Log more info about locking conflicts for memcache locking backends

Signed-off-by: Robin Appelman <robin@icewind.nl>

1 files changed, 15 insertions, 4 deletions

diff --git a/lib/private/Lock/MemcacheLockingProvider.php b/lib/private/Lock/MemcacheLockingProvider.php
index 70ad972b46d..55a82b22781 100644
--- a/lib/private/Lock/MemcacheLockingProvider.php
+++ b/lib/private/Lock/MemcacheLockingProvider.php
@@ -72,12 +72,12 @@ class MemcacheLockingProvider extends AbstractLockingProvider {
 	public function acquireLock(string $path, int $type) {
 		if ($type === self::LOCK_SHARED) {
 			if (!$this->memcache->inc($path)) {
-				throw new LockedException($path);
+				throw new LockedException($path, null, $this->getExistingLockForException($path));
 			}
 		} else {
 			$this->memcache->add($path, 0);
 			if (!$this->memcache->cas($path, 0, 'exclusive')) {
-				throw new LockedException($path);
+				throw new LockedException($path, null, $this->getExistingLockForException($path));
 			}
 		}
 		$this->setTTL($path);
@@ -115,15 +115,26 @@ class MemcacheLockingProvider extends AbstractLockingProvider {
 	public function changeLock(string $path, int $targetType) {
 		if ($targetType === self::LOCK_SHARED) {
 			if (!$this->memcache->cas($path, 'exclusive', 1)) {
-				throw new LockedException($path);
+				throw new LockedException($path, null, $this->getExistingLockForException($path));
 			}
 		} else if ($targetType === self::LOCK_EXCLUSIVE) {
 			// we can only change a shared lock to an exclusive if there's only a single owner of the shared lock
 			if (!$this->memcache->cas($path, 1, 'exclusive')) {
-				throw new LockedException($path);
+				throw new LockedException($path, null, $this->getExistingLockForException($path));
 			}
 		}
 		$this->setTTL($path);
 		$this->markChange($path, $targetType);
 	}
+
+	private function getExistingLockForException($path) {
+		$existing = $this->memcache->get($path);
+		if (!$existing) {
+			return 'none';
+		} else if ($existing === 'exclusive') {
+			return $existing;
+		} else {
+			return $existing . ' shared locks';
+		}
+	}
 }