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Support/Windows: Add efficent RW mutex on Windows. Patch by Aaron Ballman!

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141907 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael J. Spencer 2011-10-13 23:10:56 +00:00
parent 87d5cb81fb
commit 7d2bc08254
1 changed files with 87 additions and 11 deletions
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98
lib/Support/Windows/RWMutex.inc
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@ -18,39 +18,115 @@
#include "Windows.h"
// FIXME: Windows does not have reader-writer locks pre-Vista. If you want
// real reader-writer locks, you a threads implementation for Windows.
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 = ::LoadLibrary(TEXT("Kernel32"));
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() {
data_ = calloc(1, sizeof(CRITICAL_SECTION));
InitializeCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
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() {
DeleteCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
free(data_);
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() {
EnterCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
if (sHasSRW) {
fpAcquireSRWLockShared(static_cast<PSRWLOCK>(data_));
} else {
EnterCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
}
return true;
}
bool RWMutexImpl::reader_release() {
LeaveCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
if (sHasSRW) {
fpReleaseSRWLockShared(static_cast<PSRWLOCK>(data_));
} else {
LeaveCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
}
return true;
}
bool RWMutexImpl::writer_acquire() {
EnterCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
if (sHasSRW) {
fpAcquireSRWLockExclusive(static_cast<PSRWLOCK>(data_));
} else {
EnterCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
}
return true;
}
bool RWMutexImpl::writer_release() {
LeaveCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
if (sHasSRW) {
fpReleaseSRWLockExclusive(static_cast<PSRWLOCK>(data_));
} else {
LeaveCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
}
return true;
}