OClCollMeshEngn: Use shouldAcceptRequests stop/finalize() pattern

This makes the stop() method capable of synchronously stopping all
engine/server-type async services which don't act in a self-moved
fashion but instead wait for a request.

stimBuffApis/livoxGen1/openClCollatingAndMeshingEngine.cpp

@@ -92,8 +92,9 @@ slotCompactorProgram(nullptr), collateProgram(nullptr),
 slotCompactorKernel(nullptr), collateKernel(nullptr),
 clAssemblyBuffer(nullptr),
 clCollationBuffer(nullptr),
-compactIsSetup(false), compactIsRunning(false),
-collateIsSetup(false), collateIsRunning(false),
+shouldAcceptRequests(false),
+compactIsRunning(false),
+collateIsRunning(false),
 currentCompactKernelEvent(nullptr), currentCollateKernelEvent(nullptr),
 assemblyBufferPtr(nullptr),
 assemblyBufferSize(0),
@@ -112,8 +113,14 @@ OpenClCollatingAndMeshingEngine::~OpenClCollatingAndMeshingEngine()
 
 bool OpenClCollatingAndMeshingEngine::setup()
 {
-	if (compactIsSetup && collateIsSetup) {
-		return true;
+	// Defensive check to prevent double-calling
+	{
+		SpinLock::Guard lock(shouldAcceptRequestsLock);
+		if (shouldAcceptRequests)
+		{
+			throw std::runtime_error(std::string(__func__) + ": setup() called "
+				"while already set up");
+		}
 	}
 
 	cl_int err;
@@ -235,8 +242,7 @@ bool OpenClCollatingAndMeshingEngine::setup()
 		goto cleanup;
 	}
 
-	compactIsSetup = true;
-	collateIsSetup = true;
+	shouldAcceptRequests = true;
 	return true;
 
 cleanup:
@@ -246,8 +252,13 @@ cleanup:
 
 void OpenClCollatingAndMeshingEngine::finalize()
 {
-	// Call stop() first
-	stop();
+	// Call stop() to set shouldAcceptRequests to false and get previous state
+	bool wasAcceptingRequests = stop();
+	(void)wasAcceptingRequests;
+
+	// Complete any running kernels
+	compactKernelComplete();
+	collateKernelComplete();
 
 	// Release OpenCL buffers in reverse order
 	if (clCollationBuffer)
@@ -302,9 +313,7 @@ void OpenClCollatingAndMeshingEngine::finalize()
 	// Reset state variables
 	device = nullptr;
 	platform = nullptr;
-	compactIsSetup = false;
 	compactIsRunning = false;
-	collateIsSetup = false;
 	collateIsRunning = false;
 	currentCompactKernelEvent = nullptr;
 	currentCollateKernelEvent = nullptr;
@@ -400,7 +409,6 @@ bool OpenClCollatingAndMeshingEngine::startCompactKernel(
 		1,  // globalWorkSize
 		compactKernelEventCallback,
 		"slotCompactor",
-		compactIsSetup,
 		compactIsRunning);
 
 	if (!success) { return false; }
@@ -459,7 +467,6 @@ bool OpenClCollatingAndMeshingEngine::startCollateKernel(
 		globalWorkSize,
 		collateKernelEventCallback,
 		"collateDgrams",
-		collateIsSetup,
 		collateIsRunning);
 
 	if (!success) { return false; }
@@ -683,13 +690,16 @@ bool OpenClCollatingAndMeshingEngine::setupCollateDgramsArgs(
 	return true;
 }
 
-void OpenClCollatingAndMeshingEngine::stop()
+bool OpenClCollatingAndMeshingEngine::stop()
 {
-	stopCompactKernel();
-	stopCollateKernel();
+	// Acquire and release lock tightly around setting the flag
+	SpinLock::Guard lock(shouldAcceptRequestsLock);
+	bool wasAcceptingRequests = shouldAcceptRequests;
+	shouldAcceptRequests = false;
+	return wasAcceptingRequests;
 }
 
-void OpenClCollatingAndMeshingEngine::stopCompactKernel()
+void OpenClCollatingAndMeshingEngine::compactKernelComplete()
 {
 	/**	EXPLANATION:
 	 * Technically we should only need to do this if we plan to read the
@@ -706,12 +716,12 @@ void OpenClCollatingAndMeshingEngine::stopCompactKernel()
 		clWaitForEvents(1, &currentCompactKernelEvent);
 		clReleaseEvent(currentCompactKernelEvent);
 		currentCompactKernelEvent = nullptr;
-		compactIsRunning = false;
 	}
 	compactKernelCb = [](cl_int){};
+	compactIsRunning = false;
 }
 
