Properly deal with time changes (2nd attempt).

lib/base/application.cpp

@@ -99,7 +99,9 @@ void Application::RunEventLoop(void)
 	double nextProfile = 0;
 #endif /* _DEBUG */
 
-	double lastLoop = Utility::GetTime();
+	/* Start the system time watch thread. */
+	thread t(&Application::TimeWatchThreadProc);
+	t.detach();
 
 	while (!m_ShuttingDown) {
 		Object::ClearHeldObjects();
@@ -109,7 +111,7 @@ void Application::RunEventLoop(void)
 		if (m_ShuttingDown)
 			break;
 
-		Event::ProcessEvents(boost::get_system_time() + boost::posix_time::milliseconds(sleep * 1000));
+		Event::ProcessEvents(boost::posix_time::milliseconds(sleep * 1000));
 
 		DynamicObject::FinishTx();
 		DynamicObject::BeginTx();
@@ -125,17 +127,36 @@ void Application::RunEventLoop(void)
 			nextProfile = Utility::GetTime() + 15.0;
 		}
 #endif /* _DEBUG */
+	}
+}
+
+/**
+ * Watches for changes to the system time. Adjusts timers if necessary.
+ */
+void Application::TimeWatchThreadProc(void)
+{
+	double lastLoop = Utility::GetTime();
+
+	for (;;) {
+		Sleep(5);
 
 		double now = Utility::GetTime();
+		double timeDiff = lastLoop - now;
 
-		if (now < lastLoop) {
-			/* We moved backwards in time - cool. */
-			double lostTime = lastLoop - now;
+		if (abs(timeDiff) > 15) {
+			/* We made a significant jump in time. */
 			stringstream msgbuf;
-			msgbuf << "We moved backwards in time: " << lostTime
-			       << " seconds";
+			msgbuf << "We jumped "
+			       << (timeDiff < 0 ? "forwards" : "backwards")
+			       << " in time: " << abs(timeDiff) << " seconds";
 			Logger::Write(LogInformation, "base", msgbuf.str());
-			Timer::AdjustTimers(-lostTime);
+
+			/* in addition to rescheduling the timers this
+			 * causes the event loop to wake up thereby
+			 * solving the problem that timed_wait()
+			 * uses an absolute timestamp for the timeout */
+			Event::Post(boost::bind(&Timer::AdjustTimers,
+			    -timeDiff));
 		}
 
 		lastLoop = now;

lib/base/application.h

@@ -79,6 +79,8 @@ private:
 #else /* _WIN32 */
 	static BOOL WINAPI CtrlHandler(DWORD type);
 #endif /* _WIN32 */
+
+	static void TimeWatchThreadProc(void);
 };
 
 }

lib/base/event.cpp

@@ -38,9 +38,9 @@ Event::Event(const Event::Callback& callback)
  * Waits for events using the specified timeout value and processes
  * them.
  *
- * @param wait_until The wait timeout.
+ * @param timeout The wait timeout.
  */
-void Event::ProcessEvents(const system_time& wait_until)
+void Event::ProcessEvents(millisec timeout)
 {
 	vector<Event> events;
 
@@ -50,7 +50,7 @@ void Event::ProcessEvents(const system_time& wait_until)
 		boost::mutex::scoped_lock lock(m_Mutex);
 
 		while (m_Events.empty()) {
-			if (!m_EventAvailable.timed_wait(lock, wait_until))
+			if (!m_EventAvailable.timed_wait(lock, timeout))
 				return;
 		}
 

lib/base/event.h

@@ -33,7 +33,7 @@ class I2_BASE_API Event
 public:
 	typedef function<void ()> Callback;
 
-	static void ProcessEvents(const system_time& wait_until);
+	static void ProcessEvents(millisec timeout);
 	static void Post(const Callback& callback);
 
 private:

lib/base/i2-base.h

@@ -139,6 +139,7 @@ using boost::thread;
 using boost::thread_group;
 using boost::condition_variable;
 using boost::system_time;
+using boost::posix_time::millisec;
 using boost::tie;
 using boost::throw_exception;
 using boost::rethrow_exception;

lib/base/timer.cpp

@@ -37,7 +37,7 @@ Timer::Timer(void)
  */
 double Timer::ProcessTimers(void)
 {
-	double wakeup = 30;
+	double wakeup = 30; /* wake up at least once after this many seconds */
 
 	double st = Utility::GetTime();
 
@@ -164,7 +164,14 @@ void Timer::Reschedule(double next)
  */
 void Timer::AdjustTimers(double adjustment)
 {
-	BOOST_FOREACH(Timer::Ptr timer, m_Timers) {
-		timer->m_Next += adjustment;
+	double now = Utility::GetTime();
+
+	Timer::CollectionType::iterator i;
+        for (i = m_Timers.begin(); i != m_Timers.end(); i++) {
+		Timer::Ptr timer = i->lock();
+
+		if (abs(now - (timer->m_Next + adjustment)) <
+		    abs(now - timer->m_Next))
+			timer->m_Next += adjustment;
 	}
 }