/*
 * MVKQueue.mm
 *
 * Copyright (c) 2014-2018 The Brenwill Workshop Ltd. (http://www.brenwill.com)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "MVKQueue.h"
#include "MVKSwapchain.h"
#include "MVKSync.h"
#include "MVKFoundation.h"
#include "MVKOSExtensions.h"
#include "MVKLogging.h"

using namespace std;


#pragma mark -
#pragma mark MVKQueueFamily

// MTLCommandQueues are cached in MVKQueueFamily/MVKPhysicalDevice because they are very
// limited in number. An app that creates multiple VkDevices over time (such as a test suite)
// will soon find 15 second delays when creating subsequent MTLCommandQueues.
id<MTLCommandQueue> MVKQueueFamily::getMTLCommandQueue(uint32_t queueIndex) {
	lock_guard<mutex> lock(_qLock);
	id<MTLCommandQueue> mtlQ = _mtlQueues[queueIndex];
	if ( !mtlQ ) {
		mtlQ = [_physicalDevice->getMTLDevice() newCommandQueue];	// retained
		_mtlQueues[queueIndex] = mtlQ;
	}
	return mtlQ;
}

MVKQueueFamily::MVKQueueFamily(MVKPhysicalDevice* physicalDevice, uint32_t queueFamilyIndex, const VkQueueFamilyProperties* pProperties) {
	_physicalDevice = physicalDevice;
	_queueFamilyIndex = queueFamilyIndex;
	_properties = *pProperties;
	_mtlQueues.assign(_properties.queueCount, nil);
}

MVKQueueFamily::~MVKQueueFamily() {
	mvkReleaseContainerContents(_mtlQueues);
}


#pragma mark -
#pragma mark MVKQueue


#pragma mark Queue submissions

// Executes the submmission, either immediately, or by dispatching to an execution queue.
// Submissions to the execution queue are wrapped in a dedicated autorelease pool.
// Relying on the dispatch queue to find time to drain the autorelease pool can
// result in significant memory creep under heavy workloads.
VkResult MVKQueue::submit(MVKQueueSubmission* qSubmit) {
	if ( !qSubmit ) { return VK_SUCCESS; }     // Ignore nils

	VkResult rslt = qSubmit->_submissionResult;     // Extract result before submission to avoid race condition with early destruction
	if (_execQueue) {
		dispatch_async(_execQueue, ^{ @autoreleasepool { qSubmit->execute(); } } );
	} else {
		qSubmit->execute();
	}
	return rslt;
}

VkResult MVKQueue::submit(uint32_t submitCount, const VkSubmitInfo* pSubmits,
                          VkFence fence, MVKCommandUse cmdBuffUse) {

	// Fence-only submission
	if (submitCount == 0 && fence) {
		return submit(new MVKQueueCommandBufferSubmission(_device, this, VK_NULL_HANDLE, fence, cmdBuffUse));
	}

	VkResult rslt = VK_SUCCESS;
    for (uint32_t sIdx = 0; sIdx < submitCount; sIdx++) {
        VkFence fenceOrNil = (sIdx == (submitCount - 1)) ? fence : VK_NULL_HANDLE;	// last one gets the fence
        VkResult subRslt = submit(new MVKQueueCommandBufferSubmission(_device, this, &pSubmits[sIdx], fenceOrNil, cmdBuffUse));
		if (rslt == VK_SUCCESS) { rslt = subRslt; }
    }
    return rslt;
}

VkResult MVKQueue::submit(const VkPresentInfoKHR* pPresentInfo) {
	return submit(new MVKQueuePresentSurfaceSubmission(_device, this, pPresentInfo));
}

// Create an empty submit struct and fence, submit to queue and wait on fence.
VkResult MVKQueue::waitIdle(MVKCommandUse cmdBuffUse) {

	VkSubmitInfo vkSbmtInfo = {
		.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO,
		.pNext = NULL,
		.waitSemaphoreCount = 0,
		.pWaitSemaphores = VK_NULL_HANDLE,
		.commandBufferCount = 0,
		.pCommandBuffers = VK_NULL_HANDLE,
		.signalSemaphoreCount = 0,
		.pSignalSemaphores = VK_NULL_HANDLE
	};

	VkFenceCreateInfo vkFenceInfo = {
		.sType = VK_STRUCTURE_TYPE_FENCE_CREATE_INFO,
		.pNext = NULL,
		.flags = 0,
	};

	MVKFence mvkFence(_device, &vkFenceInfo);
	VkFence fence = (VkFence)&mvkFence;
	submit(1, &vkSbmtInfo, fence, cmdBuffUse);
	return mvkWaitForFences(1, &fence, false);
}

