michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef nsHtml5StreamListener_h
michael@0: #define nsHtml5StreamListener_h
michael@0: 
michael@0: #include "nsIStreamListener.h"
michael@0: #include "nsIThreadRetargetableStreamListener.h"
michael@0: #include "nsHtml5RefPtr.h"
michael@0: #include "nsHtml5StreamParser.h"
michael@0: 
michael@0: /**
michael@0:  * The purpose of this class is to reconcile the problem that
michael@0:  * nsHtml5StreamParser is a cycle collection participant, which means that it
michael@0:  * can only be refcounted on the main thread, but
michael@0:  * nsIThreadRetargetableStreamListener can be refcounted from another thread,
michael@0:  * so nsHtml5StreamParser being an nsIThreadRetargetableStreamListener was
michael@0:  * a memory corruption problem.
michael@0:  *
michael@0:  * mDelegate is an nsHtml5RefPtr, which releases the object that it points
michael@0:  * to from a runnable on the main thread. DropDelegate() is only called on
michael@0:  * the main thread. This call will finish before the main-thread derefs the
michael@0:  * nsHtml5StreamListener itself, so there is no risk of another thread making
michael@0:  * the refcount of nsHtml5StreamListener go to zero and running the destructor
michael@0:  * concurrently. Other than that, the thread-safe nsISupports implementation
michael@0:  * takes care of the destructor not running concurrently from different
michael@0:  * threads, so there is no need to have a mutex around nsHtml5RefPtr to
michael@0:  * prevent it from double-releasing nsHtml5StreamParser.
michael@0:  */
michael@0: class nsHtml5StreamListener : public nsIStreamListener,
michael@0:                               public nsIThreadRetargetableStreamListener
michael@0: {
michael@0: public:
michael@0:   nsHtml5StreamListener(nsHtml5StreamParser* aDelegate);
michael@0:   virtual ~nsHtml5StreamListener();
michael@0: 
michael@0:   NS_DECL_THREADSAFE_ISUPPORTS
michael@0:   NS_DECL_NSIREQUESTOBSERVER
michael@0:   NS_DECL_NSISTREAMLISTENER
michael@0:   NS_DECL_NSITHREADRETARGETABLESTREAMLISTENER
michael@0: 
michael@0:   inline nsHtml5StreamParser* GetDelegate()
michael@0:   {
michael@0:     return mDelegate;
michael@0:   }
michael@0: 
michael@0:   void DropDelegate();
michael@0: 
michael@0: private:
michael@0:   nsHtml5RefPtr<nsHtml5StreamParser> mDelegate;
michael@0: };
michael@0: 
michael@0: #endif // nsHtml5StreamListener_h