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dd0cb7b321
Depends on D109320 Differential Revision: https://phabricator.services.mozilla.com/D109321
96 lines
3.4 KiB
C++
96 lines
3.4 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim:set ts=2 sw=2 sts=2 et cindent: */
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/* 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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#if !defined(MediaShutdownManager_h_)
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# define MediaShutdownManager_h_
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# include "mozilla/Monitor.h"
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# include "mozilla/RefPtr.h"
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# include "mozilla/StaticPtr.h"
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# include "nsCOMPtr.h"
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# include "nsIAsyncShutdown.h"
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# include "nsIThread.h"
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# include "nsTHashSet.h"
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namespace mozilla {
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class MediaDecoder;
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// The MediaShutdownManager manages shutting down the MediaDecoder
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// infrastructure in response to an xpcom-shutdown notification.
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// This happens when Gecko is shutting down in the middle of operation.
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// This is tricky, as there are a number of moving parts that must
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// be shutdown in a particular order. The MediaShutdownManager
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// encapsulates all these dependencies to ensure that no shutdown
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// order dependencies leak out of the MediaDecoder stack.
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// The MediaShutdownManager is a singleton.
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//
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// The MediaShutdownManager ensures that the MediaDecoder stack
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// is shutdown before exiting xpcom-shutdown stage by registering
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// itself with nsIAsyncShutdownService to receive notification
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// when the stage of shutdown has started and then calls Shutdown()
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// on every MediaDecoder. Shutdown will not proceed until all
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// MediaDecoders finish shutdown and MediaShutdownManager unregisters
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// itself from the async shutdown service.
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//
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// Note that calling the Unregister() functions may result in the singleton
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// being deleted, so don't store references to the singleton, always use the
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// singleton by derefing the referenced returned by
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// MediaShutdownManager::Instance(), which ensures that the singleton is
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// created when needed.
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// i.e. like this:
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// MediaShutdownManager::Instance()::Unregister(someDecoder);
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// MediaShutdownManager::Instance()::Register(someOtherDecoder);
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// Not like this:
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// MediaShutdownManager& instance = MediaShutdownManager::Instance();
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// instance.Unregister(someDecoder); // Warning! May delete instance!
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// instance.Register(someOtherDecoder); // BAD! instance may be dangling!
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class MediaShutdownManager : public nsIAsyncShutdownBlocker {
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public:
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NS_DECL_ISUPPORTS
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NS_DECL_NSIASYNCSHUTDOWNBLOCKER
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static void InitStatics();
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// The MediaShutdownManager is a singleton, access its instance with
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// this accessor.
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static MediaShutdownManager& Instance();
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// Notifies the MediaShutdownManager that it needs to track the shutdown
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// of this MediaDecoder.
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nsresult Register(MediaDecoder* aDecoder);
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// Notifies the MediaShutdownManager that a MediaDecoder that it was
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// tracking has shutdown, and it no longer needs to be shutdown in the
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// xpcom-shutdown listener.
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void Unregister(MediaDecoder* aDecoder);
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private:
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enum InitPhase {
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NotInited,
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InitSucceeded,
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InitFailed,
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XPCOMShutdownStarted,
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XPCOMShutdownEnded
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};
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static InitPhase sInitPhase;
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MediaShutdownManager();
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virtual ~MediaShutdownManager();
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void RemoveBlocker();
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static StaticRefPtr<MediaShutdownManager> sInstance;
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// References to the MediaDecoder. The decoders unregister themselves
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// in their Shutdown() method, so we'll drop the reference naturally when
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// we're shutting down (in the non xpcom-shutdown case).
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nsTHashSet<RefPtr<MediaDecoder>> mDecoders;
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};
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} // namespace mozilla
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#endif
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