// This function is guarded against conflict with the mtlCommandBufferHasCompleted()
// function, but is not theadsafe against calls to this function itself, or to the
// registerMTLCommandBufferCountdown() function from multiple threads. It is assumed
// that this function and the registerMTLCommandBufferCountdown() function are called
// from a single thread.
id<MTLCommandBuffer> MVKQueue::makeMTLCommandBuffer(NSString* mtlCmdBuffLabel) {

	// Retrieve a MTLCommandBuffer from the MTLCommandQueue.
	id<MTLCommandBuffer> mtlCmdBuffer = [_mtlQueue commandBufferWithUnretainedReferences];
    mtlCmdBuffer.label = mtlCmdBuffLabel;

	// Assign a unique ID to the MTLCommandBuffer, and track when it completes.
    MVKMTLCommandBufferID mtlCmdBuffID = _nextMTLCmdBuffID++;
	[mtlCmdBuffer addCompletedHandler: ^(id<MTLCommandBuffer> mtlCmdBuff) {
		this->mtlCommandBufferHasCompleted(mtlCmdBuff, mtlCmdBuffID);
	}];

    // Keep a running count of the active MTLCommandBuffers.
    // This needs to be guarded against a race condition with a MTLCommandBuffer completing.
    lock_guard<mutex> lock(_completionLock);
	_activeMTLCommandBufferCount++;

	return mtlCmdBuffer;
}

// This function must be called after all corresponding calls to makeMTLCommandBuffer() and from the same thead.
void MVKQueue::registerMTLCommandBufferCountdown(MVKMTLCommandBufferCountdown* countdown) {
	lock_guard<mutex> lock(_completionLock);

	if ( !countdown->setActiveMTLCommandBufferCount(_activeMTLCommandBufferCount, _nextMTLCmdBuffID) ) {
		_completionCountdowns.push_back(countdown);
	}
}

void MVKQueue::mtlCommandBufferHasCompleted(id<MTLCommandBuffer> mtlCmdBuff, MVKMTLCommandBufferID mtlCmdBuffID) {
	lock_guard<mutex> lock(_completionLock);

	_activeMTLCommandBufferCount--;

	// Iterate through the countdowns, letting them know about the completion, and
	// remove any countdowns that have completed by eliding them out of the array.
	uint32_t ccCnt = (uint32_t)_completionCountdowns.size();
	uint32_t currCCIdx = 0;
	for (uint32_t ccIdx = 0; ccIdx < ccCnt; ccIdx++) {
		MVKMTLCommandBufferCountdown* mvkCD = _completionCountdowns[ccIdx];
		if ( !mvkCD->mtlCommandBufferHasCompleted(mtlCmdBuffID) ) {
			// Only retain the countdown if it has not just completed.
			// Move it forward in the array if any preceding countdowns have been removed.
			if (currCCIdx != ccIdx) { _completionCountdowns[currCCIdx] = mvkCD; }
			currCCIdx++;
		}
	}
	// If any countdowns were removed, clear out the extras at the end
	if (currCCIdx < ccCnt) { _completionCountdowns.resize(currCCIdx); }
}


#pragma mark Construction

#define MVK_DISPATCH_QUEUE_QOS_CLASS		QOS_CLASS_USER_INITIATED

MVKQueue::MVKQueue(MVKDevice* device, MVKQueueFamily* queueFamily, uint32_t index, float priority)
        : MVKDispatchableDeviceObject(device), _commandEncodingPool(device) {

	_queueFamily = queueFamily;
	_index = index;
	_priority = priority;
	initExecQueue();
	initMTLCommandQueue();
	_activeMTLCommandBufferCount = 0;
	_nextMTLCmdBuffID = 1;
}

// Unless synchronous submission processing was configured,
// creates and initializes the prioritized execution dispatch queue.
void MVKQueue::initExecQueue() {
	if (_device->_mvkConfig.synchronousQueueSubmits) {
		_execQueue = nullptr;
	} else {
		// Create a name for the dispatch queue
		const char* dqNameFmt = "MoltenVKDispatchQueue-%d-%d-%.1f";
		char dqName[strlen(dqNameFmt) + 32];
		sprintf(dqName, dqNameFmt, _queueFamily->getIndex(), _index, _priority);

		// Determine the dispatch queue priority
		dispatch_qos_class_t dqQOS = MVK_DISPATCH_QUEUE_QOS_CLASS;
		int dqPriority = (1.0 - _priority) * QOS_MIN_RELATIVE_PRIORITY;
		dispatch_queue_attr_t dqAttr = dispatch_queue_attr_make_with_qos_class(DISPATCH_QUEUE_SERIAL, dqQOS, dqPriority);

		// Create the dispatch queue
		_execQueue = dispatch_queue_create(dqName, dqAttr);		// retained
	}
}

