PHP Fibers - Async Examples Without External Dependencies

True asynchronous PHP I/O and HTTP without frameworks, extensions, or annoying code behemoths of libraries to install.

More examples to come - currently only HTTP GET and asynchronous MySQLi queries are shown.

Requirement

Must be running PHP 8.1 - that is when PHP Fibers were introduced.

Rundown of How It Works

Because the internal PHP functions (such as file_get_contents) are blocking by default, to implement asynchronous HTTP with PHP 8.1 Fibers, you must rebuild an HTTP request wrapper with native socket_ functions. Sockets in PHP can be set to be non-blocking. With this, a simple event loop can be created that can run all the Fibers in the event loop stack. If a socket isn't ready to be read (such as, the HTTP request is still pending) the Fiber will suspend and the next one can run.

This is all done in native PHP (version 8.1+) with no libraries. A language, such as JavaScript, has an internal event loop (which PHP does not) so that is why we have to create our own event loop (in the src/Async/Async.php file) to manage our Fibers and run them.

Async HTTP GET Example

For the full example, checkout the http-example.php file. A small snippet is shown below.

The classes Async and Http are provided in the classes folder of this repository.

$request1 = new Http("get", "http://example.com");
$request2 = new Http("get", "http://example.com");

foreach ([$request1, $request2] as $request){
	$child = new Fiber(function() use ($request){
		// ::await only blocks the _current_ thread. All other Fibers can still run
		Async::await($request->connect());
		Async::await($request->fetch());

		// Code here runs as soon as this URL is done fetching
		// and doesn't wait for others to finish :)
	});
	$child->start();
}

// Currently, ::run() is blocking the program and nothing below this
// call will run until the fibers above are finished.
// In the future, a top-level fiber can be introduced to make the entire
// application fully asynchronous. One is used in the example.php file
Async::run();

Async MySQL Query Example

For the full example, checkout the mysql-example.php file. A small snippet is shown below.

The classes Async and Http are provided in the classes folder of this repository.

// Initial connections are blocking. All queries are asynchronous.
// Spawn 10 connections in the pool.
$connectionsPool = new MySQLPool(10, "localhost", "root", "", "test");
$queryFiber = new Fiber(function() use ($connectionsPool){
	// ::await only blocks the _current_ thread. All other Fibers can still run
	$result = Async::await($connectionsPool->execute(
		"SELECT * FROM `test_table` WHERE `name` = :name",
		[':name'=>"nox7"],
	));
	print_r($result->fetch_assoc());
});
$child->start();
Async::run();

Result of the http-example.php run

Shown below from a run of http-example.php within an Apache server request, URLs connected and fetched as soon as they were ready, and not in linear order - but asynchronously.

The Future of This Repository

I will continue to implement standalone asynchronous methods for common waitable tasks. Currently HTTP is implemented with basic fetching of content from a URL. Moving forward, I will support different HTTP requests and abstractions, asynchronous MySQLi queries, and asynchronous local file I/O.

The goal is to have a location where you can get the smallest amount of open source code to perform asynchronous tasks in PHP. A framework like AmpPHP will always be superior if you would like to center your codebase around it, but my goal is to give you the option to leave a smaller footprint or simply made an addition to your existing codebase.

Want to spin up a quick Apache or nginx server on your Linux machine or via XAMPP for windows and grab a couple files for asynchronous MySQLi? That's what I want to give you the choice to do.