batch_example.module

<?php


/**
 * @file
 * Outlines how a module can use the Batch API.
 */

/**
 * @defgroup batch_example Example: Batch API
 * @ingroup examples
 * @{
 * Outlines how a module can use the Batch API.
 *
 * Batches allow heavy processing to be spread out over several page
 * requests, ensuring that the processing does not get interrupted
 * because of a PHP timeout, while allowing the user to receive feedback
 * on the progress of the ongoing operations. It also can reduce out of memory
 * situations.
 *
 * The @link batch_example.install .install file @endlink also shows how the
 * Batch API can be used to handle long-running hook_update_N() functions.
 *
 * Two harmless batches are defined:
 * - batch 1: Load the node with the lowest nid 100 times.
 * - batch 2: Load all nodes, 20 times and uses a progressive op, loading nodes
 *   by groups of 5.
 *
 * @see batch
 */

/**
 * Batch operation for batch 1: one at a time.
 *
 * This is the function that is called on each operation in batch 1.
 */
function batch_example_op_1($id, $operation_details, &$context) {
    // Simulate long process by waiting 1/50th of a second.
    usleep(20000);
    // Store some results for post-processing in the 'finished' callback.
    // The contents of 'results' will be available as $results in the
    // 'finished' function (in this example, batch_example_finished()).
    $context['results'][] = $id;
    // Optional message displayed under the progressbar.
    $context['message'] = t('Running Batch "@id" @details', [
        '@id' => $id,
        '@details' => $operation_details,
    ]);
}

/**
 * Batch operation for batch 2: five at a time.
 *
 * This is the function that is called on each operation in batch 2.
 *
 * After each group of 5 control is returned to the batch API for later
 * continuation.
 */
function batch_example_op_2($operation_details, &$context) {
    // Use the $context['sandbox'] at your convenience to store the
    // information needed to track progression between successive calls.
    if (empty($context['sandbox'])) {
        $context['sandbox'] = [];
        $context['sandbox']['progress'] = 0;
        $context['sandbox']['current_node'] = 0;
        // Save node count for the termination message.
        $context['sandbox']['max'] = 30;
    }
    // Process in groups of 5 (arbitrary value).
    // When a group of five is processed, the batch update engine determines
    // whether it should continue processing in the same request or provide
    // progress feedback to the user and wait for the next request.
    // That way even though we're already processing at the operation level
    // the operation itself is interruptible.
    $limit = 5;
    // Retrieve the next group.
    $result = range($context['sandbox']['current_node'] + 1, $context['sandbox']['current_node'] + 1 + $limit);
    foreach ($result as $row) {
        // Here we actually perform our dummy 'processing' on the current node.
        usleep(20000);
        // Store some results for post-processing in the 'finished' callback.
        // The contents of 'results' will be available as $results in the
        // 'finished' function (in this example, batch_example_finished()).
        $context['results'][] = $row . ' ' . $operation_details;
        // Update our progress information.
        $context['sandbox']['progress']++;
        $context['sandbox']['current_node'] = $row;
        $context['message'] = t('Running Batch "@id" @details', [
            '@id' => $row,
            '@details' => $operation_details,
        ]);
    }
    // Inform the batch engine that we are not finished,
    // and provide an estimation of the completion level we reached.
    if ($context['sandbox']['progress'] != $context['sandbox']['max']) {
        $context['finished'] = $context['sandbox']['progress'] >= $context['sandbox']['max'];
    }
}

/**
 * Batch 'finished' callback used by both batch 1 and batch 2.
 */
function batch_example_finished($success, $results, $operations) {
    $messenger = \Drupal::messenger();
    if ($success) {
        // Here we could do something meaningful with the results.
        // We just display the number of nodes we processed...
        $messenger->addMessage(t('@count results processed.', [
            '@count' => count($results),
        ]));
        $messenger->addMessage(t('The final result was "%final"', [
            '%final' => end($results),
        ]));
    }
    else {
        // An error occurred.
        // $operations contains the operations that remained unprocessed.
        $error_operation = reset($operations);
        $messenger->addMessage(t('An error occurred while processing @operation with arguments : @args', [
            '@operation' => $error_operation[0],
            '@args' => print_r($error_operation[0], TRUE),
        ]));
    }
}

/**
 * @} End of "defgroup batch_example".
 */