PcloudStimBuff: Add skeleton daemon; frame rate limiting

Basic implementation of the stimbuff mechanism's frame rate
limiting behaviour.

stimBuffApis/livoxGen1/pcloudStimulusBuffer.cpp

@@ -1,10 +1,118 @@
-#include "pcloudStimulusBuffer.h"
+#include <config.h>
 #include <opts.h>
 #include <iostream>
 #include <algorithm>
+#include <functional>
+#include <componentThread.h>
+#include <asynchronousBridge.h>
+#include "pcloudStimulusBuffer.h"
 
 namespace smo {
 namespace stim_buff {
 
+PcloudStimulusBuffer::PcloudStimulusBuffer(
+	const device::DeviceAttachmentSpec& deviceAttachmentSpec,
+	std::shared_ptr<livoxProto1::Device> &device,
+	const PcloudFormatDesc& formatDesc,
+	size_t nDgramsPerStagingBufferFrame)
+:	StimulusBuffer(deviceAttachmentSpec),
+deviceAttachmentSpec(deviceAttachmentSpec), device(device),
+formatDesc(formatDesc), stagingBuffer(
+	StagingBuffer::InputEngineConstraints::ioUringConstraints,
+	OpenClConstraints(), nDgramsPerStagingBufferFrame),
+shouldContinue(false), timer(device->componentThread->getIoService())
+{
+}
+
+void PcloudStimulusBuffer::start()
+{
+	shouldContinue.store(true);
+	scheduleNextTimeout();
+}
+
+void PcloudStimulusBuffer::stop()
+{
+	shouldContinue.store(false);
+
+	// Set up a timeout bridge using the device's component thread's io_service
+	auto& ioService = device->componentThread->getIoService();
+	boost::asio::deadline_timer delayTimer(ioService);
+	AsynchronousBridge bridge(ioService);
+
+	// Set up the delay for CONFIG_STIMBUFF_FRAME_PERIOD_MS to let in-flight
+	// operation finish
+	delayTimer.expires_from_now(
+		boost::posix_time::milliseconds(CONFIG_STIMBUFF_FRAME_PERIOD_MS));
+
+	delayTimer.async_wait(
+		[&bridge](const boost::system::error_code& error)
+		{
+			(void)error;
+
+			// Always signal complete, whether timeout expired or was cancelled
+			bridge.setAsyncOperationComplete();
+		});
+
+	bridge.waitForAsyncOperationCompleteOrIoServiceStopped();
+
+	// After delay, cancel timer and perform cleanup
+	timer.cancel();
+}
+
+void PcloudStimulusBuffer::scheduleNextTimeout(int delayMs)
+{
+	if (!shouldContinue.load())
+		{ return; }
+
+	// Schedule the next timeout using the provided delay
+	timer.expires_from_now(
+		boost::posix_time::milliseconds(delayMs));
+
+	timer.async_wait(
+		std::bind(
+			&PcloudStimulusBuffer::onTimeout, this, std::placeholders::_1));
+}
+
+void PcloudStimulusBuffer::onTimeout(const boost::system::error_code& error)
+{
+	// Timer was cancelled, which is expected when stopping
+	if (error == boost::asio::error::operation_aborted) {
+		return;
+	}
+
+	if (error)
+	{
+		std::cerr << "PcloudStimulusBuffer: Timer error: " << error.message()
+			<< std::endl;
+		return;
+	}
+
+	if (!shouldContinue.load())
+		{ 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
+	 * use a spinlock.
+	 *
+	 * When a new frame is to be produced, the async producer will first acquire
+	 * the frameAssemblyLimiter spinlock. This way, when the next timeout is
+	 * fired it can check whether its predecessor stimframe has finished being
+	 * produced. If the preceding stimframe is still being produced, then we'll
+	 * sleep for CONFIG_STIMBUFF_FRAME_RETRY_PERIOD_MS ms before trying again.
+	 */
+	int nextWakeupDelayMs;
+	if (frameAssemblyRateLimiter.tryAcquire())
+		{ nextWakeupDelayMs = CONFIG_STIMBUFF_FRAME_PERIOD_MS; }
+	else
+		{ nextWakeupDelayMs = CONFIG_STIMBUFF_FRAME_RETRY_DELAY_MS; }
+
+	// Placeholder handler (empty for now)
+	// Note: The lock should be released when frame production completes
+
+	// Schedule next timeout with the pre-determined duration
+	scheduleNextTimeout(nextWakeupDelayMs);
+}
+
 } // namespace stim_buff
 } // namespace smo

stimBuffApis/livoxGen1/pcloudStimulusBuffer.h

@@ -1,6 +1,10 @@
 #ifndef _LIVOX_GEN1_PCLOUD_STIMULUS_BUFFER_H
 #define _LIVOX_GEN1_PCLOUD_STIMULUS_BUFFER_H
 
+#include <config.h>
+#include <atomic>
+#include <boost/asio/deadline_timer.hpp>
+#include <spinLock.h>
 #include <user/stimulusBuffer.h>
 #include <user/stimFrame.h>
 #include <livoxProto1/device.h>
@@ -26,13 +30,7 @@ public:
 		const device::DeviceAttachmentSpec& deviceAttachmentSpec,
 		std::shared_ptr<livoxProto1::Device> &device,
 		const PcloudFormatDesc& formatDesc,
-		size_t nDgramsPerStagingBufferFrame)
+		size_t nDgramsPerStagingBufferFrame);
-	:	StimulusBuffer(deviceAttachmentSpec),
-	deviceAttachmentSpec(deviceAttachmentSpec), device(device),
-	formatDesc(formatDesc), stagingBuffer(
-		StagingBuffer::InputEngineConstraints::ioUringConstraints,
-		OpenClConstraints(), nDgramsPerStagingBufferFrame)
-	{}
 
 	~PcloudStimulusBuffer() = default;
 
@@ -42,12 +40,25 @@ public:
 	PcloudStimulusBuffer(PcloudStimulusBuffer&&) = default;
 	PcloudStimulusBuffer& operator=(PcloudStimulusBuffer&&) = default;
 
+	// Control methods
+	void start();
+	void stop();
+
 public:
 	device::DeviceAttachmentSpec deviceAttachmentSpec;
 	std::shared_ptr<livoxProto1::Device> device;
 	PcloudFormatDesc formatDesc;
 	StagingBuffer stagingBuffer;
 	IoUringAssemblyEngine ioUringAssemblyEngine;
+
+private:
+	std::atomic<bool> shouldContinue;
+	boost::asio::deadline_timer timer;
+	SpinLock frameAssemblyRateLimiter;
+
+private:
+	void scheduleNextTimeout(int delayMs = CONFIG_STIMBUFF_FRAME_PERIOD_MS);
+	void onTimeout(const boost::system::error_code& error);
 };
 
 } // namespace stim_buff