### Install CodeIgniter Queue

Source: https://github.com/codeigniter4/queue/blob/develop/README.md

Install the CodeIgniter Queue library using Composer.

```bash
composer require codeigniter4/queue
```

--------------------------------

### Job Handlers Example

Source: https://github.com/codeigniter4/queue/blob/develop/docs/configuration.md

Map job names to their corresponding class names, for example, associating 'email' with the Email::class.

```php
public array $jobHandlers = [
    'email' => Email::class,
];
```

--------------------------------

### Queue Priorities Example

Source: https://github.com/codeigniter4/queue/blob/develop/docs/configuration.md

Define multiple priorities for jobs within a specific queue, like 'emails' supporting 'high' and 'low' priorities.

```php
public array $queuePriorities = [
    'emails' => ['high', 'low'],
];
```

--------------------------------

### Default Queue Priority Example

Source: https://github.com/codeigniter4/queue/blob/develop/docs/configuration.md

Set a default priority for jobs added to a specific queue, such as 'emails' with 'low' priority.

```php
public array $queueDefaultPriority = [
    'emails' => 'low',
];
```

--------------------------------

### Manually Add Queue Namespace to Autoloader

Source: https://github.com/codeigniter4/queue/blob/develop/docs/installation.md

For manual installation, add the 'CodeIgniter\Queue' namespace to the \$psr4 array in app/Config/Autoload.php, pointing to the library's source directory.

```php
<?php

// ...

public $psr4 = [
    APP_NAMESPACE => APPPATH,
    'Config'      => APPPATH . 'Config',
    'CodeIgniter\Queue' => APPPATH . 'ThirdParty/queue/src',
];

// ...

```

--------------------------------

### Run Queue Worker

Source: https://github.com/codeigniter4/queue/blob/develop/README.md

Start the queue worker process to execute jobs from a specified queue.

```bash
php spark queue:work queueName
```

--------------------------------

### Consume Jobs from a Queue

Source: https://github.com/codeigniter4/queue/blob/develop/docs/commands.md

Starts a worker to process jobs from a specified queue. You can configure options like sleep time, maximum jobs, memory limits, and priority.

```bash
php spark queue:work emails -max-jobs 5
```

```bash
php spark queue:work emails -max-jobs 5 -priority low,high
```

--------------------------------

### Accessing Event Metadata

Source: https://github.com/codeigniter4/queue/blob/develop/docs/events.md

Retrieve specific metadata values by key or get all metadata associated with the event.

```php
// Get specific metadata
$event->getMetadata('worker_id');
$event->getMetadata('priority', 'default');

// Get all metadata
$metadata = $event->getAllMetadata();
```

--------------------------------

### Migrate Database for Queue

Source: https://github.com/codeigniter4/queue/blob/develop/README.md

Run database migrations to set up the necessary tables for the queue system.

```bash
php spark migrate --all
```

--------------------------------

### Publish Queue Configuration

Source: https://github.com/codeigniter4/queue/blob/develop/README.md

Publish the queue configuration file to your application's config directory.

```bash
php spark queue:publish
```

--------------------------------

### Registering Queue Event Listeners

Source: https://github.com/codeigniter4/queue/blob/develop/docs/events.md

Add these listeners in `app/Config/Events.php` to react to job completion, failures, and worker lifecycle changes.

```php
<?php

use CodeIgniter\Events\Events;
use CodeIgniter\Queue\Events\QueueEvent;
use CodeIgniter\Queue\Events\QueueEventManager;

// Listen to job completion
Events::on(QueueEventManager::JOB_PROCESSING_COMPLETED, static function (QueueEvent $event) {
    log_message('info', 'Job completed: {job} in {time}s', [
        'job'  => $event->getJobClass(),
        'time' => $event->getProcessingTime(),
    ]);
});

// Listen to job failures
Events::on(QueueEventManager::JOB_FAILED, static function (QueueEvent $event) {
    log_message('error', 'Job failed: {job} - {error}', [
        'job'   => $event->getJobClass(),
        'error' => $event->getExceptionMessage(),
    ]);
});

// Listen to worker lifecycle
Events::on(QueueEventManager::WORKER_STARTED, static function (QueueEvent $event) {
    log_message('info', 'Worker started for queue: {queue}', [
        'queue' => $event->getQueue(),
    ]);
});

Events::on(QueueEventManager::WORKER_STOPPED, static function (QueueEvent $event) {
    $metadata = $event->getAllMetadata();

    log_message('info', 'Worker stopped: {reason}, processed {jobs} jobs in {time}s', [
        'reason' => $metadata['stop_reason'],
        'jobs'   => $metadata['jobs_processed'],
        'time'   => round($metadata['uptime_seconds'], 2),
    ]);
});
```

