add event system and use it to propagate to print traces

src/lib/CMakeLists.txt

@@ -1,11 +1,12 @@
 SET(HDRS)
 SET(SRCS)
 
-add_subdirectory(core)
 add_subdirectory(config)
+add_subdirectory(core)
+add_subdirectory(ecs)
+add_subdirectory(eventsystem)
 add_subdirectory(utility)
 add_subdirectory(sim)
-add_subdirectory(ecs)
 
 SET(HDRS
 	${HDRS}

src/lib/eventsystem/CMakeLists.txt

@@ -0,0 +1,23 @@
+add_subdirectory(event)
+
+SET(HDRS
+	${HDRS}
+	${CMAKE_CURRENT_SOURCE_DIR}/Event.h
+	${CMAKE_CURRENT_SOURCE_DIR}/EventHandler.h
+	${CMAKE_CURRENT_SOURCE_DIR}/EventHandlerBase.h
+	${CMAKE_CURRENT_SOURCE_DIR}/EventManager.h
+	PARENT_SCOPE
+)
+
+SET(SRCS
+	${SRCS}
+	${CMAKE_CURRENT_SOURCE_DIR}/EventHandlerBase.cpp
+	${CMAKE_CURRENT_SOURCE_DIR}/EventManager.cpp
+	PARENT_SCOPE
+)
+
+SET(LIB_INCLUDE_PATH
+	${LIB_INCLUDE_PATH}
+	${CMAKE_CURRENT_SOURCE_DIR}
+	PARENT_SCOPE
+)

src/lib/eventsystem/Event.h

@@ -0,0 +1,10 @@
+#ifndef EVENT_H
+#define EVENT_H
+
+class Event
+{
+public:
+	virtual ~Event() = default;
+};
+
+#endif   // EVENT_H

src/lib/eventsystem/EventHandler.h

@@ -0,0 +1,80 @@
+#ifndef EVENT_HANDLER_H
+#define EVENT_HANDLER_H
+
+#include <memory>
+
+#include "EventHandlerBase.h"
+#include "EventManager.h"
+
+template <typename T>
+class EventHandler: public EventHandlerBase
+{
+public:
+	void registerForEvent()
+	{
+		EventManager::getInstance()->registerEventHandler(this);
+	}
+
+	void unregisterForEvent()
+	{
+		EventManager::getInstance()->unregisterEventHandler(this);
+	}
+
+	void handleBaseEvent(std::shared_ptr<const Event> event) override
+	{
+		std::shared_ptr<const T> specificEvent = std::dynamic_pointer_cast<const T>(event);
+		if (specificEvent)
+		{
+			handleEvent(specificEvent);
+		}
+	}
+
+private:
+	virtual void handleEvent(std::shared_ptr<const T> event) = 0;
+};
+
+
+template <typename... Ts> class CombinedEventHandlerHelper 
+{
+protected:
+	void registerForEventsHelper() {}
+	void unregisterForEventsHelper() {}
+};
+
+
+template <typename T, typename... Ts>
+class CombinedEventHandlerHelper<T, Ts...>
+    : public EventHandler<T>
+    , public CombinedEventHandlerHelper<Ts...>
+{
+protected:
+	void registerForEventsHelper()
+	{
+		EventHandler<T>::registerForEvent();
+		CombinedEventHandlerHelper<Ts...>::registerForEventsHelper();
+	}
+
+	void unregisterForEventsHelper()
+	{
+		EventHandler<T>::unregisterForEvent();
+		CombinedEventHandlerHelper<Ts...>::unregisterForEventsHelper();
+	}
+};
+
+
+template <typename... Ts>
+class CombinedEventHandler: public CombinedEventHandlerHelper<Ts...>
+{
+protected:
+	void registerForEvents()
+	{
+		CombinedEventHandlerHelper<Ts...>::registerForEventsHelper();
+	}
+
+	void unregisterForEvents()
+	{
+		CombinedEventHandlerHelper<Ts...>::unregisterForEventsHelper();
+	}
+};
+
+#endif   // EVENT_HANDLER_H

src/lib/eventsystem/EventHandlerBase.cpp

@@ -0,0 +1,7 @@
+#include "EventHandlerBase.h"
+
+unsigned int EventHandlerBase::s_nextId = 0;
+
+EventHandlerBase::EventHandlerBase(): m_id(s_nextId++)
+{
+}

src/lib/eventsystem/EventHandlerBase.h

@@ -0,0 +1,25 @@
+#ifndef EVENT_HANDLER_BASE_H
+#define EVENT_HANDLER_BASE_H
+
+#include <memory>
+
+class Event;
+class EventManager;
+
+class EventHandlerBase
+{
+private:
+	static unsigned int s_nextId;
+
+public:
+	EventHandlerBase();
+	virtual ~EventHandlerBase() = default;
+	virtual void handleBaseEvent(std::shared_ptr<const Event> event) = 0;
+
+private:
+	const unsigned int m_id;
+
+	friend EventManager;
+};
+
+#endif   // EVENT_HANDLER_BASE_H

