Revert "LivoxGen1: Use syncCancelerForAsyncWork in producer pipeline"

This reverts commit d788810a05.

We're doing this because it's not necessary. We will be porting to
coros soon and we can just use brace-scopes.

commonLibs/attachmentSupport/stimulusProducer.cpp

@@ -8,6 +8,7 @@
 #include <boost/system/error_code.hpp>
 #include <opts.h>
 #include <componentThread.h>
+#include <spinscale/spinLock.h>
 #include <user/stimulusProducer.h>
 #include <user/stimulusBuffer.h>
 
@@ -90,7 +91,10 @@ void StimulusProducer::destroyAttachedStimulusBuffer(
 
 void StimulusProducer::stop()
 {
-	(void)stimulusProducerCanceler.requestStop();
+	{
+		sscl::SpinLock::Guard lock(shouldContinueLock);
+		shouldContinue = false;
+	}
 
 	// Cancel timer immediately
 	timer.cancel();
@@ -101,7 +105,7 @@ void StimulusProducer::stop()
 
 void StimulusProducer::scheduleNextTimeout(int delayMs)
 {
-	if (stimulusProducerCanceler.isCancellationRequestedUnlocked())
+	if (!shouldContinue)
 		{ return; }
 
 	// Schedule the next timeout using the provided delay
@@ -127,6 +131,10 @@ void StimulusProducer::onTimeout(const boost::system::error_code& error)
 		return;
 	}
 
+	sscl::SpinLock::Guard lock(shouldContinueLock);
+	if (!shouldContinue)
+		{ return; }
+
 	/**	EXPLANATION:
 	 * We need to ensure that there's only ever one stimframe being produced
 	 * during any CONFIG_STIMBUFF_FRAME_PERIOD_MS period. To guarantee this, we
@@ -140,10 +148,6 @@ void StimulusProducer::onTimeout(const boost::system::error_code& error)
 	 */
 	int nextWakeupDelayMs;
 	bool deferred = false;
-	bool shouldContinue;
-	shouldContinue = stimulusProducerCanceler.execUncancelableSegmentOrAbort(
-		[&]()
-	{
 	if (frameAssemblyRateLimiter.tryAcquire())
 	{
 		nextWakeupDelayMs = CONFIG_STIMBUFF_FRAME_PERIOD_MS;
@@ -170,9 +174,9 @@ void StimulusProducer::onTimeout(const boost::system::error_code& error)
 		 * release the lock when frame production completes
 		 */
 		stimFrameProductionTimesliceInd();
-			return;
 	}
-
+	else
+	{
 		nextWakeupDelayMs = CONFIG_STIMBUFF_FRAME_RETRY_DELAY_MS;
 		deferred = true;
 
@@ -185,9 +189,7 @@ void StimulusProducer::onTimeout(const boost::system::error_code& error)
 				"Configured deferral period: " << nextWakeupDelayMs << "ms"
 				<< std::endl;
 		}
-	});
+	}
-
-	if (!shouldContinue) { return; }
 
 	scheduleNextTimeout(nextWakeupDelayMs);
 

include/user/stimulusProducer.h

@@ -14,7 +14,6 @@
 #include <boost/asio/io_service.hpp>
 #include <boost/asio/deadline_timer.hpp>
 #include <spinscale/spinLock.h>
-#include <spinscale/syncCancelerForAsyncWork.h>
 #include "deviceAttachmentSpec.h"
 
 namespace smo {
@@ -41,7 +40,8 @@ public:
 			&deviceAttachmentSpec,
 		boost::asio::io_service& ioService_)
 	: deviceAttachmentSpec(deviceAttachmentSpec),
-	ioService(ioService_), timer(ioService),
+	ioService(ioService_),
+	shouldContinue(false), timer(ioService),
 	nDeferrals(0)
 	{}
 
@@ -59,7 +59,7 @@ public:
 		std::cout << __func__ << ": Starting stimulus producer for device "
 			<< deviceAttachmentSpec->deviceSelector << std::endl;
 
