From 0b86ade1c2f3dcd2407e535baad1654e65252316 Mon Sep 17 00:00:00 2001
From: Tatsuo Ishii <ishii@postgresql.org>
Date: Thu, 11 Mar 2004 01:47:41 +0000
Subject: [PATCH] Add NOWAIT option to LOCK command
---
doc/src/sgml/ref/lock.sgml | 10 ++++++----
src/backend/access/heap/heapam.c | 29 ++++++++++++++++++++++++++++-
src/backend/commands/lockcmds.c | 4 ++--
src/backend/nodes/copyfuncs.c | 3 ++-
src/backend/nodes/equalfuncs.c | 3 ++-
src/backend/parser/gram.y | 13 ++++++++++---
src/backend/parser/keywords.c | 3 ++-
src/include/access/heapam.h | 3 ++-
src/include/nodes/parsenodes.h | 3 ++-
9 files changed, 56 insertions(+), 15 deletions(-)
diff --git a/doc/src/sgml/ref/lock.sgml b/doc/src/sgml/ref/lock.sgml
index e78ee548fc5..a2c2a78a7aa 100644
--- 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 d98e3fd16c2..902f0621377 100644
--- 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 4634593ada5..58bee42f8fe 100644
--- 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 39f454fd3c9..c1c4ddfed8b 100644
--- 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 7951fad039c..b23002ff947 100644
--- 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 20db7fc6213..9fd2e5b5795 100644
--- 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 24430a9cc60..54ac767126f 100644
--- 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 1b7e19fe073..c6579ea2462 100644
--- 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 01ff239a444..ab505939bc3 100644
--- 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;
/* ----------------------
--
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