src/lib/eventsystem/EventManager.cpp

@@ -0,0 +1,123 @@
+#include "EventManager.h"
+
+#include <set>
+
+#include "EventHandlerBase.h"
+
+std::shared_ptr<EventManager> EventManager::getInstance()
+{
+	if (!s_instance)
+	{
+		s_instance = std::shared_ptr<EventManager>(new EventManager());
+	}
+	return s_instance;
+}
+
+void EventManager::destroyInstance()
+{
+	if (s_instance)
+	{
+		s_instance.reset();
+	}
+}
+
+std::shared_ptr<EventManager> EventManager::s_instance = std::shared_ptr<EventManager>();
+
+void EventManager::registerEventHandler(EventHandlerBase *eventHandler)
+{
+	std::scoped_lock<std::mutex> lock(m_eventHandlersMutex);
+	m_eventHandlers[eventHandler->m_id] = eventHandler;
+}
+
+void EventManager::unregisterEventHandler(EventHandlerBase *eventHandler)
+{
+	std::scoped_lock<std::mutex> lock(m_eventHandlersMutex);
+	m_eventHandlers.erase(eventHandler->m_id);
+}
+
+void EventManager::sendEventImmediately(std::shared_ptr<Event> event)
+{
+	if (event)
+	{
+		std::set<unsigned int> eventHandlerIds;
+		{
+			std::scoped_lock<std::mutex> lock(m_eventHandlersMutex);
+			for (auto it : m_eventHandlers)
+			{
+				eventHandlerIds.insert(it.first);
+			}
+		}
+
+		for (unsigned int id : eventHandlerIds)
+		{
+			// this is necessary to allow HandleBaseEvent() to remove event handlers without causing a crash
+			EventHandlerBase *eventHandler = nullptr;
+			{
+				std::scoped_lock<std::mutex> lock(m_eventHandlersMutex);
+				auto it = m_eventHandlers.find(id);
+				if (it != m_eventHandlers.end())
+				{
+					eventHandler = it->second;
+				}
+			}
+			if (eventHandler)
+			{
+				eventHandler->handleBaseEvent(event);
+			}
+		}
+	}
+}
+
+void EventManager::addEvent(std::shared_ptr<Event> event)
+{
+	if (event)
+	{
+		std::scoped_lock<std::mutex> lock(m_eventsMutex);
+		m_events.push_back(event);
+	}
+}
+
+void EventManager::processEvents()
+{
+	std::vector<std::shared_ptr<Event>> events;
+	{
+		std::scoped_lock<std::mutex> lock(m_eventsMutex);
+		events = m_events;
+		m_events.clear();
+	}
+
+	std::set<unsigned int> eventHandlerIds;
+	{
+		std::scoped_lock<std::mutex> lock(m_eventHandlersMutex);
+		for (auto it : m_eventHandlers)
+		{
+			eventHandlerIds.insert(it.first);
+		}
+	}
+
+	for (std::shared_ptr<Event> event : events)
+	{
+		for (unsigned int id : eventHandlerIds)
+		{
+			// this is necessary to allow HandleBaseEvent() to remove event handlers without causing a crash
+			EventHandlerBase *eventHandler = nullptr;
+			{
+				std::scoped_lock<std::mutex> lock(m_eventHandlersMutex);
+				auto it = m_eventHandlers.find(id);
+				if (it != m_eventHandlers.end())
+				{
+					eventHandler = it->second;
+				}
+			}
+			if (eventHandler)
+			{
+				eventHandler->handleBaseEvent(event);
+			}
+		}
+	}
+}
+
+bool EventManager::hasEvents() const
+{
+	return !m_events.empty();
+}

src/lib/eventsystem/EventManager.h

@@ -0,0 +1,43 @@
+#ifndef EVENT_MANAGER_H
+#define EVENT_MANAGER_H
+
+#include <map>
+#include <memory>
+#include <mutex>
+#include <vector>
+
+#include "Event.h"
+
+class EventHandlerBase;
+
+class EventManager
+{
+public:
+	static std::shared_ptr<EventManager> getInstance();
+	static void destroyInstance();
+
+private:
+	static std::shared_ptr<EventManager> s_instance;
+
+public:
+	EventManager(EventManager const &) = delete;
+	void operator=(EventManager const &) = delete;
+
+	void registerEventHandler(EventHandlerBase *eventHandler);
+	void unregisterEventHandler(EventHandlerBase *eventHandler);
+	void sendEventImmediately(std::shared_ptr<Event> event);
+	void addEvent(std::shared_ptr<Event> event);
+	void processEvents();
+
+	bool hasEvents() const;
+
+private:
+	EventManager() = default;
+
+	std::map<unsigned int, EventHandlerBase *> m_eventHandlers;
+	std::vector<std::shared_ptr<Event>> m_events;
+	std::mutex m_eventHandlersMutex;
+	std::mutex m_eventsMutex;
+};
+
+#endif   // EVENT_MANAGER_H

