[9.x] Fix race condition in locks issued by the file cache driver (#4…

…6011)

* Fix file lock race condition

* wip

* revert first commit

* wip

src/Illuminate/Cache/FileLock.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace Illuminate\Cache;
+
+class FileLock extends CacheLock
+{
+    /**
+     * Attempt to acquire the lock.
+     *
+     * @return bool
+     */
+    public function acquire()
+    {
+        return $this->store->add($this->name, $this->owner, $this->seconds);
+    }
+}

src/Illuminate/Cache/FileStore.php

@@ -12,7 +12,7 @@
 
 class FileStore implements Store, LockProvider
 {
-    use InteractsWithTime, HasCacheLock, RetrievesMultipleKeys;
+    use InteractsWithTime, RetrievesMultipleKeys;
 
     /**
      * The Illuminate Filesystem instance.
@@ -200,6 +200,31 @@ public function forever($key, $value)
         return $this->put($key, $value, 0);
     }
 
+    /**
+     * Get a lock instance.
+     *
+     * @param  string  $name
+     * @param  int  $seconds
+     * @param  string|null  $owner
+     * @return \Illuminate\Contracts\Cache\Lock
+     */
+    public function lock($name, $seconds = 0, $owner = null)
+    {
+        return new FileLock($this, $name, $seconds, $owner);
+    }
+
+    /**
+     * Restore a lock instance using the owner identifier.
+     *
+     * @param  string  $name
+     * @param  string  $owner
+     * @return \Illuminate\Contracts\Cache\Lock
+     */
+    public function restoreLock($name, $owner)
+    {
+        return $this->lock($name, 0, $owner);
+    }
+
     /**
      * Remove an item from the cache.
      *