redis_flush.module

<?php

/**
 * @file
 * {@inheritdoc}
 */

use Drupal\redis\ClientFactory;
use Drupal\Core\Cache\Cache;
use Drupal\Core\Site\Settings;

/**
 * Implements hook_cache_flush().
 *
 *    Empties all Drupal cache from a Redis DB instance upon cache flush
 *    action (ie. when running `drush cache-rebuild`). Supports several
 *    flush modes. @see README.md for more details.
 */
function redis_cache_flush() {
  // Ensure that we are connected to Redis and can get a reference to.
  // the active client before proceeding.
  if (!ClientFactory::hasClient() ||
      !$redis = ClientFactory::getClient()) {

    return;
  }

  $redis_flush_settings = Settings::get('redis_flush');
  $redis_connection_settings = Settings::get('redis.connection');

  // If a redis connection is not configured, abort.
  if (empty($redis_connection_settings)) {
    return;
  }

  if (empty($redis_flush_settings)) {
    $redis_flush_settings = [];
  } elseif ($redis_flush_settings['mode'] === false) {
    return;
  }

  // Default settings if none were provided in settings.php.
  $redis_flush_settings += [
    'mode'      => 'bin',
    'skip_bins' => [],
  ];

  $redis_base_index = !isset($redis_connection_settings['base']) ? 0 : $redis_connection_settings['base'];

  // Allow for non-default (0) instance DB to be flushed.
  if (isset($redis_base_index) &&
      is_numeric($redis_base_index) &&
      $redis_base_index >= 0 &&
  // Redis instance supports up to 16 DBs.
      $redis_base_index <= 16) {

    $redis->select($redis_base_index);
  }

  // @see README for more details on the flush modes
  switch ($redis_flush_settings['mode']) {
    case 'develop':
      // Using flushDb() instead of flushAll() since the Redis Module only
      // supports 1 database for Drupal cache at this time.
      $redis->flushDb();

      break;

    case 'bin':
      $redis->setOption(Redis::OPT_SCAN, Redis::SCAN_RETRY);
      $flush_keys = [];
      $cache_prefix = Settings::get('cache_prefix');

      // checksum, lock, and queue are not cache bins so we do not need.
      // any logic to skip them.
      foreach (Cache::getBins() as $bin => $cache_interface) {
        // Reset the SCAN iterator for each bin.
        $iterator = NULL;
        $keys = [];

        if (get_class($cache_interface) !== 'Drupal\redis\Cache\PhpRedis' ||
          in_array($bin, $redis_flush_settings['skip_bins'])) {

          continue;
        }

        // Use SCAN to locate the keys for this bin.
        // (https://redis.io/commands/scan).
        while ($arr_keys = $redis->scan($iterator, "${cache_prefix}:${bin}:*")) {
          foreach ($arr_keys as $str_key) {
            $keys[] = $str_key;
          }
        }

        // Delete the keys found for this bin.
        $redis->delete($keys);
      }
  }
}