EventLoop Component

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Event loop abstraction layer that libraries can use for evented I/O.

In order for async based libraries to be interoperable, they need to use the same event loop. This component provides a common LoopInterface that any library can target. This allows them to be used in the same loop, with one single run() call that is controlled by the user.

Table of Contents

Quickstart example

Here is an async HTTP server built with just the event loop.

$loop = React\EventLoop\Factory::create();

$server = stream_socket_server('tcp://127.0.0.1:8080');
stream_set_blocking($server, 0);

$loop->addReadStream($server, function ($server) use ($loop) {
    $conn = stream_socket_accept($server);
    $data = "HTTP/1.1 200 OK\r\nContent-Length: 3\r\n\r\nHi\n";
    $loop->addWriteStream($conn, function ($conn) use (&$data, $loop) {
        $written = fwrite($conn, $data);
        if ($written === strlen($data)) {
            fclose($conn);
            $loop->removeStream($conn);
        } else {
            $data = substr($data, $written);
        }
    });
});

$loop->addPeriodicTimer(5, function () {
    $memory = memory_get_usage() / 1024;
    $formatted = number_format($memory, 3).'K';
    echo "Current memory usage: {$formatted}\n";
});

$loop->run();

Usage

Typical applications use a single event loop which is created at the beginning and run at the end of the program.

// [1]
$loop = React\EventLoop\Factory::create();

// [2]
$loop->addPeriodicTimer(1, function () {
    echo "Tick\n";
});

$stream = new React\Stream\ReadableResourceStream(
    fopen('file.txt', 'r'),
    $loop
);

// [3]
$loop->run();
  1. The loop instance is created at the beginning of the program. A convenience factory React\EventLoop\Factory::create() is provided by this library which picks the best available loop implementation.
  2. The loop instance is used directly or passed to library and application code. In this example, a periodic timer is registered with the event loop which simply outputs Tick every second and a readable stream is created by using ReactPHP's stream component for demonstration purposes.
  3. The loop is run with a single $loop->run() call at the end of the program.

Loop implementations

In addition to the interface there are the following implementations provided:

All of the loops support these features:

Install

The recommended way to install this library is through Composer. New to Composer?

This will install the latest supported version:

$ composer require react/event-loop

Tests

To run the test suite, you first need to clone this repo and then install all dependencies through Composer:

$ composer install

To run the test suite, go to the project root and run:

$ php vendor/bin/phpunit

License

MIT, see LICENSE file.