batch.inc

  1. drupal
    1. 6
    2. 8
    3. 7

Batch processing API for processes to run in multiple HTTP requests.

Note that batches are usually invoked by form submissions, which is why the core interaction functions of the batch processing API live in form.inc.

See also

form.inc

batch_set()

batch_process()

batch_get()

Functions & methods

NameDescription
batch_loadLoads a batch from the database.
_batch_api_percentageHelper function for _batch_process(): returns the formatted percentage.
_batch_current_setReturn the batch set being currently processed.
_batch_doDo one execution pass in JavaScript-mode and return progress to the browser.
_batch_finishedEnd the batch processing.
_batch_next_setRetrieve the next set in a batch.
_batch_pageState-based dispatcher for the batch processing page.
_batch_processProcess sets in a batch.
_batch_progress_page_jsOutput a batch processing page with JavaScript support.
_batch_progress_page_nojsOutput a batch processing page without JavaScript support.
_batch_shutdownShutdown function; store the current batch data for the next request.
_batch_startInitialize the batch processing.
View source
<?php


/**
 * @file
 * Batch processing API for processes to run in multiple HTTP requests.
 *
 * Note that batches are usually invoked by form submissions, which is
 * why the core interaction functions of the batch processing API live in
 * form.inc.
 *
 * @see form.inc
 * @see batch_set()
 * @see batch_process()
 * @see batch_get()
 */

/**
 * Loads a batch from the database.
 *
 * @param $id
 *   The ID of the batch to load. When a progressive batch is being processed,
 *   the relevant ID is found in $_REQUEST['id'].
 * @return
 *   An array representing the batch, or FALSE if no batch was found.
 */
function batch_load($id) {
  $batch = db_query("SELECT batch FROM {batch} WHERE bid = :bid AND token = :token", array(
    ':bid' => $id,
    ':token' => drupal_get_token($id),
  ))->fetchField();
  if ($batch) {
    return unserialize($batch);
  }
  return FALSE;
}

/**
 * State-based dispatcher for the batch processing page.
 *
 * @see _batch_shutdown()
 */
function _batch_page() {
  $batch = &batch_get();

  if (!isset($_REQUEST['id'])) {
    return FALSE;
  }

  // Retrieve the current state of the batch.
  if (!$batch) {
    $batch = batch_load($_REQUEST['id']);
    if (!$batch) {
      drupal_set_message(t('No active batch.'), 'error');
      drupal_goto();
    }
  }

  // Register database update for the end of processing.
  drupal_register_shutdown_function('_batch_shutdown');

  // Add batch-specific CSS.
  foreach ($batch['sets'] as $batch_set) {
    if (isset($batch_set['css'])) {
      foreach ($batch_set['css'] as $css) {
        drupal_add_css($css);
      }
    }
  }

  $op = isset($_REQUEST['op']) ? $_REQUEST['op'] : '';
  $output = NULL;
  switch ($op) {
    case 'start':
      $output = _batch_start();
      break;

    case 'do':
      // JavaScript-based progress page callback.
      _batch_do();
      break;

    case 'do_nojs':
      // Non-JavaScript-based progress page.
      $output = _batch_progress_page_nojs();
      break;

    case 'finished':
      $output = _batch_finished();
      break;
  }

  return $output;
}

/**
 * Initialize the batch processing.
 *
 * JavaScript-enabled clients are identified by the 'has_js' cookie set in
 * drupal.js. If no JavaScript-enabled page has been visited during the current
 * user's browser session, the non-JavaScript version is returned.
 */
function _batch_start() {
  if (isset($_COOKIE['has_js']) && $_COOKIE['has_js']) {
    return _batch_progress_page_js();
  }
  else {
    return _batch_progress_page_nojs();
  }
}

/**
 * Output a batch processing page with JavaScript support.
 *
 * This initializes the batch and error messages. Note that in JavaScript-based
 * processing, the batch processing page is displayed only once and updated via
 * AHAH requests, so only the first batch set gets to define the page title.
 * Titles specified by subsequent batch sets are not displayed.
 *
 * @see batch_set()
 * @see _batch_do()
 */
function _batch_progress_page_js() {
  $batch = batch_get();

  $current_set = _batch_current_set();
  drupal_set_title($current_set['title'], PASS_THROUGH);

  // Merge required query parameters for batch processing into those provided by
  // batch_set() or hook_batch_alter().
  $batch['url_options']['query']['id'] = $batch['id'];

