hosting_queued.drush.inc in Hosting 6.2

Dispatcher daemon

This file is the heart of the dispatcher drush command. It implements most of the backend functionality.

File

queued/hosting_queued.drush.inc

<?php

/**
 * @file
 * Dispatcher daemon
 *
 * This file is the heart of the dispatcher drush command. It
 * implements most of the backend functionality.
 */

// This is necessary for signal handling to work
declare (ticks=1);

/**
 * Implementation of hook_drush_command().
 */
function hosting_queued_drush_command() {
  $items = array();
  $items['hosting-queued'] = array(
    'description' => 'Runs the tasks queue',
    'bootstrap' => DRUSH_BOOTSTRAP_DRUPAL_FULL,
    'drupal dependencies' => array(
      'hosting_queued',
    ),
  );
  return $items;
}

/**
 * Drush command to execute hosting tasks.
 */
function drush_hosting_queued() {
  if (function_exists('pcntl_signal')) {

    // reload the server on SIGHUP
    pcntl_signal(SIGHUP, 'hosting_queued_restart');
    pcntl_signal(SIGINT, 'hosting_queued_stop');
    pcntl_signal(SIGTERM, 'hosting_queued_stop');
  }

  // Set a nice high time limit, if we can:
  if (function_exists('set_time_limit')) {
    @set_time_limit(0);
  }

  // in some environments (e.g. in "productin") ENV is not actually
  // set (!) so try to guess from $_SERVER
  if (strpos(ini_get('variables_order'), 'E') === FALSE) {
    if (strpos(ini_get('variables_order'), 'S') === FALSE) {
      drush_log(dt('Neither $_ENV nor $_SERVER are available to set up proper environment inheritance; ensure E and/or S is set in your php.ini\'s "variables_order" setting.'), 'warning');
    }
    else {
      $_ENV = $_SERVER;
    }
  }
  $end_time = variable_get('hosting_queued_process_lifetime', 3600) + time();

  // Record the fact that we're running, so we can give some feedback in the
  // frontend.
  variable_set('hosting_queued_process_started', time());
  watchdog('hosting_queued', 'Started Hosting queue daemon, waiting for new tasks');
  while (TRUE) {

    // Should we terminate.
    if (time() > $end_time) {

      // Restart the daemon to recycle leaked memory
      hosting_queued_restart();
    }

    // Check if there was a database error, so we can recover gracefully if needed.
    // See: https://drupal.org/node/1992254.
    if (db_error()) {
      drush_log('Caught database error.', 'warning');
      $db = drush_convert_db_from_db_url($GLOBALS['db_url']);
      drush_log('Waiting for database to become available.', 'warning');
      do {

        // Give the database time to come back.
        sleep(1);

        // Check connection
        $connect = @mysqli_connect($db['host'], $db['username'], $db['password']);
        drush_log('.', 'warning');
      } while (!$connect);

      // Close connection
      mysqli_close($connect);
      drush_log('Restarting queue daemon.', 'warning');
      hosting_queued_restart();
    }
    else {

      // Get some tasks to run
      $tasks = @_hosting_get_new_tasks();
    }
    foreach ($tasks as $task) {

      // We sleep for a second just in case others want to run the task first.
      // This guards against other processes that want to add a hosting task
      // with arguments and run it immediately, they should be able to do this
      // without us getting in there first.
      // This is a workaround for http://drupal.org/node/1003536
      drush_log(dt('Found task to execute. Pausing before execution.'));
      sleep(1);

      // Execute the task in the backend
      drush_invoke_process('@self', 'hosting-task', array(
        $task->nid,
      ), array(
        'strict' => FALSE,
      ), array(
        'interactive' => TRUE,
      ));
      drush_log(dt('Finished executing task.'));

      // Delay for a configurable amount of time.
      $delay = variable_get('hosting_queued_post_task_delay', 0);
      if (!empty($delay)) {
        drush_log(dt('Going to sleep for @count seconds after completing task.', array(
          '@count' => $delay,
        )));
        sleep($delay);
      }

      // We're done with this task, this unset might help reduce memory usage.
      unset($task);

      // Should we terminate.
      if (time() > $end_time) {

        // Restart the daemon to recycle leaked memory
        hosting_queued_restart();
      }
    }

    // wait here only if we didn't process tasks
    // this is to avoid an infinite loop if there are no tasks in the queue
    if (!$tasks) {
      sleep(1);
    }
    if (drush_get_option('onetime')) {
      drush_log(dt("exiting after processing all tasks, as requested by --onetime"));
      break;
    }
    unset($tasks);
  }
}

/**
 * Handle interruption signals gracefully
 *
 * We do not want to interrupt children tasks, so we wait for them
 * before stopping.
 */
function hosting_queued_stop($signal) {
  watchdog('hosting_queued', 'Received signal @signal, waiting for children to die.', array(
    '@signal' => $signal,
  ));
  $status = NULL;
  pcntl_wait($status);
  watchdog('hosting_queued', 'Stopped daemon');
  exit($status);
}

/**
 * Restart the dispatcher to work around memory leaks
 */
function hosting_queued_restart($signal = NULL) {

  // If we received a singal, process it.
  if (!is_null($signal)) {
    watchdog('hosting_queued', 'Received signal @signal, waiting for children to die.', array(
      '@signal' => $signal,
    ));
    $status = NULL;
    pcntl_wait($status);
  }

  // We need the PCNTL extension to be able to auto restart.
  if (function_exists('pcntl_exec')) {
    $args = $_ENV['argv'];
    $drush = array_shift($args);

    // Strip sub-array to avoid warning "Array to string conversion"
    unset($_ENV['argv']);
    watchdog('hosting_queued', 'Restarting queue daemon with @drush @args.', array(
      '@drush' => $drush,
      '@args' => implode(" ", $args),
    ));
    pcntl_exec($drush, $args, $_ENV);
    watchdog('hosting_queued', 'Could not restart the queue daemon, aborting.', array(), WATCHDOG_ERROR);

    /* NOTREACHED */
  }
  else {
    watchdog('hosting_queued', 'PCNTL not installed, unable to auto-restart.', array(), WATCHDOG_WARNING);
  }

  // Explicit exit in case we're handling a signal
  exit(1);
}

/**
 * Get the proper way to call drush again.
 *
 * Note that unlike drush_find_drush() we return an array of parts, and we trim
 * the 'php' option of extra single quotes.
 *
 * @see drush_find_drush()
 */
function hosting_queued_drush_find_drush() {
  $php = drush_get_option('php');
  if (isset($php)) {
    $php = trim($php, "'");
    $drush = array(
      $php,
      realpath($_SERVER['argv'][0]),
      "--php='{$php}'",
    );
  }
  else {
    $drush = array(
      realpath($_SERVER['argv']['0']),
    );
  }
  return $drush;
}

Functions

Name	Description
drush_hosting_queued	Drush command to execute hosting tasks.
hosting_queued_drush_command	Implementation of hook_drush_command().
hosting_queued_drush_find_drush	Get the proper way to call drush again.
hosting_queued_restart	Restart the dispatcher to work around memory leaks
hosting_queued_stop	Handle interruption signals gracefully