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.
The master branch contains the code for the upcoming 0.5 release. For the code of the current stable 0.4.x release, checkout the 0.4 branch.
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
Tick
every 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 simpleselect
system call. It's not the most performant of loops, but still does the job quite well. -
LibEventLoop
: This uses thelibevent
pecl extension.libevent
itself supports a number of system-specific backends (epoll, kqueue). -
LibEvLoop
: This uses thelibev
pecl extension (github). It supports the same backends as libevent. -
ExtEventLoop
: This uses theevent
pecl 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-loop
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
MIT, see LICENSE file.