/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsISupports.idl"
#include "nsIStreamListener.idl"
/**
 * nsIThreadRetargetableStreamListener
 *
 * To be used by classes which implement nsIStreamListener and whose
 * OnDataAvailable callback may be retargeted for delivery off the main thread.
 */
[scriptable, uuid(fb2304b8-f82f-4433-af68-d874a2ebbdc1)]
interface nsIThreadRetargetableStreamListener : nsIStreamListener
{
  /**
   * Checks this listener and any next listeners it may have to verify that
   * they can receive OnDataAvailable off the main thread. It is the
   * responsibility of the implementing class to decide on the criteria to
   * determine if retargeted delivery of these methods is possible, but it must
   * check any and all nsIStreamListener objects that might be called in the
   * listener chain.
   *
   * An exception should be thrown if a listener in the chain does not
   * support retargeted delivery, i.e. if the next listener does not implement
   * nsIThreadRetargetableStreamListener, or a call to its checkListenerChain()
   * fails.
   */
  void checkListenerChain();

  /**
   * Used for notifying listeners about data stop.
   * After this notification, the listeners could potentially start processing
   * the data. Note that onDataFinished can be called on or off the main thread.
   * It is the responsibility of the listeners to handle this correctly.
   *
   * The ChannelEventQueue implementation ensures that the OnDataFinished is
   * run on the ODA target thread after the last OnDataAvailable is executed on
   * the ODA target thread and before OnStopRequest is called.
   * Hence, the following order is guaranteed for the listeners, even with ODA/ODF running off MainThread.
   * 1. OnStartRequest
   * 2. OnDataAvailable
   * 3. OnDataFinished
   * 4. OnStopRequest
   */
  void onDataFinished(in nsresult aStatusCode);
};