265 lines
7.2 KiB
PHP
265 lines
7.2 KiB
PHP
<?php
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/**
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* @author Individual IT Services <info@individual-it.net>
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* @author Robin Appelman <icewind@owncloud.com>
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*
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* @copyright Copyright (c) 2015, ownCloud, Inc.
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* @license AGPL-3.0
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*
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* This code is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License, version 3,
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* as published by the Free Software Foundation.
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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 Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License, version 3,
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* along with this program. If not, see <http://www.gnu.org/licenses/>
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*
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*/
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namespace OC\Lock;
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use OCP\AppFramework\Utility\ITimeFactory;
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use OCP\IDBConnection;
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use OCP\ILogger;
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use OCP\Lock\ILockingProvider;
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use OCP\Lock\LockedException;
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/**
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* Locking provider that stores the locks in the database
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*/
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class DBLockingProvider extends AbstractLockingProvider {
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/**
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* @var \OCP\IDBConnection
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*/
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private $connection;
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/**
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* @var \OCP\ILogger
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*/
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private $logger;
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/**
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* @var \OCP\AppFramework\Utility\ITimeFactory
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*/
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private $timeFactory;
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private $sharedLocks = [];
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const TTL = 3600; // how long until we clear stray locks in seconds
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protected function isLocallyLocked($path) {
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return isset($this->sharedLocks[$path]) && $this->sharedLocks[$path];
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}
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/**
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* Mark a locally acquired lock
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*
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* @param string $path
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* @param int $type self::LOCK_SHARED or self::LOCK_EXCLUSIVE
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*/
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protected function markAcquire($path, $type) {
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parent::markAcquire($path, $type);
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if ($type === self::LOCK_SHARED) {
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$this->sharedLocks[$path] = true;
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}
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}
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/**
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* Change the type of an existing tracked lock
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*
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* @param string $path
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* @param int $targetType self::LOCK_SHARED or self::LOCK_EXCLUSIVE
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*/
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protected function markChange($path, $targetType) {
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parent::markChange($path, $targetType);
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if ($targetType === self::LOCK_SHARED) {
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$this->sharedLocks[$path] = true;
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} else if ($targetType === self::LOCK_EXCLUSIVE) {
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$this->sharedLocks[$path] = false;
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}
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}
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/**
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* @param \OCP\IDBConnection $connection
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* @param \OCP\ILogger $logger
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* @param \OCP\AppFramework\Utility\ITimeFactory $timeFactory
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*/
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public function __construct(IDBConnection $connection, ILogger $logger, ITimeFactory $timeFactory) {
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$this->connection = $connection;
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$this->logger = $logger;
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$this->timeFactory = $timeFactory;
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}
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/**
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* Insert a file locking row if it does not exists.
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*
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* @param string $path
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* @param int $lock
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* @return int number of inserted rows
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*/
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protected function initLockField($path, $lock = 0) {
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$expire = $this->getExpireTime();
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return $this->connection->insertIfNotExist('*PREFIX*file_locks', ['key' => $path, 'lock' => $lock, 'ttl' => $expire], ['key']);
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}
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/**
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* @return int
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*/
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protected function getExpireTime() {
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return $this->timeFactory->getTime() + self::TTL;
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}
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/**
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* @param string $path
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* @param int $type self::LOCK_SHARED or self::LOCK_EXCLUSIVE
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* @return bool
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*/
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public function isLocked($path, $type) {
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if ($this->hasAcquiredLock($path, $type)) {
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return true;
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}
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$query = $this->connection->prepare('SELECT `lock` from `*PREFIX*file_locks` WHERE `key` = ?');
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$query->execute([$path]);
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$lockValue = (int)$query->fetchColumn();
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if ($type === self::LOCK_SHARED) {
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if ($this->isLocallyLocked($path)) {
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// if we have a shared lock we kept open locally but it's released we always have at least 1 shared lock in the db
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return $lockValue > 1;
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} else {
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return $lockValue > 0;
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}
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} else if ($type === self::LOCK_EXCLUSIVE) {
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return $lockValue === -1;
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} else {
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return false;
