FIX(client): Racecondition deleting ChannelListeners

As ChannelListeners are only synchronised with the server once
msgServerSync has been received, there is still a racecondition for them
even though we only save them if the ServerSync has happened yet.
The connection could be terminated before the answer of the server for
the request to add the respective listeners reaches the client. In that
case the listeners would be erased by the call to
ChannelListener::saveToDB().

Thus this commit introduces yet another flag indicating whether the
listeners have synchronised with the server yet.

1 files changed, 16 insertions, 0 deletions

diff --git a/src/ChannelListener.cpp b/src/ChannelListener.cpp
index 5bb9ee951..64d2fbc18 100644
--- a/src/ChannelListener.cpp
+++ b/src/ChannelListener.cpp
@@ -32,6 +32,7 @@ ChannelListener::ChannelListener()
 #ifdef MUMBLE
 	, m_volumeLock()
 	, m_listenerVolumeAdjustments()
+	, m_initialSyncDone(false)
 #endif
 {}
 
@@ -125,6 +126,10 @@ QHash<int, float> ChannelListener::getAllListenerLocalVolumeAdjustmentsImpl(bool
 		return volumeMap;
 	}
 }
+
+void ChannelListener::setInitialServerSyncDoneImpl(bool done) {
+	m_initialSyncDone.store(done);
+}
 #endif
 
 void ChannelListener::clearImpl() {
@@ -241,12 +246,23 @@ QHash<int, float> ChannelListener::getAllListenerLocalVolumeAdjustments(bool fil
 	return get().getAllListenerLocalVolumeAdjustmentsImpl(filter);
 }
 
+void ChannelListener::setInitialServerSyncDone(bool done) {
+	get().setInitialServerSyncDoneImpl(done);
+}
+
 void ChannelListener::saveToDB() {
 	if (!g.sh || g.sh->qbaDigest.isEmpty() || g.uiSession == 0) {
 		// Can't save as we don't have enough context
 		return;
 	}
 
+	if (!get().m_initialSyncDone.load()) {
+		// If we were to save the listeners before the sync is done, we'd overwrite the list of listeners in the
+		// DB with an empty set, effectively erasing all set-up listeners.
+		qWarning("ChannelListener: Aborting save of user's listeners as initial ServerSync is not done yet");
+		return;
+	}
+
 	// Save the currently listened channels
 	g.db->setChannelListeners(g.sh->qbaDigest, ChannelListener::getListenedChannelsForUser(g.uiSession));
 	// And also the currently set volume adjustments (if they're not set to 1.0)