  $js_setting = array(
    'batch' => array(
      'errorMessage' => $current_set['error_message'] . '<br />' . $batch['error_message'],
      'initMessage' => $current_set['init_message'],
      'uri' => url($batch['url'], $batch['url_options']),
    ),
  );
  drupal_add_js($js_setting, 'setting');
  drupal_add_library('system', 'drupal.batch');

  return '<div id="progress"></div>';
}

/**
 * Do one execution pass in JavaScript-mode and return progress to the browser.
 *
 * @see _batch_progress_page_js()
 * @see _batch_process()
 */
function _batch_do() {
  // HTTP POST required.
  if ($_SERVER['REQUEST_METHOD'] != 'POST') {
    drupal_set_message(t('HTTP POST is required.'), 'error');
    drupal_set_title(t('Error'));
    return '';
  }

  // Perform actual processing.
  list($percentage, $message) = _batch_process();

  drupal_json_output(array('status' => TRUE, 'percentage' => $percentage, 'message' => $message));
}

/**
 * Output a batch processing page without JavaScript support.
 *
 * @see _batch_process()
 */
function _batch_progress_page_nojs() {
  $batch = &batch_get();

  $current_set = _batch_current_set();
  drupal_set_title($current_set['title'], PASS_THROUGH);

  $new_op = 'do_nojs';

  if (!isset($batch['running'])) {
    // This is the first page so we return some output immediately.
    $percentage       = 0;
    $message          = $current_set['init_message'];
    $batch['running'] = TRUE;
  }
  else {
    // This is one of the later requests; do some processing first.

    // Error handling: if PHP dies due to a fatal error (e.g. a nonexistent
    // function), it will output whatever is in the output buffer, followed by
    // the error message.
    ob_start();
    $fallback = $current_set['error_message'] . '<br />' . $batch['error_message'];
    $fallback = theme('maintenance_page', array('content' => $fallback, 'show_messages' => FALSE));

    // We strip the end of the page using a marker in the template, so any
    // additional HTML output by PHP shows up inside the page rather than below
    // it. While this causes invalid HTML, the same would be true if we didn't,
    // as content is not allowed to appear after </html> anyway.
    list($fallback) = explode('<!--partial-->', $fallback);
    print $fallback;

    // Perform actual processing.
    list($percentage, $message) = _batch_process($batch);
    if ($percentage == 100) {
      $new_op = 'finished';
    }

    // PHP did not die; remove the fallback output.
    ob_end_clean();
  }

  // Merge required query parameters for batch processing into those provided by
  // batch_set() or hook_batch_alter().
  $batch['url_options']['query']['id'] = $batch['id'];
  $batch['url_options']['query']['op'] = $new_op;

  $url = url($batch['url'], $batch['url_options']);
  $element = array(
    '#tag' => 'meta',
    '#attributes' => array(
      'http-equiv' => 'Refresh',
      'content' => '0; URL=' . $url,
    ),
  );
  drupal_add_html_head($element, 'batch_progress_meta_refresh');

  return theme('progress_bar', array('percent' => $percentage, 'message' => $message));
}

/**
 * Process sets in a batch.
 *
 * If the batch was marked for progressive execution (default), this executes as
 * many operations in batch sets until an execution time of 1 second has been
 * exceeded. It will continue with the next operation of the same batch set in
 * the next request.
 *
 * @return
 *   An array containing a completion value (in percent) and a status message.
 */
function _batch_process() {
  $batch       = &batch_get();
  $current_set = &_batch_current_set();
  // Indicate that this batch set needs to be initialized.
  $set_changed = TRUE;

  // If this batch was marked for progressive execution (e.g. forms submitted by
  // drupal_form_submit()), initialize a timer to determine whether we need to
  // proceed with the same batch phase when a processing time of 1 second has
  // been exceeded.
  if ($batch['progressive']) {
    timer_start('batch_processing');
  }

  if (empty($current_set['start'])) {
    $current_set['start'] = microtime(TRUE);
  }

  $queue = _batch_queue($current_set);

  while (!$current_set['success']) {
    // If this is the first time we iterate this batch set in the current
    // request, we check if it requires an additional file for functions
    // definitions.
    if ($set_changed && isset($current_set['file']) && is_file($current_set['file'])) {
      include_once DRUPAL_ROOT . '/' . $current_set['file'];
    }