/** Creates and initializes the Metal queue. */
void MVKQueue::initMTLCommandQueue() {
	uint64_t startTime = _device->getPerformanceTimestamp();
	_mtlQueue = _queueFamily->getMTLCommandQueue(_index);	// not retained (cached in queue family)
	_device->addActivityPerformance(_device->_performanceStatistics.queue.mtlQueueAccess, startTime);
    [_mtlQueue insertDebugCaptureBoundary];                 // Allow Xcode to capture the first frame if desired.
}

MVKQueue::~MVKQueue() {
    // Delay destroying this queue until registerMTLCommandBufferCountdown() is done.
    // registerMTLCommandBufferCountdown() can trigger a queue submission to finish(),
    // which may trigger semaphores that control a queue waitIdle(). If that waitIdle()
    // is being called by the app just prior to device and queue destruction, a rare race
    // condition exists if registerMTLCommandBufferCountdown() does not complete before
    // this queue is destroyed. If _completionLock is destroyed along with this queue,
    // before registerMTLCommandBufferCountdown() completes, a SIGABRT crash will arise
    // in the destructor of the lock created in registerMTLCommandBufferCountdown().
    lock_guard<mutex> lock(_completionLock);
	destroyExecQueue();
}

// Destroys the execution dispatch queue.
void MVKQueue::destroyExecQueue() {
	if (_execQueue) { dispatch_release(_execQueue); }
}


#pragma mark -
#pragma mark MVKQueueCommandBufferSubmissionCountdown

MVKQueueCommandBufferSubmissionCountdown::MVKQueueCommandBufferSubmissionCountdown(MVKQueueCommandBufferSubmission* qSub) {
	_qSub = qSub;
}

void MVKQueueCommandBufferSubmissionCountdown::finish() { _qSub->finish(); }


#pragma mark -
#pragma mark MVKQueueSubmission

MVKQueueSubmission::MVKQueueSubmission(MVKDevice* device,
									   MVKQueue* queue,
									   uint32_t waitSemaphoreCount,
									   const VkSemaphore* pWaitSemaphores) : MVKBaseDeviceObject(device) {
	_queue = queue;
	_prev = VK_NULL_HANDLE;
	_next = VK_NULL_HANDLE;
	_submissionResult = VK_SUCCESS;

	_isAwaitingSemaphores = waitSemaphoreCount > 0;
	_waitSemaphores.reserve(waitSemaphoreCount);
	for (uint32_t i = 0; i < waitSemaphoreCount; i++) {
		_waitSemaphores.push_back((MVKSemaphore*)pWaitSemaphores[i]);
	}
}

void MVKQueueSubmission::recordResult(VkResult vkResult) {
    if (_submissionResult == VK_SUCCESS) { _submissionResult = vkResult; }
}


#pragma mark -
#pragma mark MVKQueueCommandBufferSubmission

std::atomic<uint32_t> _subCount;

void MVKQueueCommandBufferSubmission::execute() {

//	MVKLogDebug("Executing submission %p.", this);

    // Execute each command buffer, or if no command buffers, but a fence or semaphores,
    // create an empty MTLCommandBuffer to trigger the semaphores and fence.
    if ( !_cmdBuffers.empty() ) {
		MVKCommandBufferBatchPosition cmdBuffPos = {1, uint32_t(_cmdBuffers.size()), _cmdBuffUse};
		for (auto& cb : _cmdBuffers) {
			cb->execute(this, cmdBuffPos);
			cmdBuffPos.index++;
		}
    } else {
		if (_fence || !_signalSemaphores.empty() ) {
			getActiveMTLCommandBuffer();
		}
    }

	commitActiveMTLCommandBuffer();

    // Register for callback when MTLCommandBuffers have completed
    _queue->registerMTLCommandBufferCountdown(&_cmdBuffCountdown);
}

id<MTLCommandBuffer> MVKQueueCommandBufferSubmission::getActiveMTLCommandBuffer() {
	if ( !_activeMTLCommandBuffer ) {
		_activeMTLCommandBuffer = _queue->makeMTLCommandBuffer(getMTLCommandBufferName());
		[_activeMTLCommandBuffer enqueue];
	}
	return _activeMTLCommandBuffer;
}

void MVKQueueCommandBufferSubmission::commitActiveMTLCommandBuffer() {

	// Wait on each wait semaphore in turn. It doesn't matter which order they are signalled.
	// We have delayed this as long as possible to allow as much filling of the MTLCommandBuffer
	// as possible before forcing a wait. We only wait for each semaphore once per submission.
	if (_isAwaitingSemaphores) {
		_isAwaitingSemaphores = false;
		for (auto& ws : _waitSemaphores) { ws->wait(); }
	}

	[_activeMTLCommandBuffer commit];
	_activeMTLCommandBuffer = nil;			// not retained
}

