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, 74 insertions, 47 deletions

diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 19ffbb1be70..236061eee2a 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -18,11 +18,13 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.220 2004/05/10 22:44:44 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.221 2004/05/26 04:41:19 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
 
+#define DISABLE_LIST_COMPAT
+
 #include "postgres.h"
 
 #include "nodes/params.h"
@@ -52,20 +54,6 @@
 			return false; \
 	} while (0)
 
-/* Compare a field that is a pointer to a list of integers */
-#define COMPARE_INTLIST_FIELD(fldname) \
-	do { \
-		if (!equali(a->fldname, b->fldname)) \
-			return false; \
-	} while (0)
-
-/* Compare a field that is a pointer to a list of Oids */
-#define COMPARE_OIDLIST_FIELD(fldname) \
-	do { \
-		if (!equalo(a->fldname, b->fldname)) \
-			return false; \
-	} while (0)
-
 /* Compare a field that is a pointer to a Bitmapset */
 #define COMPARE_BITMAPSET_FIELD(fldname) \
 	do { \
@@ -328,7 +316,7 @@ _equalSubLink(SubLink *a, SubLink *b)
 	COMPARE_SCALAR_FIELD(useOr);
 	COMPARE_NODE_FIELD(lefthand);
 	COMPARE_NODE_FIELD(operName);
-	COMPARE_OIDLIST_FIELD(operOids);
+	COMPARE_NODE_FIELD(operOids);
 	COMPARE_NODE_FIELD(subselect);
 
 	return true;
@@ -340,14 +328,14 @@ _equalSubPlan(SubPlan *a, SubPlan *b)
 	COMPARE_SCALAR_FIELD(subLinkType);
 	COMPARE_SCALAR_FIELD(useOr);
 	COMPARE_NODE_FIELD(exprs);
-	COMPARE_INTLIST_FIELD(paramIds);
+	COMPARE_NODE_FIELD(paramIds);
 	/* should compare plans, but have to settle for comparing plan IDs */
 	COMPARE_SCALAR_FIELD(plan_id);
 	COMPARE_NODE_FIELD(rtable);
 	COMPARE_SCALAR_FIELD(useHashTable);
 	COMPARE_SCALAR_FIELD(unknownEqFalse);
-	COMPARE_INTLIST_FIELD(setParam);
-	COMPARE_INTLIST_FIELD(parParam);
+	COMPARE_NODE_FIELD(setParam);
+	COMPARE_NODE_FIELD(parParam);
 	COMPARE_NODE_FIELD(args);
 
 	return true;
@@ -636,7 +624,7 @@ _equalQuery(Query *a, Query *b)
 	COMPARE_SCALAR_FIELD(hasSubLinks);
 	COMPARE_NODE_FIELD(rtable);
 	COMPARE_NODE_FIELD(jointree);
-	COMPARE_INTLIST_FIELD(rowMarks);
+	COMPARE_NODE_FIELD(rowMarks);
 	COMPARE_NODE_FIELD(targetList);
 	COMPARE_NODE_FIELD(groupClause);
 	COMPARE_NODE_FIELD(havingQual);
@@ -645,7 +633,7 @@ _equalQuery(Query *a, Query *b)
 	COMPARE_NODE_FIELD(limitOffset);
 	COMPARE_NODE_FIELD(limitCount);
 	COMPARE_NODE_FIELD(setOperations);
-	COMPARE_INTLIST_FIELD(resultRelations);
+	COMPARE_NODE_FIELD(resultRelations);
 	COMPARE_NODE_FIELD(in_info_list);
 	COMPARE_SCALAR_FIELD(hasJoinRTEs);
 
@@ -720,7 +708,7 @@ _equalSetOperationStmt(SetOperationStmt *a, SetOperationStmt *b)
 	COMPARE_SCALAR_FIELD(all);
 	COMPARE_NODE_FIELD(larg);
 	COMPARE_NODE_FIELD(rarg);
-	COMPARE_OIDLIST_FIELD(colTypes);
+	COMPARE_NODE_FIELD(colTypes);
 
 	return true;
 }
@@ -764,7 +752,7 @@ _equalGrantStmt(GrantStmt *a, GrantStmt *b)
 	COMPARE_SCALAR_FIELD(is_grant);
 	COMPARE_SCALAR_FIELD(objtype);
 	COMPARE_NODE_FIELD(objects);
-	COMPARE_INTLIST_FIELD(privileges);
+	COMPARE_NODE_FIELD(privileges);
 	COMPARE_NODE_FIELD(grantees);
 	COMPARE_SCALAR_FIELD(grant_option);
 	COMPARE_SCALAR_FIELD(behavior);
@@ -1389,7 +1377,7 @@ _equalPrepareStmt(PrepareStmt *a, PrepareStmt *b)
 {
 	COMPARE_STRING_FIELD(name);
 	COMPARE_NODE_FIELD(argtypes);
-	COMPARE_OIDLIST_FIELD(argtype_oids);
+	COMPARE_NODE_FIELD(argtype_oids);
 	COMPARE_NODE_FIELD(query);
 
 	return true;
@@ -1649,6 +1637,65 @@ _equalFkConstraint(FkConstraint *a, FkConstraint *b)
  */
 
 static bool
+_equalList(List *a, List *b)
+{
+	ListCell *item_a;
+	ListCell *item_b;
+
+	/*
+	 * Try to reject by simple scalar checks before grovelling through
+	 * all the list elements...
+	 */
+	COMPARE_SCALAR_FIELD(type);
+	COMPARE_SCALAR_FIELD(length);
+
+	/*
+	 * We place the switch outside the loop for the sake of
+	 * efficiency; this may not be worth doing...
+	 */
+	switch (a->type)
+	{
+		case T_List:
+			forboth(item_a, a, item_b, b)
+			{
+				if (!equal(lfirst(item_a), lfirst(item_b)))
+					return false;
+			}
+			break;
+		case T_IntList:
+			forboth(item_a, a, item_b, b)
+			{
+				if (lfirst_int(item_a) != lfirst_int(item_b))
+					return false;
+			}
+			break;
+		case T_OidList:
+			forboth(item_a, a, item_b, b)
+			{
+				if (lfirst_oid(item_a) != lfirst_oid(item_b))
+					return false;
+			}
+			break;
+		default:
+			elog(ERROR, "unrecognized list node type: %d",
+				 (int) a->type);
+			return false;		/* keep compiler quiet */
+	}
+
+	/*
+	 * If we got here, we should have run out of elements of both lists
+	 */
+	Assert(item_a == NULL);
+	Assert(item_b == NULL);
+
+	return true;
+}
+
+/*
+ * Stuff from value.h
+ */
+
+static bool
 _equalValue(Value *a, Value *b)
 {
 	COMPARE_SCALAR_FIELD(type);
@@ -1818,30 +1865,10 @@ equal(void *a, void *b)
 		case T_InClauseInfo:
 			retval = _equalInClauseInfo(a, b);
 			break;
-
-			/*
-			 * LIST NODES
-			 */
 		case T_List:
-			{
-				List	   *la = (List *) a;
-				List	   *lb = (List *) b;
-				List	   *l;
-
-				/*
-				 * Try to reject by length check before we grovel through
-				 * all the elements...
-				 */
-				if (length(la) != length(lb))
-					return false;
-				foreach(l, la)
-				{
-					if (!equal(lfirst(l), lfirst(lb)))
-						return false;
-					lb = lnext(lb);
-				}
-				retval = true;
-			}
+		case T_IntList:
+		case T_OidList:
+			retval = _equalList(a, b);
 			break;
 
 		case T_Integer: