Deferring Tasks in Laravel Using Queues

This article explores Laravel's Queue API, a powerful tool for deferring computationally intensive tasks to improve user experience and website performance. We'll cover key concepts and illustrate them with a practical example.

Website speed significantly impacts SEO and user satisfaction. Slow page load times often stem from resource-heavy code blocks. The solution? Deferring non-critical tasks to improve overall speed. Laravel's Queue API provides a streamlined way to achieve this.

Laravel's Queue API manages jobs added to a queue. These queues are associated with connections, which in turn utilize specific queue drivers. Let's break down the components:

Queue Drivers

Similar to database connections, the Queue API supports various drivers, including database, beanstalkd, SQS, and Redis. The driver determines where queue information is stored (e.g., a database or Redis server). Two special drivers, null, are useful for testing; null skips job execution.

Connections

Queue configuration requires specifying a default connection. This connection defines:

• The queue driver to use.
• Driver-specific configuration settings.
• The default queue name for new jobs.

Queues

Jobs are added to the default queue unless otherwise specified.

Now, let's build a real-world example: generating image thumbnails.

Creating Your First Queue Job

Generating multiple image thumbnails in real-time can negatively impact user experience, especially with large images or many thumbnail sizes. Instead of real-time processing, we'll defer this task to a queue. This approach offers a superior user experience as the main page loads quickly, and the thumbnail generation happens asynchronously.

Creating the Image Model

First, we'll create an Image model to manage uploaded images:

php artisan make:model Image --migration

This generates the Image model and a migration file. Modify the migration (database/migrations/YYYY_MM_DD_HHMMSS_create_images_table.php) to include the original image path:

<?php
// database/migrations/YYYY_MM_DD_HHMMSS_create_images_table.php
// ...
$table->string('org_path');
// ...
?>

Run the migration:

php artisan migrate

Creating a Laravel Job

We'll use the Intervention Image library for thumbnail processing. Install it via Composer:

php composer.phar require intervention/image

Create the job using the artisan command:

php artisan make:job ProcessImageThumbnails

Replace the contents of app/Jobs/ProcessImageThumbnails.php with:

<?php
// app/Jobs/ProcessImageThumbnails.php
// ...
public function handle()
{
    $image = $this->image;
    $full_image_path = public_path($image->org_path);
    $resized_image_path = public_path('thumbs' . DIRECTORY_SEPARATOR . $image->org_path);
    $img = \Image::make($full_image_path)->resize(300, 200);
    $img->save($resized_image_path);
}
// ...
?>

The handle method contains the thumbnail generation logic.

Testing the Job

Let's create a simple image upload form. Create a controller (app/Http/Controllers/ImageController.php):

php artisan make:model Image --migration

Create a view (resources/views/upload_form.blade.php) and add routes in routes/web.php:

<?php
// database/migrations/YYYY_MM_DD_HHMMSS_create_images_table.php
// ...
$table->string('org_path');
// ...
?>

The upload method handles file uploads, database entries, and dispatches the ProcessImageThumbnails job.

After uploading, verify the job's addition to the jobs table using a database query.

The Queue Worker

The queue worker processes queued jobs. Start it with:

php artisan migrate

This command processes pending jobs. The output will show job processing status. For continuous background processing, use a process manager like Supervisor, Circus, or similar.

Conclusion

Laravel's Queue API efficiently handles resource-intensive tasks, enhancing user experience. This article provided a foundational understanding and a practical implementation example. For further learning, explore resources at Envato Market.

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