README

A lightweight semaphore component for the yii2-framework

Installation

Add dependency

The preferred way to install this extension is through composer.

Either run

$ composer require asinfotrack/yii2-semaphore

or add

"asinfotrack/yii2-semaphore": "~1.0.0"

to the require section of your composer.json file.

Configuration

All you need to do is add the component config to your corresponding config file.

return [
    //...
    'components' => [        
        //...        
        'semaphore' => [
            //use the file based implementation
            'class' => \asinfotrack\yii2\semaphore\components\FileSemaphore::class,
            'lockFolderAlias' => '@runtime/semaphores',
        ],
        //...
    ],
    //...
];

Usage

The following example code shows how to work with the component within a console command. The two methods differ in the way the handle the case when a semaphore is taken already: the first method waits for the lock to become available, while the second doesn't. Without the second param of acquire() set to false, the lock is awaited.

For each semaphore you work with a string constant which can be freely defined. In this manner multiple semaphores can be used in parallel.

class SemaphoreDemoController extends \yii\console\Controller
{
    
    public function actionWaitForLock()
    {
        Yii::$app->semaphore->acquire('my-lock', true);

        //do the actual work

        Yii::$app->semaphore->release('my-lock');
    }
    
    public function actionSkipIfNotAvailable()
    {
        if (!Yii::$app->semaphore->acquire('my-lock', false)) {
            $this->stderr('Lock already taken');
            return ExitCode::UNAVAILABLE;
        }

        //do the actual work
    
        Yii::$app->semaphore->release('my-lock');
    }

}

Implementations

File based implementation

Class: asinfotrack\yii2\semaphore\components\FileSemaphore
Internally the component works with the php flock()-function. Therefore you have to keep in mind the differences between the underlying operating systems.

Chagelog

v1.0.0

• initial release
• main class in a stable condition