    $task_message = '';
    // Assume a single pass operation and set the completion level to 1 by
    // default.
    $finished = 1;

    if ($item = $queue->claimItem()) {
      list($function, $args) = $item->data;

      // Build the 'context' array and execute the function call.
      $batch_context = array(
        'sandbox'  => &$current_set['sandbox'],
        'results'  => &$current_set['results'],
        'finished' => &$finished,
        'message'  => &$task_message,
      );
      call_user_func_array($function, array_merge($args, array(&$batch_context)));

      if ($finished >= 1) {
        // Make sure this step is not counted twice when computing $current.
        $finished = 0;
        // Remove the processed operation and clear the sandbox.
        $queue->deleteItem($item);
        $current_set['count']--;
        $current_set['sandbox'] = array();
      }
    }

    // When all operations in the current batch set are completed, browse
    // through the remaining sets, marking them 'successfully processed'
    // along the way, until we find a set that contains operations.
    // _batch_next_set() executes form submit handlers stored in 'control'
    // sets (see form_execute_handlers()), which can in turn add new sets to
    // the batch.
    $set_changed = FALSE;
    $old_set = $current_set;
    while (empty($current_set['count']) && ($current_set['success'] = TRUE) && _batch_next_set()) {
      $current_set = &_batch_current_set();
      $current_set['start'] = microtime(TRUE);
      $set_changed = TRUE;
    }

    // At this point, either $current_set contains operations that need to be
    // processed or all sets have been completed.
    $queue = _batch_queue($current_set);

    // If we are in progressive mode, break processing after 1 second.
    if ($batch['progressive'] && timer_read('batch_processing') > 1000) {
      // Record elapsed wall clock time.
      $current_set['elapsed'] = round((microtime(TRUE) - $current_set['start']) * 1000, 2);
      break;
    }
  }

  if ($batch['progressive']) {
    // Gather progress information.

    // Reporting 100% progress will cause the whole batch to be considered
    // processed. If processing was paused right after moving to a new set,
    // we have to use the info from the new (unprocessed) set.
    if ($set_changed && isset($current_set['queue'])) {
      // Processing will continue with a fresh batch set.
      $remaining        = $current_set['count'];
      $total            = $current_set['total'];
      $progress_message = $current_set['init_message'];
      $task_message     = '';
    }
    else {
      // Processing will continue with the current batch set.
      $remaining        = $old_set['count'];
      $total            = $old_set['total'];
      $progress_message = $old_set['progress_message'];
    }

    // Total progress is the number of operations that have fully run plus the
    // completion level of the current operation.
    $current    = $total - $remaining + $finished;
    $percentage = _batch_api_percentage($total, $current);
    $elapsed    = isset($current_set['elapsed']) ? $current_set['elapsed'] : 0;
    $values     = array(
      '@remaining'  => $remaining,
      '@total'      => $total,
      '@current'    => floor($current),
      '@percentage' => $percentage,
      '@elapsed'    => format_interval($elapsed / 1000),
      // If possible, estimate remaining processing time.
      '@estimate'   => ($current > 0) ? format_interval(($elapsed * ($total - $current) / $current) / 1000) : '-',
    );
    $message = strtr($progress_message, $values);
    if (!empty($message)) {
      $message .= '<br />';
    }
    if (!empty($task_message)) {
      $message .= $task_message;
    }

    return array($percentage, $message);
  }
  else {
    // If we are not in progressive mode, the entire batch has been processed.
    return _batch_finished();
  }
}

/**
 * Helper function for _batch_process(): returns the formatted percentage.
 *
 * @param $total
 *   The total number of operations.
 * @param $current
 *   The number of the current operation. This may be a floating point number
 *   rather than an integer in the case of a multi-step operation that is not
 *   yet complete; in that case, the fractional part of $current represents the
 *   fraction of the operation that has been completed.
 * @return
 *   The properly formatted percentage, as a string. We output percentages
 *   using the correct number of decimal places so that we never print "100%"
 *   until we are finished, but we also never print more decimal places than
 *   are meaningful.
 */
function _batch_api_percentage($total, $current) {
  if (!$total || $total == $current) {
    // If $total doesn't evaluate as true or is equal to the current set, then
    // we're finished, and we can return "100".
    $percentage = "100";
  }
  else {
    // We add a new digit at 200, 2000, etc. (since, for example, 199/200
    // would round up to 100% if we didn't).
    $decimal_places = max(0, floor(log10($total / 2.0)) - 1);
    do {
      // Calculate the percentage to the specified number of decimal places.
      $percentage = sprintf('%01.' . $decimal_places . 'f', round($current / $total * 100, $decimal_places));
      // When $current is an integer, the above calculation will always be
      // correct. However, if $current is a floating point number (in the case
      // of a multi-step batch operation that is not yet complete), $percentage
      // may be erroneously rounded up to 100%. To prevent that, we add one
      // more decimal place and try again.
      $decimal_places++;
    } while ($percentage == '100');
  }
  return $percentage;
}