-void OpenClCollatingAndMeshingEngine::stopCollateKernel()
+void OpenClCollatingAndMeshingEngine::collateKernelComplete()
 {
 	/**	EXPLANATION:
 	 * Technically we should only need to do this if we plan to read the
@@ -727,9 +737,9 @@ void OpenClCollatingAndMeshingEngine::stopCollateKernel()
 		clWaitForEvents(1, &currentCollateKernelEvent);
 		clReleaseEvent(currentCollateKernelEvent);
 		currentCollateKernelEvent = nullptr;
-		collateIsRunning = false;
 	}
 	collateKernelCb = [](cl_int){};
+	collateIsRunning = false;
 }
 
 bool OpenClCollatingAndMeshingEngine::mapBuffer(
@@ -869,6 +879,13 @@ public:
 	void compactCollateAndMeshFrameReq1_doCompact_posted(
 		std::shared_ptr<CompactCollateAndMeshFrameReq> context)
 	{
+		SpinLock::Guard lock(engine.shouldAcceptRequestsLock);
+		if (!engine.shouldAcceptRequests)
+		{
+			callOriginalCallback(false);
+			return;
+		}
+
 		// Record compact kernel start time
 		engine.compactKernelStartTime = std::chrono::high_resolution_clock::now();
 
@@ -883,7 +900,7 @@ public:
 
 		if (!success)
 		{
-			engine.stopCompactKernel();
+			engine.compactKernelComplete();
 			callOriginalCallback(false);
 			return;
 		}
@@ -893,7 +910,20 @@ public:
 		std::shared_ptr<CompactCollateAndMeshFrameReq> context,
 		cl_int compactStatus)
 	{
-		engine.stopCompactKernel();
+		SpinLock::Guard lock(engine.shouldAcceptRequestsLock);
+		if (!engine.shouldAcceptRequests)
+		{
+			/**	EXPLANATION:
+			 * We intentionally don't call compactKernelComplete() here because
+			 * if shouldAcceptRequests is false, then the caller that called
+			 * finalize() will also be forced to call compactKernelComplete()
+			 * inside of finalize().
+			 */
+			callOriginalCallback(false);
+			return;
+		}
+
+		engine.compactKernelComplete();
 		// Record compact kernel end time
 		engine.compactKernelEndTime = std::chrono::high_resolution_clock::now();
 
@@ -914,12 +944,20 @@ public:
 		}
 #endif
 
+		lock.unlockPrematurely();
 		context->compactCollateAndMeshFrameReq3_doCollate_posted(context);
 	}
 
 	void compactCollateAndMeshFrameReq3_doCollate_posted(
 		std::shared_ptr<CompactCollateAndMeshFrameReq> context)
 	{
+		SpinLock::Guard lock(engine.shouldAcceptRequestsLock);
+		if (!engine.shouldAcceptRequests)
+		{
+			callOriginalCallback(false);
+			return;
+		}
+
 		// Record collate kernel start time
 		engine.collateKernelStartTime = std::chrono::high_resolution_clock::now();
 
@@ -933,7 +971,7 @@ public:
 
 		if (!success)
 		{
-			engine.stopCollateKernel();
+			engine.collateKernelComplete();
 			callOriginalCallback(false);
 			return;
 		}
@@ -943,7 +981,17 @@ public:
 		[[maybe_unused]] std::shared_ptr<CompactCollateAndMeshFrameReq> context,
 		cl_int collateStatus)
 	{
-		engine.stopCollateKernel();
+		SpinLock::Guard lock(engine.shouldAcceptRequestsLock);
+		if (!engine.shouldAcceptRequests)
+		{
+			/* We intentionally don't call collateKernelComplete() here for the
+			 * same reason as above.
+			 */
+			callOriginalCallback(false);
+			return;
+		}
+
+		engine.collateKernelComplete();
 		// Record collate kernel end time
 		engine.collateKernelEndTime = std::chrono::high_resolution_clock::now();
 
@@ -986,6 +1034,15 @@ void OpenClCollatingAndMeshingEngine::compactCollateAndMeshFrameReq(
 	AsynchronousLoop& asyncLoop, StimulusFrame& stimulusFrame,
 	Callback<compactCollateAndMeshFrameReqCbFn> callback)
 {
+	{
+		SpinLock::Guard lock(shouldAcceptRequestsLock);
+		if (!shouldAcceptRequests)
+		{
+			callback.callbackFn(false, stimulusFrame);
+			return;
+		}
+	}
+
 	auto caller = smoHooksPtr->ComponentThread_getSelf();
 	auto request = std::make_shared<CompactCollateAndMeshFrameReq>(
 		*this, asyncLoop, stimulusFrame,