-		stimulusProducerCanceler.startAcceptingWork();
+		shouldContinue = true;
 		nDeferrals = 0;
 		scheduleNextTimeout();
 	}
@@ -109,7 +109,8 @@ public:
 private:
 	boost::asio::io_service& ioService;
 protected:
-	sscl::SyncCancelerForAsyncWork stimulusProducerCanceler;
+	sscl::SpinLock shouldContinueLock;
+	bool shouldContinue;
 private:
 	boost::asio::deadline_timer timer;
 	size_t nDeferrals;

stimBuffApis/livoxGen1/ioUringAssemblyEngine.cpp

@@ -22,6 +22,7 @@
 #include <spinscale/cps/asynchronousBridge.h>
 #include <spinscale/cps/callback.h>
 #include <spinscale/cps/callableTracer.h>
+#include <spinscale/spinLock.h>
 #include "ioUringAssemblyEngine.h"
 #include "pcloudStimulusProducer.h"
 #include "livoxGen1.h"
@@ -58,6 +59,7 @@ IoUringAssemblyEngine::IoUringAssemblyEngine(
 frameAssemblyDesc(nullptr), ring{},
 eventfdFd(-1), eventfdDesc(nullptr), eventfd_value(0),
 stallTimer(parent_.device->componentThread->getIoService()),
+shouldAcceptRequests(false),
 nDgramsPerStagingBufferFrame(nDgramsPerStagingBufferFrame_),
 assembledSlotsTracker(nDgramsPerStagingBufferFrame_),
 randomDevice(), randomGenerator(randomDevice())
@@ -66,11 +68,14 @@ randomDevice(), randomGenerator(randomDevice())
 bool IoUringAssemblyEngine::setup()
 {
 	// Defensive check to prevent double-calling
-	if (!ioUringAssemblyEngnCanceler.isCancellationRequested())
+	{
+		sscl::SpinLock::Guard lock(shouldAcceptRequestsLock);
+		if (shouldAcceptRequests)
 		{
 			throw std::runtime_error(std::string(__func__) + ": setup() called "
 				"while already set up");
 		}
+	}
 
 	// Get FrameAssemblyDesc from staging buffer
 	frameAssemblyDesc = static_cast<std::shared_ptr<FrameAssemblyDesc>>(
@@ -151,7 +156,7 @@ bool IoUringAssemblyEngine::setup()
 	if (ret < 0)
 		{ goto cleanup_eventfd; }
 
-	ioUringAssemblyEngnCanceler.startAcceptingWork();
+	shouldAcceptRequests = true;
 	return true;
 
 cleanup_eventfd:
@@ -224,7 +229,7 @@ void IoUringAssemblyEngine::resetAndAssembleFrame(
 			+ ": onCqeReady callback is invalid");
 	}
 
-	if (ioUringAssemblyEngnCanceler.isCancellationRequestedUnlocked())
+	if (!shouldAcceptRequests)
 	{
 		throw std::runtime_error(std::string(__func__)
 			+ ": engine is not accepting requests");
@@ -316,7 +321,11 @@ void IoUringAssemblyEngine::resetAndAssembleFrame(
 
 bool IoUringAssemblyEngine::stop()
 {
-	return ioUringAssemblyEngnCanceler.requestStop();
+	// Acquire and release lock tightly around setting the flag
+	sscl::SpinLock::Guard lock(shouldAcceptRequestsLock);
+	bool wasAcceptingRequests = shouldAcceptRequests;
+	shouldAcceptRequests = false;
+	return wasAcceptingRequests;
 }
 
 void IoUringAssemblyEngine::assemblyCycleComplete()
@@ -435,17 +444,19 @@ public:
 	void assembleFrameReq1_posted(
 		std::shared_ptr<AssembleFrameReq> context)
 	{
-		auto& canceler = engine.ioUringAssemblyEngnCanceler;
+		sscl::SpinLock::Guard lock(engine.shouldAcceptRequestsLock);
-		const bool started = canceler.execUncancelableSegmentOrAbort(
+
-			[context, this]()
+		if (!engine.shouldAcceptRequests)
 		{
+			context->callOriginalCallback(false, sscl::AsynchronousLoop(0));
+			return;
+		}
+
 		// Initialize loop with number of slots
-			context->loop = sscl::AsynchronousLoop(
+		context->loop = sscl::AsynchronousLoop(engine.frameAssemblyDesc->numSlots);
-				engine.frameAssemblyDesc->numSlots);
 
 		// Record assembly start time
-			engine.assemblyStartTime =
+		engine.assemblyStartTime = std::chrono::high_resolution_clock::now();
-				std::chrono::high_resolution_clock::now();
 
