队列Queueing

执行如处理视频，调整图片或发送电子邮件不适合被实时在线执行，因为它可能慢的页面加载时间,影响用户体验。

Perform activities like process a video, resize images or send emails aren’t suitable to be executed online or in real time because it may slow the loading time of pages, impacting the user experience.

这里的最佳解决方案是实现后台的工作。一个web应用程序必须把这些工作做成一个队列,然后等后台去处理它们。

The best solution here is implementing background jobs. A web application must put the job into a queue and wait that it will be processed.

可以使用RabbitMQ_通过PHP扩展。Phalcon提供一个 Beanstalk 的客户端。一个由 Memcache 激发而来的任务消息队列。很简单、轻量级和完全专业的队列。

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 on job queueing.

将任务加入队列Putting Jobs into the Queue

在连接到Bens后可以插入任意多的工作。开发人员可以根据应用程序的需要结构定义消息:

After connecting to Bens can insert as many jobs as required. The developer can define the message structure according to the needs of the application:

<?php
//Connect to the queue
$queue = new Phalcon\Queue\Beanstalk(array(
    'host' => '192.168.0.21'
));
//Insert the job in the queue
$queue->put(array('processVideo' => 4871));

可用的连接选项：

Available connection options are:

在上面的例子中我们存储消息,将添加一个后台作业过程去处理一段视频。立即存储在队列的消息,并没有一个特定的时间去完成它。

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 life.

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

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

下面的选项可用：

The following options are available:

添加到队列的任务将获得一个队列id，开发者可以跟踪任务情况：

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

<?php
$jobId = $queue->put(array('processVideo' => 4871));

获取消息Retrieving Messages

一旦放入队列中中工作,可以被后台有足够的时间来完成任务并产生消息:

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

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

工作完成后必须从队列中删除,以避免双重处理。如果实现了多个后台作业, 任务在处理中就不能再被另一个处理:

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())) {
    $message = $job->getBody();
    var_dump($message);
    $job->delete();
}

虽然Beanstalkd提供足够多的功能，但是我们也可以去创建自己队列实现。

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