use std::shared_ptr<> to the queue instead of reference, to avoid destruction of the queue while it is used.

server/json-adapter.cc

@@ -70,7 +70,7 @@ typedef variant<std::thread::id, std::string> EventListenerKey;
 
 struct EventListenerValue
 {
-	utility::locked_queue<js::Object> Q;
+	std::shared_ptr<utility::locked_queue<js::Object>> Q = std::make_shared<utility::locked_queue<js::Object>>();;
 };
 
 static std::hash<std::thread::id> hash_tid;
@@ -144,8 +144,8 @@ struct JsonAdapter::Internal
 		
 		for(auto& e : eventListener)
 		{
-			Log << Logger::Debug << " ~~~ " << to_log(e.first)  << " has " << e.second.Q.size() << " old events waiting.";
-			e.second.Q.push_back(request);
+			Log << Logger::Debug << " ~~~ " << to_log(e.first)  << " has " << e.second.Q->size() << " old events waiting.";
+			e.second.Q->push_back(request);
 		}
 	}
 	
@@ -305,13 +305,15 @@ catch (std::exception const &e)
 void JsonAdapter::connection_close_cb()
 {
 	Lock L{_mtx};
-	auto q = i->eventListener.find( std::this_thread::get_id() );
-	Log() << "Connection Close Callback: " << (q==i->eventListener.end() ? "NO" : "1") << " entry in eventListener map";
+	const auto tid = std::this_thread::get_id();
+	auto q = i->eventListener.find( tid );
+	i->Log << Logger::Debug << "Connection Close Callback: " << (q==i->eventListener.end() ? "NO" : "1") << " entry in eventListener map for Thread " << tid << ".";
 	if(q != i->eventListener.end())
 	{
-		while(q->second.Q.waiting() > 0)
+		i->Log.debug("%d listener(s) waiting on event queue", q->second.Q->waiting());
+		while(q->second.Q->waiting() > 0)
 		{
-			q->second.Q.push_back(queue_close_event);
+			q->second.Q->push_back(queue_close_event);
 			std::this_thread::sleep_for( std::chrono::milliseconds(333) );
 		}
 		i->eventListener.erase(q);
@@ -323,12 +325,13 @@ void JsonAdapter::close_session(const std::string& session_id)
 {
 	Lock L{_mtx};
 	auto q = i->eventListener.find( session_id );
-	Log() << "Close session \"" << session_id << "\": " << (q==i->eventListener.end() ? "NO" : "1") << " entry in eventListener map";
+	i->Log << Logger::Debug << "Close session \"" << session_id << "\": " << (q==i->eventListener.end() ? "NO" : "1") << " entry in eventListener map for session_id \"" << session_id << "\".";
 	if(q != i->eventListener.end())
 	{
-		while(q->second.Q.waiting() > 0)
+		i->Log.debug("%d listener(s) waiting on event queue", q->second.Q->waiting());
+		while(q->second.Q->waiting() > 0)
 		{
-			q->second.Q.push_back(queue_close_event);
+			q->second.Q->push_back(queue_close_event);
 			std::this_thread::sleep_for( std::chrono::milliseconds(333) );
 		}
 		i->eventListener.erase(q);
@@ -389,17 +392,17 @@ js::Array JsonAdapter::Internal::pollForEvents(const EventListenerKey& key, unsi
 	Logger L("JAI:poll");
 
 	Lock LCK{_mtx};
-	EventListenerValue& el = eventListener[key];  // adds an entry, if not already there. :-)
+	auto elQ = eventListener[key].Q;  // adds an entry, if not already there. :-)
 	LCK.unlock();
 	
-	const size_t size = el.Q.size();
+	const size_t size = elQ->size();
 	if(size)
 	{
 		L << Logger::Debug << size << " events in queue for key " << to_log(key) << ":";
 		// fetch all elements from queue
 		for(size_t i=0; i<size; ++i)
 		{
-			js::Object obj{ el.Q.pop_front() };
+			js::Object obj{ elQ->pop_front() };
 			const std::string obj_s = js::write( obj );
 			L << Logger::Debug << "\t#" << i << ": " << obj_s;
 			
@@ -409,7 +412,7 @@ js::Array JsonAdapter::Internal::pollForEvents(const EventListenerKey& key, unsi
 		// block until there is at least one element or timeout
 		L << Logger::Debug << "Queue for key " << to_log(key) << " is empty. I'll block for " << timeout_seconds << " seconds.";
 		js::Object event;
-		const bool success = el.Q.try_pop_front( event, std::chrono::seconds(timeout_seconds) );
+		const bool success = elQ->try_pop_front( event, std::chrono::seconds(timeout_seconds) );
 		if(success)
 		{
 			const std::string event_s = js::write(event);