mirror of
https://github.com/silverstripe/silverstripe-docsviewer
synced 2024-10-22 11:05:56 +02:00
237 lines
8.6 KiB
PHP
Executable File
237 lines
8.6 KiB
PHP
Executable File
<?php
|
|
/**
|
|
* Zend Framework
|
|
*
|
|
* LICENSE
|
|
*
|
|
* This source file is subject to the new BSD license that is bundled
|
|
* with this package in the file LICENSE.txt.
|
|
* It is also available through the world-wide-web at this URL:
|
|
* http://framework.zend.com/license/new-bsd
|
|
* If you did not receive a copy of the license and are unable to
|
|
* obtain it through the world-wide-web, please send an email
|
|
* to license@zend.com so we can send you a copy immediately.
|
|
*
|
|
* @category Zend
|
|
* @package Zend_Search_Lucene
|
|
* @copyright Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)
|
|
* @license http://framework.zend.com/license/new-bsd New BSD License
|
|
* @version $Id: LockManager.php 20096 2010-01-06 02:05:09Z bkarwin $
|
|
*/
|
|
|
|
/** Zend_Search_Lucene_Storage_Directory */
|
|
require_once 'Zend/Search/Lucene/Storage/Directory.php';
|
|
|
|
/** Zend_Search_Lucene_Storage_File */
|
|
require_once 'Zend/Search/Lucene/Storage/File.php';
|
|
|
|
/**
|
|
* This is an utility class which provides index locks processing functionality
|
|
*
|
|
* @category Zend
|
|
* @package Zend_Search_Lucene
|
|
* @copyright Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)
|
|
* @license http://framework.zend.com/license/new-bsd New BSD License
|
|
*/
|
|
class Zend_Search_Lucene_LockManager
|
|
{
|
|
/**
|
|
* consts for name of file to show lock status
|
|
*/
|
|
const WRITE_LOCK_FILE = 'write.lock.file';
|
|
const READ_LOCK_FILE = 'read.lock.file';
|
|
const READ_LOCK_PROCESSING_LOCK_FILE = 'read-lock-processing.lock.file';
|
|
const OPTIMIZATION_LOCK_FILE = 'optimization.lock.file';
|
|
|
|
/**
|
|
* Obtain exclusive write lock on the index
|
|
*
|
|
* @param Zend_Search_Lucene_Storage_Directory $lockDirectory
|
|
* @return Zend_Search_Lucene_Storage_File
|
|
* @throws Zend_Search_Lucene_Exception
|
|
*/
|
|
public static function obtainWriteLock(Zend_Search_Lucene_Storage_Directory $lockDirectory)
|
|
{
|
|
$lock = $lockDirectory->createFile(self::WRITE_LOCK_FILE);
|
|
if (!$lock->lock(LOCK_EX)) {
|
|
require_once 'Zend/Search/Lucene/Exception.php';
|
|
throw new Zend_Search_Lucene_Exception('Can\'t obtain exclusive index lock');
|
|
}
|
|
return $lock;
|
|
}
|
|
|
|
/**
|
|
* Release exclusive write lock
|
|
*
|
|
* @param Zend_Search_Lucene_Storage_Directory $lockDirectory
|
|
*/
|
|
public static function releaseWriteLock(Zend_Search_Lucene_Storage_Directory $lockDirectory)
|
|
{
|
|
$lock = $lockDirectory->getFileObject(self::WRITE_LOCK_FILE);
|
|
$lock->unlock();
|
|
}
|
|
|
|
/**
|
|
* Obtain the exclusive "read escalation/de-escalation" lock
|
|
*
|
|
* Required to protect the escalate/de-escalate read lock process
|
|
* on GFS (and potentially other) mounted filesystems.
|
|
*
|
|
* Why we need this:
|
|
* While GFS supports cluster-wide locking via flock(), it's
|
|
* implementation isn't quite what it should be. The locking
|
|
* semantics that work consistently on a local filesystem tend to
|
|
* fail on GFS mounted filesystems. This appears to be a design defect
|
|
* in the implementation of GFS. How this manifests itself is that
|
|
* conditional promotion of a shared lock to exclusive will always
|
|
* fail, lock release requests are honored but not immediately
|
|
* processed (causing erratic failures of subsequent conditional
|
|
* requests) and the releasing of the exclusive lock before the
|
|
* shared lock is set when a lock is demoted (which can open a window
|
|
* of opportunity for another process to gain an exclusive lock when
|
|
* it shoudln't be allowed to).
|
|
*
|
|
* @param Zend_Search_Lucene_Storage_Directory $lockDirectory
|
|
* @return Zend_Search_Lucene_Storage_File
|
|
* @throws Zend_Search_Lucene_Exception
|
|
*/
|
|
private static function _startReadLockProcessing(Zend_Search_Lucene_Storage_Directory $lockDirectory)
|
|
{
|
|
$lock = $lockDirectory->createFile(self::READ_LOCK_PROCESSING_LOCK_FILE);
|
|
if (!$lock->lock(LOCK_EX)) {
|
|
require_once 'Zend/Search/Lucene/Exception.php';
|
|
throw new Zend_Search_Lucene_Exception('Can\'t obtain exclusive lock for the read lock processing file');
|
|
}
|
|
return $lock;
|
|
}
|
|
|
|
/**
|
|
* Release the exclusive "read escalation/de-escalation" lock
|
|
*
|
|
* Required to protect the escalate/de-escalate read lock process
|
|
* on GFS (and potentially other) mounted filesystems.
