst(l);
 		Datum		expr_value;
 		bool		isNull;
 
@@ -3179,7 +3180,7 @@ int
 ExecCleanTargetListLength(List *targetlist)
 {
 	int			len = 0;
-	List	   *tl;
+	ListCell   *tl;
 
 	foreach(tl, targetlist)
 	{
@@ -3219,7 +3220,7 @@ ExecTargetList(List *targetlist,
 			   ExprDoneCond *isDone)
 {
 	MemoryContext oldContext;
-	List	   *tl;
+	ListCell   *tl;
 	bool		isNull;
 	bool		haveDoneSets;