The Promised Land

Handling asynchronous behaviour in PHP

Warren Seymour

warren@radify.io

@woogoose

Asynchronous PHP

• HHVM/Hack - async/await
• Guzzle - Promises
• React - Callbacks + Promises
• PHP 7+ (maybe?)

Callback Hell - Serial

step1('foo', function($result1) {
    
    // step2 depends on result of step1
    step2($resultOne, function($result2) {

        // Do something with result of step2
    });
});

Callback Hell - Parallel

$counter = 0;
$handler = function($result) use (&$counter) {
    $counter += 1;
    if ($counter === 2) {
        // Do something...
    }
};

doSomething('foo', $handler);
doSomethingElse('bar', $handler);

[spaghetti intensifies]

All hail the Promise

promiseMe('foo')
->then(function($result) {
    // do something with result
})
->otherwise(function($error) {
    // handle error
})
->always(function() {
    // clean up
});

Serial Calls

promiseMe('foo')
->then(function($result) {
    return promiseMe('bar');
})
->then(function($result2) {
    // do something with second result
});

Parallel Calls

use React\Promise;

Promise\all([
    promiseMe('foo'),
    promiseMe('bar')
])
->then(function($results) {
    // Do something with array of results
})->catch(function() {
    // Handle error immediately
});

Isn't this where we came in?

use React\Promise\Deferred;

function promiseMe($params) {
    $deferred = new Deferred();

    doSomething($params, function($result) use ($deferred) {
        $deferred->resolve($result);
    });

    return $deferred->promise();
}

What now?

• Async is may be coming to PHP
• Promises > Callbacks
• A powerful pattern to be aware of