concurrency_with_cache.php

<?php
use GuzzleHttp\Promise\EachPromise;
use GuzzleHttp\Promise\FulfilledPromise;
use GuzzleHttp\Psr7\Response;
use Cache;

$users = ['one', 'two', 'three'];
$cache = new Cache();

$promises = (function () use ($users, $cache) {
  foreach ($users as $user) {
    
    // check cache is exist
    if ($cache->hasItem('cache_user_' . $user)) {
      $profile = $cache->getItem($user)->get();

      yield new FulfilledPromise($profile);
      continue;
  }
    // don't forget using generator
    yield $this->getAsync('https://api.demo.com/v1/users?username=' . $user)
      ->then(function (Response $response) use ($cache, $user) {
        
          $profile = json_decode($response->getBody(), true);
          // save to cache expiry to 300s
          $cache->put('cache_user_' . $user, $profile, $expiry = 300);

          return $profile;
      });
  }
})();
$eachPromise = new EachPromise($promises, [
  // how many concurrency we are use
  'concurrency' => 4,
  'fulfilled' => function ($profile) {
      // process object profile of user here
    },
  'rejected' => function ($reason) {
    // handle promise rejected here
  }
]);
$eachPromise->promise()->wait();