PHP Asynchronous programming Using Amp event loop
Example
Amp harnesses Promises [another name for Awaitables] and Generators for coroutine creation.
require __DIR__ . '/vendor/autoload.php';
use Amp\Dns;
// Try our system defined resolver or googles, whichever is fastest
function queryStackOverflow($recordtype) {
$requests = [
Dns\query("stackoverflow.com", $recordtype),
Dns\query("stackoverflow.com", $recordtype, ["server" => "8.8.8.8"]),
];
// returns a Promise resolving when the first one of the requests resolves
return yield Amp\first($request);
}
\Amp\run(function() { // main loop, implicitly a coroutine
try {
// convert to coroutine with Amp\resolve()
$promise = Amp\resolve(queryStackOverflow(Dns\Record::NS));
list($ns, $type, $ttl) = // we need only one NS result, not all
current(yield Amp\timeout($promise, 2000 /* milliseconds */));
echo "The result of the fastest server to reply to our query was $ns";
} catch (Amp\TimeoutException $e) {
echo "We've heard no answer for 2 seconds! Bye!";
} catch (Dns\NoRecordException $e) {
echo "No NS records there? Stupid DNS nameserver!";
}
});
