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, 30 insertions, 28 deletions

diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 604dd9819eb..7a4390538b6 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.414 2004/05/23 03:50:45 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/tcop/postgres.c,v 1.415 2004/05/26 04:41:35 neilc Exp $
  *
  * NOTES
  *	  this is the "main" module of the postgres backend and
@@ -428,7 +428,7 @@ pg_parse_and_rewrite(const char *query_string,	/* string to execute */
 {
 	List	   *raw_parsetree_list;
 	List	   *querytree_list;
-	List	   *list_item;
+	ListCell   *list_item;
 
 	/*
 	 * (1) parse the request string into a list of raw parse trees.
@@ -443,7 +443,7 @@ pg_parse_and_rewrite(const char *query_string,	/* string to execute */
 	{
 		Node	   *parsetree = (Node *) lfirst(list_item);
 
-		querytree_list = nconc(querytree_list,
+		querytree_list = list_concat(querytree_list,
 							   pg_analyze_and_rewrite(parsetree,
 													  paramTypes,
 													  numParams));
@@ -468,8 +468,8 @@ pg_parse_and_rewrite(const char *query_string,	/* string to execute */
 List *
 pg_parse_query(const char *query_string)
 {
-	List	   *raw_parsetree_list,
-			   *parsetree_item;
+	List	   *raw_parsetree_list;
+	ListCell   *parsetree_item;
 
 	if (log_statement == LOGSTMT_ALL)
 		ereport(LOG,
@@ -571,7 +571,7 @@ List *
 pg_rewrite_queries(List *querytree_list)
 {
 	List	   *new_list = NIL;
-	List	   *list_item;
+	ListCell   *list_item;
 
 	if (log_parser_stats)
 		ResetUsage();
@@ -598,7 +598,7 @@ pg_rewrite_queries(List *querytree_list)
 			/* rewrite regular queries */
 			List	   *rewritten = QueryRewrite(querytree);
 
-			new_list = nconc(new_list, rewritten);
+			new_list = list_concat(new_list, rewritten);
 		}
 	}
 
@@ -691,7 +691,7 @@ List *
 pg_plan_queries(List *querytrees, bool needSnapshot)
 {
 	List	   *plan_list = NIL;
-	List	   *query_list;
+	ListCell   *query_list;
 
 	foreach(query_list, querytrees)
 	{
@@ -730,8 +730,8 @@ exec_simple_query(const char *query_string)
 {
 	CommandDest dest = whereToSendOutput;
 	MemoryContext oldcontext;
-	List	   *parsetree_list,
-			   *parsetree_item;
+	List	   *parsetree_list;
+	ListCell   *parsetree_item;
 	struct timeval start_t,
 				stop_t;
 	bool		save_log_duration = log_duration;
@@ -946,7 +946,7 @@ exec_simple_query(const char *query_string)
 			 */
 			finish_xact_command();
 		}
-		else if (lnext(parsetree_item) == NIL)
+		else if (lnext(parsetree_item) == NULL)
 		{
 			/*
 			 * If this is the last parsetree of the query string, close
@@ -1129,14 +1129,14 @@ exec_parse_message(const char *query_string,	/* string to execute */
 	 * is mainly to keep the protocol simple --- otherwise we'd need to
 	 * worry about multiple result tupdescs and things like that.
 	 */
-	if (length(parsetree_list) > 1)
+	if (list_length(parsetree_list) > 1)
 		ereport(ERROR,
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("cannot insert multiple commands into a prepared statement")));
 
 	if (parsetree_list != NIL)
 	{
-		Node	   *parsetree = (Node *) lfirst(parsetree_list);
+		Node	   *parsetree = (Node *) linitial(parsetree_list);
 		int			i;
 
 		/*
@@ -1198,7 +1198,7 @@ exec_parse_message(const char *query_string,	/* string to execute */
 						(errcode(ERRCODE_INDETERMINATE_DATATYPE),
 				  errmsg("could not determine data type of parameter $%d",
 						 i + 1)));
-			param_list = lappendo(param_list, ptype);
+			param_list = lappend_oid(param_list, ptype);
 		}
 
 		if (log_parser_stats)
@@ -1342,11 +1342,11 @@ exec_bind_message(StringInfo input_message)
 				   errmsg("unnamed prepared statement does not exist")));
 	}
 
