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<?php
/**
* @copyright Copyright (c) 2016, ownCloud, Inc.
*
* @author Christoph Wurst <christoph@winzerhof-wurst.at>
* @author Individual IT Services <info@individual-it.net>
* @author Joas Schilling <coding@schilljs.com>
* @author Morris Jobke <hey@morrisjobke.de>
* @author Ole Ostergaard <ole.c.ostergaard@gmail.com>
* @author Robin Appelman <robin@icewind.nl>
* @author Roeland Jago Douma <roeland@famdouma.nl>
* @author Carl Schwan <carl@carlschwan.eu>
*
* @license AGPL-3.0
*
* This code is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License, version 3,
* along with this program. If not, see <http://www.gnu.org/licenses/>
*
*/
namespace OC\Lock;
use OC\DB\QueryBuilder\Literal;
use OCP\AppFramework\Utility\ITimeFactory;
use OCP\DB\QueryBuilder\IQueryBuilder;
use OCP\IDBConnection;
use OCP\Lock\ILockingProvider;
use OCP\Lock\LockedException;
/**
* Locking provider that stores the locks in the database
*/
class DBLockingProvider extends AbstractLockingProvider {
private array $sharedLocks = [];
public function __construct(
private IDBConnection $connection,
private ITimeFactory $timeFactory,
int $ttl = 3600,
private bool $cacheSharedLocks = true
) {
parent::__construct($ttl);
}
/**
* Check if we have an open shared lock for a path
*/
protected function isLocallyLocked(string $path): bool {
return isset($this->sharedLocks[$path]) && $this->sharedLocks[$path];
}
/** @inheritDoc */
protected function markAcquire(string $path, int $targetType): void {
parent::markAcquire($path, $targetType);
if ($this->cacheSharedLocks) {
if ($targetType === self::LOCK_SHARED) {
$this->sharedLocks[$path] = true;
}
}
}
/**
* Change the type of an existing tracked lock
*/
protected function markChange(string $path, int $targetType): void {
parent::markChange($path, $targetType);
if ($this->cacheSharedLocks) {
if ($targetType === self::LOCK_SHARED) {
$this->sharedLocks[$path] = true;
} elseif ($targetType === self::LOCK_EXCLUSIVE) {
$this->sharedLocks[$path] = false;
}
}
}
/**
* Insert a file locking row if it does not exists.
*/
protected function initLockField(string $path, int $lock = 0): int {
$expire = $this->getExpireTime();
return $this->connection->insertIgnoreConflict('file_locks', [
'key' => $path,
'lock' => $lock,
'ttl' => $expire
]);
}
protected function getExpireTime(): int {
return $this->timeFactory->getTime() + $this->ttl;
}
/** @inheritDoc */
public function isLocked(string $path, int $type): bool {
if ($this->hasAcquiredLock($path, $type)) {
return true;
}
$query = $this->connection->getQueryBuilder();
$query->select('lock')
->from('file_locks')
->where($query->expr()->eq('key', $query->createNamedParameter($path)));
$result = $query->executeQuery();
$lockValue = (int)$result->fetchOne();
if ($type === self::LOCK_SHARED) {
if ($this->isLocallyLocked($path)) {
// 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
return $lockValue > 1;
} else {
return $lockValue > 0;
}
} elseif ($type === self::LOCK_EXCLUSIVE) {
return $lockValue === -1;
} else {
return false;
}
}
/** @inheritDoc */
public function acquireLock(string $path, int $type, ?string $readablePath = null): void {
$expire = $this->getExpireTime();
if ($type === self::LOCK_SHARED) {
if (!$this->isLocallyLocked($path)) {
$result = $this->initLockField($path, 1);
if ($result <= 0) {
$query = $this->connection->getQueryBuilder();
$query->update('file_locks')
->set('lock', $query->func()->add('lock', $query->createNamedParameter(1, IQueryBuilder::PARAM_INT)))
->set('ttl', $query->createNamedParameter($expire))
->where($query->expr()->eq('key', $query->createNamedParameter($path)))
->andWhere($query->expr()->gte('lock', $query->createNamedParameter(0, IQueryBuilder::PARAM_INT)));
$result = $query->executeStatement();
}
} else {
$result = 1;
}
} else {
$existing = 0;
if ($this->hasAcquiredLock($path, ILockingProvider::LOCK_SHARED) === false && $this->isLocallyLocked($path)) {
$existing = 1;
}
$result = $this->initLockField($path, -1);
if ($result <= 0) {
$query = $this->connection->getQueryBuilder();
