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# Predis # [![Software license][ico-license]](LICENSE) [![Latest stable][ico-version-stable]][link-packagist] [![Latest development][ico-version-dev]][link-packagist] [![Monthly installs][ico-downloads-monthly]][link-downloads] [![Build status][ico-travis]][link-travis] [![HHVM support][ico-hhvm]][link-hhvm] [![Gitter room][ico-gitter]][link-gitter] Flexible and feature-complete [Redis](http://redis.io) client for PHP >= 5.3 and HHVM >= 2.3.0. Predis does not require any additional C extension by default, but it can be optionally paired with [phpiredis](https://github.com/nrk/phpiredis) to lower the overhead of the serialization and parsing of the [Redis RESP Protocol](http://redis.io/topics/protocol). For an __experimental__ asynchronous implementation of the client you can refer to [Predis\Async](https://github.com/nrk/predis-async). More details about this project can be found on the [frequently asked questions](FAQ.md). ## Main features ## - Support for different versions of Redis (from __2.0__ to __3.2__) using profiles. - Support for clustering using client-side sharding and pluggable keyspace distributors. - Support for [redis-cluster](http://redis.io/topics/cluster-tutorial) (Redis >= 3.0). - Support for master-slave replication setups and [redis-sentinel](http://redis.io/topics/sentinel). - Transparent key prefixing of keys using a customizable prefix strategy. - Command pipelining on both single nodes and clusters (client-side sharding only). - Abstraction for Redis transactions (Redis >= 2.0) and CAS operations (Redis >= 2.2). - Abstraction for Lua scripting (Redis >= 2.6) and automatic switching between `EVALSHA` or `EVAL`. - Abstraction for `SCAN`, `SSCAN`, `ZSCAN` and `HSCAN` (Redis >= 2.8) based on PHP iterators. - Connections are established lazily by the client upon the first command and can be persisted. - Connections can be established via TCP/IP (also TLS/SSL-encrypted) or UNIX domain sockets. - Support for [Webdis](http://webd.is) (requires both `ext-curl` and `ext-phpiredis`). - Support for custom connection classes for providing different network or protocol backends. - Flexible system for defining custom commands and profiles and override the default ones. ## How to _install_ and use Predis ## This library can be found on [Packagist](http://packagist.org/packages/predis/predis) for an easier management of projects dependencies using [Composer](http://packagist.org/about-composer) or on our [own PEAR channel](http://pear.nrk.io) for a more traditional installation using PEAR. Ultimately, compressed archives of each release are [available on GitHub](https://github.com/nrk/predis/tags). ### Loading the library ### Predis relies on the autoloading features of PHP to load its files when needed and complies with the [PSR-4 standard](https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-4-autoloader.md). Autoloading is handled automatically when dependencies are managed through Composer, but it is also possible to leverage its own autoloader in projects or scripts lacking any autoload facility: ```php // Prepend a base path if Predis is not available in your "include_path". require 'Predis/Autoloader.php'; Predis\Autoloader::register(); ``` It is also possible to create a [phar](http://www.php.net/manual/en/intro.phar.php) archive directly from the repository by launching the `bin/create-phar` script. The generated phar already contains a stub defining its own autoloader, so you just need to `require()` it to start using the library. ### Connecting to Redis ### When creating a client instance without passing any connection parameter, Predis assumes `127.0.0.1` and `6379` as default host and port. The default timeout for the `connect()` operation is 5 seconds: ```php $client = new Predis\Client(); $client->set('foo', 'bar'); $value = $client->get('foo'); ``` Connection parameters can be supplied either in the form of URI strings or named arrays. The latter is the preferred way to supply parameters, but URI strings can be useful when parameters are read from non-structured or partially-structured sources: ```php // Parameters passed using a named array: $client = new Predis\Client([ 'scheme' => 'tcp', 'host' => '10.0.0.1', 'port' => 6379, ]); // Same set of parameters, passed using an URI string: $client = new Predis\Client('tcp://10.0.0.1:6379'); ``` It is also possible to connect to local instances of Redis using UNIX domain sockets, in this case the parameters must use the `unix` scheme and specify a path for the socket file: ```php $client = new Predis\Client(['scheme' => 'unix', 'path' => '/path/to/redis.sock']); $client = new Predis\Client('unix:/path/to/redis.sock'); ``` The client can leverage TLS/SSL encryption to connect to secured remote Redis instances without the need to configure an SSL proxy like stunnel. This can be useful when connecting to nodes running on various cloud hosting providers. Encryption can be enabled with using the `tls` scheme and an array of suitable [options](http://php.net/manual/context.ssl.php) passed via the `ssl` parameter: ```php // Named array of connection parameters: $client = new Predis\Client([ 'scheme' => 'tls', 'ssl' => ['cafile' => 'private.pem', 'verify_peer' => true], ]); // Same set of parameters, but using an URI string: $client = new Predis\Client('tls://127.0.0.1?ssl[cafile]=private.pem&ssl[verify_peer]=1'); ``` The connection schemes [`redis`](http://www.iana.org/assignments/uri-schemes/prov/redis) (alias of `tcp`) and [`rediss`](http://www.iana.org/assignments/uri-schemes/prov/rediss) (alias of `tls`) are also supported, with the difference that URI strings containing these schemes are parsed following the rules described on their respective IANA provisional registration documents. The actual list of supported connection parameters can vary depending on each connection backend so it is recommended to refer to their specific documentation or implementation for details. When an array of connection parameters is provided, Predis automatically works in cluster mode using client-side sharding. Both named arrays and URI strings can be mixed when providing configurations for each node: ```php $client = new Predis\Client([ 'tcp://10.0.0.1?alias=first-node', ['host' => '10.0.0.2', 'alias' => 'second-node'], ]); ``` See the [aggregate connections](#aggregate-connections) section of this document for more details. Connections to Redis are lazy meaning that the client connects to a server only if and when needed. While it is recommended to let the client do its own stuff under the hood, there may be times when it is still desired to have control of when the connection is opened or closed: this can easily be achieved by invoking `$client->connect()` and `$client->disconnect()`. Please note that the effect of these methods on aggregate connections may differ depending on each specific implementation. ### Client configuration ### Many aspects and behaviors of the client can be configured by passing specific client options to the second argument of `Predis\Client::__construct()`: ```php $client = new Predis\Client($parameters, ['profile' => '2.8', 'prefix' => 'sample:']); ``` Options are managed using a mini DI-alike container and their values can be lazily initialized only when needed. The client options supported by default in Predis are: - `profile`: specifies the profile to use to match a specific version of Redis. - `prefix`: prefix string automatically applied to keys found in commands. - `exceptions`: whether the client should throw or return responses upon Redis errors. - `connections`: list of connection backends or a connection factory instance. - `cluster`: specifies a cluster backend (`predis`, `redis` or callable object). - `replication`: specifies a replication backend (`TRUE`, `sentinel` or callable object). - `aggregate`: overrides `cluster` and `replication` to provide a custom conn