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https://github.com/YunoHost-Apps/mediawiki_ynh.git
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260 lines
8 KiB
PHP
260 lines
8 KiB
PHP
<?php
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/**
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* @defgroup LockManager Lock management
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* @ingroup FileBackend
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*/
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/**
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* Resource locking handling.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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* @ingroup LockManager
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* @author Aaron Schulz
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*/
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/**
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* @brief Class for handling resource locking.
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*
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* Locks on resource keys can either be shared or exclusive.
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*
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* Implementations must keep track of what is locked by this proccess
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* in-memory and support nested locking calls (using reference counting).
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* At least LOCK_UW and LOCK_EX must be implemented. LOCK_SH can be a no-op.
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* Locks should either be non-blocking or have low wait timeouts.
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*
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* Subclasses should avoid throwing exceptions at all costs.
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*
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* @ingroup LockManager
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* @since 1.19
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*/
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abstract class LockManager {
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/** @var Array Mapping of lock types to the type actually used */
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protected $lockTypeMap = array(
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self::LOCK_SH => self::LOCK_SH,
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self::LOCK_UW => self::LOCK_EX, // subclasses may use self::LOCK_SH
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self::LOCK_EX => self::LOCK_EX
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);
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/** @var Array Map of (resource path => lock type => count) */
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protected $locksHeld = array();
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protected $domain; // string; domain (usually wiki ID)
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protected $lockTTL; // integer; maximum time locks can be held
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/** Lock types; stronger locks have higher values */
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const LOCK_SH = 1; // shared lock (for reads)
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const LOCK_UW = 2; // shared lock (for reads used to write elsewhere)
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const LOCK_EX = 3; // exclusive lock (for writes)
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/**
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* Construct a new instance from configuration
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*
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* $config paramaters include:
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* - domain : Domain (usually wiki ID) that all resources are relative to [optional]
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* - lockTTL : Age (in seconds) at which resource locks should expire.
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* This only applies if locks are not tied to a connection/process.
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*
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* @param $config Array
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*/
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public function __construct( array $config ) {
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$this->domain = isset( $config['domain'] ) ? $config['domain'] : wfWikiID();
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if ( isset( $config['lockTTL'] ) ) {
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$this->lockTTL = max( 1, $config['lockTTL'] );
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} elseif ( PHP_SAPI === 'cli' ) {
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$this->lockTTL = 2 * 3600;
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} else {
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$met = ini_get( 'max_execution_time' ); // this is 0 in CLI mode
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$this->lockTTL = max( 5 * 60, 2 * (int)$met );
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}
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}
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/**
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* Lock the resources at the given abstract paths
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*
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* @param array $paths List of resource names
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* @param $type integer LockManager::LOCK_* constant
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* @param integer $timeout Timeout in seconds (0 means non-blocking) (since 1.21)
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* @return Status
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*/
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final public function lock( array $paths, $type = self::LOCK_EX, $timeout = 0 ) {
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return $this->lockByType( array( $type => $paths ), $timeout );
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}
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/**
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* Lock the resources at the given abstract paths
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*
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* @param array $pathsByType Map of LockManager::LOCK_* constants to lists of paths
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* @param integer $timeout Timeout in seconds (0 means non-blocking) (since 1.21)
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* @return Status
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* @since 1.22
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*/
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final public function lockByType( array $pathsByType, $timeout = 0 ) {
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wfProfileIn( __METHOD__ );
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$status = Status::newGood();
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$pathsByType = $this->normalizePathsByType( $pathsByType );
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$msleep = array( 0, 50, 100, 300, 500 ); // retry backoff times
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$start = microtime( true );
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do {
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$status = $this->doLockByType( $pathsByType );
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$elapsed = microtime( true ) - $start;
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if ( $status->isOK() || $elapsed >= $timeout || $elapsed < 0 ) {
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break; // success, timeout, or clock set back
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}
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usleep( 1e3 * ( next( $msleep ) ?: 1000 ) ); // use 1 sec after enough times
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$elapsed = microtime( true ) - $start;
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} while ( $elapsed < $timeout && $elapsed >= 0 );
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wfProfileOut( __METHOD__ );
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return $status;
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}
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/**
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* Unlock the resources at the given abstract paths
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*
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* @param array $paths List of paths
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* @param $type integer LockManager::LOCK_* constant
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* @return Status
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*/
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final public function unlock( array $paths, $type = self::LOCK_EX ) {
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return $this->unlockByType( array( $type => $paths ) );
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}
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/**
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* Unlock the resources at the given abstract paths
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*
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* @param array $pathsByType Map of LockManager::LOCK_* constants to lists of paths
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* @return Status
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* @since 1.22
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*/
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final public function unlockByType( array $pathsByType ) {
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wfProfileIn( __METHOD__ );
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$pathsByType = $this->normalizePathsByType( $pathsByType );
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$status = $this->doUnlockByType( $pathsByType );
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wfProfileOut( __METHOD__ );
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return $status;
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}
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/**
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* Get the base 36 SHA-1 of a string, padded to 31 digits.