// Returns an NSString suitable for use as a label
NSString* MVKQueueCommandBufferSubmission::getMTLCommandBufferName() {
    switch (_cmdBuffUse) {
        case kMVKCommandUseQueueSubmit:
            return [NSString stringWithFormat: @"%@ (virtual for sync)", mvkMTLCommandBufferLabel(_cmdBuffUse)];
        default:
            return mvkMTLCommandBufferLabel(_cmdBuffUse);
    }
}

void MVKQueueCommandBufferSubmission::finish() {

//	MVKLogDebug("Finishing submission %p. Submission count %u.", this, _subCount--);

	// Signal each of the signal semaphores.
    for (auto& ss : _signalSemaphores) { ss->signal(); }

    // If a fence exists, signal it.
    if (_fence) { _fence->signal(); }
    
    this->destroy();
}

MVKQueueCommandBufferSubmission::MVKQueueCommandBufferSubmission(MVKDevice* device,
																 MVKQueue* queue,
																 const VkSubmitInfo* pSubmit,
                                                                 VkFence fence,
                                                                 MVKCommandUse cmdBuffUse)
        : MVKQueueSubmission(device,
							 queue,
							 (pSubmit ? pSubmit->waitSemaphoreCount : 0),
							 (pSubmit ? pSubmit->pWaitSemaphores : nullptr)), _cmdBuffCountdown(this) {

    // pSubmit can be null if just tracking the fence alone
    if (pSubmit) {
        uint32_t cbCnt = pSubmit->commandBufferCount;
        _cmdBuffers.reserve(cbCnt);
        for (uint32_t i = 0; i < cbCnt; i++) {
            MVKCommandBuffer* cb = MVKCommandBuffer::getMVKCommandBuffer(pSubmit->pCommandBuffers[i]);
            _cmdBuffers.push_back(cb);
            recordResult(cb->getRecordingResult());
        }

        uint32_t ssCnt = pSubmit->signalSemaphoreCount;
        _signalSemaphores.reserve(ssCnt);
        for (uint32_t i = 0; i < ssCnt; i++) {
            _signalSemaphores.push_back((MVKSemaphore*)pSubmit->pSignalSemaphores[i]);
        }
    }

	_fence = (MVKFence*)fence;
    _cmdBuffUse= cmdBuffUse;
	_activeMTLCommandBuffer = nil;

//	MVKLogDebug("Creating submission %p. Submission count %u.", this, ++_subCount);
}


#pragma mark -
#pragma mark MVKQueuePresentSurfaceSubmission

#define MVK_PRESENT_VIA_CMD_BUFFER		0

void MVKQueuePresentSurfaceSubmission::execute() {
    id<MTLCommandQueue> mtlQ = _queue->getMTLCommandQueue();

	if (_device->_mvkConfig.presentWithCommandBuffer || _device->_mvkConfig.displayWatermark) {
		// Create a command buffer, present surfaces via the command buffer,
		// then wait on the semaphores before committing.
		id<MTLCommandBuffer> mtlCmdBuff = [mtlQ commandBufferWithUnretainedReferences];
		mtlCmdBuff.label = mvkMTLCommandBufferLabel(kMVKCommandUseQueuePresent);
		[mtlCmdBuff enqueue];

		for (auto& si : _surfaceImages) { si->presentCAMetalDrawable(mtlCmdBuff); }
		for (auto& ws : _waitSemaphores) { ws->wait(); }

		[mtlCmdBuff commit];
	} else {
		// Wait on semaphores, then present directly.
		for (auto& ws : _waitSemaphores) { ws->wait(); }
		for (auto& si : _surfaceImages) { si->presentCAMetalDrawable(nil); }
	}

    // Let Xcode know the frame is done, in case command buffer is not used
    if (_device->_mvkConfig.debugMode) { [mtlQ insertDebugCaptureBoundary]; }

    this->destroy();
}

MVKQueuePresentSurfaceSubmission::MVKQueuePresentSurfaceSubmission(MVKDevice* device,
																   MVKQueue* queue,
																   const VkPresentInfoKHR* pPresentInfo)
		: MVKQueueSubmission(device,
							 queue,
							 pPresentInfo->waitSemaphoreCount,
							 pPresentInfo->pWaitSemaphores) {

	// Populate the array of swapchain images, testing each one for a change in surface size
	_surfaceImages.reserve(pPresentInfo->swapchainCount);
	for (uint32_t i = 0; i < pPresentInfo->swapchainCount; i++) {
		MVKSwapchain* mvkSC = (MVKSwapchain*)pPresentInfo->pSwapchains[i];
		_surfaceImages.push_back(mvkSC->getImage(pPresentInfo->pImageIndices[i]));
		if (mvkSC->getHasSurfaceSizeChanged()) {
			_submissionResult = VK_ERROR_OUT_OF_DATE_KHR;
		}
	}
}