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