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