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# Predis #
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[![Software license][ico-license]](LICENSE)
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[![Latest stable][ico-version-stable]][link-releases]
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[![Latest development][ico-version-dev]][link-releases]
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[![Monthly installs][ico-downloads-monthly]][link-downloads]
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[![Build status][ico-build]][link-actions]
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[![Coverage Status][ico-coverage]][link-coverage]
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A flexible and feature-complete [Redis](http://redis.io) client for PHP 7.2 and newer.
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More details about this project can be found on the [frequently asked questions](FAQ.md).
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## Main features ##
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- Support for Redis from __3.0__ to __7.0__.
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- Support for clustering using client-side sharding and pluggable keyspace distributors.
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- Support for [redis-cluster](http://redis.io/topics/cluster-tutorial) (Redis >= 3.0).
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- Support for master-slave replication setups and [redis-sentinel](http://redis.io/topics/sentinel).
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- Transparent key prefixing of keys using a customizable prefix strategy.
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- Command pipelining on both single nodes and clusters (client-side sharding only).
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- Abstraction for Redis transactions (Redis >= 2.0) and CAS operations (Redis >= 2.2).
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- Abstraction for Lua scripting (Redis >= 2.6) and automatic switching between `EVALSHA` or `EVAL`.
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- Abstraction for `SCAN`, `SSCAN`, `ZSCAN` and `HSCAN` (Redis >= 2.8) based on PHP iterators.
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- Connections are established lazily by the client upon the first command and can be persisted.
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- Connections can be established via TCP/IP (also TLS/SSL-encrypted) or UNIX domain sockets.
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- Support for custom connection classes for providing different network or protocol backends.
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- Flexible system for defining custom commands and override the default ones.
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## How to _install_ and use Predis ##
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This library can be found on [Packagist](http://packagist.org/packages/predis/predis) for an easier
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management of projects dependencies using [Composer](http://packagist.org/about-composer).
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Compressed archives of each release are [available on GitHub](https://github.com/predis/predis/releases).
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```shell
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composer require predis/predis
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```
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### Loading the library ###
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Predis relies on the autoloading features of PHP to load its files when needed and complies with the
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[PSR-4 standard](https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-4-autoloader.md).
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Autoloading is handled automatically when dependencies are managed through Composer, but it is also
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possible to leverage its own autoloader in projects or scripts lacking any autoload facility:
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```php
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// Prepend a base path if Predis is not available in your "include_path".
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require 'Predis/Autoloader.php';
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Predis\Autoloader::register();
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```
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### Connecting to Redis ###
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When creating a client instance without passing any connection parameter, Predis assumes `127.0.0.1`
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and `6379` as default host and port. The default timeout for the `connect()` operation is 5 seconds:
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```php
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$client = new Predis\Client();
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$client->set('foo', 'bar');
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$value = $client->get('foo');
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```
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Connection parameters can be supplied either in the form of URI strings or named arrays. The latter
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is the preferred way to supply parameters, but URI strings can be useful when parameters are read
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from non-structured or partially-structured sources:
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```php
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// Parameters passed using a named array:
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$client = new Predis\Client([
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'scheme' => 'tcp',
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'host' => '10.0.0.1',
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'port' => 6379,
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]);
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// Same set of parameters, passed using an URI string:
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$client = new Predis\Client('tcp://10.0.0.1:6379');
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```
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Password protected servers can be accessed by adding `password` to the parameters set. When ACLs are
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enabled on Redis >= 6.0, both `username` and `password` are required for user authentication.