$query->update('file_locks')
->set('lock', $query->createNamedParameter(-1, IQueryBuilder::PARAM_INT))
->set('ttl', $query->createNamedParameter($expire, IQueryBuilder::PARAM_INT))
->where($query->expr()->eq('key', $query->createNamedParameter($path)))
->andWhere($query->expr()->eq('lock', $query->createNamedParameter($existing)));
$result = $query->executeStatement();
}
}
if ($result !== 1) {
throw new LockedException($path, null, null, $readablePath);
}
$this->markAcquire($path, $type);
}
/** @inheritDoc */
public function releaseLock(string $path, int $type): void {
$this->markRelease($path, $type);
// we keep shared locks till the end of the request so we can re-use them
if ($type === self::LOCK_EXCLUSIVE) {
$qb = $this->connection->getQueryBuilder();
$qb->update('file_locks')
->set('lock', $qb->createNamedParameter(0, IQueryBuilder::PARAM_INT))
->where($qb->expr()->eq('key', $qb->createNamedParameter($path)))
->andWhere($qb->expr()->eq('lock', $qb->createNamedParameter(-1, IQueryBuilder::PARAM_INT)));
$qb->executeStatement();
} elseif (!$this->cacheSharedLocks) {
$qb = $this->connection->getQueryBuilder();
$qb->update('file_locks')
->set('lock', $qb->func()->subtract('lock', $qb->createNamedParameter(1, IQueryBuilder::PARAM_INT)))
->where($qb->expr()->eq('key', $qb->createNamedParameter($path)))
->andWhere($qb->expr()->gt('lock', $qb->createNamedParameter(0, IQueryBuilder::PARAM_INT)));
$qb->executeStatement();
}
}
/** @inheritDoc */
public function changeLock(string $path, int $targetType): void {
$expire = $this->getExpireTime();
if ($targetType === self::LOCK_SHARED) {
$qb = $this->connection->getQueryBuilder();
$result = $qb->update('file_locks')
->set('lock', $qb->createNamedParameter(1, IQueryBuilder::PARAM_INT))
->set('ttl', $qb->createNamedParameter($expire, IQueryBuilder::PARAM_INT))
->where($qb->expr()->andX(
$qb->expr()->eq('key', $qb->createNamedParameter($path)),
$qb->expr()->eq('lock', $qb->createNamedParameter(-1, IQueryBuilder::PARAM_INT))
))->executeStatement();
} else {
// since we only keep one shared lock in the db we need to check if we have more then one shared lock locally manually
if (isset($this->acquiredLocks['shared'][$path]) && $this->acquiredLocks['shared'][$path] > 1) {
throw new LockedException($path);
}
$qb = $this->connection->getQueryBuilder();
$result = $qb->update('file_locks')
->set('lock', $qb->createNamedParameter(-1, IQueryBuilder::PARAM_INT))
->set('ttl', $qb->createNamedParameter($expire, IQueryBuilder::PARAM_INT))
->where($qb->expr()->andX(
$qb->expr()->eq('key', $qb->createNamedParameter($path)),
$qb->expr()->eq('lock', $qb->createNamedParameter(1, IQueryBuilder::PARAM_INT))
))->executeStatement();
}
if ($result !== 1) {
throw new LockedException($path);
}
$this->markChange($path, $targetType);
}
/** @inheritDoc */
public function cleanExpiredLocks(): void {
$expire = $this->timeFactory->getTime();
try {
$qb = $this->connection->getQueryBuilder();
$qb->delete('file_locks')
->where($qb->expr()->lt('ttl', $qb->createNamedParameter($expire, IQueryBuilder::PARAM_INT)))
->executeStatement();
} catch (\Exception $e) {
// If the table is missing, the clean up was successful
if ($this->connection->tableExists('file_locks')) {
throw $e;
}
}
}
/** @inheritDoc */
public function releaseAll(): void {
parent::releaseAll();
if (!$this->cacheSharedLocks) {
return;
}
// since we keep shared locks we need to manually clean those
$lockedPaths = array_keys($this->sharedLocks);
$lockedPaths = array_filter($lockedPaths, function ($path) {
return $this->sharedLocks[$path];
});
$chunkedPaths = array_chunk($lockedPaths, 100);
$qb = $this->connection->getQueryBuilder();
$qb->update('file_locks')
->set('lock', $qb->func()->subtract('lock', $qb->expr()->literal(1)))
->where($qb->expr()->in('key', $qb->createParameter('chunk')))
->andWhere($qb->expr()->gt('lock', new Literal(0)));
foreach ($chunkedPaths as $chunk) {
$qb->setParameter('chunk', $chunk, IQueryBuilder::PARAM_STR_ARRAY);
$qb->executeStatement();
}
}
}
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