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PhutilFileLock.php
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Created
Mon, Jul 8, 04:10
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3 KB
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text/x-php
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Wed, Jul 10, 04:10 (2 d)
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blob
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Handle
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rPHU libphutil
PhutilFileLock.php
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<?php
/*
* Copyright 2012 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* Wrapper around `flock()` for advisory filesystem locking. Usage is
* straightforward:
*
* $path = '/path/to/lock.file';
* $lock = new PhutilFileLock($path);
* $lock->lock();
*
* do_contentious_things();
*
* $lock->unlock();
*
* For more information on locks, see @{class:PhutilLock}.
*
* @task construct Constructing Locks
* @task impl Implementation
*
* @group filesystem
*/
final
class
PhutilFileLock
extends
PhutilLock
{
private
$lockfile
;
private
$handle
;
/* -( Constructing Locks )------------------------------------------------- */
/**
* Create a new lock on a lockfile. The file need not exist yet.
*
* @param string The lockfile to use.
* @return PhutilFileLock New lock object.
*
* @task construct
*/
public
static
function
newForPath
(
$lockfile
)
{
$lockfile
=
Filesystem
::
resolvePath
(
$lockfile
);
$name
=
'file:'
.
$lockfile
;
$lock
=
self
::
getLock
(
$name
);
if
(!
$lock
)
{
$lock
=
new
PhutilFileLock
(
$name
);
$lock
->
lockfile
=
$lockfile
;
self
::
registerLock
(
$lock
);
}
return
$lock
;
}
/* -( Locking )------------------------------------------------------------ */
/**
* Acquire the lock. If lock acquisition fails because the lock is held by
* another process, throws @{class:PhutilLockException}. Other exceptions
* indicate that lock acquisition has failed for reasons unrelated to locking.
*
* If the lock is already held, this method throws. You can test the lock
* status with @{method:isLocked}.
*
* @param float Seconds to block waiting for the lock.
* @return void
*
* @task lock
*/
protected
function
doLock
(
$wait
)
{
$path
=
$this
->
lockfile
;
$handle
=
@
fopen
(
$path
,
'a+'
);
if
(!
$handle
)
{
throw
new
FilesystemException
(
$path
,
"Unable to open lock '{$path}' for writing!"
);
}
$start_time
=
microtime
(
true
);
do
{
$would_block
=
null
;
$ok
=
flock
(
$handle
,
LOCK_EX
|
LOCK_NB
,
$would_block
);
if
(
$ok
)
{
break
;
}
else
{
usleep
(
10000
);
}
}
while
(
$wait
&&
$wait
>
(
microtime
(
true
)
-
$start_time
));
if
(!
$ok
)
{
fclose
(
$handle
);
throw
new
PhutilLockException
(
$this
->
getName
());
}
$this
->
handle
=
$handle
;
}
/**
* Release the lock. Throws an exception on failure, e.g. if the lock is not
* currently held.
*
* @return void
*
* @task lock
*/
protected
function
doUnlock
()
{
$ok
=
flock
(
$this
->
handle
,
LOCK_UN
|
LOCK_NB
);
if
(!
$ok
)
{
throw
new
Exception
(
"Unable to unlock file!"
);
}
$ok
=
fclose
(
$this
->
handle
);
if
(!
$ok
)
{
throw
new
Exception
(
"Unable to close file!"
);
}
$this
->
handle
=
null
;
}
}
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