--------------------------------

### Configure Job Handlers in Queue.php

Source: https://github.com/codeigniter4/queue/blob/develop/docs/basic-usage.md

Add your custom job classes to the `$jobHandlers` array in `app/Config/Queue.php` to register them with the queue system.

```php
// app/Config/Queue.php

use App\Jobs\Email;

// ...

/**
 * Your jobs handlers.
 */
public array $jobHandlers = [
    'email' => Email::class,
];

// ...
```

--------------------------------

### Implement a Basic Email Job

Source: https://github.com/codeigniter4/queue/blob/develop/docs/basic-usage.md

Define the `process` method within your job class to contain the logic for sending an email. The `$this->data` variable holds any data passed to the job.

```php
<?php

namespace App\Jobs;

use Exception;
use CodeIgniter\Queue\BaseJob;

class Email extends BaseJob
{
    /**
     * @throws Exception
     */
    public function process()
    {
        $email  = service('email', null, false);
        $result = $email
            ->setTo('test@email.test')
            ->setSubject('My test email')
            ->setMessage($this->data['message'])
            ->send(false);

        if (! $result) {
            throw new Exception($email->printDebugger('headers'));
        }

        return $result;
    }
}
```

--------------------------------

### Create a New Job

Source: https://github.com/codeigniter4/queue/blob/develop/README.md

Generate a new job class using the spark command.

```bash
php spark queue:job Example
```

--------------------------------

### Generate New Job File

Source: https://github.com/codeigniter4/queue/blob/develop/docs/commands.md

Creates a new job class file. Specify the desired class name. You can also set a custom namespace or append a suffix to the class name.

```bash
php spark queue:job Email
```

--------------------------------

### Push a Job to the Queue

Source: https://github.com/codeigniter4/queue/blob/develop/docs/basic-usage.md

Use the `push` method to send a single job to a specified queue with optional parameters. The method returns a `QueuePushResult` object.

```php
service('queue')->push('queueName', 'jobName', ['array' => 'parameters']);
```

```php
service('queue')->push('emails', 'email', ['message' => 'Email message goes here']);
```

--------------------------------

### Configure Job Retry Options

Source: https://github.com/codeigniter4/queue/blob/develop/docs/basic-usage.md

Set the `$retryAfter` and `$tries` properties in your job class to define how many times a job should be retried and the delay between retries. These are the default values.

```php
// ...

class Email extends BaseJob
{
    protected int $retryAfter = 60;
    protected int $tries      = 1;

    // ...

}
```

--------------------------------

### Accessing Basic Event Information

Source: https://github.com/codeigniter4/queue/blob/develop/docs/events.md

Retrieve fundamental details about the event, such as its type, handler, queue, and timestamp.

```php
$event->getType();      // Event type (e.g., 'queue.job.pushed')
$event->getHandler();   // Handler name (e.g., 'database', 'redis')
$event->getQueue();     // Queue name (e.g., 'emails', 'default')
$event->getTimestamp(); // Time object when event occurred
```

--------------------------------

### Configure Job Handlers

Source: https://github.com/codeigniter4/queue/blob/develop/README.md

Add your custom job handler to the `app\Config\Queue.php` configuration file. This maps a job name to its corresponding class.

```php
// ...

use App\Jobs\Example;

// ...

public array $jobHandlers = [
    'my-example' => Example::class
];

// ...
```

--------------------------------

### Add a Job to the Queue

Source: https://github.com/codeigniter4/queue/blob/develop/docs/index.md

Use this method to add a new job to a specified queue with associated parameters. Ensure the queue service is available.

```php
service('queue')->push('queueName', 'jobName', ['array' => 'parameters']);
```

--------------------------------

### Add Job to Queue

Source: https://github.com/codeigniter4/queue/blob/develop/README.md

Push a new job onto the queue with its name and associated data. The data can be any array.

```php
service('queue')->push('queueName', 'my-example', ['data' => 'array']);
```

