xpcom/base/JSObjectHolder.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_JSObjectHolder_h
   8 #define mozilla_JSObjectHolder_h
   9
  10 #include "js/RootingAPI.h"
  11 #include "nsISupportsImpl.h"
  12
  13 namespace mozilla {
  14
  15 // This class is useful when something on one thread needs to keep alive
  16 // a JS Object from another thread. If they are both on the same thread, the
  17 // owning class should instead be made a cycle collected SCRIPT_HOLDER class.
  18 // This object should only be AddRefed and Released on the same thread as
  19 // mJSObject.
  20 //
  21 // Note that this keeps alive the JS object until it goes away, so be sure not
  22 // to create cycles that keep alive the holder.
  23 //
  24 // JSObjectHolder is ISupports to make it usable with
  25 // NS_ReleaseOnMainThread.
  26 class JSObjectHolder final : public nsISupports {
  27  public:
  28   JSObjectHolder(JSContext* aCx, JSObject* aObject) : mJSObject(aCx, aObject) {}
  29
  30   NS_DECL_ISUPPORTS
  31
  32   JSObject* GetJSObject() { return mJSObject; }
  33
  34  private:
  35   ~JSObjectHolder() = default;
  36
  37   JS::PersistentRooted<JSObject*> mJSObject;
  38 };
  39
  40 }  // namespace mozilla
  41
  42 #endif  // mozilla_JSObjectHolder_h