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/*
* Copyright © 2012 Intel Corporation
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*
* Author: Benjamin Segovia <benjamin.segovia@intel.com>
*/
//////////////////////////////////////////////////////////////////////////////////////////
// Part of this file is taken from the Apache licensed Intel Embree project here: //
// http://software.intel.com/en-us/articles/embree-photo-realistic-ray-tracing-kernels/ //
//////////////////////////////////////////////////////////////////////////////////////////
#include "sys/condition.hpp"
#if defined(__WIN32__)
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#if defined(__GNUC__)
namespace gbe
{
// This is an implementation of POSIX "compatible" condition variables for
// Win32, as described by Douglas C. Schmidt and Irfan Pyarali:
// http://www.cs.wustl.edu/~schmidt/win32-cv-1.html. The code is directly
// readapted from the glfw source code that may be found here:
// http://www.glfw.org
enum {
MINGW32_COND_SIGNAL = 0,
MINGW32_COND_BROADCAST = 1
};
/*! Implement the internal condition variable implementation Mingw lacks */
struct Mingw32Cond
{
HANDLE events[2]; //<! Signal and broadcast event HANDLEs
unsigned int waiters_count; //<! Count of the number of waiters
CRITICAL_SECTION waiters_count_lock;//!< Serialize access to <waiters_count>
};
ConditionSys::ConditionSys ()
{
cond = (Mingw32Cond *) GBE_NEW(Mingw32Cond);
((Mingw32Cond *)cond)->waiters_count = 0;
((Mingw32Cond *)cond)->events[MINGW32_COND_SIGNAL] = CreateEvent(NULL, FALSE, FALSE, NULL);
((Mingw32Cond *)cond)->events[MINGW32_COND_BROADCAST] = CreateEvent(NULL, TRUE, FALSE, NULL);
InitializeCriticalSection(&((Mingw32Cond *)cond)->waiters_count_lock);
}
ConditionSys::~ConditionSys ()
{
CloseHandle(((Mingw32Cond *)cond)->events[MINGW32_COND_SIGNAL]);
CloseHandle(((Mingw32Cond *)cond)->events[MINGW32_COND_BROADCAST]);
DeleteCriticalSection(&((Mingw32Cond *)cond)->waiters_count_lock);
GBE_DELETE((Mingw32Cond *)cond);
}
void ConditionSys::wait(MutexSys& mutex)
{
Mingw32Cond *cv = (Mingw32Cond *) cond;
int result, last_waiter;
DWORD timeout_ms;
// Avoid race conditions
EnterCriticalSection(&cv->waiters_count_lock);
cv->waiters_count ++;
LeaveCriticalSection(&cv->waiters_count_lock);
// It's ok to release the mutex here since Win32 manual-reset events
// maintain state when used with SetEvent()
LeaveCriticalSection((CRITICAL_SECTION *) mutex.mutex);
timeout_ms = INFINITE;
// Wait for either event to become signaled
result = WaitForMultipleObjects(2, cv->events, FALSE, timeout_ms);
// Check if we are the last waiter
EnterCriticalSection(&cv->waiters_count_lock);
cv->waiters_count --;
last_waiter = (result == WAIT_OBJECT_0 + MINGW32_COND_BROADCAST) &&
(cv->waiters_count == 0);
LeaveCriticalSection(&cv->waiters_count_lock);
// Some thread called broadcast
if (last_waiter) {
// We're the last waiter to be notified or to stop waiting, so
// reset the manual event
ResetEvent(cv->events[MINGW32_COND_BROADCAST]);
}
// Reacquire the mutex
EnterCriticalSection((CRITICAL_SECTION *) mutex.mutex);
}
void ConditionSys::broadcast()
{
Mingw32Cond *cv = (Mingw32Cond *) cond;
int have_waiters;
// Avoid race conditions
EnterCriticalSection(&cv->waiters_count_lock);
have_waiters = cv->waiters_count > 0;
LeaveCriticalSection(&cv->waiters_count_lock);
if (have_waiters)
SetEvent(cv->events[MINGW32_COND_BROADCAST]);
}
} /* namespace gbe */
#else
namespace gbe
{
/*! system condition using windows API */
ConditionSys::ConditionSys () { cond = GBE_NEW(CONDITION_VARIABLE); InitializeConditionVariable((CONDITION_VARIABLE*)cond); }
ConditionSys::~ConditionSys() { GBE_DELETE((CONDITION_VARIABLE*)cond); }
void ConditionSys::wait(MutexSys& mutex) { SleepConditionVariableCS((CONDITION_VARIABLE*)cond, (CRITICAL_SECTION*)mutex.mutex, INFINITE); }
void ConditionSys::broadcast() { WakeAllConditionVariable((CONDITION_VARIABLE*)cond); }
} /* namespace gbe */
#endif /* __GNUC__ */
#endif /* __WIN32__ */
#if defined(__UNIX__)
#include <pthread.h>
namespace gbe
{
ConditionSys::ConditionSys () { cond = GBE_NEW(pthread_cond_t); pthread_cond_init((pthread_cond_t*)cond,NULL); }
ConditionSys::~ConditionSys() { GBE_DELETE((pthread_cond_t*)cond); }
void ConditionSys::wait(MutexSys& mutex) { pthread_cond_wait((pthread_cond_t*)cond, (pthread_mutex_t*)mutex.mutex); }
void ConditionSys::broadcast() { pthread_cond_broadcast((pthread_cond_t*)cond); }
} /* namespace gbe */
#endif /* __UNIX__ */
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