BansheeEngine/CamelotCore/Source/CmCoreThread.cpp

#include "CmCoreThread.h"
#include "CmCoreThreadAccessor.h"

namespace CamelotFramework
{
	CoreThread::CoreThread()
		: mCoreThreadFunc(nullptr)
		, mCoreThreadStarted(false)
		, mCoreThreadShutdown(false)
		, mCommandQueue(nullptr)
		, mMaxCommandNotifyId(0)
		, mSyncedCoreAccessor(nullptr)
	{
		mCoreThreadId = CM_THREAD_CURRENT_ID;
		mCommandQueue = cm_new<CommandQueue<CommandQueueSync>>(CM_THREAD_CURRENT_ID);

		initCoreThread();
	}

	CoreThread::~CoreThread()
	{
		// TODO - What if something gets queued between the queued call to destroy_internal and this!?
		shutdownCoreThread();

		if(mCommandQueue != nullptr)
		{
			cm_delete(mCommandQueue);
			mCommandQueue = nullptr;
		}
	}

	void CoreThread::initCoreThread()
	{
#if !CM_FORCE_SINGLETHREADED_RENDERING
		mCoreThreadFunc = cm_new<CoreThreadWorkerFunc>(this);

#if CM_THREAD_SUPPORT
		CM_THREAD_CREATE(t, *mCoreThreadFunc);
		mCoreThread = t;

		CM_LOCK_MUTEX_NAMED(mCoreThreadStartMutex, lock);

		while(!mCoreThreadStarted)
			CM_THREAD_WAIT(mCoreThreadStartCondition, mCoreThreadStartMutex, lock);

#else
		CM_EXCEPT(InternalErrorException, "Attempting to start a core thread but Camelot isn't compiled with thread support.");
#endif
#endif
	}

	void CoreThread::runCoreThread()
	{
#if !CM_FORCE_SINGLETHREADED_RENDERING
		MemStack::beginThread();

		mCoreThreadId = CM_THREAD_CURRENT_ID;
		mSyncedCoreAccessor = cm_new<CoreThreadAccessor<CommandQueueSync>>(CM_THREAD_CURRENT_ID);

		{
			CM_LOCK_MUTEX(mCoreThreadStartMutex);

			mCoreThreadStarted = true;
		}

		CM_THREAD_NOTIFY_ALL(mCoreThreadStartCondition)

		while(true)
		{
			// Wait until we get some ready commands
			Queue<QueuedCommand>::type* commands = nullptr;
			{
				CM_LOCK_MUTEX_NAMED(mCommandQueueMutex, lock)

				while(mCommandQueue->isEmpty())
				{
					if(mCoreThreadShutdown)
					{
						MemStack::endThread();
						return;
					}

					CM_THREAD_WAIT(mCommandReadyCondition, mCommandQueueMutex, lock);
				}

				commands = mCommandQueue->flush();
			}

			// Play commands
			mCommandQueue->playback(commands, boost::bind(&CoreThread::commandCompletedNotify, this, _1)); 
		}

		cm_delete(mSyncedCoreAccessor);
		MemStack::endThread();
#endif
	}

	void CoreThread::shutdownCoreThread()
	{
#if !CM_FORCE_SINGLETHREADED_RENDERING

		{
			CM_LOCK_MUTEX(mCommandQueueMutex);
			mCoreThreadShutdown = true;
		}

		// Wake all threads. They will quit after they see the shutdown flag
		CM_THREAD_NOTIFY_ALL(mCommandReadyCondition);

		mCoreThread->join();
		CM_THREAD_DESTROY(mCoreThread);

		mCoreThread = nullptr;
		mCoreThreadId = CM_THREAD_CURRENT_ID;

		if(mCoreThreadFunc != nullptr)
		{
			cm_delete(mCoreThreadFunc);
			mCoreThreadFunc = nullptr;
		}
#endif

		mCoreThreadStarted = false;
	}

	CoreAccessorPtr CoreThread::createAccessor()
	{
		return cm_shared_ptr<CoreThreadAccessor<CommandQueueNoSync>>(CM_THREAD_CURRENT_ID);
	}

