From: Pierre Ossman <ossman@cendio.se>
Date: Fri, 23 Nov 2018 16:48:02 +0000 (+0100)
Subject: Abort unsafe lossless refresh early
X-Git-Tag: v1.9.90~57
X-Git-Url: https://source.dussan.org/?a=commitdiff_plain;h=812da460cfbd147a7fe0e8b480d1bd5c43f41661;p=tigervnc.git

Abort unsafe lossless refresh early

We need to check earlier if we are going to send this refresh or
not. Otherwise we send out pings pointlessly, and we also stall
the request loop with a client as we clear the requested region
without actually sending an update message.
---

diff --git a/common/rfb/VNCSConnectionST.cxx b/common/rfb/VNCSConnectionST.cxx
index 46c5b1a4..dbbf1d80 100644
--- a/common/rfb/VNCSConnectionST.cxx
+++ b/common/rfb/VNCSConnectionST.cxx
@@ -989,6 +989,7 @@ void VNCSConnectionST::writeLosslessRefresh()
   const RenderedCursor *cursor;
 
   int nextRefresh, nextUpdate;
+  size_t bandwidth, maxUpdateSize;
 
   if (continuousUpdates)
     req = cuRegion.union_(requested);
@@ -1028,27 +1029,28 @@ void VNCSConnectionST::writeLosslessRefresh()
   if (needRenderedCursor())
     cursor = server->getRenderedCursor();
 
-  writeRTTPing();
-
   // FIXME: If continuous updates aren't used then the client might
   //        be slower than frameRate in its requests and we could
   //        afford a larger update size
   nextUpdate = server->msToNextUpdate();
-  if (nextUpdate > 0) {
-    size_t bandwidth, maxUpdateSize;
 
-    // FIXME: Bandwidth estimation without congestion control
-    bandwidth = congestion.getBandwidth();
+  // Don't bother if we're about to send a real update
+  if (nextUpdate == 0)
+    return;
 
-    // FIXME: Hard coded value for maximum CPU throughput
-    if (bandwidth > 5000000)
-      bandwidth = 5000000;
+  // FIXME: Bandwidth estimation without congestion control
+  bandwidth = congestion.getBandwidth();
 
-    maxUpdateSize = bandwidth * nextUpdate / 1000;
+  // FIXME: Hard coded value for maximum CPU throughput
+  if (bandwidth > 5000000)
+    bandwidth = 5000000;
 
-    encodeManager.writeLosslessRefresh(req, server->getPixelBuffer(),
-                                       cursor, maxUpdateSize);
-  }
+  maxUpdateSize = bandwidth * nextUpdate / 1000;
+
+  writeRTTPing();
+
+  encodeManager.writeLosslessRefresh(req, server->getPixelBuffer(),
+                                     cursor, maxUpdateSize);
 
   writeRTTPing();