Task Tracker

A library for tracking long-running tasks in PHP (when a simple progress bar isn't enough)

At a Glance:

• Reports on memory usage and a number of progress statistics during long-running tasks
• Useful for long-running processes where a large number of small jobs are executed
• Event-driven architecture using the Symfony Event-Dispatcher Component
  • Can report on task progress to any EventSubscriberInterface
• Provides built-in utilities for reporting task progress:
  • Symfony Console Progress Bar
  • Symfony Console Running Log of Task Messages
  • Sending Task Progress to PSR-3 Compatible Loggers

For example, you may want to display a progress bar on the console during execution of a task, but also send periodic snapshots of the state of the system to Monolog while a task is executing. Using a single Tracker object, you can accomplish both of these goals:

use Symfony\Component\Console\Output\ConsoleOutput;
use Symfony\Component\Console\Output\OutputInterface;
use TaskTracker\Subscriber\SymfonyConsoleLog;
use TaskTracker\Tracker;
use TaskTracker\Tick;
use TaskTracker\Subscriber\SymfonyConsoleProgress;
use TaskTracker\Subscriber\Psr3Logger;
use Monolog\Logger as MonologLogger;

require_once __DIR__ . '/vendor/autoload.php';

$consoleOutput = new ConsoleOutput(OutputInterface::VERBOSITY_DEBUG);

// Setup subscribers
$subscribers = [
    // new SymfonyConsoleProgress($consoleOutput), // <-- This outputs a standard Symfony Console Progress Bar
    new SymfonyConsoleLog($consoleOutput),         // <-- This outputs a running log of task messages
    new Psr3Logger(new MonologLogger('logger'))    // <-- This logs events to a standard Monolog Logger
];

// Create a tracker for a job with 100 items
$tracker = Tracker::build($subscribers, 500);

$tracker->start("Let's go");
for ($i = 0; $i < 500; $i++) {
    usleep(10000);
    $tracker->tick();
}
$tracker->finish("All done");

Installation

Install via Composer:

composer require caseyamcl/tasktracker:~2.0

Install manually:

1. Download the source from http://github.com/caseyamcl/tasktracker.
2. Include the src/TaskTracker folder in your code using a PSR-4 compatible autoloader.

Usage

To track a task, create an instance of the Tracker class:

use TaskTracker\Tracker;

// Instantiate a tracker to track 100 items
$tracker = new Tracker(100);

You can omit the number of items if you are working with an unknown number:

$tracker = new Tracker();

The Tracker class creates its own EventDispatcher, but you can optionally inject your own if you need to:

$dispatcher = new \Symfony\Component\EventDispatcher\EventDispatcher();

$tracker = new Tracker(100, $dispatcher);
// ..or..
$tracker = new Tracker(Tracker::UNKNOWN, $dispatcher);

To start tracking, simply call the Tracker::start() method:

// Start the tracker
$tracker->start('optional starting message');

For every element you process, call the Tracker::tick() method until you are done:

// Tick
$tracker->tick();

There are three types of Ticks: Success (default), Fail, and Skip:

use Tracker\Tick;

$tracker->tick(Tick::SUCCESS);
$tracker->tick(Tick::FAIL);
$tracker->tick(Tick::SKIP);

You can also supply an optional message:

$tracker->tick(Tick::SUCCESS, 'Things are going well.');
$tracker->tick(Tick::FAIL,    'Crud.  Something went wrong');
$tracker->tick(Tick::SKIP,    'Skipping this record for whatever reason');

You can add custom data to the Tick in the form of an array:

$tracker->tick(Tick::SUCCESS, 'Things are going well.', ['foo' => 'bar', 'baz' => 'biz]);

And, you can increment by more than one item at a time:

// Increment by 5 items
$tracker->tick(Tick::SUCCESS, '', [], 5);

// Three items failed
$tracker->tick(Tick::FAIL, 'Something went wrong', [], 3);

When you are done, call the Tracker::finish() method:

$tracker->finish('Optional finish manage');

Or, if things go wrong during processing, you can abort:

$tracker->abort('Optional abort message');

The class contains a few helper methods, too:

// Have we started processing yet?
$tracker->isRunning();

// Get the last tick (instance of \Tracker\Tick class)
$tracker->getLastTick();

