Locking: Add contin tracing to detect deadlocks

We added the code to trace all the contins linked to a particular
Lockvoker, into SerializedAsyncContinuation. This basically
ensures that we'll almost never deal with a deadlock. So cool.

include/asynchronousContinuation.h

@@ -38,7 +38,6 @@ public:
 		std::shared_ptr<AsynchronousContinuation<OriginalCbFnT>>
 			lifetimePreservingConveyance);
 
-
 	/**	EXPLANATION:
 	 * When an exception is thrown in a an async callee, which pertains to an
 	 * error in the data given by the caller, we ought not to throw the
@@ -67,6 +66,11 @@ public:
 			{ std::rethrow_exception(exception); }
 	}
 
+	// Implement the virtual method from AsynchronousContinuationChainLink
+	virtual std::shared_ptr<AsynchronousContinuationChainLink>
+	getCallersContinuation() override
+		{ return originalCallback.callerContinuation; }
+
 public:
 	Callback<OriginalCbFnT> originalCallback;
 	std::exception_ptr exception;

include/asynchronousContinuationChainLink.h

@@ -18,6 +18,9 @@ class AsynchronousContinuationChainLink
 {
 public:
     virtual ~AsynchronousContinuationChainLink() = default;
+
+	virtual std::shared_ptr<AsynchronousContinuationChainLink>
+	getCallersContinuation() = 0;
 };
 
 } // namespace smo

include/serializedAsynchronousContinuation.h

@@ -100,7 +100,14 @@ public:
 					{ return; }
 
 #ifdef CONFIG_ENABLE_DEBUG_LOCKS
-				handleLikelyDeadlock(*firstFailedQutexPtr);
+				Qutex	&firstFailedQutex = *firstFailedQutexPtr;
+				bool isDeadlock = traceContinuationHistoryForDeadlockOn(
+					firstFailedQutex);
+
+				if (!isDeadlock)
+					{ return; }
+
+				handleDeadlock(firstFailedQutex);
 #endif
 				return;
 			}
@@ -186,12 +193,13 @@ public:
 #endif
 		}
 
+#ifdef CONFIG_ENABLE_DEBUG_LOCKS
+		bool traceContinuationHistoryForDeadlockOn(Qutex &firstFailedQutex);
 		/**
 		 * @brief Handle a likely deadlock situation by logging debug information
 		 * @param firstFailedQutex The first qutex that failed acquisition
 		 */
-#ifdef CONFIG_ENABLE_DEBUG_LOCKS
-		void handleLikelyDeadlock(Qutex& firstFailedQutex);
+		void handleDeadlock(Qutex& firstFailedQutex);
 #endif
 
 	private: