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
|
//= llvm/Support/Win32/Mutex.inc - Win32 Reader/Writer Mutual Exclusion Lock =//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the Win32 specific (non-pthread) RWMutex class.
//
//===----------------------------------------------------------------------===//
//===----------------------------------------------------------------------===//
//=== WARNING: Implementation here must contain only generic Win32 code that
//=== is guaranteed to work on *all* Win32 variants.
//===----------------------------------------------------------------------===//
#include "WindowsSupport.h"
namespace llvm {
// Windows has slim read-writer lock support on Vista and higher, so we
// will attempt to load the APIs. If they exist, we will use them, and
// if not, we will fall back on critical sections. When we drop support
// for XP, we can stop lazy-loading these APIs and just use them directly.
#if defined(__MINGW32__)
// Taken from WinNT.h
typedef struct _RTL_SRWLOCK {
PVOID Ptr;
} RTL_SRWLOCK, *PRTL_SRWLOCK;
// Taken from WinBase.h
typedef RTL_SRWLOCK SRWLOCK, *PSRWLOCK;
#endif
static VOID (WINAPI *fpInitializeSRWLock)(PSRWLOCK lock) = NULL;
static VOID (WINAPI *fpAcquireSRWLockExclusive)(PSRWLOCK lock) = NULL;
static VOID (WINAPI *fpAcquireSRWLockShared)(PSRWLOCK lock) = NULL;
static VOID (WINAPI *fpReleaseSRWLockExclusive)(PSRWLOCK lock) = NULL;
static VOID (WINAPI *fpReleaseSRWLockShared)(PSRWLOCK lock) = NULL;
static bool sHasSRW = false;
static bool loadSRW() {
static bool sChecked = false;
if (!sChecked) {
sChecked = true;
if (HMODULE hLib = ::GetModuleHandleW(L"Kernel32.dll")) {
fpInitializeSRWLock =
(VOID (WINAPI *)(PSRWLOCK))::GetProcAddress(hLib,
"InitializeSRWLock");
fpAcquireSRWLockExclusive =
(VOID (WINAPI *)(PSRWLOCK))::GetProcAddress(hLib,
"AcquireSRWLockExclusive");
fpAcquireSRWLockShared =
(VOID (WINAPI *)(PSRWLOCK))::GetProcAddress(hLib,
"AcquireSRWLockShared");
fpReleaseSRWLockExclusive =
(VOID (WINAPI *)(PSRWLOCK))::GetProcAddress(hLib,
"ReleaseSRWLockExclusive");
fpReleaseSRWLockShared =
(VOID (WINAPI *)(PSRWLOCK))::GetProcAddress(hLib,
"ReleaseSRWLockShared");
if (fpInitializeSRWLock != NULL) {
sHasSRW = true;
}
}
}
return sHasSRW;
}
sys::RWMutexImpl::RWMutexImpl() {
if (loadSRW()) {
data_ = calloc(1, sizeof(SRWLOCK));
fpInitializeSRWLock(static_cast<PSRWLOCK>(data_));
} else {
data_ = calloc(1, sizeof(CRITICAL_SECTION));
InitializeCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
}
}
sys::RWMutexImpl::~RWMutexImpl() {
if (!sHasSRW)
DeleteCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
// Nothing to do in the case of slim reader/writers except free the memory.
free(data_);
}
bool sys::RWMutexImpl::reader_acquire() {
if (sHasSRW) {
fpAcquireSRWLockShared(static_cast<PSRWLOCK>(data_));
} else {
EnterCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
}
return true;
}
bool sys::RWMutexImpl::reader_release() {
if (sHasSRW) {
fpReleaseSRWLockShared(static_cast<PSRWLOCK>(data_));
} else {
LeaveCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
}
return true;
}
bool sys::RWMutexImpl::writer_acquire() {
if (sHasSRW) {
fpAcquireSRWLockExclusive(static_cast<PSRWLOCK>(data_));
} else {
EnterCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
}
return true;
}
bool sys::RWMutexImpl::writer_release() {
if (sHasSRW) {
fpReleaseSRWLockExclusive(static_cast<PSRWLOCK>(data_));
} else {
LeaveCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
}
return true;
}
}
|