	SyncedCoreAccessor& CoreThread::getSyncedAccessor()
	{
		return *mSyncedCoreAccessor;
	}

	AsyncOp CoreThread::queueReturnCommand(boost::function<void(AsyncOp&)> commandCallback, bool blockUntilComplete)
	{
		AsyncOp op;

		if(CM_THREAD_CURRENT_ID == getCoreThreadId())
		{
			commandCallback(op); // Execute immediately
			return op;
		}

		UINT32 commandId = -1;
		{
			CM_LOCK_MUTEX(mCommandQueueMutex);

			if(blockUntilComplete)
			{
				commandId = mMaxCommandNotifyId++;
				op = mCommandQueue->queueReturn(commandCallback, true, commandId);
			}
			else
				op = mCommandQueue->queueReturn(commandCallback);
		}

		CM_THREAD_NOTIFY_ALL(mCommandReadyCondition);

		if(blockUntilComplete)
			blockUntilCommandCompleted(commandId);

		return op;
	}

	void CoreThread::queueCommand(boost::function<void()> commandCallback, bool blockUntilComplete)
	{
		if(CM_THREAD_CURRENT_ID == getCoreThreadId())
		{
			commandCallback(); // Execute immediately
			return;
		}

		UINT32 commandId = -1;
		{
			CM_LOCK_MUTEX(mCommandQueueMutex);

			if(blockUntilComplete)
			{
				commandId = mMaxCommandNotifyId++;
				mCommandQueue->queue(commandCallback, true, commandId);
			}
			else
				mCommandQueue->queue(commandCallback);
		}

		CM_THREAD_NOTIFY_ALL(mCommandReadyCondition);

		if(blockUntilComplete)
			blockUntilCommandCompleted(commandId);
	}

	void CoreThread::blockUntilCommandCompleted(UINT32 commandId)
	{
#if !CM_FORCE_SINGLETHREADED_RENDERING
		CM_LOCK_MUTEX_NAMED(mCommandNotifyMutex, lock);

		while(true)
		{
			// TODO - This might be causing a deadlock in Release mode. I'm thinking because mCommandsCompleted isn't marked as volatile.

			// Check if our command id is in the completed list
			auto iter = mCommandsCompleted.begin();
			for(; iter != mCommandsCompleted.end(); ++iter)
			{
				if(*iter == commandId)
					break;
			}

			if(iter != mCommandsCompleted.end())
			{
				mCommandsCompleted.erase(iter);
				break;
			}

			CM_THREAD_WAIT(mCommandCompleteCondition, mCommandNotifyMutex, lock);
		}
#endif
	}

	void CoreThread::commandCompletedNotify(UINT32 commandId)
	{
		{
			CM_LOCK_MUTEX(mCommandNotifyMutex);

			mCommandsCompleted.push_back(commandId);
		}

		CM_THREAD_NOTIFY_ALL(mCommandCompleteCondition);
	}

	CoreThread& gCoreThread()
	{
		return CoreThread::instance();
	}

	void throwIfNotCoreThread()
	{
#if !CM_FORCE_SINGLETHREADED_RENDERING
		if(CM_THREAD_CURRENT_ID != CoreThread::instance().getCoreThreadId())
			CM_EXCEPT(InternalErrorException, "This method can only be accessed from the core thread.");
#endif
	}

	/************************************************************************/
	/* 								THREAD WORKER                      		*/
	/************************************************************************/

	CoreThread::CoreThreadWorkerFunc::CoreThreadWorkerFunc(CoreThread* owner)
		:mOwner(owner)
	{
		assert(mOwner != nullptr);
	}

	void CoreThread::CoreThreadWorkerFunc::operator()()
	{
		mOwner->runCoreThread();
	}
}