diff --git a/components/lock.rst b/components/lock.rst index 49bb0581dac..8bfba02494f 100644 --- a/components/lock.rst +++ b/components/lock.rst @@ -176,6 +176,7 @@ Store Scope Blocking Expiring :ref:`PdoStore ` remote no yes :ref:`RedisStore ` remote no yes :ref:`SemaphoreStore ` local yes no +:ref:`ZookeeperStore ` remote no no ============================================ ====== ======== ======== .. _lock-store-flock: @@ -324,6 +325,31 @@ the stores. working when a single server fails (because this strategy requires that the lock is acquired in more than half of the servers). +.. _lock-store-zookeeper: + +ZookeeperStore +~~~~~~~~~~~~~~ + +.. versionadded:: 4.2 + The ZookeeperStore was introduced Symfony 4.2. + +The ZookeeperStore saves locks on a Zookeeper server, it requires a Zookeeper +connection implementing the ``\Zookeeper`` class. This store does not +support blocking and expiration but the lock is automatically released when the +PHP process is terminated:: + + use Symfony\Component\Lock\Store\ZookeeperStore; + + $zookeeper_server = 'localhost:2181'; // For High Availablity Cluster you can pass 'localhost1:2181,localhost2:2181,localhost3:2181' + $zookeeper = new \Zookeeper($zookeeper_server); + + $store = new ZookeeperStore($zookeeper); + +.. note:: + + Zookeeper does not require a TTL as the nodes used for locking are ephemeral and die when the PHP process is terminated. + + Reliability ----------- @@ -334,8 +360,8 @@ Remote Stores ~~~~~~~~~~~~~ Remote stores (:ref:`MemcachedStore `, -:ref:`PdoStore ` and :ref:`RedisStore `) use -a unique token to recognize the true owner of the lock. This token is stored +:ref:`PdoStore `, :ref:`RedisStore `) and :ref:`ZookeeperStore `) +use a unique token to recognize the true owner of the lock. This token is stored in the :class:`Symfony\\Component\\Lock\\Key` object and is used internally by the ``Lock``, therefore this key must not be shared between processes (session, caching, fork, ...). @@ -560,6 +586,26 @@ can be two running containers in parallel. concurrent process on a new machine, check that other process are stopped on the old one. +ZookeeperStore +~~~~~~~~~~~~~~ + +The way ZookeeperStore works is by maintaining locks as ephemeral nodes on the server. That means that by using +the :ref:`ZookeeperStore ` the locks will be automatically released at the end of the session +in case the client cannot unlock for any reason. + +If the Zookeeper service or the machine hosting it restarts, every lock would +be lost without notifying the running processes. + +.. tip:: + + To use Zookeeper's High Availability feature, you can setup a cluster of multiple servers so that in case one of + the server goes down, the majority will still be up and serving the requests. All the available servers in the + cluster will see the same state. + +.. note:: + As this store does not support multi-level node locks, + since the clean up of intermediate nodes becomes an overhead, all locks are maintained at the root level. + Overall ~~~~~~~ pFad - Phonifier reborn

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