--------------------------------

### Chained Push vs Regular Push Priority

Source: https://github.com/codeigniter4/queue/blob/develop/docs/running-queues.md

Illustrates the difference in setting priority for chained jobs versus regular queue jobs. For chained jobs, priority is set after `push()`; for regular jobs, it's set before.

```php
// Regular push() - priority set before pushing
service('queue')->setPriority('high')->push('queue', 'job', []);

// Chain push() - priority set after pushing
service('queue')->chain(function($chain) {
    $chain->push('queue', 'job', [])->setPriority('high');
});
```

--------------------------------

### Run Queue Worker with Supervisor

Source: https://github.com/codeigniter4/queue/blob/develop/docs/running-queues.md

Use this command to run a queue worker that continuously checks for new jobs. The wait time prevents excessive database queries when the queue is empty.

```bash
php spark queue:work emails -wait 10
```

--------------------------------

### Push Chained Jobs to the Queue

Source: https://github.com/codeigniter4/queue/blob/develop/docs/basic-usage.md

Use the `chain` method to send multiple jobs that will be executed in sequence. Subsequent jobs only run if the preceding ones are successful. Returns a `QueuePushResult` object.

```php
service('queue')->chain(function($chain) {
    $chain
        ->push('reports', 'generate-report', ['userId' => 123])
        ->push('emails', 'email', ['message' => 'Email message goes here', 'userId' => 123]);
});
```

--------------------------------

### Chaining Jobs in CodeIgniter Queue

Source: https://github.com/codeigniter4/queue/blob/develop/docs/running-queues.md

Use the `chain()` method to define a sequence of jobs that will execute in order. Each job's configuration (priority, delay) must be set after its `push()` call.

```php
service('queue')->chain(function($chain) {
    $chain
        ->push('reports', 'generate-report', ['userId' => 123])
            ->setPriority('high') // optional
        ->push('emails', 'email', ['message' => 'Email message goes here', 'userId' => 123])
            ->setDelay(30); // optional
});
```

--------------------------------

### Configure Composer Minimum Stability

Source: https://github.com/codeigniter4/queue/blob/develop/docs/installation.md

If you encounter stability issues with Composer, update your project's minimum-stability setting to 'dev' and prefer stable packages.

```bash
composer config minimum-stability dev
composer config prefer-stable true
```

--------------------------------

### Add Jobs with Specific Priorities

Source: https://github.com/codeigniter4/queue/blob/develop/docs/running-queues.md

Add jobs to the queue with either the default priority or a specified priority. The `setPriority` method allows for explicit priority setting before pushing a job.

```php
// This job will have low priority:
service('queue')->push('emails', 'email', ['message' => 'Email message with low priority']);
// But this one will have high priority
service('queue')->setPriority('high')->push('emails', 'email', ['message' => 'Email message with high priority']);
```

--------------------------------

### Run Queue Worker with Specified Priority Order

Source: https://github.com/codeigniter4/queue/blob/develop/docs/running-queues.md

Execute the queue worker, overriding the default priority order defined in the configuration. Jobs will be consumed in the order specified in the command-line argument.

```bash
php spark queue:work emails -priority low,high
```

--------------------------------

### Add a Delayed Job to the Queue

Source: https://github.com/codeigniter4/queue/blob/develop/docs/running-queues.md

Schedule a job to be executed after a specified delay. The delay is measured in seconds, and the job will not run before this time has elapsed.

```php
// This job will be run not sooner than in 5 minutes
service('queue')->setDelay(5 * MINUTE)->push('emails', 'email', ['message' => 'Email sent no sooner than 5 minutes from now']);
```

--------------------------------

### Configure Default and Custom Queue Priorities

Source: https://github.com/codeigniter4/queue/blob/develop/docs/running-queues.md

Define default and custom priority levels for queues. This configuration is used by the queue worker to process jobs in a specific order.

```php
// app/Config/Queue.php

public array $queueDefaultPriority = [
    'emails' => 'low',
];

public array $queuePriorities = [
    'emails' => ['high', 'low'],
];
```

--------------------------------

### View Failed Jobs

Source: https://github.com/codeigniter4/queue/blob/develop/docs/commands.md

Displays a list of all failed jobs. You can filter the results to show failed jobs from a specific queue.

```bash
php spark queue:failed -queue emails
```