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It is also possible to connect to local instances of Redis using UNIX domain sockets, in this case
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the parameters must use the `unix` scheme and specify a path for the socket file:
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```php
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$client = new Predis\Client(['scheme' => 'unix', 'path' => '/path/to/redis.sock']);
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$client = new Predis\Client('unix:/path/to/redis.sock');
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```
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The client can leverage TLS/SSL encryption to connect to secured remote Redis instances without the
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need to configure an SSL proxy like stunnel. This can be useful when connecting to nodes running on
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various cloud hosting providers. Encryption can be enabled with using the `tls` scheme and an array
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of suitable [options](http://php.net/manual/context.ssl.php) passed via the `ssl` parameter:
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```php
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// Named array of connection parameters:
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$client = new Predis\Client([
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'scheme' => 'tls',
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'ssl' => ['cafile' => 'private.pem', 'verify_peer' => true],
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]);
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// Same set of parameters, but using an URI string:
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$client = new Predis\Client('tls://127.0.0.1?ssl[cafile]=private.pem&ssl[verify_peer]=1');
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```
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The connection schemes [`redis`](http://www.iana.org/assignments/uri-schemes/prov/redis) (alias of
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`tcp`) and [`rediss`](http://www.iana.org/assignments/uri-schemes/prov/rediss) (alias of `tls`) are
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also supported, with the difference that URI strings containing these schemes are parsed following
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the rules described on their respective IANA provisional registration documents.
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The actual list of supported connection parameters can vary depending on each connection backend so
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it is recommended to refer to their specific documentation or implementation for details.
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Predis can aggregate multiple connections when providing an array of connection parameters and the
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appropriate option to instruct the client about how to aggregate them (clustering, replication or a
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custom aggregation logic). Named arrays and URI strings can be mixed when providing configurations
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for each node:
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```php
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$client = new Predis\Client([
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'tcp://10.0.0.1?alias=first-node', ['host' => '10.0.0.2', 'alias' => 'second-node'],
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], [
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'cluster' => 'predis',
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]);
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```
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See the [aggregate connections](#aggregate-connections) section of this document for more details.
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Connections to Redis are lazy meaning that the client connects to a server only if and when needed.
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While it is recommended to let the client do its own stuff under the hood, there may be times when
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it is still desired to have control of when the connection is opened or closed: this can easily be
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achieved by invoking `$client->connect()` and `$client->disconnect()`. Please note that the effect
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of these methods on aggregate connections may differ depending on each specific implementation.
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### Client configuration ###
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Many aspects and behaviors of the client can be configured by passing specific client options to the
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second argument of `Predis\Client::__construct()`:
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```php
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$client = new Predis\Client($parameters, ['prefix' => 'sample:']);
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```
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Options are managed using a mini DI-alike container and their values can be lazily initialized only
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when needed. The client options supported by default in Predis are:
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- `prefix`: prefix string applied to every key found in commands.
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- `exceptions`: whether the client should throw or return responses upon Redis errors.
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- `connections`: list of connection backends or a connection factory instance.
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- `cluster`: specifies a cluster backend (`predis`, `redis` or callable).
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- `replication`: specifies a replication backend (`predis`, `sentinel` or callable).
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- `aggregate`: configures the client with a custom aggregate connection (callable).
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- `parameters`: list of default connection parameters for aggregate connections.
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- `commands`: specifies a command factory instance to use through the library.
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Users can also provide custom options with values or callable objects (for lazy initialization) that
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are stored in the options container for later use through the library.
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### Aggregate connections ###
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Aggregate connections are the foundation upon which Predis implements clustering and replication and
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they are used to group multiple connections to single Redis nodes and hide the specific logic needed
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to handle them properly depending on the context. Aggregate connections usually require an array of
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connection parameters along with the appropriate client option when creating a new client instance.
