Easy-to-use threading library providing all basic features to run your code in parallel mode. All you need to have installed: pcntl and posix extensions.

1. Structure
   • What is a Threadable?
   • What is a Worker?
     • How to create your Worker
   • What is a WorkersPool?
2. How to use
   • One worker
   • Few workers with WorkerPool
3. API
   • Worker secrets and important methods
   • WorkersPool features
4. Predefined workers
   • DownloadWorker
5. Use cases

Threadable - is a trait for adding fork'ing functionality to any class. It's used in Worker class.

Worker - is a basic class for any worker. It is composed of two substances (physically, stored in one class, but providing different functionalities):

1. A Worker - a separate thread, running main worker code.
2. A Worker - manipulation manager for the first item.

The all you need it to inherit Worker class (full name is wapmorgan\Threadable\Worker) and redefine onPayload($data) public method.

For example:

use wapmorgan\Threadable\Worker;
class SleepingWorker extends Worker
{
    public function onPayload($data)
    {
        echo 'I have started at '.date('r').PHP_EOL;
        sleep(3);
        echo 'I have ended at '.date('r').PHP_EOL;
    }
}

WorkersPool (wapmorgan\Threadable\WorkersPool) - is a container for Worker's, intended for handling similar tasks. It takes care of all maintenance, payload dispatching and life-cycle of workers. Allows you change the size of the pool dynamically and other useful stuff.

If you just need to parallel some work and do it in another thread, you can utilize just Worker class without any other dependencies.

To use it correctly you need to understand the life-cycle of worker:

1. Worker starts in another thread. To do this call start().
2. Worker accepts new payload and starts working on it. Really, manager of worker send payload via local socket. Worker thread starts working on it and returns result of work on finish via the same socket. To do this call sendPayload($data).
3. Worker manager checks if worker thread has done and read result of work. To do this call checkForFinish().
4. Worker stops or being killed by stop() or kill() methods respectively.
5. Worker manager checks if worker thread has finished and marks itself terminated. To do this call checkForTermination().

Background work happens in 2 step, where worker thread runs onPayload($data) method of class with actual payload.

To summarize, this is an example of downloading file in another thread with real-time displaying of progress:

Settings and structures

// Implement class-downloader
class DownloadWorker extends Worker
{
    public function onPayload($data)
    {
        echo 'Started '.$data[0].' into '.$data[2].PHP_EOL;
        copy($data[0], $data[2]);
    }
}

// supplementary function, just to avoid hand-writing of file sizes
function remote_filesize($path)
{
    $fp = fopen($path, 'r');
    $inf = stream_get_meta_data($fp);
    fclose($fp);
    foreach($inf["wrapper_data"] as $v) {
        if (stristr($v,"content-length")) {
            $v = explode(":",$v);
            return (int)trim($v[1]);
        }
    }
}

// our function to print actual status of downloads
function show_status(&$files)
{
    foreach ($files as $i => $file) {
        if (file_exists($file[2])) {
            clearstatcache(true, $file[2]);
            $downloaded_size = filesize($file[2]);
            if ($downloaded_size == $file[1]) {
                echo $file[0].' downloaded'.PHP_EOL;
                unset($files[$i]);
                unlink($file[2]);
            } else if ($downloaded_size === 0) {
                // echo $file[0].' in queue'.PHP_EOL;
            } else  {
                echo $file[0].' downloading '.round($downloaded_size * 100 / $file[1], 2).'%'.PHP_EOL;
            }
        }
    }
}

// list of files to be downloaded
$file_sources = ['https://yandex.ru/images/today?size=1920x1080', 'http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip'];
// process of remote file size detection and creation temp local file for this downloading
$files = [];
foreach ($file_sources as $file_to_download) {
    $file_size = remote_filesize($file_to_download);
    $output = tempnam(sys_get_temp_dir(), 'thrd_test');
    $files[] = [$file_to_download, $file_size, $output];
}

Real work

// construct and start new worker
$worker = new DownloadWorker();
$worker->start();
// add files to work queue
foreach ($files as $file) {
    echo 'Enqueuing '.$file[0].' with size '.$file[1].PHP_EOL;
    $worker->sendPayload([$file]);
}