 		/**	FIXME:
 		 * I'm suspicious of this std::bind return object here. What if us
@@ -466,13 +477,6 @@ public:
 			std::bind(&AssembleFrameReq::assembleFrameReq2_1,
 				context.get(), context,
 				std::placeholders::_1));
-		});
-
-		if (!started)
-		{
-			context->callOriginalCallback(false, sscl::AsynchronousLoop(0));
-			return;
-		}
 	}
 
 	void assembleFrameReq2_1(
@@ -494,22 +498,19 @@ public:
 		 * indeed seen a SEGFAULT even in the current code with locking, so
 		 * I'm going to hold the lock here for now.
 		 */
-		auto& canceler = context->engine.ioUringAssemblyEngnCanceler;
+		sscl::SpinLock::Guard lock(context->engine.shouldAcceptRequestsLock);
-		const bool shouldContinue = canceler.execUncancelableSegmentOrAbort(
-			[context]()
-		{
-			// Set timer fired flag
-			context->timerFired.store(true);
-			context->assembleFrameReq3(context);
-		});
 
-		if (!shouldContinue)
+		if (!context->engine.shouldAcceptRequests)
 		{
 			context->engine.assemblyCycleComplete();
 			context->loop.setRemainingIterationsToFailure();
 			context->callOriginalCallback(false, context->loop);
 			return;
 		}
+
+		// Set timer fired flag
+		context->timerFired.store(true);
+		context->assembleFrameReq3(context);
 	}
 
 	void assembleFrameReq2_2(
@@ -517,8 +518,7 @@ public:
 		void *user_data, int cqe_result)
 	{
 		// NB: The lock was acquired by onEventFdRead before calling this func
-		if (context->engine.ioUringAssemblyEngnCanceler
+		if (!context->engine.shouldAcceptRequests)
-			.isCancellationRequestedUnlocked())
 		{
 			context->engine.assemblyCycleComplete();
 			context->loop.setRemainingIterationsToFailure();
@@ -549,8 +549,8 @@ public:
 	{
 		/**	EXPLANATION:
 		 * All branch paths that invoke this unifyig oracle function are
-		 * expected to already hold ioUringAssemblyEngnCanceler's lock before
+		 * expected to already hold the shouldAcceptRequestsLock before calling
-		 * calling it.
+		 * it.
 		 */
 		// Ensure we only execute once using atomic exchange
 		if (context->handlerExecuted.exchange(true)) { return; }
@@ -638,7 +638,8 @@ void IoUringAssemblyEngine::assembleFrameReq(
 	sscl::cps::Callback<assembleFrameReqCbFn> cb)
 {
 	{
-		if (ioUringAssemblyEngnCanceler.isCancellationRequested())
+		sscl::SpinLock::Guard lock(shouldAcceptRequestsLock);
+		if (!shouldAcceptRequests)
 		{
 			cb.callbackFn(false, sscl::AsynchronousLoop(0));
 			return;
@@ -669,7 +670,7 @@ void IoUringAssemblyEngine::onEventfdRead(
 	 * IoUringAssemblyEngine's per-assembly state isn't destroyed while this
 	 * handler is running.
 	 */
-	sscl::SpinLock::Guard lock(ioUringAssemblyEngnCanceler.s.lock);
+	sscl::SpinLock::Guard lock(shouldAcceptRequestsLock);
 	/**	EXPLANATION:
 	 * You'd think we should put check for shouldAcceptRequests here and
 	 * `return` here if !shouldAcceptRequests, but we shouldn't because
@@ -721,7 +722,7 @@ void IoUringAssemblyEngine::onEventfdRead(
 	 * But we do put a `return` here because we know that at this point, the
 	 * caller's callback has already been invoked.
 	 */
-	if (ioUringAssemblyEngnCanceler.isCancellationRequestedUnlocked()
+	if (!shouldAcceptRequests
 		|| eventfdDesc == nullptr || !eventfdDesc->is_open())
 	{
 		return;

stimBuffApis/livoxGen1/ioUringAssemblyEngine.h

@@ -19,7 +19,7 @@
 #include <spinscale/cps/asynchronousContinuation.h>
 #include <spinscale/asynchronousLoop.h>
 #include <spinscale/cps/callback.h>
-#include <spinscale/syncCancelerForAsyncWork.h>
+#include <spinscale/spinLock.h>
 #include <user/frameAssemblyDesc.h>
 #include <user/stagingBuffer.h>
 
