From aef251b7e5193c0906ea0aa6dbffed67df33aa42 Mon Sep 17 00:00:00 2001
From: Hayodea Hekol <hayodea@protonmail.com>
Date: Sun, 9 Nov 2025 19:34:02 -0400
Subject: [PATCH] IoUringEngn: add random dummy slot generator for debugging

---
 .../livoxGen1/ioUringAssemblyEngine.cpp       | 71 ++++++++++++++++++-
 .../livoxGen1/ioUringAssemblyEngine.h         | 12 +++-
 2 files changed, 81 insertions(+), 2 deletions(-)

diff --git a/stimBuffApis/livoxGen1/ioUringAssemblyEngine.cpp b/stimBuffApis/livoxGen1/ioUringAssemblyEngine.cpp
index 4329b35..89175c2 100644
--- a/stimBuffApis/livoxGen1/ioUringAssemblyEngine.cpp
+++ b/stimBuffApis/livoxGen1/ioUringAssemblyEngine.cpp
@@ -7,6 +7,7 @@
 #include <cstring>
 #include <stdexcept>
 #include <functional>
+#include <random>
 #include <sys/socket.h>
 #include <sys/eventfd.h>
 #include <sys/uio.h>
@@ -63,7 +64,8 @@ eventfdFd(-1), eventfdDesc(nullptr), eventfd_value(0),
 stallTimer(parent_.device->componentThread->getIoService()),
 isAssembling(false),
 nDgramsPerStagingBufferFrame(nDgramsPerStagingBufferFrame_),
-assembledSlotsTracker(nDgramsPerStagingBufferFrame_)
+assembledSlotsTracker(nDgramsPerStagingBufferFrame_),
+randomDevice(), randomGenerator(randomDevice())
 {}
 
 bool IoUringAssemblyEngine::setup()
@@ -664,6 +666,73 @@ void IoUringAssemblyEngine::fillUnAssembledSlotsWithDummyDgrams()
 	}
 }
 
+void IoUringAssemblyEngine::randomDummySlotFiller(AsynchronousLoop& loop)
+{
+	if (!frameAssemblyDesc)
+		{ return; }
+
+	// Check if there are already dummies (natural dummy instance)
+	uint32_t nSucceeded = loop.nSucceeded.load();
+	uint32_t nTotal = loop.nTotal;
+	uint32_t nFailed = loop.nFailed.load();
+
+	if (nFailed > 0 || nSucceeded < nTotal)
+	{
+		std::cout << __func__ << ": Natural dummy instance detected (nSucceeded="
+			<< nSucceeded << ", nTotal=" << nTotal << ", nFailed=" << nFailed
+			<< "), skipping artificial dummy creation" << std::endl;
+		return;
+	}
+
+	// Randomly select a number of slots to make into dummies (less than total)
+	std::uniform_int_distribution<size_t> numDummiesDist(1, nTotal - 1);
+	size_t numDummiesToCreate = numDummiesDist(randomGenerator);
+
+	std::uniform_int_distribution<size_t> slotIndexDist(0, nTotal - 1);
+	size_t dummiesCreated = 0;
+	size_t maxAttempts = nTotal * 10; // Safety limit to prevent infinite loop
+	size_t attempts = 0;
+
+	// Mark random slots as unassembled
+	while (dummiesCreated < numDummiesToCreate && attempts < maxAttempts)
+	{
+		++attempts;
+		size_t randomIndex = slotIndexDist(randomGenerator);
+
+		// Skip if already unassembled, re-roll
+		if (randomIndex >= assembledSlotsTracker.size()
+			|| !assembledSlotsTracker[randomIndex].assembled)
+		{
+			continue;
+		}
+
+		// Mark as unassembled
+		assembledSlotsTracker[randomIndex].assembled = false;
+		++dummiesCreated;
+	}
+
+	if (dummiesCreated < numDummiesToCreate)
+	{
+		std::cerr << __func__ << ": Warning: Could only create " << dummiesCreated
+			<< " dummy slots out of " << numDummiesToCreate
+			<< " requested (max attempts reached)" << std::endl;
+		numDummiesToCreate = dummiesCreated;
+	}
+
+	// Update the AsynchronousLoop to reflect the new number of dummies
+	// Since we only reach here when nSucceeded == nTotal and nFailed == 0,
+	// we can directly calculate the new values
+	uint32_t newSucceeded = nTotal - static_cast<uint32_t>(numDummiesToCreate);
+	uint32_t newFailed = static_cast<uint32_t>(numDummiesToCreate);
+
+	loop.nSucceeded.store(newSucceeded);
+	loop.nFailed.store(newFailed);
+
+	std::cout << __func__ << ": Artificially created " << numDummiesToCreate
+		<< " dummy slots (nSucceeded: " << nTotal << " -> "
+		<< newSucceeded << ", nFailed: 0 -> " << newFailed << ")" << std::endl;
+}
+
 void IoUringAssemblyEngine::printSlotBytes(size_t slotIndex, size_t nBytes)
 {
 	if (!frameAssemblyDesc)
diff --git a/stimBuffApis/livoxGen1/ioUringAssemblyEngine.h b/stimBuffApis/livoxGen1/ioUringAssemblyEngine.h
index 749b79f..2525cea 100644
--- a/stimBuffApis/livoxGen1/ioUringAssemblyEngine.h
+++ b/stimBuffApis/livoxGen1/ioUringAssemblyEngine.h
@@ -9,6 +9,7 @@
 #include <vector>
 #include <chrono>
 #include <atomic>
+#include <random>
 #include <liburing.h>
 #include <boost/asio/io_service.hpp>
 #include <boost/asio/deadline_timer.hpp>
@@ -46,6 +47,8 @@ public:
 	static size_t computePointsPerDgram(int returnMode);
 	static size_t computePointsPerFrame(int returnMode, size_t nDgramsPerFrame)
 		{ return computePointsPerDgram(returnMode) * nDgramsPerFrame; }
+	static bool compactionIsNeeded(uint32_t nSucceeded, uint32_t nTotal)
+		{ return nSucceeded != 0 && nTotal != 0 && nSucceeded != nTotal; }
 
 private:
 	PcloudStimulusBuffer& parent;
@@ -86,13 +89,20 @@ private:
 	// Track which slots have been successfully assembled and maintain persistent iovecs
 	std::vector<SlotAssemblyDesc> assembledSlotsTracker;
 
+	// Random number generation for dummy slot creation
+	std::random_device randomDevice;
+	std::mt19937 randomGenerator;
+
 	void fillUnAssembledSlotsWithDummyDgrams();
-	void printSlotBytes(size_t slotIndex, size_t nBytes);
+	void randomDummySlotFiller(AsynchronousLoop& loop);
 	void onEventfdRead(
 		const boost::system::error_code& error, std::size_t bytes_transferred);
 
 	class AssembleFrameReq;
 	friend class AssembleFrameReq;
+
+public:
+	void printSlotBytes(size_t slotIndex, size_t nBytes);
 };
 
 } // namespace stim_buff