CODEWITHSUNDEEP
phplaravel-5interruptjobs
tam5
tam5

Reputation: 3237

How to interrupt a PHP loop?

I have a Laravel 5.2 job that I generally want running non-stop. For illustration, let's say it generates some random number and then broadcasts it through an event to the front-end.

/**
 * Execute the job. Generate a random number.
 */
public function handle()
{
    $number = rand();
    event(new NumberWasGenerated($number)); 
}

For whatever reason, I want this job to run indefinitely. So, I made another job which loops and keeps dispatching new GenerateNumberjobs.

/**
 * Execute the job. Continuously generate numbers.
 *
 * @return void
 */
public function handle()
{
    while (true) {
        $this->dispatch(new GenerateNumber());
    }
}

I do however want to be able to "turn off" the generator should I decide to. This is where I am having trouble.

Ideally I would like to be able to hit a route like /abortwhich would then send an interrupt to my generator loop and halt its execution. How can I do this?

Alternatively, I could try a polling approach. I tried to use something like:

/**
 * Execute the job. Continuously generate numbers.
 *
 * @return void
 */
public function handle()
{
    Config::set('shouldGenerate', true);

    while (Config::get('shouldGenerate')) {
        $this->dispatch(new GenerateNumber());
    }
}

Then, in my controller method for /abort I have

public function abort()
{
    Config::set('shouldGenerate', false);
}

However, the abort doesn't seem to be working. I think the problem seems to be that the abort method never gets a chance to execute because the generator loop is being a ball hog, but I am not sure why that would be the case.

Question:

1) Can I achieve this using an interrupt approach?
2) If not, how can I achieve this through polling?

Upvotes: 0

Views: 874

Answers (1)

Alankar More
Alankar More

Reputation: 1115

You can achieve this by combination of both options

  • Interrupt
  • Polling

You can rewrite your abort action as follow

public function abort()
{
    Config::set('shouldGenerate', false);
    exec('PATH/TO/YOUR/RDIS/SERVER/src/redis-cli FLUSHDB');    
}

And change the handle method as follow:

/**
 * Execute the job. Continuously generate numbers.
 *
 * @return void
 */
public function handle()
{
    $shouldGenerate = Config::get('shouldGenerate');
    while ($shouldGenerate) {
        $this->dispatch(new GenerateNumber());
    }
}

You can read more about the FLUSHDB of Redis server HERE Delete all the keys of the currently selected DB. This command never fails

I hope this will work for you. Make sure your operating system user must have permission to execute the shell commands via script.

Upvotes: 2

Related Questions