Added simple deadlock detection code.

This will assert and then deliberately crash the server once a deadlock is detected. For detection, only the world tick threads are considered, cWorld's m_WorldAge is checked periodically and if it doesn't increment for several seconds, a deadlock is reported.

source/DeadlockDetect.cpp

@@ -0,0 +1,155 @@
+
+// DeadlockDetect.cpp
+
+// Declares the cDeadlockDetect class that tries to detect deadlocks and aborts the server when it detects one
+
+#include "Globals.h"
+#include "DeadlockDetect.h"
+#include "Root.h"
+#include "World.h"
+
+
+
+
+
+/// Number of milliseconds per cycle
+const int CYCLE_MILLISECONDS = 500;
+
+/// When the number of cycles for the same world age hits this value, it is considered a deadlock
+const int NUM_CYCLES_LIMIT = 40;  // 40 = twenty seconds
+
+
+
+
+
+cDeadlockDetect::cDeadlockDetect(void) :
+	super("DeadlockDetect")
+{
+}
+
+
+
+
+
+bool cDeadlockDetect::Start(void)
+{
+	// Read the initial world data:
+	class cFillIn :
+		public cWorldListCallback
+	{
+	public:
+		cFillIn(cDeadlockDetect * a_Detect) :
+			m_Detect(a_Detect)
+		{
+		}
+		
+		virtual bool Item(cWorld * a_World) override
+		{
+			m_Detect->SetWorldAge(a_World->GetName(), a_World->GetWorldAge());
+			return false;
+		}
+		
+	protected:
+		cDeadlockDetect * m_Detect;
+	} FillIn(this);
+	cRoot::Get()->ForEachWorld(FillIn);
+	return super::Start();
+}
+
+
+
+
+
+void cDeadlockDetect::Stop(void)
+{
+	m_EvtTerminate.Set();
+	super::Stop();
+}
+
+
+
+
+
+void cDeadlockDetect::Execute(void)
+{
+	// Loop until the event is signalled
+	while (m_EvtTerminate.Wait(CYCLE_MILLISECONDS) == cEvent::wrTimeout)
+	{
+		// Check the world ages:
+		class cChecker :
+			public cWorldListCallback
+		{
+		public:
+			cChecker(cDeadlockDetect * a_Detect) :
+				m_Detect(a_Detect)
+			{
+			}
+			
+		protected:
+			cDeadlockDetect * m_Detect;
+			
+			virtual bool Item(cWorld * a_World) override
+			{
+				m_Detect->CheckWorldAge(a_World->GetName(), a_World->GetWorldAge());
+				return false;
+			}
+		} Checker(this);
+		cRoot::Get()->ForEachWorld(Checker);
+	}  // while (should run)
+}
+
+
+
+
+
+void cDeadlockDetect::SetWorldAge(const AString & a_WorldName, Int64 a_Age)
+{
+	m_WorldAges[a_WorldName].m_Age = a_Age;
+	m_WorldAges[a_WorldName].m_NumCyclesSame = 0;
+}
+
+
+
+
+
+void cDeadlockDetect::CheckWorldAge(const AString & a_WorldName, Int64 a_Age)
+{
+	WorldAges::iterator itr = m_WorldAges.find(a_WorldName);
+	if (itr == m_WorldAges.end())
+	{
+		ASSERT(!"Unknown world in cDeadlockDetect");
+		return;
+	}
+	if (itr->second.m_Age == a_Age)
+	{
+		itr->second.m_NumCyclesSame += 1;
+		if (itr->second.m_NumCyclesSame > NUM_CYCLES_LIMIT)
+		{
+			DeadlockDetected();
+			return;
+		}
+	}
+	else
+	{
+		itr->second.m_Age = a_Age;
+		itr->second.m_NumCyclesSame = 0;
+	}
+}
+
+
+
+
+
+void cDeadlockDetect::DeadlockDetected(void)
+{
+	ASSERT(!"Deadlock detected");
+	
+	// TODO: Make a crashdump / coredump
+	
+	// Crash the server intentionally:
+	*((int *)0) = 0;
+}
+
+
+
+