===================================================================
RCS file: /cvsroot/pgsql-server/doc/src/sgml/ref/lock.sgml,v
retrieving revision 1.40
diff -c -r1.40 lock.sgml
*** doc/src/sgml/ref/lock.sgml	14 Dec 2003 00:05:29 -0000	1.40
--- doc/src/sgml/ref/lock.sgml	10 Mar 2004 01:35:18 -0000
***************
*** 20,26 ****
  
   <refsynopsisdiv>
  <synopsis>
! LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> [, ...] [ IN <replaceable class="PARAMETER">lockmode</replaceable> MODE ]
  
  where <replaceable class="PARAMETER">lockmode</replaceable> is one of:
  
--- 20,26 ----
  
   <refsynopsisdiv>
  <synopsis>
! LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> [, ...] [ IN <replaceable class="PARAMETER">lockmode</replaceable> MODE ] [ NOWAIT ]
  
  where <replaceable class="PARAMETER">lockmode</replaceable> is one of:
  
***************
*** 34,41 ****
  
    <para>
     <command>LOCK TABLE</command> obtains a table-level lock, waiting if
!    necessary for any conflicting locks to be released.  Once obtained,
!    the lock is held for the remainder of the current transaction.
     (There is no <command>UNLOCK TABLE</command> command; locks are always
     released at transaction end.)
    </para>
--- 34,43 ----
  
    <para>
     <command>LOCK TABLE</command> obtains a table-level lock, waiting if
!    necessary for any conflicting locks to be released.
!    If <literal>NOWAIT</literal> is given, <command>LOCK TABLE</command>
!    does not wait for acquiring lock, and throws an error instead.
!    Once obtained, the lock is held for the remainder of the current transaction.
     (There is no <command>UNLOCK TABLE</command> command; locks are always
     released at transaction end.)
    </para>
Index: src/backend/access/heap/heapam.c
===================================================================
RCS file: /cvsroot/pgsql-server/src/backend/access/heap/heapam.c,v
retrieving revision 1.162
diff -c -r1.162 heapam.c
*** src/backend/access/heap/heapam.c	16 Jan 2004 20:51:30 -0000	1.162
--- src/backend/access/heap/heapam.c	10 Mar 2004 01:35:21 -0000
***************
*** 464,469 ****
--- 464,496 ----
  	return r;
  }
  
+ Relation
+ conditional_relation_open(Oid relationId, LOCKMODE lockmode, bool nowait)
+ {
+ 	Relation	r;
+ 
+ 	Assert(lockmode >= NoLock && lockmode < MAX_LOCKMODES);
+ 
+ 	/* The relcache does all the real work... */
+ 	r = RelationIdGetRelation(relationId);
+ 
+ 	if (!RelationIsValid(r))
+ 		elog(ERROR, "could not open relation with OID %u", relationId);
+ 
+ 	if (lockmode != NoLock)
+ 	{
+ 		if (nowait)
+ 		{
+ 			if (!ConditionalLockRelation(r, lockmode))
+ 				elog(ERROR, "could not aquire relation lock");
+ 		}
+ 		else
+ 			LockRelation(r, lockmode);
+ 	}
+ 
+ 	return r;
+ }
+ 
  /* ----------------
   *		relation_openrv - open any relation specified by a RangeVar
   *
Index: src/backend/commands/lockcmds.c
===================================================================
RCS file: /cvsroot/pgsql-server/src/backend/commands/lockcmds.c,v
retrieving revision 1.8
diff -c -r1.8 lockcmds.c
*** src/backend/commands/lockcmds.c	29 Nov 2003 19:51:47 -0000	1.8
--- src/backend/commands/lockcmds.c	10 Mar 2004 01:35:21 -0000
***************
*** 59,65 ****
  			aclcheck_error(aclresult, ACL_KIND_CLASS,
  						   get_rel_name(reloid));
  
! 		rel = relation_open(reloid, lockstmt->mode);
  
  		/* Currently, we only allow plain tables to be locked */
  		if (rel->rd_rel->relkind != RELKIND_RELATION)
--- 59,65 ----
  			aclcheck_error(aclresult, ACL_KIND_CLASS,
  						   get_rel_name(reloid));
  
! 		rel = conditional_relation_open(reloid, lockstmt->mode, lockstmt->nowait);
  
  		/* Currently, we only allow plain tables to be locked */
  		if (rel->rd_rel->relkind != RELKIND_RELATION)
Index: src/backend/nodes/copyfuncs.c
===================================================================
RCS file: /cvsroot/pgsql-server/src/backend/nodes/copyfuncs.c,v
retrieving revision 1.277
diff -c -r1.277 copyfuncs.c
*** src/backend/nodes/copyfuncs.c	14 Jan 2004 23:01:54 -0000	1.277
--- src/backend/nodes/copyfuncs.c	10 Mar 2004 01:35:25 -0000
***************
*** 2316,2321 ****
--- 2316,2322 ----
  
