gistfile1.txt

    protected $recursiveInvoker;

    protected function getRecursiveInvoker() {
        if ($this->recursiveInvoker instanceof RecursiveInvoker) {
            return $this->recursiveInvoker;
        }

        $this->recursiveInvoker = new RecursiveInvoker($this);
        return $this->recursiveInvoker;
    }

    public function chownRecursive($uid = -1, $gid = -1) {
        return $this->getRecursiveInvoker('chown', $uid, $gid);
    }

gistfile2.txt

<?php

namespace React\Filesystem;

class RecursiveInvoker {

    protected $node;

    public function __construct(Directory $node) {
        $this->node = $node;
    }

    public function execute($method, $args) {
        $deferred = new Deferred();

        $this->ls()->then(function($list) use ($deferred, $method, $args) {
            $this->filesystem->getLoop()->futureTick(function() use ($list, $deferred, $method, $args) {
                $this->iterateNode($list, $deferred, $method, $args);
            });
        });

        return $deferred->promise();
    }

    protected function iterateNode($list, $deferred, $method, $args) {
        $promises = [];

        foreach ($list as $node) {
            if ($node instanceof Directory) {
                $promises[] = call_user_func_array([$node, $method . 'Recursive'], $args);
            } else {
                $promises[] = call_user_func_array([$node, $method], $args);
            }
        }

        \React\Promise\all($promises)->then(function() use ($deferred, $method, $args) {
            call_user_func_array([$this, $method], $args)->then(function() use ($deferred) {
                $deferred->resolve();
            });
        });
    }
}