队列（Queueing）

Activities like processing videos, resizing images or sending emails aren’t suitable to be executed online or in real time because it may slow the loading time of pages and severely impact the user experience.

The best solution here is to implement background jobs. The web application puts jobs into a queue and which will be processed separately.

While you can find more sophisticated PHP extensions to address queueing in your applications like RabbitMQ; Phalcon provides a client for Beanstalk, a job queueing backend inspired by Memcache. It’s simple, lightweight, and completely specialized for job queueing.

注意

Some of the returns from queue methods require that the module Yaml be installed. Please refer to http://php.net/manual/book.yaml.php for more information. For PHP < 7, Yaml 1.3.0 is acceptable. For PHP >= 7, you will need to use Yaml >= 2.0.0.

将任务加入队列（Putting Jobs into the Queue）

After connecting to Beanstalk you can insert as many jobs as required. You can define the message structure according to the needs of the application:

<?php
use Phalcon\Queue\Beanstalk;
// Connect to the queue
$queue = new Beanstalk(
    [
        "host" => "192.168.0.21",
        "port" => "11300",
    ]
);
// Insert the job in the queue
$queue->put(
    [
        "processVideo" => 4871,
    ]
);

Available connection options are:

In the above example we stored a message which will allow a background job to process a video. The message is stored in the queue immediately and does not have a certain time to live.

Additional options as time to run, priority and delay can be passed as second parameter:

<?php
// Insert the job in the queue with options
$queue->put(
    [
        "processVideo" => 4871,
    ],
    [
        "priority" => 250,
        "delay"    => 10,
        "ttr"      => 3600,
    ]
);

The following options are available:

Every job put into the queue returns a “job id” which you can use to track the status of the job:

<?php
$jobId = $queue->put(
    [
        "processVideo" => 4871,
    ]
);

检索信息（Retrieving Messages）

Once a job is placed into the queue, those messages can be consumed by a background worker which will have enough time to complete the task:

<?php
while (($job = $queue->peekReady()) !== false) {
    $message = $job->getBody();
    var_dump($message);
    $job->delete();
}

Jobs must be removed from the queue to avoid double processing. If multiple background jobs workers are implemented, jobs must be “reserved” so other workers don’t re-process them while other workers have them reserved:

<?php
while (($job = $queue->reserve()) !== false) {
    $message = $job->getBody();
    var_dump($message);
    $job->delete();
}

Our client implement a basic set of the features provided by Beanstalkd but enough to allow you to build applications implementing queues.