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#### Cluster ####
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Predis can be configured to work in clustering mode with a traditional client-side sharding approach
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to create a cluster of independent nodes and distribute the keyspace among them. This approach needs
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some sort of external health monitoring of nodes and requires the keyspace to be rebalanced manually
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when nodes are added or removed:
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```php
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$parameters = ['tcp://10.0.0.1', 'tcp://10.0.0.2', 'tcp://10.0.0.3'];
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$options = ['cluster' => 'predis'];
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$client = new Predis\Client($parameters);
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```
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Along with Redis 3.0, a new supervised and coordinated type of clustering was introduced in the form
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of [redis-cluster](http://redis.io/topics/cluster-tutorial). This kind of approach uses a different
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algorithm to distribute the keyspaces, with Redis nodes coordinating themselves by communicating via
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a gossip protocol to handle health status, rebalancing, nodes discovery and request redirection. In
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order to connect to a cluster managed by redis-cluster, the client requires a list of its nodes (not
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necessarily complete since it will automatically discover new nodes if necessary) and the `cluster`
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client options set to `redis`:
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```php
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$parameters = ['tcp://10.0.0.1', 'tcp://10.0.0.2', 'tcp://10.0.0.3'];
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$options = ['cluster' => 'redis'];
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$client = new Predis\Client($parameters, $options);
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```
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#### Replication ####
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The client can be configured to operate in a single master / multiple slaves setup to provide better
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service availability. When using replication, Predis recognizes read-only commands and sends them to
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a random slave in order to provide some sort of load-balancing and switches to the master as soon as
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it detects a command that performs any kind of operation that would end up modifying the keyspace or
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the value of a key. Instead of raising a connection error when a slave fails, the client attempts to
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fall back to a different slave among the ones provided in the configuration.
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The basic configuration needed to use the client in replication mode requires one Redis server to be
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identified as the master (this can be done via connection parameters by setting the `role` parameter
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to `master`) and one or more slaves (in this case setting `role` to `slave` for slaves is optional):
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```php
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$parameters = ['tcp://10.0.0.1?role=master', 'tcp://10.0.0.2', 'tcp://10.0.0.3'];
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$options = ['replication' => 'predis'];
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$client = new Predis\Client($parameters, $options);
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```
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The above configuration has a static list of servers and relies entirely on the client's logic, but
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it is possible to rely on [`redis-sentinel`](http://redis.io/topics/sentinel) for a more robust HA
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environment with sentinel servers acting as a source of authority for clients for service discovery.
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The minimum configuration required by the client to work with redis-sentinel is a list of connection
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parameters pointing to a bunch of sentinel instances, the `replication` option set to `sentinel` and
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the `service` option set to the name of the service:
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```php
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$sentinels = ['tcp://10.0.0.1', 'tcp://10.0.0.2', 'tcp://10.0.0.3'];
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$options = ['replication' => 'sentinel', 'service' => 'mymaster'];
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$client = new Predis\Client($sentinels, $options);
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```
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If the master and slave nodes are configured to require an authentication from clients, a password
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must be provided via the global `parameters` client option. This option can also be used to specify
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a different database index. The client options array would then look like this:
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```php
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$options = [
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'replication' => 'sentinel',
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'service' => 'mymaster',
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'parameters' => [
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'password' => $secretpassword,
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'database' => 10,
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],
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];
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```
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While Predis is able to distinguish commands performing write and read-only operations, `EVAL` and
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`EVALSHA` represent a corner case in which the client switches to the master node because it cannot
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tell when a Lua script is safe to be executed on slaves. While this is indeed the default behavior,
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when certain Lua scripts do not perform write operations it is possible to provide an hint to tell
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the client to stick with slaves for their execution:
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```php
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$parameters = ['tcp://10.0.0.1?role=master', 'tcp://10.0.0.2', 'tcp://10.0.0.3'];
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$options = ['replication' => function () {
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// Set scripts that won't trigger a switch from a slave to the master node.
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$strategy = new Predis\Replication\ReplicationStrategy();
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$strategy->setScriptReadOnly($LUA_SCRIPT);
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return new Predis\Connection\Replication\MasterSlaveReplication($strategy);
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}];
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$client = new Predis\Client($parameters, $options);
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$client->eval($LUA_SCRIPT, 0); // Sticks to slave using `eval`...
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$client->evalsha(sha1($LUA_SCRIPT), 0); // ... and `evalsha`, too.
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```
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The [`examples`](examples/) directory contains a few scripts that demonstrate how the client can be
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configured and used to leverage replication in both basic and complex scenarios.
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### Command pipelines ###
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Pipelining can help with performances when many commands need to be sent to a server by reducing the
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latency introduced by network round-trip timings. Pipelining also works with aggregate connections.
