trait RequirementsTrait

trait RequirementsTrait {
  
  /**
   * Returns runtime requirements.
   */
  public function getRuntimeRequirements(Connection $connection) : array {
    $requirements = [];
    // Transaction isolation level.
    $query = $connection->isMariaDb() ? 'SELECT @@SESSION.tx_isolation' : 'SELECT @@SESSION.transaction_isolation';
    $isolation_level = $connection->query($query)
      ->fetchField();
    // Tables missing primary key.
    $tables_missing_primary_key = [];
    $tables = $connection->schema()
      ->findTables('%');
    foreach ($tables as $table) {
      $primary_key_column = $connection->query("SHOW KEYS FROM {" . $table . "} WHERE Key_name = 'PRIMARY'")
        ->fetchAllAssoc('Column_name');
      if (empty($primary_key_column)) {
        $tables_missing_primary_key[] = $table;
      }
    }
    $description = [];
    if ($isolation_level == 'READ-COMMITTED') {
      if (empty($tables_missing_primary_key)) {
        $severity_level = RequirementSeverity::OK;
      }
      else {
        $severity_level = RequirementSeverity::Error;
      }
    }
    else {
      if ($isolation_level == 'REPEATABLE-READ') {
        $severity_level = RequirementSeverity::Warning;
      }
      else {
        $severity_level = RequirementSeverity::Error;
        $description[] = $this->t('This is not supported by Drupal.');
      }
      $description[] = $this->t('The recommended level for Drupal is "READ COMMITTED".');
    }
    if (!empty($tables_missing_primary_key)) {
      $description[] = $this->t('For this to work correctly, all tables must have a primary key. The following table(s) do not have a primary key: @tables.', [
        '@tables' => implode(', ', $tables_missing_primary_key),
      ]);
    }
    $description[] = $this->t('See the <a href=":performance_doc">setting MySQL transaction isolation level</a> page for more information.', [
      ':performance_doc' => 'https://www.drupal.org/docs/system-requirements/setting-the-mysql-transaction-isolation-level',
    ]);
    $requirements['mysql_transaction_level'] = [
      'title' => $this->t('Transaction isolation level'),
      'severity' => $severity_level,
      'value' => $isolation_level,
      'description' => Markup::create(implode(' ', $description)),
    ];
    return $requirements;
  }

}