// main worker thread loop
while ($worker->state !== Worker::TERMINATED) {
    // Worker::RUNNING state indicates that worker thread is still working over some payload
    if ($worker->state == Worker::RUNNING) {

        // prints status of all files
        show_status($files);
        // call check for finishing all tasks
        $worker->checkForFinish();
        usleep(500000);
    }
    // Worker::IDLE state indicates that worker thread does not have any work right now
    else if ($worker->state == Worker::IDLE) {
        echo 'Ended. Stopping worker...'.PHP_EOL;
        // we don't need worker anymore, just stop it
        $worker->stop();
        usleep(500000);
    }
    // Worker::TERMINATING state indicates that worker thread is going to be stopped and can't be used to process data
    else if ($worker->state == Worker::TERMINATING) {
        echo 'Wait for terminating ...'.PHP_EOL;
        // just to set Worker::TERMINATED state
        $worker->checkForTermination();
        usleep(500000);
    }
}

Result:

Enqueuing https://yandex.ru/images/today?size=1920x1080 with size 343103
Enqueuing http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip with size 52693477
Started https://yandex.ru/images/today?size=1920x1080 into /tmp/thrd_test0Y3i3k
Started http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip into /tmp/thrd_testrwwYiE
https://yandex.ru/images/today?size=1920x1080 downloaded
http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip downloading 28.89%
http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip downloading 66.06%
http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip downloaded
Ended. Stopping worker...
Wait for terminating ...

This code equipped with a lot of comments, but you can simplify this example if you don't need to re-use worker when all your work is done. You can replace this huge loop with a smaller one:

// loops works only when worker is running.
// just to show information about downloaded files
while ($worker->state == Worker::RUNNING) {
    show_status($files);
    $worker->checkForFinish();
    usleep(500000);
}
// when thread is in idle state, just stop right now (`true` as 1st argument forces it to send stop command and wait it termination).
$worker->stop(true);

Result:

Enqueuing https://yandex.ru/images/today?size=1920x1080 with size 343103
Enqueuing http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip with size 52693477
Started https://yandex.ru/images/today?size=1920x1080 into /tmp/thrd_testbGsRBp
Started http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip into /tmp/thrd_testv0E5Qy
https://yandex.ru/images/today?size=1920x1080 downloaded
http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip downloading 17.4%
http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip downloading 36.82%
http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip downloading 55.95%
http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip downloading 76%
http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip downloading 95.05%
http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip downloaded

But what if you need do few jobs simultaneously? You can create few instances of your worker, but it will be pain in the a$$ to manipulate and synchronize them. In this case you can use WorkerPool, which takes care of following this:

1. Start new workers at the beginning.
2. Dispatch your payload when you call sendData to any idle worker*.
3. Create new workers or delete redundant workers when you change poolSize.
4. Accept result of workers when they done and marks them as idle.
5. Monitor all worker threads and count idle, running, active (idle or running) workers. Provides interfaces to acquire this information.
6. Stop all workers when WorkerPool object is being destructed (via unset() or when script execution is going down).
7. *Can work in dataOverhead-mode. This mode enables sending extra payload to workers even when are already working on any task. If in this mode you sent few payloads to worker, it will not switch to Worker::IDLE state until all passed payloads have been processed.
8. Provide interface to appoint progress trackers and run them periodically until all threads become in Worker::IDLE state.

Rich feature-set, right?! Let's rewrite our downloader with 2 threads to speed-up downloading.

The Settings and structures block of code remains the same, but for demonstating purposes let's use two big files:

// ...
$file_sources = ['http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip', 'http://soft.eurodir.ru/test-speed-100Mb.bin'];
// ...

We need to update only code working with threads.

