Avoid deadlock if energyplus stops running for any reason

Before this change if EnergyPlus came to the end of the run period,
threw an execption, or suffered a fatal error, then the control thread
would just hang due to a deadlock. This should address that issue. A
future change will make spawn/EnergyPlus ignore the run period
completely.

ref lbl-srg/modelica-buildings#1678

epfmi/EPComponent.cpp

@@ -53,7 +53,14 @@ int EPComponent::start() {
 
     EnergyPlus::CommandLineInterface::ProcessArgs( argc, argv );
     EnergyPlus::DataGlobals::externalHVACManager = std::bind(&EPComponent::externalHVACManager, this);
-    RunEnergyPlus();
+		try {
+    	auto result = RunEnergyPlus();
+  		std::unique_lock<std::mutex> lk(control_mutex);
+			epstatus = result ? EPStatus::ERROR : EPStatus::DONE;
+		} catch(...) {
+			epstatus = EPStatus::ERROR;
+		}
+  	control_cv.notify_one();
   };
 
   {
@@ -64,13 +71,8 @@ int EPComponent::start() {
 
   simthread = std::thread(simulation);
 
-  {
-    // Wait for E+ to go back to IDLE
-    std::unique_lock<std::mutex> lk(control_mutex);
-    control_cv.wait( lk, [&](){ return epstatus == EPStatus::NONE; } );
-  }
-
-  return 0;
+	// Wait for EnergyPlus to go through startup/warmup etc
+  return controlWait();
 }
 
 int EPComponent::stop() {
@@ -79,11 +81,14 @@ int EPComponent::stop() {
     epstatus = EPStatus::TERMINATE;
   }
 
-  stopSimulation();
-  control_cv.notify_one();
-  simthread.join();
-
-  return 0;
+	try {
+  	stopSimulation();
+  	control_cv.notify_one();
+  	simthread.join();
+  	return 0;
+	} catch(...) {
+  	return 1;
+	}
 }
 
 int EPComponent::setTime(const double & time)
@@ -98,13 +103,9 @@ int EPComponent::setTime(const double & time)
   }
   // Notify E+ to advance
   control_cv.notify_one();
-  {
-    // Wait for E+ to advance and go back to IDLE before returning
-    std::unique_lock<std::mutex> lk( control_mutex );
-    control_cv.wait( lk, [&](){ return epstatus == EPStatus::NONE; } );
-  }
 
-  return 0;
+	// Wait for EnergyPlus to complete the step
+  return controlWait();
 }
 
 fmi2Real EPComponent::currentSimTime() const {
@@ -268,6 +269,18 @@ void EPComponent::exchange()
   }
 }
 
+int EPComponent::controlWait() {
+	std::unique_lock<std::mutex> lk(control_mutex);
+	// Wait until EnergyPlus is not Advancing or Terminating (ie in the process of cleanup)
+	control_cv.wait( lk, [&](){
+		return
+			(epstatus == EPStatus::NONE) ||
+			(epstatus == EPStatus::ERROR) ||
+			(epstatus == EPStatus::DONE);
+	});
+	return epstatus == EPStatus::ERROR ? 1 : 0;
+}
+
 void EPComponent::externalHVACManager() {
   // Although we do not use the ZoneTempPredictorCorrector,
   // some global variables need to be initialized by InitZoneAirSetPoints

epfmi/EPComponent.hpp

@@ -60,7 +60,7 @@
 #include <sstream>
 #include <condition_variable>
 
-enum class EPStatus { ADVANCE, NONE, TERMINATE, EXCHANGE };
+enum class EPStatus { ADVANCE, NONE, TERMINATE, ERROR, DONE };
 
 class EPComponent {
 public:
@@ -111,6 +111,10 @@ class EPComponent {
 
 private:
 
+	// Wait for the EnergyPlus thread from the control thread
+	// Return 0 on success
+	// This should be called from the control thread
+	int controlWait();
   Real64 zoneHeatTransfer(const int ZoneNum);
 
   fmi2Real requestedTime;

epfmi/EPFMI.cpp

@@ -50,18 +50,14 @@ EPFMI_API fmi2Status fmi2SetupExperiment(fmi2Component c,
   UNUSED(stopTimeDefined);
   UNUSED(stopTime);
 
-  epcomp->start();
-
-  return fmi2OK;
+  return epcomp->start() ? fmi2Error : fmi2OK;
 }
 
 EPFMI_API fmi2Status fmi2SetTime(fmi2Component c, fmi2Real time)
 {
   EPComponent * epcomp = static_cast<EPComponent*>(c);
 
-  epcomp->setTime(time);
-
-  return fmi2OK;
+  return epcomp->setTime(time) ? fmi2Error : fmi2OK;
 }
 
 EPFMI_API fmi2Status fmi2SetReal(fmi2Component c,
@@ -113,12 +109,12 @@ EPFMI_API fmi2Status fmi2Terminate(fmi2Component c)
 {
   EPComponent * epcomp = static_cast<EPComponent*>(c);
 
-  epcomp->stop();
+  auto result = epcomp->stop();
 
   auto it = std::find(epComponents.begin(), epComponents.end(), *epcomp);
   epComponents.erase(it);
 
-  return fmi2OK;
+  return result ? fmi2Error : fmi2OK;
 }
 
 EPFMI_API const char* fmi2GetTypesPlatform(void)