// Get the status of the process as an int (Tracker::NOT_STARTED, Tracker::RUNNING, Tracker::FINISHED, or Tracker::ABORTED)
$tracker->getStatus();

// Get the number of items processed thus far
$tracker->getNumProcessedItems();

// Get only the number of failed items (works with SUCCESS and SKIP too)
$tracker->getNumProcessedItems(Tick::FAIL);

// Get the time started (in microseconds)
$tracker->getStartTime();

You can use the Tracker:run($iterator, $callback) method for cleaner syntax.
The $iterator value must be an instance of \Traversable; arrays are not accepted, but ArrayIterator objects will work:

$iterator = new \ArrayIterator(['a', 'b', 'c']);

// This code is the equivalent of...
$tracker->run($iterator, function(Tracker $tracker, $item) {
    // work on a single item
    $tracker->tick();
});

//...this code:
$tracker->start();
foreach ($iterator as $item) {
    // work on a single item
    $tracker->tick();
}
$tracker->finish();    
   

Subscribers

The Tracker class isn't very useful on its own without event subscribers to listen for tracker tick events. There are a few subscribers bundled with this library:

• TaskTracker\Subscriber\Psr3Logger - Logs Tracker events to any PSR-3 Logger
• TaskTracker\Subscriber\SymfonyConsoleLog - Logs Tracker events to a Symfony console, each event on its own line.
• TaskTracker\Subscriber\SymfonyConsoleProgress - Logs tracker events to a Symfony console progress bar indicator.

You can add event subscribers to the Tracker by calling the Tracker::addSubscriber() method:

$tacker = new Tracker(100);
$tracker->addSubscriber(new SymfonyConsoleLog($output));

If you know what subscribers you will use ahead of time, you can use the Tracker::build() method for convenience:

$subscribers = [new SymfonyConsoleLog($output), new SomeOtherSubscriber()];
$tracker = Tracker::build(100, $subscribers);

Example

As an example, suppose you are creating a Symfony Console Command, and you want to show a progress bar for some task and also log events as they occur:

use TaskTracker\Tracker;
use TaskTracker\Tick;
use TaskTracker\Subscriber\SymfonyConsoleProgress;
use Symfony\Component\Console\Command\Command;

/**
 * My Symfony Command
 */
class MyCommand extends Command
{
    protected function configure()
    {
        $this->setName('example');
        $this->setDescription("Demonstrate TaskTracker");
    }
   
    protected function execute(InputInterface $input, OutputInterface $output)
    {
        $numItems = 10;
    
        // Build Task Tracker with Symfony Console Progress Bar subscriber
        $tracker = Tracker::build([new SymfonyConsoleProgress($output)], $numItems);
        
        // Add a Monolog Listener after Tracker construction
        $monolog = new \Monolog\Logger(/* some handlers */);
        $tracker->addSubscriber(new Psr3Logger($monolog));
        
        // You can also add Event Listeners directly
        $tracker->getDispatcher()->addListener(\Tracker\Events::TRACKER_TICK, function(\Tracker\Tick $tick) {
            // do something...
        });
        
        // Tracker::start() is technically optional; if not called, it will automatically
        // be called upon the first Tick
        $tracker->start("Let's go!");
        
        // The SymfonyConsoleProgress listener will output a progress bar while the logger will log events
        for ($i = 0; $i < 10; $i++) {
            $tracker->tick(\Tick::SUCCESS, "On item: " . $i);
            sleep(1);
        }
        
        // Tracker::start(), Tracker::tick(), Tracker::abort(), and Tracker::finish() all return
        // a \Tracker\Report object.
        $report = $tracker->finish('All done!');
        
        $output->writeln(sprintf("All Done!  <info>%s</info> items processed", $report->getNumTotalItems()));
    }
}

Custom Subscribers

TaskTracker uses the Symfony EventDispatcher library, so any Symfony-compatible event listener can be used.

There are four events you can listen for:

• TaskTracker\Events::TRACKER_START
• TaskTracker\Events::TRACKER_TICK
• TaskTracker\Events::TRACKER_FINISH
• TaskTracker\Events::TRACKER_ABORT

All four events dispatch an instance of the TaskTracker\Tick class. Your subscribers/listeners should accept an object of that class as its parameter:

use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use TaskTracker\Tick;

/**
 * Listen for Tracker Events
 */
class MyEventSubs