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#include "../exceptions/exception.h"
#include "../type.h"

#include "semaphore.h"

namespace AsuraEngine
{
	namespace Threading
	{

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

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

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

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

		void Semaphore::Wait(int timeout)
		{
			ASSERT(mImpl);
			mImpl->Wait(timeout);
		}

#if ASURA_THREAD_WIN32 

		SemaphoreWin32::SemaphoreWin32(unsigned int init_value)
			: SemaphoreImpl(init_value)
		{
			mSem = CreateSemaphore(NULL, init_value, UINT_MAX, NULL);
			if (!mSem)
				throw Exception("Cant use win32 semaphore.");
		}

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

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

		bool SemaphoreWin32::Wait(int timeout)
		{
			int result;
			result = WaitForSingleObject(mSem, timeout < 0 ? INFINITE : timeout);
			if (result == WAIT_OBJECT_0)
			{
				InterlockedDecrement(&mCount);
				return true;
			}
			else
				return false;
		}

#endif // ASURA_THREAD_WIN32 

	}
}