Add NOWAIT option to LOCK command

diff --git a/doc/src/sgml/ref/lock.sgml b/doc/src/sgml/ref/lock.sgml
index e78ee548fc5a393508af76b5e6a56c612a16abec..a2c2a78a7aad29ebb9250399212527ac8c926754 100644 (file)
--- a/doc/src/sgml/ref/lock.sgml
+++ b/doc/src/sgml/ref/lock.sgml
@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/lock.sgml,v 1.40 2003/12/14 00:05:29 neilc Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/lock.sgml,v 1.41 2004/03/11 01:47:35 ishii Exp $
 PostgreSQL documentation
 -->
 
@@ -20,7 +20,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> [, ...] [ IN <replaceable class="PARAMETER">lockmode</replaceable> MODE ]
+LOCK [ TABLE ] <replaceable class="PARAMETER">name</replaceable> [, ...] [ IN <replaceable class="PARAMETER">lockmode</replaceable> MODE ] [ NOWAIT ]
 
 where <replaceable class="PARAMETER">lockmode</replaceable> is one of:
 
@@ -34,8 +34,10 @@ where <replaceable class="PARAMETER">lockmode</replaceable> is one of:
 
   <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.
+   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>

diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index d98e3fd16c248308c5ce748c29c4fa27fcf55b07..902f0621377d89620d00aa6fd2c16d072ab1f634 100644 (file)
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.162 2004/01/16 20:51:30 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.163 2004/03/11 01:47:35 ishii Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -464,6 +464,33 @@ relation_open(Oid relationId, LOCKMODE lockmode)
        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
  *

diff --git a/src/backend/commands/lockcmds.c b/src/backend/commands/lockcmds.c
index 4634593ada5d8262312a53d1926d96588141c356..58bee42f8fe8360d7539801285d9c7804edd1fe6 100644 (file)
--- a/src/backend/commands/lockcmds.c
+++ b/src/backend/commands/lockcmds.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/commands/lockcmds.c,v 1.8 2003/11/29 19:51:47 pgsql Exp $
+ *       $PostgreSQL: pgsql/src/backend/commands/lockcmds.c,v 1.9 2004/03/11 01:47:35 ishii Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -59,7 +59,7 @@ LockTableCommand(LockStmt *lockstmt)
                        aclcheck_error(aclresult, ACL_KIND_CLASS,
                                                   get_rel_name(reloid));
 
-               rel = relation_open(reloid, lockstmt->mode);
+               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)

diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 39f454fd3c9d38350ff8f0e63a6719e1173523c7..c1c4ddfed8b0fa919d3aebd312c76e31c1c1ce6b 100644 (file)
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.277 2004/01/14 23:01:54 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.278 2004/03/11 01:47:35 ishii Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2316,6 +2316,7 @@ _copyLockStmt(LockStmt *from)
 
        COPY_NODE_FIELD(relations);
        COPY_SCALAR_FIELD(mode);
+       COPY_SCALAR_FIELD(nowait);
 
        return newnode;
 }

diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 7951fad039c629baf39ea0b7e18e5674d3cc5e38..b23002ff9477c1796fc5cc62f4c8e7cfb74e42e8 100644 (file)
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -18,7 +18,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.215 2004/01/14 23:01:55 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.216 2004/03/11 01:47:35 ishii Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1252,6 +1252,7 @@ _equalLockStmt(LockStmt *a, LockStmt *b)
 {
        COMPARE_NODE_FIELD(relations);
        COMPARE_SCALAR_FIELD(mode);
+       COMPARE_SCALAR_FIELD(nowait);
 
        return true;
 }

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 20db7fc6213d280e046509af4fdc8b1a6a64527d..9fd2e5b5795e8d8726a01864658fd11e64def04a 100644 (file)
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.447 2004/03/09 05:05:41 momjian Exp $
+ *       $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.448 2004/03/11 01:47:37 ishii Exp $
  *
  * HISTORY
  *       AUTHOR                        DATE                    MAJOR EVENT
@@ -169,6 +169,7 @@ static void doNegateFloat(Value *v);
 %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
 
@@ -375,7 +376,7 @@ static void doNegateFloat(Value *v);
        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
+       NOCREATEUSER NONE NOT NOTHING NOTIFY NOTNULL NOWAIT NULL_P
        NULLIF NUMERIC
 
        OBJECT_P OF OFF OFFSET OIDS OLD ON ONLY OPERATOR OPTION OR
@@ -4347,12 +4348,13 @@ DeleteStmt: DELETE_P FROM relation_expr where_clause
                                }
                ;
 
-LockStmt:      LOCK_P opt_table qualified_name_list opt_lock
+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;
                                        $$ = (Node *)n;
                                }
                ;
@@ -4371,6 +4373,10 @@ lock_type:       ACCESS SHARE                                    { $$ = AccessShareLock; }
                        | ACCESS EXCLUSIVE                              { $$ = AccessExclusiveLock; }
                ;
 
+opt_nowait:    NOWAIT                  { $$ = TRUE; }
+                       | /*EMPTY*/                                             { $$ = FALSE; }
+               ;
+
 
 /*****************************************************************************
  *
@@ -7683,6 +7689,7 @@ reserved_keyword:
                        | LOCALTIMESTAMP
                        | NEW
                        | NOT
+                       | NOWAIT
                        | NULL_P
                        | OFF
                        | OFFSET

diff --git a/src/backend/parser/keywords.c b/src/backend/parser/keywords.c
index 24430a9cc603f386be3c55c6bf02182b06c65cfd..54ac767126f01f22789d62516d59ef1713c44671 100644 (file)
--- a/src/backend/parser/keywords.c
+++ b/src/backend/parser/keywords.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/parser/keywords.c,v 1.146 2004/03/09 05:05:41 momjian Exp $
+ *       $PostgreSQL: pgsql/src/backend/parser/keywords.c,v 1.147 2004/03/11 01:47:40 ishii Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -213,6 +213,7 @@ static const ScanKeyword ScanKeywords[] = {
        {"nothing", NOTHING},
        {"notify", NOTIFY},
        {"notnull", NOTNULL},
+       {"nowait", NOWAIT},
        {"null", NULL_P},
        {"nullif", NULLIF},
        {"numeric", NUMERIC},

diff --git a/src/include/access/heapam.h b/src/include/access/heapam.h
index 1b7e19fe073ba1796878e93d6f88a651bbe01000..c6579ea246282c2adeb1b7a55c52558947251ad9 100644 (file)
--- a/src/include/access/heapam.h
+++ b/src/include/access/heapam.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/heapam.h,v 1.86 2003/11/29 22:40:55 pgsql Exp $
+ * $PostgreSQL: pgsql/src/include/access/heapam.h,v 1.87 2004/03/11 01:47:41 ishii Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -129,6 +129,7 @@ extern Datum heap_getsysattr(HeapTuple tup, int attnum, bool *isnull);
 /* 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);

diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 01ff239a444548c9ffd915768f21c43d6cdb8dcd..ab505939bc3b3a1fc79b81668e65465c1424ab6f 100644 (file)
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.253 2004/01/14 23:01:55 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.254 2004/03/11 01:47:41 ishii Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1619,6 +1619,7 @@ typedef struct LockStmt
        NodeTag         type;
        List       *relations;          /* relations to lock */
        int                     mode;                   /* lock mode */
+       bool            nowait;         /* no wait mode */
 } LockStmt;
 
 /* ----------------------