Async

A simple PHP library for creating asynchronous processes, and handling inter-process communication via sockets.

Installation

composer require superrb/async

Usage

Getting Started

The easiest way to use this package is to use the async helper. This simply runs the supplied closure asynchronously within a forked process. The closure must return a boolean to indicate success/failure of the subprocess, and have the return type bool, as this is used to set the exit state of the process.

echo 1."\n";

async(function(): bool {
	sleep(1);
	echo 2."\n";
	return true;
});

echo 3."\n";

// Output
1
3
2

Any arguments passed to async will be passed straight to the forked process.

async(function($i, $j): bool {
	echo $i."\n";
	echo $j."\n";
	return true;
}, 1, 2);

// Output
1
2

Reusable closures

You can reuse a closure, by manually constructing an instance of Superrb\Async\Handler

$handler = new Superrb\Async\Handler(function(int $i): bool {
	echo $i;
	return true;
});

for ($i = 0; $i < 10; $i++) {
	$handler->run($i);
}

// Processing will pause here until all asynchronous processes
// have completed. $success is true if all processes returned
// true, otherwise it is false
$success = $handler->waitAll();

You can run synchronous code within forked processes by passing false as the second argument to the Handler constructor. This is useful for running long processes such as imports, as any memory consumed within the loop is dumped at the end of the process.

$handler = new Superrb\Async\Handler(function(int $i): bool {
	echo $i;
	return true;
}, false);

for ($i = 0; $i < 10; $i++) {
	// The loop will pause whilst the process runs, and continue
	// when it is completed. $success is the return value of the
	// closure
	$success = $handler->run($i);
}

Inter-process communication

Sending messages to the parent

async uses channels and socket pairs to allow for communication between the child and parent process. Communication is one way - you can pass messages from the child process back to the main process using $this->send() within your closure. Messages can be strings, objects or arrays.

$handler = new Superrb\Async\Handler(function(int $i): bool {
	$this->send('Hi from process '.$i);
	return true;
});

for ($i = 0; $i < 10; $i++) {
	$handler->run($i);
}

$handler->waitAll();

Reading messages

Messages can then be read by calling the generator $handler->getMessages() once processing has completed. For asynchronous processes, the messages will always be received in the order the handlers were run regardless of which process finished first.

foreach($handler->getMessages() as $message) {
	echo $message."\n";
}

// output
Hi from process 1
Hi from process 2
Hi from process 3
...

For synchronous processes, you can read messages at the end of each process. If you do this, you'll need to clear the message pool manually after reading them.

for ($i = 0; $i < 10; $i++) {
	$handler->run($i);
	
	foreach($handler->getMessages() as $message) {
		echo $message."\n";
	}
	
	$handler->clearMessages();
}

Increasing the communication buffer

By default messages are sent within a 1024-byte message buffer, and attempting to send data larger than this will result in an exception. You can increase/decrease the buffer by calling setMessageBuffer on the handler.

$handler->setMessageBuffer(4096);

Contributing

All contributions are welcome, and encouraged. Please read our contribution guidelines and code of conduct for more information.

License

Copyright (c) 2017 Superrb Studio tech@superrb.com

Async is licensed under The MIT License (MIT)

Team

• James Dinsdale (@molovo)