From 8610083a8e8ad66806c66d0199d0d8a900ceb358 Mon Sep 17 00:00:00 2001
From: Mattes D <github@xoft.cz>
Date: Fri, 17 Jun 2016 16:25:31 +0200
Subject: [PATCH] cNetwork: Fixed possible hang when terminating immediately
 after init.

---
 src/OSSupport/NetworkSingleton.cpp | 21 +++++++++++++++++++--
 src/OSSupport/NetworkSingleton.h   |  8 ++++++++
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/src/OSSupport/NetworkSingleton.cpp b/src/OSSupport/NetworkSingleton.cpp
index c16f92c5a..d0abafcbd 100644
--- a/src/OSSupport/NetworkSingleton.cpp
+++ b/src/OSSupport/NetworkSingleton.cpp
@@ -6,7 +6,6 @@
 
 #include "Globals.h"
 #include "NetworkSingleton.h"
-#include <event2/event.h>
 #include <event2/thread.h>
 #include <event2/bufferevent.h>
 #include <event2/dns.h>
@@ -91,8 +90,11 @@ void cNetworkSingleton::Initialise(void)
 	}
 
 	// Create the event loop thread:
-	m_EventLoopThread = std::thread(RunEventLoop, this);
 	m_HasTerminated = false;
+	m_StartupEvent.reset(new cEvent);
+	m_EventLoopThread = std::thread(RunEventLoop, this);
+	m_StartupEvent->Wait();  // Wait for the LibEvent loop to actually start running (otherwise calling Terminate too soon would hang, see #3228)
+	m_StartupEvent.reset();  // Don't need the cEvent any more, release all its resources
 }
 
 
@@ -153,6 +155,9 @@ void cNetworkSingleton::LogCallback(int a_Severity, const char * a_Msg)
 
 void cNetworkSingleton::RunEventLoop(cNetworkSingleton * a_Self)
 {
+	auto timer = evtimer_new(a_Self->m_EventBase, SignalizeStartup, a_Self);
+	timeval timeout{};  // Zero timeout - execute immediately
+	evtimer_add(timer, &timeout);
 	event_base_loop(a_Self->m_EventBase, EVLOOP_NO_EXIT_ON_EMPTY);
 }
 
@@ -160,6 +165,18 @@ void cNetworkSingleton::RunEventLoop(cNetworkSingleton * a_Self)
 
 
 
+void cNetworkSingleton::SignalizeStartup(evutil_socket_t a_Socket, short a_Events, void * a_Self)
+{
+	auto self = reinterpret_cast<cNetworkSingleton *>(a_Self);
+	ASSERT(self != nullptr);
+	ASSERT(self->m_StartupEvent != nullptr);
+	self->m_StartupEvent->Set();
+}
+
+
+
+
+
 void cNetworkSingleton::AddHostnameLookup(cHostnameLookupPtr a_HostnameLookup)
 {
 	ASSERT(!m_HasTerminated);
diff --git a/src/OSSupport/NetworkSingleton.h b/src/OSSupport/NetworkSingleton.h
index c72df38ec..75713d261 100644
--- a/src/OSSupport/NetworkSingleton.h
+++ b/src/OSSupport/NetworkSingleton.h
@@ -13,6 +13,7 @@
 
 #pragma once
 
+#include <event2/event.h>
 #include "Network.h"
 #include "CriticalSection.h"
 #include "Event.h"
@@ -127,11 +128,18 @@ protected:
 	/** The thread in which the main LibEvent loop runs. */
 	std::thread m_EventLoopThread;
 
+	/** Event that is signalled once the startup is finished and the LibEvent loop is running. */
+	UniquePtr<cEvent> m_StartupEvent;
+
+
 	/** Converts LibEvent-generated log events into log messages in MCS log. */
 	static void LogCallback(int a_Severity, const char * a_Msg);
 
 	/** Implements the thread that runs LibEvent's event dispatcher loop. */
 	static void RunEventLoop(cNetworkSingleton * a_Self);
+
+	/** Callback called by LibEvent when the event loop is started. */
+	static void SignalizeStartup(evutil_socket_t a_Socket, short a_Events, void * a_Self);
 };