@@ -80,7 +80,12 @@ private:
 	boost::asio::deadline_timer stallTimer;
 	// Callback for CQE ntfns (called with user_data+result from each CQE)
 	resetAndAssembleFrameCbFn onCqeReadyCallback;
-	sscl::SyncCancelerForAsyncWork ioUringAssemblyEngnCanceler;
+	/**	EXPLANATION:
+	 * Flag to indicate whether engine should accept new requests.
+	 * Set by setup(), cleared by stop().
+	 */
+	sscl::SpinLock shouldAcceptRequestsLock;
+	bool shouldAcceptRequests;
 
 	size_t nDgramsPerStagingBufferFrame;
 

stimBuffApis/livoxGen1/openClCollatingAndMeshingEngine.cpp

@@ -39,6 +39,7 @@ clAverageIntensityBufferClBuffer(nullptr),
 clAssemblyBuffer(nullptr),
 clCollationBuffer(nullptr),
 clAverageIntensityBuffer(nullptr),
+shouldAcceptRequests(false),
 compactIsRunning(false),
 collateIsRunning(false),
 currentCompactKernelEvent(nullptr), currentCollateKernelEvent(nullptr),
@@ -63,11 +64,14 @@ OpenClCollatingAndMeshingEngine::~OpenClCollatingAndMeshingEngine()
 bool OpenClCollatingAndMeshingEngine::setup()
 {
 	// Defensive check to prevent double-calling
-	if (!openClCollMeshEngnCanceler.isCancellationRequested())
+	{
+		sscl::SpinLock::Guard lock(shouldAcceptRequestsLock);
+		if (shouldAcceptRequests)
 		{
 			throw std::runtime_error(std::string(__func__) + ": setup() called "
 				"while already set up");
 		}
+	}
 
 	if (!smoHooksPtr || !smoHooksPtr->ComputeManager_getDevice)
 	{
@@ -198,7 +202,7 @@ bool OpenClCollatingAndMeshingEngine::setup()
 
 	clFlush(computeDevice->commandQueue);
 	clFinish(computeDevice->commandQueue);
-	openClCollMeshEngnCanceler.startAcceptingWork();
+	shouldAcceptRequests = true;
 	return true;
 }
 
@@ -767,7 +771,11 @@ bool OpenClCollatingAndMeshingEngine::setupCollateDgramsArgs(
 
 bool OpenClCollatingAndMeshingEngine::stop()
 {
-	return openClCollMeshEngnCanceler.requestStop();
+	// Acquire and release lock tightly around setting the flag
+	sscl::SpinLock::Guard lock(shouldAcceptRequestsLock);
+	bool wasAcceptingRequests = shouldAcceptRequests;
+	shouldAcceptRequests = false;
+	return wasAcceptingRequests;
 }
 
 void OpenClCollatingAndMeshingEngine::compactKernelComplete(bool isFinalizing)
@@ -1043,18 +1051,19 @@ public:
 	void compactCollateAndMeshFrameReq1_doCompact_posted(
 		std::shared_ptr<CompactCollateAndMeshFrameReq> context)
 	{
-		auto& canceler = engine.openClCollMeshEngnCanceler;
+		sscl::SpinLock::Guard lock(engine.shouldAcceptRequestsLock);
-		const bool shouldContinue = canceler.execUncancelableSegmentOrAbort(
+		if (!engine.shouldAcceptRequests)
-			[context, this]()
 		{
+			callOriginalCallback(false);
+			return;
+		}
+
 		// Record compact kernel start time
-			engine.compactKernelStartTime =
+		engine.compactKernelStartTime = std::chrono::high_resolution_clock::now();
-				std::chrono::high_resolution_clock::now();
 
