Symfony News

New in Symfony 4.2: PDO-based lock storage

Contributed by
Jérémy Derussé
in #27456.

The Lock component was introduced in Symfony 3.4 to create and manage locks, a mechanism to provide exclusive access to a shared resource. Out of the box it supports different storages for local locks (files, semaphores) and distributed locks (Memcache, Redis). In Symfony 4.2 we've added a new PDO-based lock storage.

This makes sense because most Symfony applications already use MySQL/MariaDB or PostgreSQL for data persistence, so this PDO-based storage doesn't require to add a new service (like Redis or Memcache) to the infrastructure/stack.

The new PdoStore class requires a PDO object, a Doctrine DBAL Connection object or a DSN (Data Source Name) string to configure the storage:

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use Symfony\Component\Lock\Store\PdoStore;

// a PDO, a Doctrine DBAL connection or DSN for lazy connecting through PDO
$databaseConnectionOrDSN = 'mysql:host=127.0.0.1;dbname=lock';
$store = new PdoStore($databaseConnectionOrDSN, [
    'db_username' => 'myuser',
    'db_password' => 'mypassword'
]);

Then, create the table that stores the lock information. You can use the createTable() method of the PdoStore class to do that:

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try {
    $store->createTable();
} catch (\PDOException $exception) {
    // the table could not be created for some reason
}

Now you can create and manage the PDO-based locks as explained in the docs for any other lock type.