blob: 071e93229edb4d019fe7b1300c8eff610497408f (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
|
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* 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/. */
#if !defined(MediaShutdownManager_h_)
#define MediaShutdownManager_h_
#include "mozilla/Monitor.h"
#include "mozilla/RefPtr.h"
#include "mozilla/StaticPtr.h"
#include "nsCOMPtr.h"
#include "nsIAsyncShutdown.h"
#include "nsIThread.h"
#include "nsHashKeys.h"
#include "nsTHashtable.h"
namespace mozilla {
class MediaDecoder;
// The MediaShutdownManager manages shutting down the MediaDecoder
// infrastructure in response to an xpcom-shutdown notification.
// This happens when Gecko is shutting down in the middle of operation.
// This is tricky, as there are a number of moving parts that must
// be shutdown in a particular order. The MediaShutdownManager
// encapsulates all these dependencies to ensure that no shutdown
// order dependencies leak out of the MediaDecoder stack.
// The MediaShutdownManager is a singleton.
//
// The MediaShutdownManager ensures that the MediaDecoder stack
// is shutdown before exiting xpcom-shutdown stage by registering
// itself with nsIAsyncShutdownService to receive notification
// when the stage of shutdown has started and then calls Shutdown()
// on every MediaDecoder. Shutdown will not proceed until all
// MediaDecoders finish shutdown and MediaShutdownManager unregisters
// itself from the async shutdown service.
//
// Note that calling the Unregister() functions may result in the singleton
// being deleted, so don't store references to the singleton, always use the
// singleton by derefing the referenced returned by
// MediaShutdownManager::Instance(), which ensures that the singleton is
// created when needed.
// i.e. like this:
// MediaShutdownManager::Instance()::Unregister(someDecoder);
// MediaShutdownManager::Instance()::Register(someOtherDecoder);
// Not like this:
// MediaShutdownManager& instance = MediaShutdownManager::Instance();
// instance.Unregister(someDecoder); // Warning! May delete instance!
// instance.Register(someOtherDecoder); // BAD! instance may be dangling!
class MediaShutdownManager : public nsIAsyncShutdownBlocker {
public:
NS_DECL_ISUPPORTS
NS_DECL_NSIASYNCSHUTDOWNBLOCKER
static void InitStatics();
// The MediaShutdownManager is a singleton, access its instance with
// this accessor.
static MediaShutdownManager& Instance();
// Notifies the MediaShutdownManager that it needs to track the shutdown
// of this MediaDecoder.
nsresult Register(MediaDecoder* aDecoder);
// Notifies the MediaShutdownManager that a MediaDecoder that it was
// tracking has shutdown, and it no longer needs to be shutdown in the
// xpcom-shutdown listener.
void Unregister(MediaDecoder* aDecoder);
private:
MediaShutdownManager();
virtual ~MediaShutdownManager();
void RemoveBlocker();
static StaticRefPtr<MediaShutdownManager> sInstance;
// References to the MediaDecoder. The decoders unregister themselves
// in their Shutdown() method, so we'll drop the reference naturally when
// we're shutting down (in the non xpcom-shutdown case).
nsTHashtable<nsRefPtrHashKey<MediaDecoder>> mDecoders;
bool mIsDoingXPCOMShutDown = false;
};
} // namespace mozilla
#endif
|
