Redis

Table of Contents

1. Introduction
2. Libraries
3. Creating a Redis Connection
   1. Single Client
   2. Multiple Clients
   3. Clustering
4. Type Mappers
   1. Booleans
   2. Timestamps

Introduction

Redis is an extremely popular, in-memory key-value cache with pub/sub capabilities. Unlike Memcached, Redis can store more complex structures such as sets, sorted lists, and hashes. For more information, please visit its homepage.

Libraries

Opulence lets you choose whichever Redis library you'd like. The following are the two most popular:

1. PHPRedis
   • PHP extension written in C, giving you raw performance
2. Predis
   • PHP library that does not require you to re-compile PHP

Creating a Redis Connection

Opulence\Redis\Redis acts as a convenient wrapper around Redis. It accepts either a single client or a list of clients. Opulence uses magic methods to pass on method calls to the underlying Redis client(s).

Single Client

use Opulence\Redis\Redis;
use Redis as Client;

// Create our connection
$client = new Client();
$client->connect('localhost', 6379);
$redis = new Redis($client);

// Try it out
$redis->set('foo', 'bar');
echo $redis->get('foo'); // "bar"

You can get the client instance:

$redis->getClient();

Multiple Clients

If you pass in multiple clients, one of them MUST be named default.

use Opulence\Redis\Redis;
use Redis as Client;

$defaultClient = new Client();
$defaultClient->connect('127.0.0.1', 6379);
$backupClient = new Client();
$backupClient->connect('127.0.0.2', 6379);
$clients = [
    'default' => $defaultClient,
    'backup' => $backupClient
];
$redis = new Redis($clients);

You can get a particular client instance:

$redis->getClient('backup');

Note: The default client will always be used unless you call getClient($name) and make calls to that client directly.

Clustering

Redis 3.0 added the ability to automatically shard your Redis database across a cluster. Let's take a look at how we can use Predis to connect to a cluster:

use Opulence\Redis\Redis;
use Predis\Client;

$client = new Client(
    [
        'tcp://127.0.0.1',
        'tcp://127.0.0.2'
    ],
    [
        'cluster' => 'redis'
    ]
);
$redis = new Redis($client);

You can get the client instance:

$redis->getClient();

Type Mappers

Opulence\Redis\Types\TypeMapper helps you translate to and from Redis data types. For example, you cannot store a DateTime object in Redis, so you need to convert to a Unix timestamp when storing it. Conversely, when you read from Redis, you can use a type mapper to convert the Unix timestamp back into a DateTime object.

You can also use a factory to create type mappers:

use Opulence\Redis\Types\Factories\TypeMapperFactory;

$typeMapper = (new TypeMapperFactory)->createTypeMapper();

Booleans

To Redis

$phpBoolean = true;
echo $typeMapper->toRedisBoolean($phpBoolean); // 1

From Redis

$redisBoolean = 1;
echo $typeMapper->fromRedisBoolean($redisBoolean) === true; // 1

Timestamps

To Redis

$phpDate = new DateTime('1987-07-24 12:34:56');
echo $typeMapper->toRedisTimestamp($phpDate); // 554128496

Note: This method accepts any object implementing DateTimeInterface, including DateTimeImmutable.

From Redis

$redisDate = 554128496;
$phpDate = $typeMapper->fromRedisTimestamp($redisDate);
echo $phpDate->format('Y-m-d'); // "1987-07-24"