From 49884d7e600da087d3268aa543b5f679cbdc2006 Mon Sep 17 00:00:00 2001
From: sippeangelo <holmberg.simon@gmail.com>
Date: Wed, 6 Jan 2016 13:47:02 +0100
Subject: [PATCH] Fix for crash when unsubscription during event processing
 (untested)

---
 include/Engine/Core/EventBroker.h |  8 ++++--
 src/Engine/Core/EventBroker.cpp   | 47 ++++++++++++++++++-------------
 2 files changed, 33 insertions(+), 22 deletions(-)

diff --git a/include/Engine/Core/EventBroker.h b/include/Engine/Core/EventBroker.h
index f04c7715..dde5242a 100644
--- a/include/Engine/Core/EventBroker.h
+++ b/include/Engine/Core/EventBroker.h
@@ -13,6 +13,8 @@
 	relay = decltype(relay)(std::bind(handler, this, std::placeholders::_1)); \
 	m_EventBroker->Subscribe(relay);
 
+typedef unsigned int EventID;
+
 class EventBroker;
 
 class BaseEventRelay
@@ -31,6 +33,7 @@ public:
     virtual bool Receive(const std::shared_ptr<Event> event) = 0;
 
 protected:
+    EventID m_EventID;
     std::string m_ContextTypeName;
     std::string m_EventTypeName;
     EventBroker* m_Broker;
@@ -95,6 +98,7 @@ public:
 
 private:
     bool m_IsProcessing = false;
+    EventID m_NextEventID = 0;
 
     typedef std::string ContextTypeName_t; // typeid(ContextType).name()
     typedef std::string EventTypeName_t; // typeid(EventType).name()
@@ -103,14 +107,14 @@ private:
     typedef std::unordered_map<ContextTypeName_t, EventRelays_t> ContextRelays_t;
     ContextRelays_t m_ContextRelays;
     std::vector<BaseEventRelay*> m_RelaysToSubscribe;
-    std::vector<BaseEventRelay*> m_RelaysToUnsubscribe;
+    std::vector<std::tuple<EventID, ContextTypeName_t, EventTypeName_t>> m_RelaysToUnsubscribe;
 
     typedef std::list<std::pair<EventTypeName_t, std::shared_ptr<Event>>> EventQueue_t;
     std::shared_ptr<EventQueue_t> m_EventQueueRead;
     std::shared_ptr<EventQueue_t> m_EventQueueWrite;
 
     void subscribeImmediate(BaseEventRelay& relay);
-    void unsubscribeImmediate(BaseEventRelay& relay);
+    void unsubscribeImmediate(std::tuple<EventID, ContextTypeName_t, EventTypeName_t> identifier);
 };
 
 template <typename EventType>
diff --git a/src/Engine/Core/EventBroker.cpp b/src/Engine/Core/EventBroker.cpp
index 76c243e8..6767878f 100644
--- a/src/Engine/Core/EventBroker.cpp
+++ b/src/Engine/Core/EventBroker.cpp
@@ -2,21 +2,24 @@
 
 BaseEventRelay::~BaseEventRelay()
 {
-	if (m_Broker != nullptr) {
-		m_Broker->Unsubscribe(*this);
-	}
+    if (m_Broker != nullptr) {
+        m_Broker->Unsubscribe(*this);
+    }
 }
 
-void EventBroker::Unsubscribe(BaseEventRelay &relay) // ?
+void EventBroker::Unsubscribe(BaseEventRelay& relay) // ?
 {
-	if (m_IsProcessing) {
-		m_RelaysToUnsubscribe.push_back(&relay);
-	} else {
-		unsubscribeImmediate(relay);
-	}
+    auto identifier = std::make_tuple(relay.m_EventID, relay.m_ContextTypeName, relay.m_EventTypeName);
+
+    relay.m_Broker = nullptr;
+    if (m_IsProcessing) {
+        m_RelaysToUnsubscribe.push_back(identifier);
+    } else {
+        unsubscribeImmediate(identifier);
+    }
 }
 
-void EventBroker::Subscribe(BaseEventRelay &relay)
+void EventBroker::Subscribe(BaseEventRelay& relay)
 {
 	if (m_IsProcessing) {
 		m_RelaysToSubscribe.push_back(&relay);
@@ -38,12 +41,11 @@ int EventBroker::Process(std::string contextTypeName)
 
 	int eventsProcessed = 0;
 	for (auto &pair : *m_EventQueueRead) {
-		std::string &eventTypeName = pair.first;
+		std::string& eventTypeName = pair.first;
 		std::shared_ptr<Event> event = pair.second;
 
 		auto itpair = relays.equal_range(eventTypeName);
-		for (auto it2 = itpair.first; it2 != itpair.second; it2++)
-		{
+		for (auto it2 = itpair.first; it2 != itpair.second; it2++) {
 			std::string name = it2->first;
 			BaseEventRelay* relay = it2->second;
 			relay->Receive(event);
@@ -60,8 +62,8 @@ int EventBroker::Process(std::string contextTypeName)
 	m_RelaysToSubscribe.clear();
 
 	// Process pending unsubscriptions
-	for (auto& r : m_RelaysToUnsubscribe) {
-		unsubscribeImmediate(*r);
+	for (auto& identifier : m_RelaysToUnsubscribe) {
+		unsubscribeImmediate(identifier);
 	}
 	m_RelaysToUnsubscribe.clear();
 
@@ -81,21 +83,26 @@ void EventBroker::Clear()
 void EventBroker::subscribeImmediate(BaseEventRelay& relay)
 {
 	relay.m_Broker = this;
+    relay.m_EventID = m_NextEventID++;
 	m_ContextRelays[relay.m_ContextTypeName].insert(std::make_pair(relay.m_EventTypeName, &relay));
 }
 
-void EventBroker::unsubscribeImmediate(BaseEventRelay& relay)
+void EventBroker::unsubscribeImmediate(std::tuple<EventID, ContextTypeName_t, EventTypeName_t> identifier)
 {
-	auto contextIt = m_ContextRelays.find(relay.m_ContextTypeName);
+    EventID eventID;
+    ContextTypeName_t contextTypeName;
+    EventTypeName_t eventTypeName;
+    std::tie(eventID, contextTypeName, eventTypeName) = identifier;
+
+	auto contextIt = m_ContextRelays.find(contextTypeName);
 	if (contextIt == m_ContextRelays.end()) {
 		return;
 	}
 
 	auto eventRelays = contextIt->second;
-	auto itpair = eventRelays.equal_range(relay.m_EventTypeName);
+	auto itpair = eventRelays.equal_range(eventTypeName);
 	for (auto it = itpair.first; it != itpair.second; ++it) {
-		if (it->second == &relay) {
-			relay.m_Broker = nullptr;
+		if (it->second->m_EventID == eventID) {
 			eventRelays.erase(it);
 			break;
 		}