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Merge pull request #10180 from nextcloud/lock-negative-13 

[13] prevent lock values from going negative with memcache backend
This commit is contained in:
Morris Jobke 2018-07-11 09:02:19 +02:00 committed by GitHub
parent ef1a695707 1fa6115779
commit 922c2c64b5
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 20 additions and 2 deletions
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10
lib/private/Lock/MemcacheLockingProvider.php
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@ -89,14 +89,20 @@ class MemcacheLockingProvider extends AbstractLockingProvider {
*/
public function releaseLock($path, $type) {
if ($type === self::LOCK_SHARED) {
$newValue = 0;
if ($this->getOwnSharedLockCount($path) === 1) {
$removed = $this->memcache->cad($path, 1); // if we're the only one having a shared lock we can remove it in one go
if (!$removed) { //someone else also has a shared lock, decrease only
$this->memcache->dec($path);
$newValue = $this->memcache->dec($path);
}
} else {
// if we own more than one lock ourselves just decrease
$this->memcache->dec($path);
$newValue = $this->memcache->dec($path);
}
// if we somehow release more locks then exists, reset the lock
if ($newValue < 0) {
$this->memcache->cad($path, $newValue);
}
} else if ($type === self::LOCK_EXCLUSIVE) {
$this->memcache->cad($path, 'exclusive');

12
tests/lib/Lock/LockingProvider.php
View File

@ -243,4 +243,16 @@ abstract class LockingProvider extends TestCase {
$this->instance->acquireLock('foo', ILockingProvider::LOCK_SHARED);
$this->instance->changeLock('foo', ILockingProvider::LOCK_SHARED);
}
public function testReleaseNonExistingShared() {
$this->instance->acquireLock('foo', ILockingProvider::LOCK_SHARED);
$this->instance->releaseLock('foo', ILockingProvider::LOCK_SHARED);
// releasing a lock once to many should not result in a locked state
$this->instance->releaseLock('foo', ILockingProvider::LOCK_SHARED);
$this->instance->acquireLock('foo', ILockingProvider::LOCK_EXCLUSIVE);
$this->assertTrue($this->instance->isLocked('foo', ILockingProvider::LOCK_EXCLUSIVE));
$this->instance->releaseLock('foo', ILockingProvider::LOCK_EXCLUSIVE);
}
}