batch.inc

<?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;
}

/**
 * Renders the batch processing page based on the current state of the batch.
 *
 * @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':
            // Display the full progress page on startup and on each additional
            // non-JavaScript iteration.
            $output = _batch_progress_page();
            break;
        case 'do':
            // JavaScript-based progress page callback.
            _batch_do();
            break;
        case 'do_nojs':
            // Non-JavaScript-based progress page.
            $output = _batch_progress_page();
            break;
        case 'finished':
            $output = _batch_finished();
            break;
    }
    return $output;
}

/**
 * Does one execution pass with JavaScript and returns progress to the browser.
 *
 * @see _batch_process()
 */
function _batch_do() {
    // Perform actual processing.
    list($percentage, $message) = _batch_process();
    drupal_json_output(array(
        'status' => TRUE,
        'percentage' => $percentage,
        'message' => $message,
    ));
}

/**
 * Outputs a batch processing page.
 *
 * @see _batch_process()
 */
function _batch_progress_page() {
    $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(
        // Redirect through a 'Refresh' meta tag if JavaScript is disabled.
'#prefix' => '<noscript>',
        '#suffix' => '</noscript>',
        '#tag' => 'meta',
        '#attributes' => array(
            'http-equiv' => 'Refresh',
            'content' => '0; URL=' . $url,
        ),
    );
    drupal_add_html_head($element, 'batch_progress_meta_refresh');
    // Adds JavaScript code and settings for clients where JavaScript is enabled.
    $js_setting = array(
        'batch' => array(
            'errorMessage' => $current_set['error_message'] . '<br />' . $batch['error_message'],
            'initMessage' => $current_set['init_message'],
            'uri' => $url,
        ),
    );
    drupal_add_js($js_setting, 'setting');
    drupal_add_library('system', 'drupal.batch');
    return theme('progress_bar', array(
        'percent' => $percentage,
        'message' => $message,
    ));
}

/**
 * Processes 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();
    }
}

/**
 * Formats the percent completion for a batch set.
 *
 * @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 $current represents the
 *   fraction of the operation that has been completed.
 *
 * @return
 *   The properly formatted percentage, as a string. We output percentages
 *   using the correct number of decimal places so that we never print "100%"
 *   until we are finished, but we also never print more decimal places than
 *   are meaningful.
 *
 * @see _batch_process()
 */
function _batch_api_percentage($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;
}

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

/**
 * Retrieves 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;
    }
}

/**
 * Ends 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 . '/' . $batch_set['file'];
            }
            if (is_callable($batch_set['finished'])) {
                $queue = _batch_queue($batch_set);
                $operations = $queue->getAllItems();
                call_user_func($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)) {
                $queue->deleteQueue();
            }
        }
        // Clean-up the session. Not needed for CLI updates.
        if (isset($_SESSION)) {
            unset($_SESSION['batches'][$batch['id']]);
            if (empty($_SESSION['batches'])) {
                unset($_SESSION['batches']);
            }
        }
    }
    $_batch = $batch;
    $batch = NULL;
    // Redirect if needed.
    if ($_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: Stores the current batch data for the next request.
 *
 * @see _batch_page()
 * @see drupal_register_shutdown_function()
 */
function _batch_shutdown() {
    if ($batch = batch_get()) {
        db_update('batch')->fields(array(
            'batch' => serialize($batch),
        ))
            ->condition('bid', $batch['id'])
            ->execute();
    }
}