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thread: use native windows cond var if available

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Vista / Server 2008 and up. no speed difference observed.

Change-Id: Ice19704777cb679b290dc107a751a0f36dd0c0a9
This commit is contained in:
James Zern 2015-11-23 19:49:58 -08:00
parent 158763dea3
commit 110ad5835e
1 changed files with 22 additions and 0 deletions
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22
src/utils/thread.c
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@ -23,11 +23,17 @@
#include <windows.h>
typedef HANDLE pthread_t;
typedef CRITICAL_SECTION pthread_mutex_t;
#if _WIN32_WINNT >= 0x0600 // Windows Vista / Server 2008 or greater
#define USE_WINDOWS_CONDITION_VARIABLE
typedef CONDITION_VARIABLE pthread_cond_t;
#else
typedef struct {
HANDLE waiting_sem_;
HANDLE received_sem_;
HANDLE signal_event_;
} pthread_cond_t;
#endif // _WIN32_WINNT >= 0x600
#else // !_WIN32
@ -97,14 +103,21 @@ static int pthread_mutex_destroy(pthread_mutex_t* const mutex) {
// Condition
static int pthread_cond_destroy(pthread_cond_t* const condition) {
int ok = 1;
#ifdef USE_WINDOWS_CONDITION_VARIABLE
(void)condition;
#else
ok &= (CloseHandle(condition->waiting_sem_) != 0);
ok &= (CloseHandle(condition->received_sem_) != 0);
ok &= (CloseHandle(condition->signal_event_) != 0);
#endif
return !ok;
}
static int pthread_cond_init(pthread_cond_t* const condition, void* cond_attr) {
(void)cond_attr;
#ifdef USE_WINDOWS_CONDITION_VARIABLE
InitializeConditionVariable(condition);
#else
condition->waiting_sem_ = CreateSemaphore(NULL, 0, 1, NULL);
condition->received_sem_ = CreateSemaphore(NULL, 0, 1, NULL);
condition->signal_event_ = CreateEvent(NULL, FALSE, FALSE, NULL);
@ -114,11 +127,15 @@ static int pthread_cond_init(pthread_cond_t* const condition, void* cond_attr) {
pthread_cond_destroy(condition);
return 1;
}
#endif
return 0;
}
static int pthread_cond_signal(pthread_cond_t* const condition) {
int ok = 1;
#ifdef USE_WINDOWS_CONDITION_VARIABLE
WakeConditionVariable(condition);
#else
if (WaitForSingleObject(condition->waiting_sem_, 0) == WAIT_OBJECT_0) {
// a thread is waiting in pthread_cond_wait: allow it to be notified
ok = SetEvent(condition->signal_event_);
@ -127,12 +144,16 @@ static int pthread_cond_signal(pthread_cond_t* const condition) {
ok &= (WaitForSingleObject(condition->received_sem_, INFINITE) !=
WAIT_OBJECT_0);
}
#endif
return !ok;
}
static int pthread_cond_wait(pthread_cond_t* const condition,
pthread_mutex_t* const mutex) {
int ok;
#ifdef USE_WINDOWS_CONDITION_VARIABLE
ok = SleepConditionVariableCS(condition, mutex, INFINITE);
#else
// note that there is a consumer available so the signal isn't dropped in
// pthread_cond_signal
if (!ReleaseSemaphore(condition->waiting_sem_, 1, NULL))
@ -143,6 +164,7 @@ static int pthread_cond_wait(pthread_cond_t* const condition,
WAIT_OBJECT_0);
ok &= ReleaseSemaphore(condition->received_sem_, 1, NULL);
pthread_mutex_lock(mutex);
#endif
return !ok;
}