commit 7a368c9e20afd681242068cccf8cbf64f40e231f
author Peter Åstrand (astrand) <astrand@cendio.se> Wed Sep 19 12:45:17 2018 +0200
committer Pierre Ossman <ossman@cendio.se> Thu Sep 20 12:08:41 2018 +0200
tree c5cbc4ede62aee33ab5c4eb6c931dd047e9459f8
parent c3dcff09369086b862870953f3f3ce5b5b10403f

Avoid refresh of recently changed areas

If an area recently changed then we can guess that it will most likely
change again very soon. In such a case it is meaningless to send a
lossless refresh as it will directly be overwritten. Keep track of
such areas and avoid refreshing them until we no longer see any
changes to them.

common/rfb/VNCSConnectionST.cxx

diff --git a/common/rfb/VNCSConnectionST.cxx b/common/rfb/VNCSConnectionST.cxx
index f22b993..41c6d23 100644
--- a/common/rfb/VNCSConnectionST.cxx
+++ b/common/rfb/VNCSConnectionST.cxx
@@ -1,5 +1,6 @@
 /* Copyright (C) 2002-2005 RealVNC Ltd.  All Rights Reserved.
  * Copyright 2009-2018 Pierre Ossman for Cendio AB
+ * Copyright 2018 Peter Astrand for Cendio AB
  * 
  * This is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -48,7 +49,7 @@
     inProcessMessages(false),
     pendingSyncFence(false), syncFence(false), fenceFlags(0),
     fenceDataLen(0), fenceData(NULL), congestionTimer(this),
-    server(server_), updates(false),
+    losslessTimer(this), server(server_), updates(false),
     updateRenderedCursor(false), removeRenderedCursor(false),
     continuousUpdates(false), encodeManager(this), pointerEventTime(0),
     clientHasCursor(false),
@@ -839,7 +840,8 @@
 bool VNCSConnectionST::handleTimeout(Timer* t)
 {
   try {
-    if (t == &congestionTimer)
+    if ((t == &congestionTimer) ||
+        (t == &losslessTimer))
       writeFramebufferUpdate();
   } catch (rdr::Exception& e) {
     close(e.str());
@@ -1065,10 +1067,20 @@
   }
 
   // Return if there is nothing to send the client.
+  if (ui.is_empty() && !writer()->needFakeUpdate()) {
+    int eta;
 
-  if (ui.is_empty() && !writer()->needFakeUpdate() &&
-      !encodeManager.needsLosslessRefresh(req))
-    return;
+    // Any lossless refresh that needs handling?
+    if (!encodeManager.needsLosslessRefresh(req))
+      return;
+
+    // Now? Or later?
+    eta = encodeManager.getNextLosslessRefresh(req);
+    if (eta > 0) {
+      losslessTimer.start(eta);
+      return;
+    }
+  }
 
   writeRTTPing();