blob: dac31d8c8a0ba413b6285d29177302a7359f4a19 (
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
|
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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/. */
#ifndef MOZILLA_SHAREDBUFFER_H_
#define MOZILLA_SHAREDBUFFER_H_
#include "mozilla/CheckedInt.h"
#include "mozilla/mozalloc.h"
#include "nsCOMPtr.h"
namespace mozilla {
class AudioBlockBuffer;
/**
* Base class for objects with a thread-safe refcount and a virtual
* destructor.
*/
class ThreadSharedObject {
public:
NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ThreadSharedObject)
bool IsShared() { return mRefCnt.get() > 1; }
virtual AudioBlockBuffer* AsAudioBlockBuffer() { return nullptr; };
virtual size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
{
return 0;
}
virtual size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
{
return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
}
protected:
// Protected destructor, to discourage deletion outside of Release():
virtual ~ThreadSharedObject() {}
};
/**
* Heap-allocated chunk of arbitrary data with threadsafe refcounting.
* Typically you would allocate one of these, fill it in, and then treat it as
* immutable while it's shared.
* This only guarantees 4-byte alignment of the data. For alignment we simply
* assume that the memory from malloc is at least 4-byte aligned and the
* refcount's size is large enough that SharedBuffer's size is divisible by 4.
*/
class SharedBuffer : public ThreadSharedObject {
public:
void* Data() { return this + 1; }
static already_AddRefed<SharedBuffer> Create(size_t aSize)
{
CheckedInt<size_t> size = sizeof(SharedBuffer);
size += aSize;
if (!size.isValid()) {
MOZ_CRASH();
}
void* m = moz_xmalloc(size.value());
RefPtr<SharedBuffer> p = new (m) SharedBuffer();
NS_ASSERTION((reinterpret_cast<char*>(p.get() + 1) - reinterpret_cast<char*>(p.get())) % 4 == 0,
"SharedBuffers should be at least 4-byte aligned");
return p.forget();
}
size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const override
{
return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
}
private:
SharedBuffer() {}
};
} // namespace mozilla
#endif /* MOZILLA_SHAREDBUFFER_H_ */
|