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The client can execute the pipeline inside a callable block or return a pipeline instance with the
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ability to chain commands thanks to its fluent interface:
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```php
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// Executes a pipeline inside the given callable block:
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$responses = $client->pipeline(function ($pipe) {
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for ($i = 0; $i < 1000; $i++) {
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$pipe->set("key:$i", str_pad($i, 4, '0', 0));
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$pipe->get("key:$i");
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}
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});
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// Returns a pipeline that can be chained thanks to its fluent interface:
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$responses = $client->pipeline()->set('foo', 'bar')->get('foo')->execute();
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```
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### Transactions ###
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The client provides an abstraction for Redis transactions based on `MULTI` and `EXEC` with a similar
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interface to command pipelines:
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```php
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// Executes a transaction inside the given callable block:
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$responses = $client->transaction(function ($tx) {
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$tx->set('foo', 'bar');
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$tx->get('foo');
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});
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// Returns a transaction that can be chained thanks to its fluent interface:
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$responses = $client->transaction()->set('foo', 'bar')->get('foo')->execute();
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```
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This abstraction can perform check-and-set operations thanks to `WATCH` and `UNWATCH` and provides
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automatic retries of transactions aborted by Redis when `WATCH`ed keys are touched. For an example
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of a transaction using CAS you can see [the following example](examples/transaction_using_cas.php).
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### Adding new commands ###
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While we try to update Predis to stay up to date with all the commands available in Redis, you might
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prefer to stick with an old version of the library or provide a different way to filter arguments or
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parse responses for specific commands. To achieve that, Predis provides the ability to implement new
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command classes to define or override commands in the default command factory used by the client:
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```php
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// Define a new command by extending Predis\Command\Command:
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class BrandNewRedisCommand extends Predis\Command\Command
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{
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public function getId()
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{
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return 'NEWCMD';
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}
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}
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// Inject your command in the current command factory:
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$client = new Predis\Client($parameters, [
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'commands' => [
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'newcmd' => 'BrandNewRedisCommand',
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],
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]);
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$response = $client->newcmd();
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```
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There is also a method to send raw commands without filtering their arguments or parsing responses.
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Users must provide the list of arguments for the command as an array, following the signatures as
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defined by the [Redis documentation for commands](http://redis.io/commands):
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||||
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```php
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$response = $client->executeRaw(['SET', 'foo', 'bar']);
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||||
```
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||||
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### Script commands ###
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||||
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While it is possible to leverage [Lua scripting](http://redis.io/commands/eval) on Redis 2.6+ using
|
||||
directly [`EVAL`](http://redis.io/commands/eval) and [`EVALSHA`](http://redis.io/commands/evalsha),
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Predis offers script commands as an higher level abstraction built upon them to make things simple.
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Script commands can be registered in the command factory used by the client and are accessible as if
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||||
they were plain Redis commands, but they define Lua scripts that get transmitted to the server for
|
||||
remote execution. Internally they use [`EVALSHA`](http://redis.io/commands/evalsha) by default and
|
||||
identify a script by its SHA1 hash to save bandwidth, but [`EVAL`](http://redis.io/commands/eval)
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||||
is used as a fall back when needed:
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||||
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||||
```php
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// Define a new script command by extending Predis\Command\ScriptCommand:
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class ListPushRandomValue extends Predis\Command\ScriptCommand
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{
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||||
public function getKeysCount()
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{
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return 1;
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||||
}
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||||
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||||
public function getScript()
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||||
{
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||||
return <<<LUA
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math.randomseed(ARGV[1])
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local rnd = tostring(math.random())
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redis.call('lpush', KEYS[1], rnd)
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||||
return rnd
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||||
LUA;
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||||
}
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||||
}
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||||
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||||
// Inject the script command in the current command factory:
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$client = new Predis\Client($parameters, [
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'commands' => [
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'lpushrand' => 'ListPushRandomValue',
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||||
],
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||||
]);
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||||
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||||
$response = $client->lpushrand('random_values', $seed = mt_rand());
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||||
```
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||||
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||||
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||||
### Customizable connection backends ###
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||||
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||||
Predis can use different connection backends to connect to Redis. The builtin Relay integration
|
||||
leverages the [Relay](https://github.com/cachewerk/relay) extension for PHP for major performance
|
||||
gains, by caching a partial replica of the Redis dataset in PHP shared runtime memory.