 		bool success = engine.startCompactKernel(
 			engine.parent.assemblyBuffer,
-				static_cast<uint32_t>(
+			static_cast<uint32_t>(context->frameAssemblyResult.nSucceeded.load()),
-					context->frameAssemblyResult.nSucceeded.load()),
 			std::bind(
 				&CompactCollateAndMeshFrameReq
 					::compactCollateAndMeshFrameReq2_compactDone_posted,
@@ -1065,12 +1074,6 @@ public:
 		{
 			engine.compactKernelComplete();
 			callOriginalCallback(false);
-			}
-		});
-
-		if (!shouldContinue)
-		{
-			callOriginalCallback(false);
 			return;
 		}
 	}
@@ -1079,27 +1082,8 @@ public:
 		std::shared_ptr<CompactCollateAndMeshFrameReq> context,
 		cl_int compactStatus)
 	{
-		bool compactFailed = false;
+		sscl::SpinLock::Guard lock(engine.shouldAcceptRequestsLock);
-
+		if (!engine.shouldAcceptRequests)
-		auto& canceler = engine.openClCollMeshEngnCanceler;
-		const bool shouldContinue = canceler.execUncancelableSegmentOrAbort(
-			[context, this, compactStatus, &compactFailed]()
-		{
-			engine.compactKernelComplete();
-			// Record compact kernel end time
-			engine.compactKernelEndTime =
-				std::chrono::high_resolution_clock::now();
-
-			// If compact failed, call callback directly with failure
-			if (compactStatus != CL_SUCCESS)
-			{
-				compactFailed = true;
-				callOriginalCallback(false);
-				return;
-			}
-		});
-
-		if (!shouldContinue)
 		{
 			/**	EXPLANATION:
 			 * We intentionally don't call compactKernelComplete() here because
@@ -1111,7 +1095,16 @@ public:
 			return;
 		}
 
-		if (compactFailed) { return; }
+		engine.compactKernelComplete();
+		// Record compact kernel end time
+		engine.compactKernelEndTime = std::chrono::high_resolution_clock::now();
+
+		// If compact failed, call callback directly with failure
+		if (compactStatus != CL_SUCCESS)
+		{
+			callOriginalCallback(false);
+			return;
+		}
 
 #if 0
 		// Print first 4 bytes of each slot
@@ -1123,19 +1116,22 @@ public:
 		}
 #endif
 
+		lock.unlockPrematurely();
 		context->compactCollateAndMeshFrameReq3_doCollate_posted(context);
 	}
 
 	void compactCollateAndMeshFrameReq3_doCollate_posted(
 		std::shared_ptr<CompactCollateAndMeshFrameReq> context)
 	{
-		auto& canceler = engine.openClCollMeshEngnCanceler;
+		sscl::SpinLock::Guard lock(engine.shouldAcceptRequestsLock);
-		const bool shouldContinue = canceler.execUncancelableSegmentOrAbort(
+		if (!engine.shouldAcceptRequests)
-			[context, this]()
 		{
+			callOriginalCallback(false);
+			return;
+		}
+
 		// Record collate kernel start time
-			engine.collateKernelStartTime =
+		engine.collateKernelStartTime = std::chrono::high_resolution_clock::now();
-				std::chrono::high_resolution_clock::now();
 
 		bool success = engine.startCollateKernel(
 			context->intensityStimFrame, context->anyAmbienceAttached(),
@@ -1151,12 +1147,6 @@ public:
 				context->intensityStimFrame, context->anyAmbienceAttached());
 
 			callOriginalCallback(false);
-			}
-		});
-
-		if (!shouldContinue)
-		{
-			callOriginalCallback(false);
 			return;
 		}
 	}
@@ -1165,6 +1155,16 @@ public:
 		[[maybe_unused]] std::shared_ptr<CompactCollateAndMeshFrameReq> context,
 		cl_int collateStatus)
 	{
+		sscl::SpinLock::Guard lock(engine.shouldAcceptRequestsLock);
+		if (!engine.shouldAcceptRequests)
+		{
+			/* We intentionally don't call collateKernelComplete() here for the
+			 * same reason as above.
+			 */
+			callOriginalCallback(false);
+			return;
+		}
+
 		/**	EXPLANATION:
 		 * The reason we don't call collateKernelComplete before checking
 		 * shouldAcceptRequests is because if shouldAcceptRequests is false, then
@@ -1174,10 +1174,6 @@ public:
 		 * Therefore it's finalize()'s responsibility to ensure that it properly
 		 * completes/cleans up any in-flight operations.
 		 */
-		auto& canceler = engine.openClCollMeshEngnCanceler;
-		const bool shouldContinue = canceler.execUncancelableSegmentOrAbort(
-			[context, this, collateStatus]()
-		{
 		engine.collateKernelComplete(
 			context->intensityStimFrame, context->anyAmbienceAttached());
 
