llvm-6502/lib/Support/Windows/RWMutex.inc
David Majnemer ae06a63be5 Windows: Be more explicit with Win32 APIs
This addresses several issues in a similar vein:
 - Use the Unicode APIs when possible, running nm on clang shows that we
   only use Unicode APIs except for FormatMessage, CreateSemaphore, and
   GetModuleHandle.  AFAICT, the latter two are coming from MinGW and
   not LLVM itself.
 - Make getMainExecutable more resilient.  It previously considered
   return values of zero from ::GetModuleFileNameA to be acceptable.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192096 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-07 09:52:36 +00:00

135 lines
4.1 KiB
C++

//= 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 "Windows.h"
namespace llvm {
using namespace sys;
// 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;
HMODULE hLib = ::LoadLibraryW(L"Kernel32.dll");
if (hLib) {
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");
::FreeLibrary(hLib);
if (fpInitializeSRWLock != NULL) {
sHasSRW = true;
}
}
}
return sHasSRW;
}
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_));
}
}
RWMutexImpl::~RWMutexImpl() {
if (sHasSRW) {
// Nothing to do in the case of slim reader/writers
} else {
DeleteCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
free(data_);
}
}
bool RWMutexImpl::reader_acquire() {
if (sHasSRW) {
fpAcquireSRWLockShared(static_cast<PSRWLOCK>(data_));
} else {
EnterCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
}
return true;
}
bool RWMutexImpl::reader_release() {
if (sHasSRW) {
fpReleaseSRWLockShared(static_cast<PSRWLOCK>(data_));
} else {
LeaveCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
}
return true;
}
bool RWMutexImpl::writer_acquire() {
if (sHasSRW) {
fpAcquireSRWLockExclusive(static_cast<PSRWLOCK>(data_));
} else {
EnterCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
}
return true;
}
bool RWMutexImpl::writer_release() {
if (sHasSRW) {
fpReleaseSRWLockExclusive(static_cast<PSRWLOCK>(data_));
} else {
LeaveCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
}
return true;
}
}