README

Shipped with PhpRedis BrokerInterface implementation.

Every message/job pushed into a queue has the fair-tag used to handle the message processing fairly, like so:

/**
 * @var BrokerInterface $broker
 */
$message = new SomeMessageOrJob(somePayload: 'user1-job1', fairTag: 'user1');
$broker->push($message);
$message = new SomeMessageOrJob(somePayload: 'user1-job2', fairTag: 'user1');
$broker->push($message);
$message = new SomeMessageOrJob(somePayload: 'user2-job1', fairTag: 'user2');
$broker->push($message);
$message = new SomeMessageOrJob(somePayload: 'user2-job2', fairTag: 'user2');
$broker->push($message);
$message = new SomeMessageOrJob(somePayload: 'user3-job1', fairTag: 'user3');
$broker->push($message);

while (($message = $broker->pop()) !== null) {
    echo $message->getSomePayload() . "\n";
}
//Output (not same order as in input):
//user1-job1
//user2-job1
//user3-job1
//user1-job2
//user2-job2

Requirements

• PHP: ^8.1
• Redis: ^5
• PhpRedis

Basic features

• Fair messages distribution based on arbitrary string fair-tag
• Messages with same fair-tag are handled in order of pushing
• Pushing complexity: O(1)
• Popping complexity: O(1) if there are no empty queues; O(m) where m is a number of empty (not all) queues (they are getting removed during pop operation)
• Zero latency blocking popping support (forget about sleep(1);)
• Endless flexibility: add as many workers as many connections your Redis instance can handle

Blocking VS Non-blocking pop

Non-blocking pop

• returns NULL immediately if a queue is empty.

// NOT SAFE in case of an empty queue! It would cause 100% CPU load + constant Redis instance requests
while (true) {
    $message = $broker->pop();
    echo $message->getSomePayload() . "\n";
    //sleep(1); <= a classic solution to solve the 100% CPU problem
}

Blocking pop

• returns a message immediately, if any.
• else: waits for a new message for up to float timeout
• returns NULL if there are no new messages when time is up, or returns a new message immediately (without waiting for the timeout to time up) if a new message appears.

// SAFE in case of an empty queue! Zero resources (both CPU + network traffic to Redis) usage during waiting
$timeout = 1.23; //seconds
while (true) {
    $message = $broker->popBlocking($timeout);
    echo $message->getSomePayload() . "\n";
}

Full working example

<?php

declare(strict_types=1);

require_once './vendor/autoload.php';

use Fair\Queue\Broker\Broker;
use Fair\Queue\Message\MessageInterface;
use Fair\Queue\Namer\PrefixQueueNamer;
use Fair\Queue\Serializer\PhpMessageSerializer;
use Fair\Queue\Storage\RedisStorage;
use Redis;

class SomeMessageOrJob implements MessageInterface
{
    private string $somePayload;
    private string|null $fairTag;

    public function __construct(
        string $somePayload,
        string|null $fairTag = null,
    ) {
        $this->fairTag = $fairTag;
        $this->somePayload = $somePayload;
    }

    public function getFairTag(): string|null
    {
        return $this->fairTag;
    }

    public function getSomePayload(): string
    {
        return $this->somePayload;
    }
}

$redis = new Redis([
    'host' => 'redis',
    'port' => 6379,
]);
$serilizer = new PhpMessageSerializer();
$namer = new PrefixQueueNamer(prefix: 'fair/queue');
$storage = new RedisStorage($redis, $serilizer);
$broker = new Broker($storage, $namer);
$message = new SomeMessageOrJob(somePayload: 'user1-job1', fairTag: 'user1');
$broker->push($message);
$message = new SomeMessageOrJob(somePayload: 'user1-job2', fairTag: 'user1');
$broker->push($message);
$message = new SomeMessageOrJob(somePayload: 'user2-job1', fairTag: 'user2');
$broker->push($message);
$message = new SomeMessageOrJob(somePayload: 'user2-job2', fairTag: 'user2');
$broker->push($message);
$message = new SomeMessageOrJob(somePayload: 'user3-job1', fairTag: 'user3');
$broker->push($message);

while (($message = $broker->pop()) !== null) {
    echo $message->getSomePayload() . "\n";
}
// Output:
// user1-job1
// user2-job1
// user3-job1
// user1-job2
// user2-job2

Testing

There is docker-compose.yaml for testing/development/experiments.

export REDIS_HOST=redis
export REDIS_PORT=6379
make test