|
||||
|
||||
```php
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||||
$client = new Predis\Client('tcp://127.0.0.1', [
|
||||
'connections' => 'relay',
|
||||
]);
|
||||
```
|
||||
|
||||
Developers can create their own connection classes to support whole new network backends, extend
|
||||
existing classes or provide completely different implementations. Connection classes must implement
|
||||
`Predis\Connection\NodeConnectionInterface` or extend `Predis\Connection\AbstractConnection`:
|
||||
|
||||
```php
|
||||
class MyConnectionClass implements Predis\Connection\NodeConnectionInterface
|
||||
{
|
||||
// Implementation goes here...
|
||||
}
|
||||
|
||||
// Use MyConnectionClass to handle connections for the `tcp` scheme:
|
||||
$client = new Predis\Client('tcp://127.0.0.1', [
|
||||
'connections' => ['tcp' => 'MyConnectionClass'],
|
||||
]);
|
||||
```
|
||||
|
||||
For a more in-depth insight on how to create new connection backends you can refer to the actual
|
||||
implementation of the standard connection classes available in the `Predis\Connection` namespace.
|
||||
|
||||
|
||||
## Development ##
|
||||
|
||||
|
||||
### Reporting bugs and contributing code ###
|
||||
|
||||
Contributions to Predis are highly appreciated either in the form of pull requests for new features,
|
||||
bug fixes, or just bug reports. We only ask you to adhere to issue and pull request templates.
|
||||
|
||||
|
||||
### Test suite ###
|
||||
|
||||
__ATTENTION__: Do not ever run the test suite shipped with Predis against instances of Redis running
|
||||
in production environments or containing data you are interested in!
|
||||
|
||||
Predis has a comprehensive test suite covering every aspect of the library and that can optionally
|
||||
perform integration tests against a running instance of Redis (required >= 2.4.0 in order to verify
|
||||
the correct behavior of the implementation of each command. Integration tests for unsupported Redis
|
||||
commands are automatically skipped. If you do not have Redis up and running, integration tests can
|
||||
be disabled. See [the tests README](tests/README.md) for more details about testing this library.
|
||||
|
||||
Predis uses GitHub Actions for continuous integration and the history for past and current builds can be
|
||||
found [on its actions page](https://github.com/predis/predis/actions).
|
||||
|
||||
### License ###
|
||||
|
||||
The code for Predis is distributed under the terms of the MIT license (see [LICENSE](LICENSE)).
|
||||
|
||||
[ico-license]: https://img.shields.io/github/license/predis/predis.svg?style=flat-square
|
||||
[ico-version-stable]: https://img.shields.io/github/v/tag/predis/predis?label=stable&style=flat-square
|
||||
[ico-version-dev]: https://img.shields.io/github/v/tag/predis/predis?include_prereleases&label=pre-release&style=flat-square
|
||||
[ico-downloads-monthly]: https://img.shields.io/packagist/dm/predis/predis.svg?style=flat-square
|
||||
[ico-build]: https://img.shields.io/github/actions/workflow/status/predis/predis/tests.yml?branch=main&style=flat-square
|
||||
[ico-coverage]: https://img.shields.io/coverallsCoverage/github/predis/predis?style=flat-square
|
||||
|
||||
[link-releases]: https://github.com/predis/predis/releases
|
||||
[link-actions]: https://github.com/predis/predis/actions
|
||||
[link-downloads]: https://packagist.org/packages/predis/predis/stats
|
||||
[link-coverage]: https://coveralls.io/github/predis/predis
|
||||
Reference in New Issue
Block a user