layout/build/nsLayoutStatics.h
author Steven Lee <slee@mozilla.com>
Sat, 06 Oct 2012 21:53:22 -0400
changeset 109539 834fb95232af9f4e02e365f86d320c662091c0fe
parent 94484 f4157e8c410708d76703f19e4dfb61859bfe32d8
child 147778 040522aacba4f44301d427a0e0713940c6decac6
permissions -rw-r--r--
Bug 793759 - Implement HalChild::ActorDestroy and prevent HalChild calls to HalParent after ActorDestroy is called. r=cjones

/* 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/. */

#ifndef nsLayoutStatics_h__
#define nsLayoutStatics_h__

#include "nscore.h"
#include "nsThreadUtils.h"

// This isn't really a class, it's a namespace for static methods.
// Documents and other objects can hold a reference to the layout static
// objects so that they last past the xpcom-shutdown notification.

class nsLayoutStatics
{
public:
  // Called by the layout module constructor. This call performs an AddRef()
  // internally.
  static nsresult Initialize();

  static void AddRef()
  {
    NS_ASSERTION(NS_IsMainThread(),
                 "nsLayoutStatics reference counting must be on main thread");

    NS_ASSERTION(sLayoutStaticRefcnt,
                 "nsLayoutStatics already dropped to zero!");

    ++sLayoutStaticRefcnt;
    NS_LOG_ADDREF(&sLayoutStaticRefcnt, sLayoutStaticRefcnt,
                  "nsLayoutStatics", 1);
  }
  static void Release()
  {
    NS_ASSERTION(NS_IsMainThread(),
                 "nsLayoutStatics reference counting must be on main thread");

    --sLayoutStaticRefcnt;
    NS_LOG_RELEASE(&sLayoutStaticRefcnt, sLayoutStaticRefcnt,
                   "nsLayoutStatics");

    if (!sLayoutStaticRefcnt)
      Shutdown();
  }

private:
  // not to be called!
  nsLayoutStatics();

  static void Shutdown();

  static nsrefcnt sLayoutStaticRefcnt;
};

class nsLayoutStaticsRef
{
public:
  nsLayoutStaticsRef()
  {
    nsLayoutStatics::AddRef();
  }
  ~nsLayoutStaticsRef()
  {
    nsLayoutStatics::Release();
  }
};

#endif // nsLayoutStatics_h__