LockSet:tryAcquireOrBackoff use optional<ref_wrapper<Qutex>>

Replace the previous Qutex** raw pointer with a std::optional.

include/lockSet.h

@@ -7,6 +7,7 @@
 #include <stdexcept>
 #include <utility>
 #include <memory>
+#include <optional>
 #include <qutex.h>
 #include <lockerAndInvokerBase.h>
 
@@ -85,7 +86,9 @@ public:
 	 * @return true if all locks were acquired, false otherwise
 	 */
 	bool tryAcquireOrBackOff(
-		LockerAndInvokerBase &lockvoker, Qutex **firstFailedQutex = nullptr);
+		LockerAndInvokerBase &lockvoker,
+		std::optional<std::reference_wrapper<Qutex>> &firstFailedQutex
+			= std::nullopt);
 	void unregisterFromQutexQueues();
 
 	// @brief Release all locks

include/serializedAsynchronousContinuation.h

@@ -107,14 +107,12 @@ public:
 					"executing on wrong ComponentThread");
 			}
 
-			Qutex *firstFailedQutexPtr = nullptr;
+			std::optional<std::reference_wrapper<Qutex>> firstFailedQutexRet;
 			bool deadlockLikely = isDeadlockLikely();
 			bool gridlockLikely = isGridlockLikely();
 
 			if (!serializedContinuation.requiredLocks.tryAcquireOrBackOff(
-				*this,
-				((deadlockLikely || gridlockLikely)
-					? &firstFailedQutexPtr : nullptr)))
+				*this, firstFailedQutexRet))
 			{
 				// Just allow this lockvoker to be dropped from its io_service.
 				allowAwakening();
@@ -122,7 +120,7 @@ public:
 					{ return; }
 
 #ifdef CONFIG_ENABLE_DEBUG_LOCKS
-				Qutex	&firstFailedQutex = *firstFailedQutexPtr;
+				Qutex	&firstFailedQutex = firstFailedQutexRet.value().get();
 				bool isDeadlock = traceContinuationHistoryForDeadlockOn(
 					firstFailedQutex);
 

smocore/lockSet.cpp

@@ -44,7 +44,8 @@ void LockSet<OriginalCbFnT>::registerInQutexQueues(
 
 template <class OriginalCbFnT>
 bool LockSet<OriginalCbFnT>::tryAcquireOrBackOff(
-	LockerAndInvokerBase &lockvoker, Qutex **firstFailedQutex
+	LockerAndInvokerBase &lockvoker,
+	std::optional<std::reference_wrapper<Qutex>> &firstFailedQutex
 	)
 {
 	if (!registeredInQutexQueues)
@@ -71,9 +72,7 @@ bool LockSet<OriginalCbFnT>::tryAcquireOrBackOff(
 			lockvoker, nRequiredLocks))
 		{
 			// Set the first failed qutex for debugging
-			if (firstFailedQutex) {
-				*firstFailedQutex = &lockUsageDesc.first.get();
-			}
+			firstFailedQutex = std::ref(lockUsageDesc.first.get());
 			break;
 		}