/**
* Execute a callback when a stream resource becomes writable.
* Returned Generators are run as coroutines. Failures of the coroutine are forwarded to the loop error handler.
*
* @see \Interop\Async\Loop::onWritable()
*
* @param resource $stream The stream to monitor.
* @param callable(string $watcherId, resource $stream, mixed $data) $callback The callback to execute.
* @param mixed $data
*
* @return string Watcher identifier.
*/
function onWritable($stream, callable $callback, $data = null) : string
{
return Loop::onWritable($stream, function ($watcherId, $stream, $data) use($callback) {
$result = $callback($watcherId, $stream, $data);
if ($result instanceof \Generator) {
rethrow(new Coroutine($result));
}
}, $data);
}