  	COPY_NODE_FIELD(relations);
  	COPY_SCALAR_FIELD(mode);
+ 	COPY_SCALAR_FIELD(nowait);
  
  	return newnode;
  }
Index: src/backend/nodes/equalfuncs.c
===================================================================
RCS file: /cvsroot/pgsql-server/src/backend/nodes/equalfuncs.c,v
retrieving revision 1.215
diff -c -r1.215 equalfuncs.c
*** src/backend/nodes/equalfuncs.c	14 Jan 2004 23:01:55 -0000	1.215
--- src/backend/nodes/equalfuncs.c	10 Mar 2004 01:35:28 -0000
***************
*** 1252,1257 ****
--- 1252,1258 ----
  {
  	COMPARE_NODE_FIELD(relations);
  	COMPARE_SCALAR_FIELD(mode);
+ 	COMPARE_SCALAR_FIELD(nowait);
  
  	return true;
  }
Index: src/backend/parser/gram.y
===================================================================
RCS file: /cvsroot/pgsql-server/src/backend/parser/gram.y,v
retrieving revision 2.447
diff -c -r2.447 gram.y
*** src/backend/parser/gram.y	9 Mar 2004 05:05:41 -0000	2.447
--- src/backend/parser/gram.y	10 Mar 2004 01:35:42 -0000
***************
*** 169,174 ****
--- 169,175 ----
  %type <ival>	opt_lock lock_type cast_context
  %type <boolean>	opt_force opt_or_replace transaction_access_mode
  				opt_grant_grant_option opt_revoke_grant_option
+ 				opt_nowait
  
  %type <boolean>	like_including_defaults
  
***************
*** 375,381 ****
  	MATCH MAXVALUE MINUTE_P MINVALUE MODE MONTH_P MOVE
  
  	NAMES NATIONAL NATURAL NCHAR NEW NEXT NO NOCREATEDB
! 	NOCREATEUSER NONE NOT NOTHING NOTIFY NOTNULL NULL_P
  	NULLIF NUMERIC
  
  	OBJECT_P OF OFF OFFSET OIDS OLD ON ONLY OPERATOR OPTION OR
--- 376,382 ----
  	MATCH MAXVALUE MINUTE_P MINVALUE MODE MONTH_P MOVE
  
  	NAMES NATIONAL NATURAL NCHAR NEW NEXT NO NOCREATEDB
! 	NOCREATEUSER NONE NOT NOTHING NOTIFY NOTNULL NOWAIT NULL_P
  	NULLIF NUMERIC
  
  	OBJECT_P OF OFF OFFSET OIDS OLD ON ONLY OPERATOR OPTION OR
***************
*** 4347,4358 ****
  				}
  		;
  
! LockStmt:	LOCK_P opt_table qualified_name_list opt_lock
  				{
  					LockStmt *n = makeNode(LockStmt);
  
  					n->relations = $3;
  					n->mode = $4;
  					$$ = (Node *)n;
  				}
  		;
--- 4348,4360 ----
  				}
  		;
  
! LockStmt:	LOCK_P opt_table qualified_name_list opt_lock opt_nowait
  				{
  					LockStmt *n = makeNode(LockStmt);
  
  					n->relations = $3;
  					n->mode = $4;
+ 					n->nowait = $5;
  					$$ = (Node *)n;
  				}
  		;
***************
*** 4371,4376 ****
--- 4373,4382 ----
  			| ACCESS EXCLUSIVE				{ $$ = AccessExclusiveLock; }
  		;
  
+ opt_nowait:	NOWAIT 			{ $$ = TRUE; }
+ 			| /*EMPTY*/						{ $$ = FALSE; }
+ 		;
+ 
  
  /*****************************************************************************
   *
***************
*** 7683,7688 ****
--- 7689,7695 ----
  			| LOCALTIMESTAMP
  			| NEW
  			| NOT
+ 			| NOWAIT
  			| NULL_P
  			| OFF
  			| OFFSET
Index: src/backend/parser/keywords.c
===================================================================
RCS file: /cvsroot/pgsql-server/src/backend/parser/keywords.c,v
retrieving revision 1.146
diff -c -r1.146 keywords.c
*** src/backend/parser/keywords.c	9 Mar 2004 05:05:41 -0000	1.146
--- src/backend/parser/keywords.c	10 Mar 2004 01:35:42 -0000
***************
*** 213,218 ****
--- 213,219 ----
  	{"nothing", NOTHING},
  	{"notify", NOTIFY},
  	{"notnull", NOTNULL},
+ 	{"nowait", NOWAIT},
  	{"null", NULL_P},
  	{"nullif", NULLIF},
  	{"numeric", NUMERIC},
Index: src/include/access/heapam.h
===================================================================
RCS file: /cvsroot/pgsql-server/src/include/access/heapam.h,v
retrieving revision 1.86
diff -c -r1.86 heapam.h
*** src/include/access/heapam.h	29 Nov 2003 22:40:55 -0000	1.86
--- src/include/access/heapam.h	10 Mar 2004 01:35:46 -0000
***************
*** 129,134 ****
--- 129,135 ----
  /* heapam.c */
  
  extern Relation relation_open(Oid relationId, LOCKMODE lockmode);
+ extern Relation conditional_relation_open(Oid relationId, LOCKMODE lockmode, bool nowait);
  extern Relation relation_openrv(const RangeVar *relation, LOCKMODE lockmode);
  extern Relation relation_openr(const char *sysRelationName, LOCKMODE lockmode);
  extern void relation_close(Relation relation, LOCKMODE lockmode);
Index: src/include/nodes/parsenodes.h
===================================================================
RCS file: /cvsroot/pgsql-server/src/include/nodes/parsenodes.h,v
retrieving revision 1.253
diff -c -r1.253 parsenodes.h
*** src/include/nodes/parsenodes.h	14 Jan 2004 23:01:55 -0000	1.253
--- src/include/nodes/parsenodes.h	10 Mar 2004 01:35:49 -0000
***************
*** 1619,1624 ****
--- 1619,1625 ----
  	NodeTag		type;
  	List	   *relations;		/* relations to lock */
  	int			mode;			/* lock mode */
+ 	bool		nowait;		/* no wait mode */
  } LockStmt;
  
  /* ----------------------