From 2222172afaa97a8550c08c32cab3474d37fcf984 Mon Sep 17 00:00:00 2001
From: John Hurliman <jhurliman@jhurliman.org>
Date: Mon, 26 Oct 2009 11:28:02 -0700
Subject: [PATCH] Removed an unnecessary lock in LLUDPClient.UpdateRTO() and
 LLUDPClient.BackoffRTO()

---
 .../ClientStack/LindenUDP/LLUDPClient.cs      | 55 ++++++++-----------
 1 file changed, 23 insertions(+), 32 deletions(-)

diff --git a/OpenSim/Region/ClientStack/LindenUDP/LLUDPClient.cs b/OpenSim/Region/ClientStack/LindenUDP/LLUDPClient.cs
index 0948e1cf17..a823f3ba1f 100644
--- a/OpenSim/Region/ClientStack/LindenUDP/LLUDPClient.cs
+++ b/OpenSim/Region/ClientStack/LindenUDP/LLUDPClient.cs
@@ -144,9 +144,6 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         private readonly OutgoingPacket[] m_nextPackets = new OutgoingPacket[THROTTLE_CATEGORY_COUNT];
         /// <summary>A reference to the LLUDPServer that is managing this client</summary>
         private readonly LLUDPServer m_udpServer;
-        /// <summary>Locks access to the variables used while calculating round-trip
-        /// packet times and the retransmission timeout</summary>
-        private readonly object m_roundTripCalcLock = new object();
 
         /// <summary>
         /// Default constructor
@@ -487,28 +484,25 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             const float BETA = 0.25f;
             const float K = 4.0f;
 
-            lock (m_roundTripCalcLock)
+            if (RTTVAR == 0.0f)
             {
-                if (RTTVAR == 0.0f)
-                {
-                    // First RTT measurement
-                    SRTT = r;
-                    RTTVAR = r * 0.5f;
-                }
-                else
-                {
-                    // Subsequence RTT measurement
-                    RTTVAR = (1.0f - BETA) * RTTVAR + BETA * Math.Abs(SRTT - r);
-                    SRTT = (1.0f - ALPHA) * SRTT + ALPHA * r;
-                }
-
-                int rto = (int)(SRTT + Math.Max(m_udpServer.TickCountResolution, K * RTTVAR));
-
-                // Clamp the retransmission timeout to manageable values
-                rto = Utils.Clamp(RTO, 3000, 60000);
-
-                RTO = rto;
+                // First RTT measurement
+                SRTT = r;
+                RTTVAR = r * 0.5f;
             }
+            else
+            {
+                // Subsequence RTT measurement
+                RTTVAR = (1.0f - BETA) * RTTVAR + BETA * Math.Abs(SRTT - r);
+                SRTT = (1.0f - ALPHA) * SRTT + ALPHA * r;
+            }
+
+            int rto = (int)(SRTT + Math.Max(m_udpServer.TickCountResolution, K * RTTVAR));
+
+            // Clamp the retransmission timeout to manageable values
+            rto = Utils.Clamp(RTO, 3000, 60000);
+
+            RTO = rto;
 
             //m_log.Debug("[LLUDPCLIENT]: Setting agent " + this.Agent.FullName + "'s RTO to " + RTO + "ms with an RTTVAR of " +
             //    RTTVAR + " based on new RTT of " + r + "ms");
@@ -520,16 +514,13 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         /// </summary>
         public void BackoffRTO()
         {
-            lock (m_roundTripCalcLock)
-            {
-                // Reset SRTT and RTTVAR, we assume they are bogus since things
-                // didn't work out and we're backing off the timeout
-                SRTT = 0.0f;
-                RTTVAR = 0.0f;
+            // Reset SRTT and RTTVAR, we assume they are bogus since things
+            // didn't work out and we're backing off the timeout
+            SRTT = 0.0f;
+            RTTVAR = 0.0f;
 
-                // Double the retransmission timeout
-                RTO = Math.Min(RTO * 2, 60000);
-            }
+            // Double the retransmission timeout
+            RTO = Math.Min(RTO * 2, 60000);
         }
 
         /// <summary>