|
|
*
|
|
* @param Zend_Search_Lucene_Storage_Directory $lockDirectory
|
|
*/
|
|
private static function _stopReadLockProcessing(Zend_Search_Lucene_Storage_Directory $lockDirectory)
|
|
{
|
|
$lock = $lockDirectory->getFileObject(self::READ_LOCK_PROCESSING_LOCK_FILE);
|
|
$lock->unlock();
|
|
}
|
|
|
|
|
|
/**
|
|
* Obtain shared read lock on the index
|
|
*
|
|
* It doesn't block other read or update processes, but prevent index from the premature cleaning-up
|
|
*
|
|
* @param Zend_Search_Lucene_Storage_Directory $defaultLockDirectory
|
|
* @return Zend_Search_Lucene_Storage_File
|
|
* @throws Zend_Search_Lucene_Exception
|
|
*/
|
|
public static function obtainReadLock(Zend_Search_Lucene_Storage_Directory $lockDirectory)
|
|
{
|
|
$lock = $lockDirectory->createFile(self::READ_LOCK_FILE);
|
|
if (!$lock->lock(LOCK_SH)) {
|
|
require_once 'Zend/Search/Lucene/Exception.php';
|
|
throw new Zend_Search_Lucene_Exception('Can\'t obtain shared reading index lock');
|
|
}
|
|
return $lock;
|
|
}
|
|
|
|
/**
|
|
* Release shared read lock
|
|
*
|
|
* @param Zend_Search_Lucene_Storage_Directory $lockDirectory
|
|
*/
|
|
public static function releaseReadLock(Zend_Search_Lucene_Storage_Directory $lockDirectory)
|
|
{
|
|
$lock = $lockDirectory->getFileObject(self::READ_LOCK_FILE);
|
|
$lock->unlock();
|
|
}
|
|
|
|
/**
|
|
* Escalate Read lock to exclusive level
|
|
*
|
|
* @param Zend_Search_Lucene_Storage_Directory $lockDirectory
|
|
* @return boolean
|
|
*/
|
|
public static function escalateReadLock(Zend_Search_Lucene_Storage_Directory $lockDirectory)
|
|
{
|
|
self::_startReadLockProcessing($lockDirectory);
|
|
|
|
$lock = $lockDirectory->getFileObject(self::READ_LOCK_FILE);
|
|
|
|
// First, release the shared lock for the benefit of GFS since
|
|
// it will fail the conditional request to promote the lock to
|
|
// "exclusive" while the shared lock is held (even when we are
|
|
// the only holder).
|
|
$lock->unlock();
|
|
|
|
// GFS is really poor. While the above "unlock" returns, GFS
|
|
// doesn't clean up it's tables right away (which will potentially
|
|
// cause the conditional locking for the "exclusive" lock to fail.
|
|
// We will retry the conditional lock request several times on a
|
|
// failure to get past this. The performance hit is negligible
|
|
// in the grand scheme of things and only will occur with GFS
|
|
// filesystems or if another local process has the shared lock
|
|
// on local filesystems.
|
|
for ($retries = 0; $retries < 10; $retries++) {
|
|
if ($lock->lock(LOCK_EX, true)) {
|
|
// Exclusive lock is obtained!
|
|
self::_stopReadLockProcessing($lockDirectory);
|
|
return true;
|
|
}
|
|
|
|
// wait 1 microsecond
|
|
usleep(1);
|
|
}
|
|
|
|
// Restore lock state
|
|
$lock->lock(LOCK_SH);
|
|
|
|
self::_stopReadLockProcessing($lockDirectory);
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* De-escalate Read lock to shared level
|
|
*
|
|
* @param Zend_Search_Lucene_Storage_Directory $lockDirectory
|
|
*/
|
|
public static function deEscalateReadLock(Zend_Search_Lucene_Storage_Directory $lockDirectory)
|
|
{
|
|
$lock = $lockDirectory->getFileObject(self::READ_LOCK_FILE);
|
|
$lock->lock(LOCK_SH);
|
|
}
|
|
|
|
/**
|
|
* Obtain exclusive optimization lock on the index
|
|
*
|
|
* Returns lock object on success and false otherwise (doesn't block execution)
|
|
*
|
|
* @param Zend_Search_Lucene_Storage_Directory $lockDirectory
|
|
* @return mixed
|
|
*/
|
|
public static function obtainOptimizationLock(Zend_Search_Lucene_Storage_Directory $lockDirectory)
|
|
{
|
|
$lock = $lockDirectory->createFile(self::OPTIMIZATION_LOCK_FILE);
|
|
if (!$lock->lock(LOCK_EX, true)) {
|
|
return false;
|
|
}
|
|
return $lock;
|
|
}
|
|
|
|
/**
|
|
* Release exclusive optimization lock
|
|
*
|
|
* @param Zend_Search_Lucene_Storage_Directory $lockDirectory
|
|
*/
|
|
public static function releaseOptimizationLock(Zend_Search_Lucene_Storage_Directory $lockDirectory)
|
|
{
|
|
$lock = $lockDirectory->getFileObject(self::OPTIMIZATION_LOCK_FILE);
|
|
$lock->unlock();
|
|
}
|
|
|
|
}
|