Someone (David Fetter?) mentioned long ago that contrib/userlock could
not be moved into core because it is GPLed, and the author couldn't be
contacted to ask about re-licensing.
Andrew(@supernews) wrote a specification for the userlock functionality,
and I implemented the attached code based on his specification, without
consulting the existing source.
It's available under a BSD license, if there's any use for it.
-- ams
/*
* Abhijit Menon-Sen <[EMAIL PROTECTED]>
* 2006-09-03
*/
#include "postgres.h"
#include "storage/lock.h"
#include "miscadmin.h"
#include "fmgr.h"
PG_MODULE_MAGIC;
static int lock(uint32, uint32, uint32);
static int unlock(uint32, uint32, uint32);
Datum user_lock(PG_FUNCTION_ARGS);
Datum user_unlock(PG_FUNCTION_ARGS);
Datum user_write_lock(PG_FUNCTION_ARGS);
Datum user_write_unlock(PG_FUNCTION_ARGS);
Datum user_write_lock_o(PG_FUNCTION_ARGS);
Datum user_write_unlock_o(PG_FUNCTION_ARGS);
Datum user_write_lock_oid(PG_FUNCTION_ARGS);
Datum user_write_unlock_oid(PG_FUNCTION_ARGS);
Datum user_write_lock_oid_i(PG_FUNCTION_ARGS);
Datum user_write_unlock_oid_i(PG_FUNCTION_ARGS);
Datum user_unlock_all(PG_FUNCTION_ARGS);
static int lock(uint32 group, uint32 id, uint32 lockmode)
{
int r;
LOCKTAG tag;
tag.locktag_field1 = MyDatabaseId;
tag.locktag_field2 = group;
tag.locktag_field3 = id;
tag.locktag_field4 = 0;
tag.locktag_type = LOCKTAG_USERLOCK;
tag.locktag_lockmethodid = USER_LOCKMETHOD;
r = LockAcquire(&tag, lockmode, true, true);
if ( r > 1 )
r = 1;
return r;
}
static int unlock(uint32 group, uint32 id, uint32 lockmode)
{
int r;
LOCKTAG tag;
tag.locktag_field1 = MyDatabaseId;
tag.locktag_field2 = group;
tag.locktag_field3 = id;
tag.locktag_field4 = 0;
tag.locktag_type = LOCKTAG_USERLOCK;
tag.locktag_lockmethodid = USER_LOCKMETHOD;
if (LockRelease(&tag, lockmode, true))
r = 1;
else
r = 0;
return r;
}
PG_FUNCTION_INFO_V1(user_lock);
Datum user_lock(PG_FUNCTION_ARGS)
{
int r;
uint32 group = PG_GETARG_INT32(0);
uint32 id = PG_GETARG_INT32(1);
uint32 lockmode = PG_GETARG_INT32(2);
r = lock(group, id, lockmode);
PG_RETURN_INT32(r);
}
PG_FUNCTION_INFO_V1(user_unlock);
Datum user_unlock(PG_FUNCTION_ARGS)
{
int r;
uint32 group = PG_GETARG_INT32(0);
uint32 id = PG_GETARG_INT32(1);
uint32 lockmode = PG_GETARG_INT32(2);
r = unlock(group, id, lockmode);
PG_RETURN_INT32(r);
}
PG_FUNCTION_INFO_V1(user_write_lock);
Datum user_write_lock(PG_FUNCTION_ARGS)
{
int r;
uint32 group = PG_GETARG_INT32(0);
uint32 id = PG_GETARG_INT32(1);
r = lock(group, id, ExclusiveLock);
PG_RETURN_INT32(r);
}
PG_FUNCTION_INFO_V1(user_write_unlock);
Datum user_write_unlock(PG_FUNCTION_ARGS)
{
int r;
uint32 group = PG_GETARG_INT32(0);
uint32 id = PG_GETARG_INT32(1);
r = unlock(group, id, ExclusiveLock);
PG_RETURN_INT32(r);
}
PG_FUNCTION_INFO_V1(user_write_lock_o);