@@ -1203,8 +1199,7 @@ public:
 		}
 
 		// Record collate kernel end time
-			engine.collateKernelEndTime =
+		engine.collateKernelEndTime = std::chrono::high_resolution_clock::now();
-				std::chrono::high_resolution_clock::now();
 
 		bool success = (collateStatus == CL_SUCCESS);
 
@@ -1250,16 +1245,6 @@ public:
 #endif
 
 		callOriginalCallback(success);
-		});
-
-		if (!shouldContinue)
-		{
-			/* We intentionally don't call collateKernelComplete() here for the
-			 * same reason as above.
-			 */
-			callOriginalCallback(false);
-			return;
-		}
 	}
 };
 
@@ -1271,7 +1256,8 @@ void OpenClCollatingAndMeshingEngine::compactCollateAndMeshFrameReq(
 	sscl::cps::Callback<compactCollateAndMeshFrameReqCbFn> callback)
 {
 	{
-		if (openClCollMeshEngnCanceler.isCancellationRequested())
+		sscl::SpinLock::Guard lock(shouldAcceptRequestsLock);
+		if (!shouldAcceptRequests)
 		{
 			callback.callbackFn(false, stimulusFrame);
 			return;

stimBuffApis/livoxGen1/openClCollatingAndMeshingEngine.h

@@ -15,7 +15,7 @@
 #include <CL/cl.h>
 #include <spinscale/asynchronousLoop.h>
 #include <spinscale/cps/callback.h>
-#include <spinscale/syncCancelerForAsyncWork.h>
+#include <spinscale/spinLock.h>
 #include <user/stimulusFrame.h>
 #include <user/stagingBuffer.h>
 #include <user/frameAssemblyDesc.h>
@@ -150,7 +150,8 @@ private:
 	cl_mem clAverageIntensityBuffer;
 
 	// State tracking
-	sscl::SyncCancelerForAsyncWork openClCollMeshEngnCanceler;
+	sscl::SpinLock shouldAcceptRequestsLock;
+	bool shouldAcceptRequests;
 	bool compactIsRunning;
 	bool collateIsRunning;
 	cl_event currentCompactKernelEvent;

stimBuffApis/livoxGen1/pcloudStimulusProducer.cpp

@@ -464,39 +464,37 @@ public:
 	void produceFrameReq1_doAssemble_posted(
 		std::shared_ptr<ProduceFrameReq> context)
 	{
-		const bool shouldContinue = pcloudProducer.stimulusProducerCanceler
+		sscl::SpinLock::Guard lock(pcloudProducer.shouldContinueLock);
-			.execUncancelableSegmentOrAbort(
+		if (!pcloudProducer.shouldContinue)
-				[this, context]()
 		{
+			callOriginalCallback();
+			return;
+		}
+
 		pcloudProducer.ioUringAssemblyEngine.assembleFrameReq(
 			{context, std::bind(
 				&ProduceFrameReq::produceFrameReq2_assembleDone,
 				context.get(), context,
 				std::placeholders::_1, std::placeholders::_2)});
-			});
-
-		if (!shouldContinue)
-		{
-			callOriginalCallback();
-			return;
-		}
 	}
 
 	void produceFrameReq2_assembleDone(
 		std::shared_ptr<ProduceFrameReq> context,
 		bool success, sscl::AsynchronousLoop loop)
 	{
-		bool shouldContinue = pcloudProducer.stimulusProducerCanceler
+		sscl::SpinLock::Guard lock(pcloudProducer.shouldContinueLock);
-			.execUncancelableSegmentOrAbort(
+		if (!pcloudProducer.shouldContinue)
-				[this, context, success, loop]()
 		{
+			callOriginalCallback();
+			return;
+		}
+
 		if (!success)
 		{
 			callOriginalCallback();
 
 			if (pcloudProducer.attachedStimulusBuffers.size() > 0) {
-					std::cerr << __func__
+				std::cerr << __func__ << ": Failed to assemble frame.\n";
-						<< ": Failed to assemble frame.\n";
 			}
 			return;
 		}
@@ -504,8 +502,7 @@ public:
 		context->frameAssemblyResult = loop;
 
