/* 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"

interface nsIRunnable;

/**
 * Handle for the ongoing shutdown progress of a given thread which can be used
 * to observe and interrupt async shutdown progress. Methods on this interface
 * may generally only be used on the thread which called
 * `nsIThread::beginShutdown`.
 */
[scriptable, builtinclass, uuid(70a43748-6130-4ea6-a440-7c74e1b7dd7c)]
interface nsIThreadShutdown : nsISupports
{
  /**
   * Register a runnable to be executed when the thread has completed shutdown,
   * or shutdown has been cancelled due to `stopWaitingAndLeakThread()`.
   *
   * If the thread has already completed or cancelled shutdown, the runnable
   * may be executed synchronously.
   *
   * May only be called on the thread which invoked `nsIThread::beginShutdown`.
   */
  void onCompletion(in nsIRunnable aEvent);

  /**
   * Check if the target thread has completed shutdown.
   *
   * May only be accessed on the thread which called `nsIThread::beginShutdown`.
   */
  [infallible] readonly attribute boolean completed;

  /**
   * Give up on waiting for the shutting down thread to exit. Calling this
   * method will allow the thread to continue running, no longer block shutdown,
   * and the thread will never be joined or have its resources reclaimed.
   *
   * Completion callbacks attached to this `nsIThreadShutdown` may be executed
   * during this call.
   *
   * This method should NOT be called except in exceptional circumstances during
   * shutdown, as it will cause resources for the shutting down thread to be
   * leaked.
   *
   * May only be called on the thread which called `nsIThread::beginShutdown`
   *
   * @throws NS_ERROR_NOT_AVAILABLE
   *   Indicates that the target thread has already stopped running and a
   *   request to be joined is already being dispatched to the waiting thread.
   */
  void stopWaitingAndLeakThread();
};
