misterion/ko-process

Simple pcntl fork wrapper and process manager

ko-process

![Code Coverage][coverage-image] ![Scrutinizer Code Quality][code-quality-image] , _(*1)

Ko-Process allows for easy callable forking. It is object-oriented wrapper around fork part of PCNTL PHP's extension. Background process, detaching process from the controlling terminal, signals and exit codes and simple IPC via shared memory. This is well tested library used in real world high load projects., _(*2)

Installation

Requirements

PHP >= 5.4
pcntl extension installed
posix extension installed

Via Composer

The recommended way to install library is composer. You can see package information on Packagist., _(*3)

{
    "require": {
        "misterion/ko-process": "*"
    }
}

Do not use composer?

Just clone the repository and care about autoload for namespace Ko., _(*4)

Usage

Basic usage looks like this:, _(*5)

$manager = new Ko\ProcessManager();
$process = $manager->fork(function(Ko\Process $p) {
    echo 'Hello from ' . $p->getPid();
})->onSuccess(function() {
    echo 'Success finish!';
})->wait();

If should wait for all forked process, _(*6)

$manager = new Ko\ProcessManager();
for ($i = 0; $i < 10; $i++) {
    $manager->fork(function(Ko\Process $p) {
        echo 'Hello from ' . $p->getPid();
        sleep(1);
    });
}
$manager->wait();

Process title?

Yes, both ProcessManager and Process can change process title with setProcessTitle function. Or you may use trait Ko\Mixin\ProcessTitle to add this to any class you want. Take attention about ProcessManager::onShutdown - use can set callable which would be called if ProcessManager catch SIGTERM. The handler would be called before child process would be shutdown. We use demonize to detach from terminal. Run sample with code, _(*7)

$manager = new Ko\ProcessManager();
$manager->demonize();
$manager->setProcessTitle('I_am_a_master!');
$manager->onShutdown(function() use ($manager) {
    echo 'Catch sigterm.Quiting...' . PHP_EOL;
    exit();
});

echo 'Execute `kill ' . getmypid() . '` from console to stop script' . PHP_EOL;
while(true) {
    $manager->dispatch();
    sleep(1);
}

and ps aux|grep I_am_a_master or top to see you process title in linux process list., _(*8)

Spawn

Making master - child process pattern application you should care about child process be alive. The spawn function will help you with that - once spawn will keep forked process alive after he exit with some error code., _(*9)

$manager = new Ko\ProcessManager();
for ($i = 0; $i < 10; $i++) {
    $manager->spawn(function(Ko\Process $p) {
        echo 'Hello from ' . $p->getPid();
        sleep(1);
        exit(1); //exit with non 0 exit code
    });
}
$manager->wait(); //we have auto respawn for 10 forks

Let`s explain you are writing something like queue worker based on PhpAmqpLib\AMPQ. So you can write something like this, _(*10)

use PhpAmqpLib\Connection\AMQPConnection;
use PhpAmqpLib\Message\AMQPMessage;

$manager = new Ko\ProcessManager();
$manager->setProcessTitle('Master:working...');
$manager->spawn(function(Ko\Process $p) {
    $connection = new AMQPConnection('localhost', 5672, 'guest', 'guest');
    $channel = $connection->channel();

    $channel->queue_declare('hello', false, true, false, false);

    $callback = function($msg) use (&$p) {
        $p->setProcessTitle('Worker:processJob ' . $msg->body);

        //will execute our job in separate process
        $m = new Ko\ProcessManager();
        $m->fork(function(Ko\Process $jobProcess) use ($msg) {
            $jobProcess->setProcessTitle('Job:processing ' . $msg->body);

            echo " [x] Received ", $msg->body, "\n";
            sleep(2);
            echo " [x] Done", "\n";
        })->onSuccess(function() use ($msg){
            //Ack on success
            $msg->delivery_info['channel']
                ->basic_ack($msg->delivery_info['delivery_tag']);
        })->wait();

        $p->setProcessTitle('Worker:waiting for job... ');

        //IMPORTANT! You should call dispatch() them self to process pending signals.
        $p->dispatch();

        if ($p->isShouldShutdown()) {
            exit();
        }
    };

    $channel->basic_qos(null, 1, null);
    $channel->basic_consume('hello', '', false, false, false, false, $callback);

    while(count($channel->callbacks)) {
        $channel->wait();
    }

    $channel->close();
    $connection->close();
});
$manager->wait();

Shared memory and Semaphore

The Ko\SharedMemory used Semaphore for internal locks so can be safely used for inter process communications. SharedMemory implements \ArrayAccess and \Countable interface so accessible like an array:, _(*11)

$sm = new SharedMemory(5000); //allocate 5000 bytes
$sm['key1'] = 'value';

echo 'Total keys is' . count($sm) . PHP_EOL;
echo 'The key with name `key1` exists: ' . isset($sm['key1'] . PHP_EOL;
echo 'The value of key1 is ' . $sm['key1'] . PHP_EOL;

unset($sm['key1']);
echo 'The key with name `key1` after unset exists: ' . isset($sm['key1'] . PHP_EOL;

You can use Semaphore for inter process locking:, _(*12)

$s = new Semaphore();
$s->acquire();
//do some job
$s->release();

//or
$s->tryExecute(function() {
    //do some job
});

Credits

Ko-process written as a part of GameNet project by Nikolay Bondarenko (misterionkell at gmail.com)., _(*13)

License

Released under the MIT license., _(*14)

Links

• Project profile on the Ohloh