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path: root/source/modules/asura-utils/threading/semaphore.cpp
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#include "../exceptions/exception.h"
#include "../type.h"

#include "mutex.h"
#include "semaphore.h"

namespace_begin(AsuraEngine)
namespace_begin(Threading)

#define try_create_semaphore(impl) \
if (!m_Impl)												\
{																	\
	try															\
	{																\
		m_Impl = new impl(init_count);	\
	}																\
	catch (Exception& e)						\
	{																\
		m_Impl = nullptr;							\
	}																\
}

Semaphore::Semaphore(unsigned int init_count)
	: m_Impl(nullptr)
{
#ifdef ASURA_THREAD_WIN32 
	try_create_semaphore(SemaphoreWin32);
#endif
	//ASSERT(m_Impl);
}

Semaphore::~Semaphore()
{
	if (m_Impl) delete m_Impl;
}

void Semaphore::Signal()
{
	ASSERT(m_Impl);
	m_Impl->Signal();
}

bool Semaphore::Wait(int timeout /*= ASURA_MUTEX_MAXWAIT*/)
{
	ASSERT(m_Impl);
	return m_Impl->Wait(timeout);
}

#if ASURA_THREAD_WIN32 

SemaphoreWin32::SemaphoreWin32(unsigned int init_value)
	: SemaphoreImpl(init_value)
{
	// UINT_MAX get error.
	m_Sem = CreateSemaphore(NULL, init_value, INT_MAX, NULL);
	if (!m_Sem)
	{
		int errorCode = GetLastError();
		throw Exception("Cant use win32 semaphore. Error code: %d.", errorCode);
	}
}

SemaphoreWin32::~SemaphoreWin32()
{
	CloseHandle(m_Sem);
}

void SemaphoreWin32::Signal()
{
	InterlockedIncrement(&m_Count);
	if (ReleaseSemaphore(m_Sem, 1, NULL) == FALSE)
		InterlockedDecrement(&m_Count);
}

bool SemaphoreWin32::Wait(int timeout)
{
	int result;
	result = WaitForSingleObject(m_Sem, timeout);
	if (result == WAIT_OBJECT_0)
	{
		InterlockedDecrement(&m_Count);
		return true;
	}
	else if(result == WAIT_TIMEOUT)
	{
		// ʱ
		return false;
	}
	else
	{
		// δ֪
		throw Exception("WaitForSingleObject() failed");
	}
}

#endif // ASURA_THREAD_WIN32 

namespace_end
namespace_end