predis

Predis

About

Predis is a flexible and feature-complete PHP (>= 5.3) client library for the Redis key-value store.

For a version compatible with PHP 5.2 you must use the backported version of the latest release in the 0.6.x series. Please refer to the TODO file to see which issues are still pending and what is due to be implemented soon in Predis.

Main features

• Full support for Redis 1.2, 2.0 and 2.2. Different versions of Redis are supported via server profiles.
• Client-side sharding with support for consistent hashing and custom distribution strategies.
• Command pipelining on single and aggregated connections.
• Abstraction for Redis transactions (Redis >= 2.0) with support for CAS operations (Redis >= 2.2).
• Lazy connections to Redis instances are automatically estabilished upon the first call to a command.
• Ability to connect to Redis using TCP/IP or UNIX domain sockets by default.
• Flexible system to define and register your own set of commands to a client instance.

Quick examples

See the official wiki of the project for a more complete coverage of all the features available in Predis.

Loading Predis

Predis relies on the autoloading features of PHP and complies with the PSR-0 standard for interoperability with most of the major frameworks and libraries. When used in simple projects or scripts you might need to define an autoloader function:

spl_autoload_register(function($class) {
    $file = PREDIS_BASE_PATH . strtr($class, '\\', '/') . '.php';
    if (file_exists($file)) {
        require $file;
        return true;
    }
});

Optionally, you can generate a single PHP file that holds every class (just like older versions of Predis) by launching the createSingleFile.php script from the bin directory of the repository. In this way you can load Predis in your scripts simply by using functions such as require and include.

Connecting to a local instance of Redis

You don't have to specify a tcp host and port when connecting to Redis instances running on the localhost on the default port:

$redis = new Predis\Client();
$redis->set('library', 'predis');
$value = $redis->get('library');

You can also use an URI string or an array-based dictionary to specify the connection parameters:

$redis = new Predis\Client('tcp://10.0.0.1:6379');

// is equivalent to:

$redis = new Predis\Client(array(
    'scheme' => 'tcp',
    'host'   => '10.0.0.1',
    'port'   => 6379,
));

Pipelining multiple commands to multiple instances of Redis with client-side sharding

Pipelining helps with performances when there is the need to issue many commands to a server in one go. Furthermore, pipelining works transparently even on aggregated connections. Predis, in fact, supports client-side sharding of data using consistent-hashing on keys and clustered connections are supported natively by the client class.

$redis = new Predis\Client(array(
    array('host' => '10.0.0.1', 'port' => 6379),
    array('host' => '10.0.0.2', 'port' => 6379)
));

$replies = $redis->pipeline(function($pipe) {
    for ($i = 0; $i < 1000; $i++) {
        $pipe->set("key:$i", str_pad($i, 4, '0', 0));
        $pipe->get("key:$i");
    }
});

Overriding standard connection classes with custom ones

Predis allows developers to create new connection classes to add support for new protocols or override the existing ones to provide a different implementation compared to the default classes. This can be obtained by subclassing the Predis\Network\IConnectionSingle interface.

class MyConnectionClass implements Predis\Network\IConnectionSingle {
    // implementation goes here
}

// Let Predis automatically use your own class to handle the default TCP connection

Predis\Client::defineConnection('tcp', 'MyConnectionClass');

You can have a look at the Predis\Network namespace for some actual code that gives a better insight about how to create new connection classes.

Definition and runtime registration of new commands on the client

Let's suppose Redis just added the support for a brand new feature associated with a new command. If you want to start using the above mentioned new feature right away without messing with Predis source code or waiting for it to find its way into a stable Predis release, then you can start off by creating a new class that matches the command type and its behaviour and then bind it to a client instance at runtime. Actually, it is easier done than said:

class BrandNewRedisCommand extends Predis\Commands\Command {
    public function getId() { return 'NEWCMD'; }
}

$redis = new Predis\Client();
$redis->getProfile()->defineCommand('BrandNewRedisCommand', 'newcmd');
$redis->newcmd();

Development

Predis is fully backed up by a test suite which tries to cover all the aspects of the client library and the interaction of every single command with a Redis server. If you want to work on Predis, it is highly recommended that you first run the test suite to be sure that everything is OK, and report strange behaviours or bugs.

When modifying Predis please be sure that no warnings or notices are emitted by PHP by running the interpreter in your development environment with the "error_reporting" variable set to E_ALL | E_STRICT.

The recommended way to contribute to Predis is to fork the project on GitHub, create new topic branches on your newly created repository to fix or add features and then open a new pull request with a description of the applied changes. Obviously, you can use any other Git hosting provider of your preference. Diff patches will be accepted too, even though they are not the preferred way to contribute to Predis.

Dependencies

• PHP >= 5.3.0
• PHPUnit (needed to run the test suite)

Links

Project

• Source code
• Wiki
• Issue tracker

Related

• Redis
• PHP
• PHPUnit
• Git

Author

• Daniele Alessandri (twitter)

Contributors

• Lorenzo Castelli
• Jordi Boggiano (twitter)
• Sebastian Waisbrot for his work on extending phpiredis for Predis

License

The code for Predis is distributed under the terms of the MIT license (see LICENSE).