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<?php |
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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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* Self-releasing locks |
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* |
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* LockManager helper class to handle scoped locks, which |
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* release when an object is destroyed or goes out of scope. |
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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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class ScopedLock { |
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/** @var LockManager */ |
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protected $manager; |
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/** @var StatusValue */ |
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protected $status; |
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/** @var array Map of lock types to resource paths */ |
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protected $pathsByType; |
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/** |
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* @param LockManager $manager |
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* @param array $pathsByType Map of lock types to path lists |
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* @param StatusValue $status |
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*/ |
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protected function __construct( |
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LockManager $manager, array $pathsByType, StatusValue $status |
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) { |
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$this->manager = $manager; |
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$this->pathsByType = $pathsByType; |
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$this->status = $status; |
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} |
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/** |
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* Get a ScopedLock object representing a lock on resource paths. |
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* Any locks are released once this object goes out of scope. |
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* The StatusValue object is updated with any errors or warnings. |
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* |
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* @param LockManager $manager |
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* @param array $paths List of storage paths or map of lock types to path lists |
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* @param int|string $type LockManager::LOCK_* constant or "mixed" and $paths |
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* can be a map of types to paths (since 1.22). Otherwise $type should be an |
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* integer and $paths should be a list of paths. |
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* @param StatusValue $status |
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* @param int $timeout Timeout in seconds (0 means non-blocking) (since 1.22) |
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* @return ScopedLock|null Returns null on failure |
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*/ |
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public static function factory( |
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LockManager $manager, array $paths, $type, StatusValue $status, $timeout = 0 |
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) { |
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$pathsByType = is_integer( $type ) ? [ $type => $paths ] : $paths; |
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$lockStatus = $manager->lockByType( $pathsByType, $timeout ); |
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$status->merge( $lockStatus ); |
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if ( $lockStatus->isOK() ) { |
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return new self( $manager, $pathsByType, $status ); |
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} |
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return null; |
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} |
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/** |
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* Release a scoped lock and set any errors in the attatched StatusValue object. |
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* This is useful for early release of locks before function scope is destroyed. |
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* This is the same as setting the lock object to null. |
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* |
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* @param ScopedLock $lock |
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* @since 1.21 |
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*/ |
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public static function release( ScopedLock &$lock = null ) { |
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$lock = null; |
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} |
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/** |
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* Release the locks when this goes out of scope |
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*/ |
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function __destruct() { |
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$wasOk = $this->status->isOK(); |
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$this->status->merge( $this->manager->unlockByType( $this->pathsByType ) ); |
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if ( $wasOk ) { |
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// Make sure StatusValue is OK, despite any unlockFiles() fatals |
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$this->status->setResult( true, $this->status->value ); |
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} |
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} |
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} |
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Unless you are absolutely sure that the expression can never be null because of other conditions, we strongly recommend to add an additional type check to your code: