The use of Queue in Laravel

Laravel Queue Service provides a unified API for various background queues. This article mainly introduces you to the most basic operation tutorials about using Queue in Laravel. The article introduces it in great detail through sample code. I hope to be helpful.

Preface

The queue service in laravel is no different from other queue services. They are the simplest and most common ones that are most in line with human thinking. The process: There is a place to store queue information, a PHP process writes tasks when running, and another PHP daemon process polls the queue information, executes and deletes tasks that meet the execution requirements. Since PHP is a URL-driven synchronous language and inherently blocking, it is not surprising that Laravel provides a daemon tool to query and execute queue information.

It was the first time I came into contact with Laravel’s queue in the past two days, and it took a long time. . . After a lot of hard work, I still feel that I don’t know how to use Laravel. The documentation is relatively simple and summarized, and it is a bit difficult to read the source code (but slowly debugging and verifying it by looking at the source code is still the most reliable).

The following is a simple demo of mine, which only uses the most basic operations of the queue. More advanced operations require more time:)

Like me, there are some queues for getting started with Laravel. Students who are in difficulty can communicate with each other.

Configuration

Add Redis package

In composer.json Add "predis/predis": "~1.0" to the require section, and then composer up to update it.

database.php

Configure the redis database part in the database.php configuration file. There is a default connection by default. Just use this: )

According to the configuration items required in this default connection, edit the .env configuration file and fill in the REDIS_HOST, REDIS_PASSWORD, and REDIS_PORT with the corresponding values ​​of Redis in your own server.

queue.php

First you need to configure QUEUE_DRIVER in .env. Because you plan to use Redis now, you configure it to redis.

Then configure the redis connection in the connections section of queue.php, where the value corresponding to connection is the default connection of redis in database.php.

Task class

The next step is to write the actual operation class. Laravel provides the artisan command to simplify the creation of task classes:

php artisan make:job Demo

The Jobs directory will be generated in the app directory, which already has the Demo.php task class.

Lumen does not have this artisan command, but it is very convenient. By default, there will be an ExampleJob.php already written, just copy it and change the name.
First write a simple log output test, in the handle method:

Log::info('Hello, queue');

Issuing tasks

Now write an entry function to push the task to the queue. Use the auxiliary function dispatch():

Use the following method in Laravel:

Demo::dispatch();

Use the following method in Lumen:

dispatch(new Demo);

Open the queue

If everything goes well, this is the last step. Execute in the command line:

php artisan queue:listen --queue=default

It will monitor the queue and output simple execution status, such as:

[2017-11-07 02:12:47] Processing: App\Jobs\Demo
[2017-11-07 02:12:47] Processed: App\Jobs\Demo

If there are no problems, you can let this queue script execute in the background:

php artisan queue:work --daemon --quiet --queue=default 1>> /dev/null 2>&1

Advanced:)

When pushing to the queue, there is usually a need to pass parameters, so how to pass them here?

Parameter passing

Passing in

The method of passing parameters in the entry function is as follows:

Use the following method in Laravel:

$param = 'Stephen';
Demo::dispatch($param);

Use the following method in Lumen:

$param = 'Stephen';
dispatch(new Demo($param));

Receive

in the task The method of receiving parameters in the class is as follows:

protected $param;
/**
 * Create a new job instance.
 *
 * @return void
 */
public function __construct($param)
{
  $this->param = $param;
}
/**
 * Execute the job.
 *
 * @return void
 */
public function handle()
{
  Log::info('Hello, ' . $this->param);
}

This is the first attempt. There are many advanced usages, such as delayed distribution, error handling, priority, failure handling, etc. I will continue to write in the future:)

Multiple Queues

This is an issue that must be considered. It is impossible for me to put all tasks in a queue called default. , which makes it difficult to manage the queue.

To specify different queues, it is very simple. Just follow dispatch() and then follow the onQueue() method:

Demo::dispatch()->onQueue('emails');

No, I don’t seem to have defined this called emails. queue. Well, naturally we need to make some changes. The redis configuration queue in the queue.php configuration file is changed from default to {default}. The effect of this is that the name of the queue can be obtained dynamically from runtime instead of being hard-coded. .

If you use the Lumen framework, you will get an error if you write directly like this: Call to a member function onQueue() on string.

The reason is that Lumen's Job base class does not use the Illuminate\Foundation\Bus\Dispatchable trait, but directly uses the onQueue() method in Illuminate\Bus\Queueable.

So now it is clear that our Job class uses the Illuminate\Bus\Queueable trait, so we need to call this onQueue() method on the Job class.

$job = new XXXJob();
dispatch($job->onQueue('queue-name'));

When we open the queue:

php artisan queue:work --queue=emails

这里指定的队列名 emails 和 dispatch 时指定的队列名保持一致即可。

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