src/lib/eventsystem/event/CMakeLists.txt

@@ -0,0 +1,17 @@
+SET(HDRS
+	${HDRS}
+	${CMAKE_CURRENT_SOURCE_DIR}/TracePrintRequestedEvent.h
+	PARENT_SCOPE
+)
+
+SET(SRCS
+	${SRCS}
+	${CMAKE_CURRENT_SOURCE_DIR}/TracePrintRequestedEvent.cpp
+	PARENT_SCOPE
+)
+
+set(LIB_INCLUDE_PATH
+	${LIB_INCLUDE_PATH}
+	${CMAKE_CURRENT_SOURCE_DIR}
+	PARENT_SCOPE
+)

src/lib/eventsystem/event/TracePrintRequestedEvent.cpp

@@ -0,0 +1 @@
+#include "TracePrintRequestedEvent.h"

src/lib/eventsystem/event/TracePrintRequestedEvent.h

@@ -0,0 +1,10 @@
+#ifndef TRACE_PRINT_REQUESTED_EVENT_H
+#define TRACE_PRINT_REQUESTED_EVENT_H
+
+#include "Event.h"
+
+class TracePrintRequestedEvent : public Event
+{
+};
+
+#endif   // TRACE_PRINT_REQUESTED_EVENT_H

src/lib/sim/Simulation.cpp

@@ -7,6 +7,7 @@
 #include "CombatSystem.h"
 #include "DynamicBodySystem.h"
 #include "FactionComponent.h"
+#include "EventManager.h"
 #include "HealthComponent.h"
 #include "ModuleOwnerComponent.h"
 #include "MovementIntentSystem.h"
@@ -71,9 +72,13 @@ Simulation::Simulation(GameConfig config, unsigned int seed)
     }
 
     placeInitialStructures();
+	registerForEvents();
 }
 
-Simulation::~Simulation() = default;
+Simulation::~Simulation()
+{
+	unregisterForEvents();
+}
 
 const GameConfig& Simulation::config() const
 {
@@ -88,6 +93,7 @@ void Simulation::reset(GameConfig newConfig, unsigned int seed)
 
 void Simulation::reset(unsigned int seed)
 {
+	EventManager::destroyInstance();
     m_rng.seed(seed);
     m_currentTick              = 0;
     m_nextDepartureTick        = secondsToTicks(m_config.world.departureIntervalSeconds);
@@ -147,6 +153,8 @@ void Simulation::reset(unsigned int seed)
 
 void Simulation::tick()
 {
+	EventManager::getInstance()->processEvents();
+
     // Step 1: wave scheduler
     m_waveSystem->tickWaveScheduler(m_currentTick, *m_shipSystem,
                                     m_config.world.heightTiles);
@@ -199,8 +207,6 @@ void Simulation::tick()
     m_scrapSystem->tickDespawn(m_currentTick);
 
     ++m_currentTick;
-
-	PRINT_TRACES();
 }
 
 // ---------------------------------------------------------------------------
@@ -642,6 +648,11 @@ const EntityAdmin& Simulation::admin() const
     return m_admin;
 }
 
+void Simulation::handleEvent(std::shared_ptr<const TracePrintRequestedEvent> event)
+{
+	PRINT_TRACES();
+}
+
 BuildingId Simulation::allocateBuildingId()
 {
     return m_nextBuildingId++;

src/lib/sim/Simulation.h

@@ -10,15 +10,16 @@
 
 #include "BeltSystem.h"
 #include "EntityAdmin.h"
-
 #include "entt/entity/entity.hpp"
 #include "SchematicDropEvent.h"
 #include "BuildingType.h"
 #include "BuildingId.h"
+#include "EventHandler.h"
 #include "FireEvent.h"
 #include "GameConfig.h"
 #include "Rotation.h"
 #include "Tick.h"
+#include "TracePrintRequestedEvent.h"
 
 class AiSystem;
 class BuildingSystem;
@@ -29,7 +30,7 @@ class ShipSystem;
 class ScrapSystem;
 class WaveSystem;
 
-class Simulation
+class Simulation: public CombinedEventHandler<TracePrintRequestedEvent>
 {
 public:
     explicit Simulation(GameConfig config, unsigned int seed = 0);
@@ -83,6 +84,8 @@ public:
     const EntityAdmin&    admin() const;
 
 private:
+	void handleEvent(std::shared_ptr<const TracePrintRequestedEvent> event) override;
+
     BuildingId allocateBuildingId();  // Strictly increasing; never returns kInvalidBuildingId.
 
     // Populate HQ, player defence stations, and the first enemy station set.