/**
 * Return the batch set being currently processed.
 */
function &_batch_current_set() {
  $batch = &batch_get();
  return $batch['sets'][$batch['current_set']];
}

/**
 * Retrieve the next set in a batch.
 *
 * If there is a subsequent set in this batch, assign it as the new set to
 * process and execute its form submit handler (if defined), which may add
 * further sets to this batch.
 *
 * @return
 *   TRUE if a subsequent set was found in the batch.
 */
function _batch_next_set() {
  $batch = &batch_get();
  if (isset($batch['sets'][$batch['current_set'] + 1])) {
    $batch['current_set']++;
    $current_set = &_batch_current_set();
    if (isset($current_set['form_submit']) && ($function = $current_set['form_submit']) && function_exists($function)) {
      // We use our stored copies of $form and $form_state to account for
      // possible alterations by previous form submit handlers.
      $function($batch['form_state']['complete form'], $batch['form_state']);
    }
    return TRUE;
  }
}

/**
 * End the batch processing.
 *
 * Call the 'finished' callback of each batch set to allow custom handling of
 * the results and resolve page redirection.
 */
function _batch_finished() {
  $batch = &batch_get();

  // Execute the 'finished' callbacks for each batch set, if defined.
  foreach ($batch['sets'] as $batch_set) {
    if (isset($batch_set['finished'])) {
      // Check if the set requires an additional file for function definitions.
      if (isset($batch_set['file']) && is_file($batch_set['file'])) {
        include_once DRUPAL_ROOT . '/' . $batch_set['file'];
      }
      if (function_exists($batch_set['finished'])) {
        $queue = _batch_queue($batch_set);
        $operations = $queue->getAllItems();
        $batch_set['finished']($batch_set['success'], $batch_set['results'], $operations, format_interval($batch_set['elapsed'] / 1000));
      }
    }
  }

  // Clean up the batch table and unset the static $batch variable.
  if ($batch['progressive']) {
    db_delete('batch')
      ->condition('bid', $batch['id'])
      ->execute();
    foreach ($batch['sets'] as $batch_set) {
      if ($queue = _batch_queue($batch_set)) {
        $queue->deleteQueue();
      }
    }
  }
  $_batch = $batch;
  $batch = NULL;

  // Clean-up the session. Not needed for CLI updates.
  if (isset($_SESSION)) {
    unset($_SESSION['batches'][$batch['id']]);
    if (empty($_SESSION['batches'])) {
      unset($_SESSION['batches']);
    }
  }

  // Redirect if needed.
  if ($_batch['progressive']) {
    // Revert the 'destination' that was saved in batch_process().
    if (isset($_batch['destination'])) {
      $_GET['destination'] = $_batch['destination'];
    }

    // Determine the target path to redirect to.
    if (!isset($_batch['form_state']['redirect'])) {
      if (isset($_batch['redirect'])) {
        $_batch['form_state']['redirect'] = $_batch['redirect'];
      }
      else {
        $_batch['form_state']['redirect'] = $_batch['source_url'];
      }
    }

    // Use drupal_redirect_form() to handle the redirection logic.
    drupal_redirect_form($_batch['form_state']);

    // If no redirection happened, redirect to the originating page. In case the
    // form needs to be rebuilt, save the final $form_state for
    // drupal_build_form().
    if (!empty($_batch['form_state']['rebuild'])) {
      $_SESSION['batch_form_state'] = $_batch['form_state'];
    }
    $function = $_batch['redirect_callback'];
    if (function_exists($function)) {
      $function($_batch['source_url'], array('query' => array('op' => 'finish', 'id' => $_batch['id'])));
    }
  }
}

/**
 * Shutdown function; store the current batch data for the next request.
 */
function _batch_shutdown() {
  if ($batch = batch_get()) {
    db_update('batch')
      ->fields(array('batch' => serialize($batch)))
      ->condition('bid', $batch['id'])
      ->execute();
  }
}