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* Before hashing, the path will be prefixed with the domain ID.
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* This should be used interally for lock key or file names.
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*
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* @param $path string
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* @return string
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*/
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final protected function sha1Base36Absolute( $path ) {
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return wfBaseConvert( sha1( "{$this->domain}:{$path}" ), 16, 36, 31 );
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}
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/**
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* Get the base 16 SHA-1 of a string, padded to 31 digits.
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* Before hashing, the path will be prefixed with the domain ID.
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* This should be used interally for lock key or file names.
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*
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* @param $path string
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* @return string
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*/
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final protected function sha1Base16Absolute( $path ) {
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return sha1( "{$this->domain}:{$path}" );
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}
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/**
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* Normalize the $paths array by converting LOCK_UW locks into the
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* appropriate type and removing any duplicated paths for each lock type.
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*
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* @param array $paths Map of LockManager::LOCK_* constants to lists of paths
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* @return Array
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* @since 1.22
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*/
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final protected function normalizePathsByType( array $pathsByType ) {
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$res = array();
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foreach ( $pathsByType as $type => $paths ) {
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$res[$this->lockTypeMap[$type]] = array_unique( $paths );
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}
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return $res;
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}
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/**
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* @see LockManager::lockByType()
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* @param array $paths Map of LockManager::LOCK_* constants to lists of paths
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* @return Status
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* @since 1.22
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*/
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protected function doLockByType( array $pathsByType ) {
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$status = Status::newGood();
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$lockedByType = array(); // map of (type => paths)
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foreach ( $pathsByType as $type => $paths ) {
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$status->merge( $this->doLock( $paths, $type ) );
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if ( $status->isOK() ) {
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$lockedByType[$type] = $paths;
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} else {
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// Release the subset of locks that were acquired
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foreach ( $lockedByType as $type => $paths ) {
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$status->merge( $this->doUnlock( $paths, $type ) );
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}
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break;
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}
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}
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return $status;
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}
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/**
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* Lock resources with the given keys and lock type
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*
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* @param array $paths List of paths
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* @param $type integer LockManager::LOCK_* constant
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* @return Status
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*/
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abstract protected function doLock( array $paths, $type );
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/**
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* @see LockManager::unlockByType()
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* @param array $paths Map of LockManager::LOCK_* constants to lists of paths
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* @return Status
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* @since 1.22
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*/
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protected function doUnlockByType( array $pathsByType ) {
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$status = Status::newGood();
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foreach ( $pathsByType as $type => $paths ) {
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$status->merge( $this->doUnlock( $paths, $type ) );
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}
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return $status;
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}
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/**
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* Unlock resources with the given keys and lock type
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*
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* @param array $paths List of paths
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* @param $type integer LockManager::LOCK_* constant
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* @return Status
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*/
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abstract protected function doUnlock( array $paths, $type );
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}
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/**
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* Simple version of LockManager that does nothing
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* @since 1.19
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*/
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class NullLockManager extends LockManager {
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protected function doLock( array $paths, $type ) {
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return Status::newGood();
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}
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protected function doUnlock( array $paths, $type ) {
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return Status::newGood();
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}
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}
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