--------------------------------

### Run Queue Worker with CRON

Source: https://github.com/codeigniter4/queue/blob/develop/docs/running-queues.md

This command is suitable for CRON jobs, processing a maximum number of jobs per execution and stopping when the queue is empty. This prevents resource overload during high traffic.

```bash
php spark queue:work emails -max-jobs 20 --stop-when-empty
```

--------------------------------

### Accessing Error Information for Failed Events

Source: https://github.com/codeigniter4/queue/blob/develop/docs/events.md

When an event signifies a job failure, retrieve the exception details and check if an error occurred.

```php
$event->getException();        // Exception object (if any)
$event->getExceptionMessage(); // Exception message
$event->hasFailed();           // True if event contains an exception
```

--------------------------------

### Retrieving Job Details

Source: https://github.com/codeigniter4/queue/blob/develop/docs/events.md

Access specific information related to a job when the event is job-related.

```php
$event->getJobId();            // Job ID
$event->getJobClass();         // Fully qualified job class name
$event->getPriority();         // Job priority
$event->getAttempts();         // Number of attempts
$event->getStatus();           // Job status
$event->getProcessingTime();   // Processing time in seconds
$event->getProcessingTimeMs(); // Processing time in milliseconds
```

--------------------------------

### Require Specific Queue Version via Composer

Source: https://github.com/codeigniter4/queue/blob/develop/docs/installation.md

Alternatively, specify an explicit version constraint for the queue package, such as the 'dev-develop' branch, to resolve stability issues.

```bash
composer require codeigniter4/queue:dev-develop
```

--------------------------------

### Checking Event Types

Source: https://github.com/codeigniter4/queue/blob/develop/docs/events.md

Determine the category of the event using boolean checks for job, worker, connection, or operation events.

```php
$event->isJobEvent();        // True for job-related events
$event->isWorkerEvent();     // True for worker-related events
$event->isConnectionEvent(); // True for connection-related events
$event->isOperationEvent();  // True for operation events
```

--------------------------------

### Implement Job with Database Transactions

Source: https://github.com/codeigniter4/queue/blob/develop/docs/basic-usage.md

When using database transactions within a job, ensure Strict Mode is disabled for the connection to prevent issues with long-running processes. Rollback transactions if an exception occurs.

```php
// ...

class Email extends BaseJob
{
    /**
     * @throws Exception
     */
    public function process(string $data):
    {
        try {
            $db = db_connect();
            // Disable Strict Mode
            $db->transStrict(false);
            $db->transBegin();

            // Job logic goes here
            // Your code should throw an exception on error

            if ($db->transStatus() === false) {
                $db->transRollback();
            } else {
                $db->transCommit();
            }
        } catch (Exception $e) {
            $db->transRollback();
            throw $e;
        }
    }
}
```

--------------------------------

### Retry Failed Jobs

Source: https://github.com/codeigniter4/queue/blob/develop/docs/commands.md

Re-queues failed jobs to be processed again. You can retry a specific job by its ID or retry all failed jobs for a given queue.

```bash
php spark queue:retry all -queue emails
```

--------------------------------

### Clear All Jobs from a Queue

Source: https://github.com/codeigniter4/queue/blob/develop/docs/commands.md

Removes all pending jobs from a specified queue. Use with caution as this action is irreversible.

```bash
php spark queue:clear emails
```

--------------------------------

### Delete Multiple Failed Jobs

Source: https://github.com/codeigniter4/queue/blob/develop/docs/commands.md

Deletes multiple failed jobs based on their age and queue. Specify the number of hours to retain failed jobs.

```bash
php spark queue:flush -hours 6
```

--------------------------------

### Stop a Queue Safely

Source: https://github.com/codeigniter4/queue/blob/develop/docs/commands.md

Gracefully stops a queue worker after the current job is completed. This ensures no jobs are interrupted mid-process.

```bash
php spark queue:stop emails
```

--------------------------------

### Delete a Specific Failed Job

Source: https://github.com/codeigniter4/queue/blob/develop/docs/commands.md

Removes a single failed job from the system using its unique ID. This is useful for cleaning up individual failed job records.

```bash
php spark queue:forget 123
```

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