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
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();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();- 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. - 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
Tickevery second and a readable stream is created by using ReactPHP's stream component for demonstration purposes. - The loop is run with a single
$loop->run()call at the end of the program.
In addition to the interface there are the following implementations provided:
-
StreamSelectLoop: This is the only implementation which works out of the box with PHP. It does a simpleselectsystem call. It's not the most performant of loops, but still does the job quite well. -
LibEventLoop: This uses thelibeventpecl extension.libeventitself supports a number of system-specific backends (epoll, kqueue). -
LibEvLoop: This uses thelibevpecl extension (github). It supports the same backends as libevent. -
ExtEventLoop: This uses theeventpecl extension. It supports the same backends as libevent.
All of the loops support these features:
- File descriptor polling
- One-off timers
- Periodic timers
- Deferred execution of callbacks
The recommended way to install this library is through Composer. New to Composer?
This will install the latest supported version:
$ composer require react/event-loopTo run the test suite, you first need to clone this repo and then install all dependencies through Composer:
$ composer installTo run the test suite, go to the project root and run:
$ php vendor/bin/phpunitMIT, see LICENSE file.
