README

An event-loop API for writing asynchronous code in traditional PHP code, while also working seamlessly with common asynchronous frameworks like React or Amp.

Moebius Loop provides an elegant and consistent API for working with non-blocking I/O which works equally well in classic synchronous PHP code as with fully asynchronous frameworks like React or Amp.

Laravel example

Moebius\Loop can be used with most frameworks such as Laravel or Symfony. The only challenge with using asynchronous code with these frameworks, is that the framework will not wait for your promises to finish.

The solution is to use the Moebius\Loop::await($promise) function. As long as all the code that is asynchronous is written to use Moebius\Loop directly, or written for either React or Amp - then you can use Moebius\Loop to resolve the promise.

<?php
namespace App\Http\Controllers;
 
use Moebius\Loop;
use App\Http\Controllers\Controller;
use App\Models\User;
use App\Models\Profile;
 
class UserController extends Controller
{
    public function show($id)
    {
        /**
         * Go get a performance boost:
         *
         * We MUST use async functions which return a promise,
         * and internally use the event-loop API to wait for
         * IO resources to become readable or writable.
         */
        $user = User::asyncFindOrFail($id);
        $profile = Profile::asyncFindOrFail($id);

        /**
         * Also we SHOULD send off as many async calls as possible
         * before using the `Loop::await()` function to resolve
         * these promises.
         *
         * Both promises we created above will be running while you
         * await the `$user` promise. The `$profile` promise may
         * even finish first - but that does not matter below:
         */
        return view('user.profile', [
            'user' => Loop::await($user),
            'profile' => Loop::await($profile),
        ]);
    }
}

As you can see, it is easy to use asynchronous code within any framework.

API reference

`Moebius\Loop::getTime()`

Get the current event loop time. This is a time indicating a number of seconds from an arbitrary point in time.

`Moebius\Loop::await(object $promise, float $timeout=null): mixed`

Run the event loop until the promise resolves or the timeout is reached.

`Moebius\Loop::run(Closure $shouldResumeFunc=null): void`

Run the event loop until Moebius\Loop::stop() is called. If a callback is provided, the loop will keep running until the callback returns a falsey value.

`Moebius\Loop::delay(float $time, Closure $callback): Closure`

Run the callback after $time seconds have passed. The returned callback will abort the timer.

`Moebius\Loop::interval(float $interval, Closure $callback): Closure`

Run the callback after $interval seconds have passed, and keep repeating the callback every $interval second. The returned callback will abort the interval.

`Moebius\Loop::readable(resource $resource, Closure $callback): Closure`

Run the callback on every tick as long as reading from the stream resource will not block. This can also be used to accept new connections on a server socket. The returned callback will abort watching the stream.

`Moebius\Loop::writable(resource $resource, Closure $callback): Closure`

Run the callback on every tick as long as writing to the stream resource will not block. The returned callback will abort watching the stream.

`Moebius\Loop::read(resource $resource, Closure $callback): Closure`

Read a chunk of data from the stream resource and call the $callback with the chunk of data that was read. This function will stop as soon as EOF is called, unless the returned callback is called to abort the read operation first.

`Moebius\Loop::signal(int $signalNumber, Closure $callback): Closure`

Run the callback whenever a signal is received by the process. The callback will continue to be called every time the signal is received, until the returned callback is invoked.

Example

A primitive example to illustrate how to write asynchronous code with Moebius\Loop.

This code will run with both Amp and React, and if you are not using one of these in a more classic environment such as Laravel or Symfony.

<?php
require('vendor/autoload.php');

/**
 * This function returns a Promise about something that will
 * be available eventually. It will immediately return a Promise
 * object which is a *promise about a future value*.
 */
function async_read_file(string $filename) {
    return new Moebius\Promise(function($ready, $failure) use ($filename) {
        // Open the file in read non-blocking mode
        $fp = fopen($filename, 'rn');

        // Wait for the file to become readable
        Moebius\Loop::readable($fp, function($fp) use ($ready) {

            // Call the $ready callback with the value
            $ready(stream_get_contents($fp));

            // Close the file
            fclose($fp);

        });
    });    
}

/**
 * Now we will read two files in parallel using our above function.
 */
$file1 = async_read_file('file-1.txt');
$file2 = async_read_file('file-2.txt');

/**
 * ALTERNATIVE 1
 * 
 * The traditional way of waiting for results from a promise is via 
 * the "then" method. This can lead to the well known "callback hell".
 */
$file1->then(function($contents) {
    echo "FILE 1: ".$contents."\n\n";
}, function($error) {
    echo "Failed to read file 1\n";
});
$file2->then(function($contents) {
    echo "FILE 2: ".$contents."\n\n";
}, function($error) {
    echo "Failed to read file 1\n";
});


/**
 * ALTERNATIVE 2
 *
 * A much easier approach to waiting for promises is to use the
 * `Moebius\Loop::await()` function. It will block your application,
 * while allowing promises to run - until the promise is fulfilled
 * or rejected.
 */
echo "FILE 1: ".Moebius\Loop::await($file1);
echo "FILE 2: ".Moebius\Loop::await($file2);

The entire API

Moebius\Loop::defer(callable $callback) will schedule callback to be executed next.

Moebius\Loop::queueMicrotask(callable $callback) will schedule a callback to be executed as soon as possible - before any deferred callbacks.

Moebius\Loop::delay(float $time, callable $callback): EventHandle will schedule a callback to be executed later.

Moebius\Loop::readable(resource $fd, callable $callback): EventHandle will schedule a callback to be executed whenever $fd becomes readable.

Moebius\Loop::writable(resource $fd, callable $callback): EventHandle will schedule a callback to be executed whenever $fd becomes writable.

Moebius\Loop::signal(int $signum, callable $callback): EventHandle will schedule a callback to be executed whenever the application receives a signal.

Moebius\Loop::run(callable $keepRunningFunc=null): void will run the event loop until the $keepRunningFunc returns false or the event loop is empty.

EventHandle class

When subscribing to events (IO, timer, interval or signal) you will receive an EventHandle class. This handle can be used to suspend or cancel the event listener.

Example:

    $readable = Moebius\Loop::readable($fp, function($fp) {
        // read stream
    });

    // Disable listening for events
    $readable->suspend();

    // Enable listening for events
    $readable->resume();

    // Cancel listening for events (can't be resumed)
    $readable->cancel();

moebius / loop

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