-	if (numParams != length(pstmt->argtype_list))
+	if (numParams != list_length(pstmt->argtype_list))
 		ereport(ERROR,
 				(errcode(ERRCODE_PROTOCOL_VIOLATION),
 				 errmsg("bind message supplies %d parameters, but prepared statement \"%s\" requires %d",
-					numParams, stmt_name, length(pstmt->argtype_list))));
+					numParams, stmt_name, list_length(pstmt->argtype_list))));
 
 	/*
 	 * Create the portal.  Allow silent replacement of an existing portal
@@ -1374,7 +1374,7 @@ exec_bind_message(StringInfo input_message)
 	if (numParams > 0)
 	{
 		bool		isaborted = IsAbortedTransactionBlockState();
-		List	   *l;
+		ListCell   *l;
 		MemoryContext oldContext;
 
 		oldContext = MemoryContextSwitchTo(PortalGetHeapMemory(portal));
@@ -1385,7 +1385,7 @@ exec_bind_message(StringInfo input_message)
 		i = 0;
 		foreach(l, pstmt->argtype_list)
 		{
-			Oid			ptype = lfirsto(l);
+			Oid			ptype = lfirst_oid(l);
 			int32		plength;
 			bool		isNull;
 
@@ -1587,9 +1587,9 @@ exec_execute_message(const char *portal_name, long max_rows)
 	BeginCommand(portal->commandTag, dest);
 
 	/* Check for transaction-control commands */
-	if (length(portal->parseTrees) == 1)
+	if (list_length(portal->parseTrees) == 1)
 	{
-		Query	   *query = (Query *) lfirst(portal->parseTrees);
+		Query	   *query = (Query *) linitial(portal->parseTrees);
 
 		if (query->commandType == CMD_UTILITY &&
 			query->utilityStmt != NULL &&
@@ -1690,7 +1690,7 @@ exec_describe_statement_message(const char *stmt_name)
 {
 	PreparedStatement *pstmt;
 	TupleDesc	tupdesc;
-	List	   *l;
+	ListCell   *l;
 	StringInfoData buf;
 
 	/* Find prepared statement */
@@ -1713,11 +1713,11 @@ exec_describe_statement_message(const char *stmt_name)
 	 * First describe the parameters...
 	 */
 	pq_beginmessage(&buf, 't'); /* parameter description message type */
-	pq_sendint(&buf, length(pstmt->argtype_list), 2);
+	pq_sendint(&buf, list_length(pstmt->argtype_list), 2);
 
 	foreach(l, pstmt->argtype_list)
 	{
-		Oid			ptype = lfirsto(l);
+		Oid			ptype = lfirst_oid(l);
 
 		pq_sendint(&buf, (int) ptype, 4);
 	}
@@ -1732,7 +1732,7 @@ exec_describe_statement_message(const char *stmt_name)
 		List	   *targetlist;
 
 		if (ChoosePortalStrategy(pstmt->query_list) == PORTAL_ONE_SELECT)
-			targetlist = ((Query *) lfirst(pstmt->query_list))->targetList;
+			targetlist = ((Query *) linitial(pstmt->query_list))->targetList;
 		else
 			targetlist = NIL;
 		SendRowDescriptionMessage(tupdesc, targetlist, NULL);
@@ -1766,7 +1766,7 @@ exec_describe_portal_message(const char *portal_name)
 		List	   *targetlist;
 
 		if (portal->strategy == PORTAL_ONE_SELECT)
-			targetlist = ((Query *) lfirst(portal->parseTrees))->targetList;
+			targetlist = ((Query *) linitial(portal->parseTrees))->targetList;
 		else
 			targetlist = NIL;
 		SendRowDescriptionMessage(portal->tupDesc, targetlist,
@@ -2524,17 +2524,19 @@ PostgresMain(int argc, char *argv[], const char *username)
 	 */
 	if (MyProcPort != NULL)
 	{
-		List	   *gucopts = MyProcPort->guc_options;
+		ListCell   *gucopts = list_head(MyProcPort->guc_options);
 
 		while (gucopts)
 		{
-			char	   *name,
-					   *value;
+			char *name;
+			char *value;
 
 			name = lfirst(gucopts);
 			gucopts = lnext(gucopts);
+
 			value = lfirst(gucopts);
 			gucopts = lnext(gucopts);
+
 			SetConfigOption(name, value, PGC_BACKEND, PGC_S_CLIENT);
 		}