Determines whether this plugin is active.

    This plugin is active only if PR curve summary data is read by TensorBoard.

    Returns:
      Whether this plugin is active.

def is_active(self):
    """Determines whether this plugin is active.

    This plugin is active only if PR curve summary data is read by TensorBoard.

    Returns:
      Whether this plugin is active.
    """
    if self._db_connection_provider:
      # The plugin is active if one relevant tag can be found in the database.
      db = self._db_connection_provider()
      cursor = db.execute(
          '''
          SELECT 1
          FROM Tags
          WHERE Tags.plugin_name = ?
          LIMIT 1
          ''',
          (metadata.PLUGIN_NAME,))
      return bool(list(cursor))

    if not self._multiplexer:
      return False

    all_runs = self._multiplexer.PluginRunToTagToContent(metadata.PLUGIN_NAME)

    # The plugin is active if any of the runs has a tag relevant to the plugin.
    return any(six.itervalues(all_runs))