// create pool with downloading-workers
$pool = new WorkerPool('DownloadWorker');
// use only 2 workers (this is enough for our work)
$pool->setPoolSize(2);

// dispatch payload to workers. Notice! WorkerPool uses sendData() method instead of sendPayload().
foreach ($files as $file) {
    echo 'Enqueuing '.$file[0].' with size '.$file[1].PHP_EOL;
    $pool->sendData([$file]);
}

// register tracker, which should be launched every 0.5 seconds.
// This method will hold the execution until all workers finish their work and go in Worker::IDLE state
$pool->waitToFinish([
    '0.5' => function ($pool) use (&$files) {
        show_status($files);
    }]
);

Result:

Enqueuing http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip with size 52693477
Enqueuing http://soft.eurodir.ru/test-speed-100Mb.bin with size 102854656
Started http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip into /tmp/thrd_testchcHBK
Started http://soft.eurodir.ru/test-speed-100Mb.bin into /tmp/thrd_testt6dyJa
http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip downloading 23.26%
http://soft.eurodir.ru/test-speed-100Mb.bin downloading 1.3%
http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip downloading 47.08%
http://soft.eurodir.ru/test-speed-100Mb.bin downloading 3.08%
http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip downloading 72.62%
http://soft.eurodir.ru/test-speed-100Mb.bin downloading 5.66%
http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip downloading 98.7%
http://soft.eurodir.ru/test-speed-100Mb.bin downloading 8.05%
http://hosting-obzo-ru.1gb.ru/hosting-obzor.ru.zip downloaded
http://soft.eurodir.ru/test-speed-100Mb.bin downloading 19.15%
http://soft.eurodir.ru/test-speed-100Mb.bin downloading 31.31%
http://soft.eurodir.ru/test-speed-100Mb.bin downloading 43.69%
http://soft.eurodir.ru/test-speed-100Mb.bin downloading 56.87%
http://soft.eurodir.ru/test-speed-100Mb.bin downloading 71.95%
http://soft.eurodir.ru/test-speed-100Mb.bin downloading 87.56%

As you can see, we got few improvements:

1. Our code became smaller and clearer.
2. We can run as many workers as we need.
3. We don't take care of worker termination anymore. Let WorkerPool do it for us.

• stop($wait = false) - sends stop command to worker thread. It uses SIGTERM signal to allow worker thread finish work correctly and don't lose any data. If $wait = true, holds the execution until the worker is down.
• kill($wait = false) - sends stop command to worker thread. It uses SIGKILL signal and not recommended except special cases, because it simply kills the worker thread and it loses all data being processed in that moment. If $wait = true, holds the execution until the worker is down.

Warning about worker re-using! You can't restart a worker that has been terminated (with stop() or kill()), you need to create new worker and start it with start().

• countIdleWorkers(): integer - returns number of workers that are in Worker::IDLE state.

• countRunningWorkers(): integer - returns number of workers that are in Worker::RUNNING state.

• countActiveWorkers(): integer - returns number of workers that are either in Worker::RUNNING or Worker::IDLE states.

• enableDataOverhead() - enables dataOverhead-mode.

• sendData($data, $wait = false): null|boolean - dispatches payload to any free worker. Behavior depends on dataOverhead feature status:

  • When dataOverhead is disabled and $wait = false (by default), this method returns null when no free workers available or boolean with status of dispatching (true/false).
  • When dataOverhead is disabled (by default) and $wait = true, this method will hold the execution of the script until any worker became free, dispatch your payload to it and return the status of dispatching (true/false).
  • When dataOverhead is enabled, this method will dispatch your payload to any free worker. If there's not free workers, it will put new tasks in workers internal queues, which will be processed. This method uses fair distribution between all workers (so you can be sure that 24 tasks will be distributed between 6 workers as 4 per worker).

• waitToFinish(array $trackers = null)

As you've seen in examples, we created a downloading worker. But there is no need for this, we could use predefined DownloadWorker which does the same.

• Full path: wapmorgan\Threadable\DownloadWorker
• Description: downloads remote file and saves it on local server.
• Payload:
  • source - remote file url
  • targe - local file path

Examples of programs that can be built with Threadable:

• Media converters / encoders
• Data importers / exporters
• Bots for social networks / messengers
• Parsers / Scanners / Analyzers
• Servers (don't recommend, but if you want to reinvent the wheel)
• ...