 		// Check if intensity buffer is attached and acquire frame if so
-			if (auto intensityBuff = pcloudProducer
+		if (auto intensityBuff = pcloudProducer.intensityStimulusBuffer.load(
-				.intensityStimulusBuffer.load(
 			std::memory_order_acquire))
 		{
 			size_t intensityRingbuffIndex = intensityBuff
@@ -524,8 +521,7 @@ public:
 		}
 
 		// Check if light ambience buffer is attached and acquire frame if so
-			std::optional<AmbienceProductionDesc>
+		std::optional<AmbienceProductionDesc> lightAmbienceProductionDescDesc;
-				lightAmbienceProductionDescDesc;
 		if (auto lightAmbienceBuff =
 			pcloudProducer.lightAmbienceStimulusBuffer.load(
 				std::memory_order_acquire))
@@ -533,26 +529,22 @@ public:
 			size_t lightAmbienceRingbuffIndex = lightAmbienceBuff
 				->ringBuffer.getIndexToProduceInto();
 
-				StimulusFrame& lightAmbienceStimFrame =
+			StimulusFrame& lightAmbienceStimFrame = lightAmbienceBuff
-					lightAmbienceBuff->ringBuffer.getDataAtSlot(
+				->ringBuffer.getDataAtSlot(lightAmbienceRingbuffIndex);
-						lightAmbienceRingbuffIndex);
 
 			lightAmbienceStimFrame.lock.writeAcquire();
 			context->lightAmbienceStimFrame = std::make_optional(
 				std::ref(lightAmbienceStimFrame));
-				lightAmbienceProductionDescDesc =
+			lightAmbienceProductionDescDesc = AmbienceProductionDesc{
-					AmbienceProductionDesc{
 				std::ref(lightAmbienceStimFrame),
-						lightAmbienceBuff
+				lightAmbienceBuff->passbandCountGtComparator};
-							->passbandCountGtComparator};
 		}
 		else {
 			context->lightAmbienceStimFrame = std::nullopt;
 		}
 
 		// Check if dark ambience buffer is attached and acquire frame if so
-			std::optional<AmbienceProductionDesc>
+		std::optional<AmbienceProductionDesc> darkAmbienceProductionDescDesc;
-				darkAmbienceProductionDescDesc;
 		if (auto darkAmbienceBuff =
 			pcloudProducer.darkAmbienceStimulusBuffer.load(
 				std::memory_order_acquire))
@@ -560,41 +552,29 @@ public:
 			size_t darkAmbienceRingbuffIndex = darkAmbienceBuff
 				->ringBuffer.getIndexToProduceInto();
 
-				StimulusFrame& darkAmbienceStimFrame =
+			StimulusFrame& darkAmbienceStimFrame = darkAmbienceBuff
-					darkAmbienceBuff->ringBuffer.getDataAtSlot(
+				->ringBuffer.getDataAtSlot(darkAmbienceRingbuffIndex);
-						darkAmbienceRingbuffIndex);
 
 			darkAmbienceStimFrame.lock.writeAcquire();
 			context->darkAmbienceStimFrame = std::make_optional(
 				std::ref(darkAmbienceStimFrame));
-				darkAmbienceProductionDescDesc =
+			darkAmbienceProductionDescDesc = AmbienceProductionDesc{
-					AmbienceProductionDesc{
 				std::ref(darkAmbienceStimFrame),
-						darkAmbienceBuff
+				darkAmbienceBuff->passbandCountLtComparator};
-							->passbandCountLtComparator};
 		}
 		else {
 			context->darkAmbienceStimFrame = std::nullopt;
 		}
 
-			pcloudProducer.openClCollatingAndMeshingEngine
+		pcloudProducer.openClCollatingAndMeshingEngine.compactCollateAndMeshFrameReq(
-				.compactCollateAndMeshFrameReq(
+			loop, stimulusFrame,
-					context->frameAssemblyResult, stimulusFrame,
 			context->intensityStimFrame,
 			std::move(lightAmbienceProductionDescDesc),
 			std::move(darkAmbienceProductionDescDesc),
 			{context, std::bind(
-						&ProduceFrameReq
+				&ProduceFrameReq::produceFrameReq3_compactCollateDone,
-							::produceFrameReq3_compactCollateDone,
 				context.get(), context,
 				std::placeholders::_1, std::placeholders::_2)});
-		});
-
-		if (!shouldContinue)
-		{
-			callOriginalCallback();
-			return;
-		}
 	}
 
 	void produceFrameReq3_compactCollateDone(
@@ -623,10 +603,7 @@ public:
 		}
 #endif
 