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}
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}
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/**
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* @param string $path
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* @param int $type self::LOCK_SHARED or self::LOCK_EXCLUSIVE
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* @throws \OCP\Lock\LockedException
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*/
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public function acquireLock($path, $type) {
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$expire = $this->getExpireTime();
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if ($type === self::LOCK_SHARED) {
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if (!$this->isLocallyLocked($path)) {
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$result = $this->initLockField($path, 1);
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if ($result <= 0) {
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$result = $this->connection->executeUpdate(
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'UPDATE `*PREFIX*file_locks` SET `lock` = `lock` + 1, `ttl` = ? WHERE `key` = ? AND `lock` >= 0',
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[$expire, $path]
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);
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}
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} else {
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$result = 1;
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}
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} else {
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$existing = 0;
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if ($this->hasAcquiredLock($path, ILockingProvider::LOCK_SHARED) === false && $this->isLocallyLocked($path)) {
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$existing = 1;
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}
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$result = $this->initLockField($path, -1);
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if ($result <= 0) {
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$result = $this->connection->executeUpdate(
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'UPDATE `*PREFIX*file_locks` SET `lock` = -1, `ttl` = ? WHERE `key` = ? AND `lock` = ?',
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[$expire, $path, $existing]
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);
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}
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}
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if ($result !== 1) {
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throw new LockedException($path);
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}
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$this->markAcquire($path, $type);
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}
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/**
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* @param string $path
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* @param int $type self::LOCK_SHARED or self::LOCK_EXCLUSIVE
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*/
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public function releaseLock($path, $type) {
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$this->markRelease($path, $type);
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// we keep shared locks till the end of the request so we can re-use them
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if ($type === self::LOCK_EXCLUSIVE) {
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$this->connection->executeUpdate(
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'UPDATE `*PREFIX*file_locks` SET `lock` = 0 WHERE `key` = ? AND `lock` = -1',
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[$path]
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);
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}
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}
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/**
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* Change the type of an existing lock
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*
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* @param string $path
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* @param int $targetType self::LOCK_SHARED or self::LOCK_EXCLUSIVE
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* @throws \OCP\Lock\LockedException
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*/
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public function changeLock($path, $targetType) {
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$expire = $this->getExpireTime();
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if ($targetType === self::LOCK_SHARED) {
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$result = $this->connection->executeUpdate(
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'UPDATE `*PREFIX*file_locks` SET `lock` = 1, `ttl` = ? WHERE `key` = ? AND `lock` = -1',
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[$expire, $path]
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);
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} else {
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// since we only keep one shared lock in the db we need to check if we have more then one shared lock locally manually
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if (isset($this->acquiredLocks['shared'][$path]) && $this->acquiredLocks['shared'][$path] > 1) {
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throw new LockedException($path);
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}
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$result = $this->connection->executeUpdate(
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'UPDATE `*PREFIX*file_locks` SET `lock` = -1, `ttl` = ? WHERE `key` = ? AND `lock` = 1',
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[$expire, $path]
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);
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}
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if ($result !== 1) {
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throw new LockedException($path);
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}
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$this->markChange($path, $targetType);
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}
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/**
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* cleanup empty locks
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*/
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public function cleanEmptyLocks() {
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$expire = $this->timeFactory->getTime();
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$this->connection->executeUpdate(
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'DELETE FROM `*PREFIX*file_locks` WHERE `lock` = 0 AND `ttl` < ?',
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[$expire]
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);
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}
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/**
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* release all lock acquired by this instance which were marked using the mark* methods
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*/
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public function releaseAll() {
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parent::releaseAll();
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// since we keep shared locks we need to manually clean those
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foreach ($this->sharedLocks as $path => $lock) {
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if ($lock) {
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$this->connection->executeUpdate(
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'UPDATE `*PREFIX*file_locks` SET `lock` = `lock` - 1 WHERE `key` = ? AND `lock` > 0',
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[$path]
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);
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}
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}
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}
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public function __destruct() {
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try {
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$this->cleanEmptyLocks();
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} catch (\Exception $e) {
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// If the table is missing, the clean up was successful
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if ($this->connection->tableExists('file_locks')) {
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throw $e;
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}
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}
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}
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}
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