image/ShutdownTracker.h
author Aaron Klotz <aklotz@mozilla.com>
Tue, 15 Jan 2019 13:39:49 -0700
changeset 511087 61a47d6d5e2617b297148e455d0a60a875df800c
parent 505383 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1511078: Follow-up - fix mingw build failures for TestNativeNt; r=bustage

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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/. */

/**
 * ShutdownTracker is an imagelib-global service that allows callers to check
 * whether shutdown has started.
 */

#ifndef mozilla_image_ShutdownTracker_h
#define mozilla_image_ShutdownTracker_h

namespace mozilla {
namespace image {

/**
 * ShutdownTracker is an imagelib-global service that allows callers to check
 * whether shutdown has started. It exists to avoid the need for registering
 * many 'xpcom-will-shutdown' notification observers on short-lived objects,
 * which would have an unnecessary performance cost.
 */
struct ShutdownTracker {
  /**
   * Initialize static data. Called during imagelib module initialization.
   */
  static void Initialize();

  /**
   * Check whether shutdown has started. Callers can use this to check whether
   * it's safe to access XPCOM services; if shutdown has started, such calls
   * must be avoided.
   *
   * @return true if shutdown has already started.
   */
  static bool ShutdownHasStarted();

 private:
  virtual ~ShutdownTracker() = 0;  // Forbid instantiation.
};

}  // namespace image
}  // namespace mozilla

#endif  // mozilla_image_ShutdownTracker_h