-		/**	EXPLANATION:
+		// Release intensity frame if it was used
-		 * Release intensity/ambience frames if they were supplied/used,
-		 * regardless of whether or not a cancelation request occurred.
-		 */
 		if (context->intensityStimFrame.has_value()) {
 			context->intensityStimFrame->get().lock.writeRelease();
 		}
@@ -638,58 +615,18 @@ public:
 			context->darkAmbienceStimFrame->get().lock.writeRelease();
 		}
 
-		if (!success)
+		sscl::SpinLock::Guard lock(pcloudProducer.shouldContinueLock);
-		{
+		if (!pcloudProducer.shouldContinue)
-			callOriginalCallback();
-
-			std::cerr << __func__
-				<< ": Failed to compact and collate frame"
-				<< std::endl;
-
-			return;
-		}
-
-		/**	EXPLANATION:
-		 * Cancellation early exit for the success path. Analogous to the
-		 * (legacy, removed) pre-canceler check under shouldContinueLock before
-		 * lock.unlockPrematurely() in the former CPS version of this handler.
-		 *
-		 * Assumptions that make the unlocked tail (dump, debug logging, stage
-		 * durations, final callOriginalCallback()) safe without holding
-		 * stimulusProducerCanceler.s.lock:
-		 *
-		 * 1. This handler is only entered from
-		 *    CompactCollateAndMeshFrameReq4's execUncancelableSegmentOrAbort
-		 *    body, so openClCollatingAndMeshingEngine::finalize() cannot
-		 *    tear down OpenCL/engine state until this function returns.
-		 *
-		 * 2. PcloudStimulusProducer::stop() finalizes OpenCL before io_uring,
-		 *    so getCompactKernelDuration()/getCollateKernelDuration() and
-		 *    getAssemblyDuration() are not racing engine finalize here.
-		 *
-		 * 3. dump/logging reads only producer-owned state (pcloudFrameDumper,
-		 *    collationBuffer, device, context->frameAssemblyResult) that
-		 *    stop()/finalize() do not destroy.
-		 *
-		 * 4. A stop() that lands after this read but before the tail is
-		 *    intentional stale work (same as unlockPrematurely()), not UAF.
-		 *
-		 * Rework to run portions inside stimulusProducerCanceler
-		 * execUncancelableSegmentOrAbort if any of the above ceases to hold:
-		 * e.g. this callback is invoked outside the OpenCL uncancelable
-		 * segment, the tail begins touching engine or buffer state that
-		 * finalize() resets, or stop() ordering changes so teardown can
-		 * interleave with the unlocked tail.
-		 */
-		const bool shouldContinue =
-			!pcloudProducer.stimulusProducerCanceler.isCancellationRequested();
-
-		if (!shouldContinue)
 		{
 			callOriginalCallback();
 			return;
 		}
 
+		if (!success) {
+			std::cerr << __func__ << ": Failed to compact and collate frame" << std::endl;
+		} else
+		{
+			lock.unlockPrematurely();
 			if (pcloudProducer.pcloudFrameDumper.isEnabled())
 			{
 				try
@@ -801,6 +738,7 @@ public:
 				<< "ms, collateKernel=" << collateDuration.count()
 				<< "ms" << std::endl;
 #endif
+		}
 
 		callOriginalCallback();
 	}
@@ -810,9 +748,10 @@ void PcloudStimulusProducer::produceFrameReq(
 	sscl::cps::Callback<produceFrameReqCbFn> callback)
 {
 	/**	EXPLANATION:
-	 * We don't do any additional canceler-lock acquisition here because
+	 * We shouldn't acquire the StimulusProducer::shouldContinueLock here because
-	 * callback segment methods already use stimulusProducerCanceler
+	 * this function is called from
-	 * checkpoints before running uncancelable work.
+	 * StimulusProducer::stimFrameProductionTimesliceInd(), which is already
+	 * holding the lock.
 	 */
 	auto caller = smoHooksPtr->ComponentThread_getSelf();
 	auto request = std::make_shared<ProduceFrameReq>(