Datum user_write_lock_o(PG_FUNCTION_ARGS)
{
int r;
uint32 group = PG_GETARG_INT32(0);
uint32 id = PG_GETARG_OID(1);
r = lock(group, id, ExclusiveLock);
PG_RETURN_INT32(r);
}
PG_FUNCTION_INFO_V1(user_write_unlock_o);
Datum user_write_unlock_o(PG_FUNCTION_ARGS)
{
int r;
uint32 group = PG_GETARG_INT32(0);
uint32 id = PG_GETARG_OID(1);
r = unlock(group, id, ExclusiveLock);
PG_RETURN_INT32(r);
}
PG_FUNCTION_INFO_V1(user_write_lock_oid);
Datum user_write_lock_oid(PG_FUNCTION_ARGS)
{
int r;
uint32 id = PG_GETARG_OID(0);
r = lock(0, id, ExclusiveLock);
PG_RETURN_INT32(r);
}
PG_FUNCTION_INFO_V1(user_write_unlock_oid);
Datum user_write_unlock_oid(PG_FUNCTION_ARGS)
{
int r;
uint32 id = PG_GETARG_OID(0);
r = unlock(0, id, ExclusiveLock);
PG_RETURN_INT32(r);
}
PG_FUNCTION_INFO_V1(user_write_lock_oid_i);
Datum user_write_lock_oid_i(PG_FUNCTION_ARGS)
{
int r;
uint32 id = PG_GETARG_INT32(0);
r = lock(0, id, ExclusiveLock);
PG_RETURN_INT32(r);
}
PG_FUNCTION_INFO_V1(user_write_unlock_oid_i);
Datum user_write_unlock_oid_i(PG_FUNCTION_ARGS)
{
int r;
uint32 id = PG_GETARG_INT32(0);
r = unlock(0, id, ExclusiveLock);
PG_RETURN_INT32(r);
}
PG_FUNCTION_INFO_V1(user_unlock_all);
Datum user_unlock_all(PG_FUNCTION_ARGS)
{
LockReleaseAll(USER_LOCKMETHOD, true);
PG_RETURN_INT32(1);
}
CREATE FUNCTION user_lock(int4,int4,int4) returns int4
AS 'MODULE_PATHNAME', 'user_lock' LANGUAGE C VOLATILE STRICT;
CREATE FUNCTION user_unlock(int4,int4,int4) returns int4
AS 'MODULE_PATHNAME', 'user_unlock' LANGUAGE C VOLATILE STRICT;
CREATE FUNCTION user_write_lock(int4,int4) returns int4
AS 'MODULE_PATHNAME', 'user_write_lock' LANGUAGE C VOLATILE STRICT;
CREATE FUNCTION user_write_unlock(int4,int4) returns int4
AS 'MODULE_PATHNAME', 'user_write_unlock' LANGUAGE C VOLATILE STRICT;
CREATE FUNCTION user_write_lock(int4,oid) returns int4
AS 'MODULE_PATHNAME', 'user_write_lock_o' LANGUAGE C VOLATILE STRICT;
CREATE FUNCTION user_write_unlock(int4,oid) returns int4
AS 'MODULE_PATHNAME', 'user_write_unlock_o' LANGUAGE C VOLATILE STRICT;
CREATE FUNCTION user_write_lock_oid(oid) returns int4
AS 'MODULE_PATHNAME', 'user_write_lock_oid' LANGUAGE C VOLATILE STRICT;
CREATE FUNCTION user_write_unlock_oid(oid) returns int4
AS 'MODULE_PATHNAME', 'user_write_unlock_oid' LANGUAGE C VOLATILE STRICT;
CREATE FUNCTION user_write_lock_oid(int4) returns int4
AS 'MODULE_PATHNAME', 'user_write_lock_oid_i' LANGUAGE C VOLATILE STRICT;
CREATE FUNCTION user_write_unlock_oid(int4) returns int4
AS 'MODULE_PATHNAME', 'user_write_unlock_oid_i' LANGUAGE C VOLATILE STRICT;
CREATE FUNCTION user_unlock_all() returns int4
AS 'MODULE_PATHNAME', 'user_unlock_all' LANGUAGE C VOLATILE STRICT;
---------------------------(end of broadcast)---------------------------
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