phorge-phorge/src/infrastructure/daemon/workers/PhabricatorTaskmasterDaemon.php

<?php

final class PhabricatorTaskmasterDaemon extends PhabricatorDaemon {

  public function run() {
    $sleep = 0;
    do {
      $tasks = id(new PhabricatorWorkerLeaseQuery())
        ->setLimit(1)
        ->execute();

      if ($tasks) {
        foreach ($tasks as $task) {
          $id = $task->getID();
          $class = $task->getTaskClass();

          $this->log("Working on task {$id} ({$class})...");

          $task = $task->executeTask();
          $ex = $task->getExecutionException();
          if ($ex) {
            if ($ex instanceof PhabricatorWorkerPermanentFailureException) {
              $this->log("Task {$id} failed permanently.");
            } else if ($ex instanceof PhabricatorWorkerYieldException) {
              $this->log(pht('Task %s yielded.', $id));
            } else {
              $this->log("Task {$id} failed!");
              throw new PhutilProxyException(
                "Error while executing task ID {$id} from queue.",
                $ex);
            }
          } else {
            $this->log("Task {$id} complete! Moved to archive.");
          }
        }

        $sleep = 0;
      } else {
        $sleep = min($sleep + 1, 30);
      }

      $this->sleep($sleep);
    } while (!$this->shouldExit());
  }

}