Producer-Consumer algorithm example using PHP's Parallel extension

hello-parallel.php

<?php

use parallel\{Runtime, Channel};

main($argv);

function main(array $argv)
{
    if (count($argv) !== 3) {
        echo "Type: hello-parallel.php <number-of-tasks> <maximum-time-of-sleep (in seconds)>" . PHP_EOL;
        echo "Example: hello-parallel.php 5 3" . PHP_EOL;
        die;
    } else {
        $numberOfTasks = intval($argv[1]);
        $maximumTimeOfSleep = intval($argv[2]);
        $t1 = microtime(true);
        parallelize($numberOfTasks, $maximumTimeOfSleep);
        $endTime = microtime(true) - $t1;
        echo PHP_EOL."Finished $numberOfTasks task(s) in {$endTime}s".PHP_EOL;
    }
}

function parallelize(int $numberOfTasks, int $maximumTimeOfSleep)
{
    $channel = new Channel();

    $taskIds = array_map(function () use ($maximumTimeOfSleep) {
        return $id = uniqid("task::");
    }, range(0, $numberOfTasks - 1));

    $timesToSleep = array_map(function () use ($maximumTimeOfSleep) {
        return rand(1, $maximumTimeOfSleep);
    }, $taskIds);

    $producer = new Runtime();
    $producerFuture = $producer->run(function (Channel $channel, array $timesToSleep) {
        foreach ($timesToSleep as $timeToSleep) {
            $channel->send($timeToSleep);
        }
    }, [$channel, $timesToSleep]);

    $consumerFutures = array_map(function (string $id) use ($channel) {
        $runtime = new Runtime();
        return $runtime->run(function (string $id, Channel $channel) {
            $timeToSleep = $channel->recv();
            echo "Hello from $id. I will sleep for $timeToSleep second(s).".PHP_EOL;
            sleep($timeToSleep);
            echo "$id slept for $timeToSleep second(s).".PHP_EOL;
            return $timeToSleep;
        }, [$id, $channel]);
    }, $taskIds);

    wait($consumerFutures);
    wait([$producerFuture]);
}

function wait(array $futures)
{
    return array_map(function ($future) {
        return $future->value();
    }, $futures);
}