Windows: Be more explicit with Win32 APIs
[oota-llvm.git] / lib / Support / Windows / RWMutex.inc
1 //= llvm/Support/Win32/Mutex.inc - Win32 Reader/Writer Mutual Exclusion Lock  =//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the Win32 specific (non-pthread) RWMutex class.
11 //
12 //===----------------------------------------------------------------------===//
13
14 //===----------------------------------------------------------------------===//
15 //=== WARNING: Implementation here must contain only generic Win32 code that
16 //===          is guaranteed to work on *all* Win32 variants.
17 //===----------------------------------------------------------------------===//
18
19 #include "Windows.h"
20
21 namespace llvm {
22 using namespace sys;
23
24 // Windows has slim read-writer lock support on Vista and higher, so we
25 // will attempt to load the APIs.  If they exist, we will use them, and
26 // if not, we will fall back on critical sections.  When we drop support
27 // for XP, we can stop lazy-loading these APIs and just use them directly.
28 #if defined(__MINGW32__)
29   // Taken from WinNT.h
30   typedef struct _RTL_SRWLOCK {
31     PVOID Ptr;
32   } RTL_SRWLOCK, *PRTL_SRWLOCK;
33
34   // Taken from WinBase.h
35   typedef RTL_SRWLOCK SRWLOCK, *PSRWLOCK;
36 #endif
37
38 static VOID (WINAPI *fpInitializeSRWLock)(PSRWLOCK lock) = NULL;
39 static VOID (WINAPI *fpAcquireSRWLockExclusive)(PSRWLOCK lock) = NULL;
40 static VOID (WINAPI *fpAcquireSRWLockShared)(PSRWLOCK lock) = NULL;
41 static VOID (WINAPI *fpReleaseSRWLockExclusive)(PSRWLOCK lock) = NULL;
42 static VOID (WINAPI *fpReleaseSRWLockShared)(PSRWLOCK lock) = NULL;
43
44 static bool sHasSRW = false;
45
46 static bool loadSRW() {
47   static bool sChecked = false;
48   if (!sChecked) {
49     sChecked = true;
50
51     HMODULE hLib = ::LoadLibraryW(L"Kernel32.dll");
52     if (hLib) {
53       fpInitializeSRWLock =
54         (VOID (WINAPI *)(PSRWLOCK))::GetProcAddress(hLib,
55                                                "InitializeSRWLock");
56       fpAcquireSRWLockExclusive =
57         (VOID (WINAPI *)(PSRWLOCK))::GetProcAddress(hLib,
58                                                "AcquireSRWLockExclusive");
59       fpAcquireSRWLockShared =
60         (VOID (WINAPI *)(PSRWLOCK))::GetProcAddress(hLib,
61                                                "AcquireSRWLockShared");
62       fpReleaseSRWLockExclusive =
63         (VOID (WINAPI *)(PSRWLOCK))::GetProcAddress(hLib,
64                                                "ReleaseSRWLockExclusive");
65       fpReleaseSRWLockShared =
66         (VOID (WINAPI *)(PSRWLOCK))::GetProcAddress(hLib,
67                                                "ReleaseSRWLockShared");
68       ::FreeLibrary(hLib);
69
70       if (fpInitializeSRWLock != NULL) {
71         sHasSRW = true;
72       }
73     }
74   }
75   return sHasSRW;
76 }
77
78 RWMutexImpl::RWMutexImpl() {
79   if (loadSRW()) {
80     data_ = calloc(1, sizeof(SRWLOCK));
81     fpInitializeSRWLock(static_cast<PSRWLOCK>(data_));
82   } else {
83     data_ = calloc(1, sizeof(CRITICAL_SECTION));
84     InitializeCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
85   }
86 }
87
88 RWMutexImpl::~RWMutexImpl() {
89   if (sHasSRW) {
90     // Nothing to do in the case of slim reader/writers
91   } else {
92     DeleteCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
93     free(data_);
94   }
95 }
96
97 bool RWMutexImpl::reader_acquire() {
98   if (sHasSRW) {
99     fpAcquireSRWLockShared(static_cast<PSRWLOCK>(data_));
100   } else {
101     EnterCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
102   }
103   return true;
104 }
105
106 bool RWMutexImpl::reader_release() {
107   if (sHasSRW) {
108     fpReleaseSRWLockShared(static_cast<PSRWLOCK>(data_));
109   } else {
110     LeaveCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
111   }
112   return true;
113 }
114
115 bool RWMutexImpl::writer_acquire() {
116   if (sHasSRW) {
117     fpAcquireSRWLockExclusive(static_cast<PSRWLOCK>(data_));
118   } else {
119     EnterCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
120   }
121   return true;
122 }
123
124 bool RWMutexImpl::writer_release() {
125   if (sHasSRW) {
126     fpReleaseSRWLockExclusive(static_cast<PSRWLOCK>(data_));
127   } else {
128     LeaveCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
129   }
130   return true;
131 }
132
133
134 }