Distributed Redis Locker for TYPO3 Locking Mechanism

TYPO3 has three built-in Locking Strategies, that are chosen at runtime which fits best for the current system setup.

• SemaphoreLockStrategy
• SimpleLockStrategy
• FileLockStrategy

However, when dealing with a multi-tier system and a shared file system with multiple frontend nodes with a NFS filesystem, it is especially helpful to use a better suitable format. Redis is our weapon of choice for handling multi-node scenarios, and works just fine with TYPO3 and Caching.

This extension provides a Redis Locking mechanism to store the locks in a (shared) Redis database.

Requirements

This extension is available for TYPO3 v8+ LTS, and requires the PHP package php-redis as well as a Redis server.

Installation

Install this extension via composer composer require b13/distributed-locks or extensions.typo3.org / Extension Manager, and activate it in the Extension Manager.

Now add the following lines to your LocalConfiguration / AdditionalConfiguration to activate Redis Locking.

$GLOBALS['TYPO3_CONF_VARS']['SYS']['locking']['redis'] = [
    'hostname' => '127.0.0.1',
    'database' => 12
];

Other options:

'ttl' (numeric, default is 30sec)
'port' (numeric, default is 6379)
'password' (contains the password, necessary for secure authentication if required by redis)
'priority' (numeric, default is 95) - Set priority for this locking strategy. See LockingApi documentation.

Disabling it in certain contextes

If you have different TYPO3_CONTEXT or environments and you want to switch off the complete redis strategy (i.e. in your staging machine), you can set this in your LocalConfiguration / AdditionalConfiguration:

$GLOBALS['TYPO3_CONF_VARS']['SYS']['locking']['redis']['disabled'] = true;

Future Development

Should be switched to symfony/lock to allow distributed redis services and other lockers.

Credits & Background

Inspiration was taken from the now unmaintained extension "redis_lock_strategy" which we used several times, however with some drawbacks:

• No stable version for TYPO3 v9 in composer mode
• No maintainer available for releases anymore
• Destroying an object did not remove locks, ending in certain dead lock scenarios in broken scripts

Thanks to Alexander Miehe for the initial extension and the conceptual work.

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