Function shutdown

lib/log4js.js:105–148

* Shutdown all log appenders. This will first disable all writing to appenders * and then call the shutdown function each appender. * * @param {shutdownCallback} [callback] - The callback to be invoked once all appenders have * shutdown. If an error occurs, the callback will be given the error

(callback = () => {})

 *  as the first argument.
 */
function shutdown(callback = () => {}) {
  if (typeof callback !== 'function') {
    throw new TypeError('Invalid callback passed to shutdown');
  }
  debug('Shutdown called. Disabling all log writing.');
  // First, disable all writing to appenders. This prevents appenders from
  // not being able to be drained because of run-away log writes.
  enabled = false;

  // Clone out to maintain a reference
  const appendersToCheck = Array.from(appenders.values());

  // Reset immediately to prevent leaks
  appenders.init();
  categories.init();

  // Count the number of shutdown functions
  const shutdownFunctions = appendersToCheck.reduce(
    (accum, next) => (next.shutdown ? accum + 1 : accum),
    0
  );
  if (shutdownFunctions === 0) {
    debug('No appenders with shutdown functions found.');
    callback();
  }

  let completed = 0;
  let error;
  debug(`Found ${shutdownFunctions} appenders with shutdown functions.`);
  function complete(err) {
    error = error || err;
    completed += 1;
    debug(`Appender shutdowns complete: ${completed} / ${shutdownFunctions}`);
    if (completed >= shutdownFunctions) {
      debug('All shutdown functions completed.');
      callback(error);
    }
  }

  // Call each of the shutdown functions
  appendersToCheck
    .filter((a) => a.shutdown)
    .forEach((a) => a.shutdown(complete));
}

/**
 * Get a logger instance.