QtxAcqHistTracker: Add spinlock and use it

include/qutexAcquisitionHistoryTracker.h

@@ -5,6 +5,7 @@
 #include <memory>
 #include <forward_list>
 #include <functional>
+#include "spinLock.h"
 
 
 namespace smo {
@@ -75,15 +76,20 @@ public:
 			heldLocks
 		)
 	{
-		auto it = acquisitionHistory.find(continuation);
+		acquisitionHistoryLock.acquire();
 
+		auto it = acquisitionHistory.find(continuation);
 		// If a continuation already exists, don't add it again
-		if (it != acquisitionHistory.end()) {
+		if (it != acquisitionHistory.end())
+		{
+			acquisitionHistoryLock.release();
 			return;
 		}
 
 		acquisitionHistory.emplace(continuation, std::make_pair(
 			std::ref(wantedLock), std::move(heldLocks)));
+
+		acquisitionHistoryLock.release();
 	}
 
 	/**
@@ -97,20 +103,27 @@ public:
 		std::shared_ptr<AsynchronousContinuationChainLink> &continuation
 		)
 	{
+		acquisitionHistoryLock.acquire();
+
 		auto it = acquisitionHistory.find(continuation);
-		if (it != acquisitionHistory.end()) {
+		if (it != acquisitionHistory.end())
+		{
 			acquisitionHistory.erase(it);
+
+			acquisitionHistoryLock.release();
 			return true;
 		}
+
+		acquisitionHistoryLock.release();
 		return false;
 	}
 
 	bool heuristicallyTraceContinuationHistoryForGridlockOn(
 		Qutex &firstFailedQutex,
-		std::shared_ptr<AsynchronousContinuationChainLink>& currentContinuation)
-		const;
+		std::shared_ptr<AsynchronousContinuationChainLink>&
+			currentContinuation);
 	bool completelyTraceContinuationHistoryForGridlockOn(
-		Qutex &firstFailedQutex) const;
+		Qutex &firstFailedQutex);
 
 	// Disable copy constructor and assignment operator
 	QutexAcquisitionHistoryTracker(
@@ -123,6 +136,15 @@ private:
 	~QutexAcquisitionHistoryTracker() = default;
 
 private:
+	/**	EXPLANATION:
+	 * We use a SpinLock here instead of a Qutex because this acquisition
+	 * history tracker is invoked within the LockerAndInvoker.
+	 * Since LockerAndInvoker is too tightly coupled with Qutex workings, using
+	 * a Qutex here would create a circular dependency or deadlock situation.
+	 * Therefore, it's best to use a SpinLock on the history class to avoid
+	 * these coupling issues.
+	 */
+	SpinLock acquisitionHistoryLock;
 	AcquisitionHistoryMap acquisitionHistory;
 };