improve distributed dummy key

Author: mvorisek

src/Mutex/DistributedMutex.php

@@ -34,6 +34,9 @@ class DistributedMutex extends AbstractSpinlockWithTokenMutex implements LoggerA
     public function __construct(array $mutexes, float $acquireTimeout = 3, float $expireTimeout = \INF)
     {
         parent::__construct('', $acquireTimeout, $expireTimeout);
+        \Closure::bind(function () {
+            $this->key = 'distributed';
+        }, $this, AbstractSpinlockMutex::class)();
 
         $this->mutexes = $mutexes;
         $this->logger = new NullLogger();

tests/Mutex/DistributedMutexTest.php

@@ -331,7 +331,7 @@ public function testAcquireMutexLogger(): void
 
         $mutex->expects(self::exactly(3))
             ->method('acquireMutex')
-            ->with(self::isInstanceOf(AbstractSpinlockMutex::class), 'php-malkusch-lock:', 1.0, \INF)
+            ->with(self::isInstanceOf(AbstractSpinlockMutex::class), 'distributed', 1.0, \INF)
             ->willThrowException($this->createMock(/* PredisException::class */ LockAcquireException::class));
 
         $logger->expects(self::exactly(3))
@@ -357,7 +357,7 @@ public function testReleaseMutexLogger(): void
 
         $mutex->expects(self::exactly(3))
             ->method('releaseMutex')
-            ->with(self::isInstanceOf(AbstractSpinlockMutex::class), 'php-malkusch-lock:', \INF)
+            ->with(self::isInstanceOf(AbstractSpinlockMutex::class), 'distributed', \INF)
             ->willThrowException($this->createMock(/* PredisException::class */ LockReleaseException::class));
 
         $logger->expects(self::exactly(3))