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
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
|
/* 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/. */
#include "VolatileBuffer.h"
#include "mozilla/Assertions.h"
#include "mozilla/mozalloc.h"
#include "mozilla/WindowsVersion.h"
#include <windows.h>
#ifdef MOZ_MEMORY
extern "C" int posix_memalign(void** memptr, size_t alignment, size_t size);
#endif
#ifndef MEM_RESET_UNDO
#define MEM_RESET_UNDO 0x1000000
#endif
#define MIN_VOLATILE_ALLOC_SIZE 8192
namespace mozilla {
VolatileBuffer::VolatileBuffer()
: mMutex("VolatileBuffer")
, mBuf(nullptr)
, mSize(0)
, mLockCount(0)
, mHeap(false)
, mFirstLock(true)
{
}
bool
VolatileBuffer::Init(size_t aSize, size_t aAlignment)
{
MOZ_ASSERT(!mSize && !mBuf, "Init called twice");
MOZ_ASSERT(!(aAlignment % sizeof(void *)),
"Alignment must be multiple of pointer size");
mSize = aSize;
if (aSize < MIN_VOLATILE_ALLOC_SIZE) {
goto heap_alloc;
}
static bool sUndoSupported = IsWin8OrLater();
if (!sUndoSupported) {
goto heap_alloc;
}
mBuf = VirtualAllocEx(GetCurrentProcess(),
nullptr,
mSize,
MEM_COMMIT | MEM_RESERVE,
PAGE_READWRITE);
if (mBuf) {
return true;
}
heap_alloc:
#ifdef MOZ_MEMORY
posix_memalign(&mBuf, aAlignment, aSize);
#else
mBuf = _aligned_malloc(aSize, aAlignment);
#endif
mHeap = true;
return !!mBuf;
}
VolatileBuffer::~VolatileBuffer()
{
MOZ_ASSERT(mLockCount == 0, "Being destroyed with non-zero lock count?");
if (OnHeap()) {
#ifdef MOZ_MEMORY
free(mBuf);
#else
_aligned_free(mBuf);
#endif
} else {
VirtualFreeEx(GetCurrentProcess(), mBuf, 0, MEM_RELEASE);
}
}
bool
VolatileBuffer::Lock(void** aBuf)
{
MutexAutoLock lock(mMutex);
MOZ_ASSERT(mBuf, "Attempting to lock an uninitialized VolatileBuffer");
*aBuf = mBuf;
if (++mLockCount > 1 || OnHeap()) {
return true;
}
// MEM_RESET_UNDO's behavior is undefined when called on memory that
// hasn't been MEM_RESET.
if (mFirstLock) {
mFirstLock = false;
return true;
}
void* addr = VirtualAllocEx(GetCurrentProcess(),
mBuf,
mSize,
MEM_RESET_UNDO,
PAGE_READWRITE);
return !!addr;
}
void
VolatileBuffer::Unlock()
{
MutexAutoLock lock(mMutex);
MOZ_ASSERT(mLockCount > 0, "VolatileBuffer unlocked too many times!");
if (--mLockCount || OnHeap()) {
return;
}
void* addr = VirtualAllocEx(GetCurrentProcess(),
mBuf,
mSize,
MEM_RESET,
PAGE_READWRITE);
MOZ_ASSERT(addr, "Failed to MEM_RESET");
}
bool
VolatileBuffer::OnHeap() const
{
return mHeap;
}
size_t
VolatileBuffer::HeapSizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
{
if (OnHeap()) {
#ifdef MOZ_MEMORY
return aMallocSizeOf(mBuf);
#else
return mSize;
#endif
}
return 0;
}
size_t
VolatileBuffer::NonHeapSizeOfExcludingThis() const
{
if (OnHeap()) {
return 0;
}
return (mSize + 4095) & ~4095;
}
} // namespace mozilla
|
