Driver
Flow embark multiple drivers.
Coroutine
Drivers are useful to essentially provide asynchronous programming by using coroutines. Thus, this can be implemented in severals ways in most popular programming languages.
Coroutine are very similar to threads and provide concurrency but not parallelism. Advantage of using coroutine :
- this can be a preferred usage to thread for hard-realtime context.
- there is no need for synchronisation primitives such as mutexes, semaphore.
- it reduces the usage of system lock for sharing resources.
Amp Driver
To use Amp Driver, you have to require the library with composer
composer require amphp/amp
More documentation can be found https://amphp.org
Fiber Driver
More documentation can be found https://www.php.net/manual/fr/language.fibers.php
ReactPHP Driver
To use ReactPHP Driver, you have to require the library with composer
composer require react/async
More documentation can be found https://reactphp.org
Spatie Driver
To use Spatie Driver, you have to require the library with composer
composer require spatie/async
More documentation can be found https://github.com/spatie/async
Swoole Driver
To use Swoole Driver, you have to add the extension with your current running PHP
pecl install openswoole-22.0.0
More documentation can be found https://openswoole.com
Parallel Driver
To use Parallel Driver, you have to require the library with PECL
pecl install parallel
More documentation can be found https://www.php.net/manual/en/book.parallel.php
StreamSelect Driver
Native PHP Streams driver: cooperative Generators + stream_select().
Jobs that need overlapping I/O must be Generators and yield wait tokens (Fibers are not used):
use Flow\Driver\StreamSelectDriver;
$driver = new StreamSelectDriver();
// Inside a Generator job:
$ready = (yield $driver->waitReadable($stream, timeoutSeconds: 5.0));
$ready = (yield $driver->waitWritable($stream, timeoutSeconds: 5.0));
yield $driver->waitDelay(0.05);
stream_set_blocking() + stream_select() are the long-standing PHP async I/O primitives. The Driver only multiplexes readiness — HTTP, hashing, and persistence stay in Jobs. Pair with MaxIpStrategy($n) so at most $n IPs (and their stream waits) are in flight at a stage.
FiberDriver remains the default. Future PHP stream polling improvements (epoll/kqueue) may replace the mux without changing the wait-token API.
TrueAsync Driver
Experimental driver backed by the TrueAsync ext-async extension. FiberDriver remains the default.
Requires a custom PHP 8.6+ build with the extension enabled. Composer suggests it as an optional dependency:
# ext-async is not installable via Composer — build PHP with the TrueAsync fork
# See https://true-async.github.io/download.html
Check availability before instantiating the driver:
use Flow\Driver\TrueAsyncDriver;
if (TrueAsyncDriver::isSupported()) {
$driver = new TrueAsyncDriver();
}
Usage:
use Flow\Driver\TrueAsyncDriver;
use Flow\Flow\Flow;
use Flow\Ip;
$flow = (new Flow(
job: fn (int $n) => $n * 2,
driver: new TrueAsyncDriver(),
))->fn(fn (int $n) => $n + 1);
$flow(new Ip(21));
$flow->await();
Do not mix TrueAsyncDriver with FiberDriver in the same process — TrueAsync blocks userland Fiber while active.
A working example is available: php examples/flow-true-async.php
More documentation can be found https://true-async.github.io
Make your custom driver
You can make your custom driver by implementing Flow\DriverInterface