New tokenbucket algorithm. This one provides fair sharing of the queues

 when client and simulator throttles are set. This algorithm also uses
 pre-defined burst rate of 150% of the sustained rate for each of the
 throttles.

Removed the "state" queue. The state queue is not a Linden queue and
appeared to be used just to get kill packets sent.

4 files changed, 259 insertions, 145 deletions

diff --git a/OpenSim/Region/ClientStack/LindenUDP/LLClientView.cs b/OpenSim/Region/ClientStack/LindenUDP/LLClientView.cs
index 8de31d7..934a2d5 100644
--- a/OpenSim/Region/ClientStack/LindenUDP/LLClientView.cs
+++ b/OpenSim/Region/ClientStack/LindenUDP/LLClientView.cs
@@ -1610,7 +1610,8 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             }
             else
             {
-                OutPacket(kill, ThrottleOutPacketType.State);
+                // OutPacket(kill, ThrottleOutPacketType.State);
+                OutPacket(kill, ThrottleOutPacketType.Task);
             }
         }
 
@@ -2440,7 +2441,8 @@ namespace OpenSim.Region.ClientStack.LindenUDP
 
             packet.Effect = effectBlocks;
 
-            OutPacket(packet, ThrottleOutPacketType.State);
+            // OutPacket(packet, ThrottleOutPacketType.State);
+            OutPacket(packet, ThrottleOutPacketType.Task);
         }
 
         public void SendAvatarProperties(UUID avatarID, string aboutText, string bornOn, Byte[] charterMember,
diff --git a/OpenSim/Region/ClientStack/LindenUDP/LLUDPClient.cs b/OpenSim/Region/ClientStack/LindenUDP/LLUDPClient.cs
index 9a8bfd3..5a69851 100644
--- a/OpenSim/Region/ClientStack/LindenUDP/LLUDPClient.cs
+++ b/OpenSim/Region/ClientStack/LindenUDP/LLUDPClient.cs
@@ -135,7 +135,9 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         private int m_nextOnQueueEmpty = 1;
 
         /// <summary>Throttle bucket for this agent's connection</summary>
-        private readonly TokenBucket m_throttle;
+        private readonly TokenBucket m_throttleClient;
+        /// <summary>Throttle bucket for this agent's connection</summary>
+        private readonly TokenBucket m_throttleCategory;
         /// <summary>Throttle buckets for each packet category</summary>
         private readonly TokenBucket[] m_throttleCategories;
         /// <summary>Outgoing queues for throttled packets</summary>
@@ -174,7 +176,9 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                 m_maxRTO = maxRTO;
 
             // Create a token bucket throttle for this client that has the scene token bucket as a parent
-            m_throttle = new TokenBucket(parentThrottle, rates.TotalLimit, rates.Total);
+            m_throttleClient = new TokenBucket(parentThrottle, rates.TotalLimit);
+            // Create a token bucket throttle for the total categary with the client bucket as a throttle
+            m_throttleCategory = new TokenBucket(m_throttleClient, rates.TotalLimit);
             // Create an array of token buckets for this clients different throttle categories
             m_throttleCategories = new TokenBucket[THROTTLE_CATEGORY_COUNT];
 
@@ -185,7 +189,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                 // Initialize the packet outboxes, where packets sit while they are waiting for tokens
                 m_packetOutboxes[i] = new OpenSim.Framework.LocklessQueue<OutgoingPacket>();
                 // Initialize the token buckets that control the throttling for each category
-                m_throttleCategories[i] = new TokenBucket(m_throttle, rates.GetLimit(type), rates.GetRate(type));
+                m_throttleCategories[i] = new TokenBucket(m_throttleCategory, rates.GetLimit(type));
             }
 
             // Default the retransmission timeout to three seconds
@@ -206,6 +210,9 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                 m_packetOutboxes[i].Clear();
                 m_nextPackets[i] = null;
             }
+
+            // pull the throttle out of the scene throttle
+            m_throttleClient.Parent.UnregisterRequest(m_throttleClient);
             OnPacketStats = null;
             OnQueueEmpty = null;
         }
@@ -216,6 +223,26 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         /// <returns>Information about the client connection</returns>
         public ClientInfo GetClientInfo()
         {
+///<mic>
+            TokenBucket tb;
+
+            tb = m_throttleClient.Parent;
+            m_log.WarnFormat("[TOKENS] {3}: Actual={0},Request={1},TotalRequest={2}",tb.DripRate,tb.RequestedDripRate,tb.TotalDripRequest,"ROOT");
+
+            tb = m_throttleClient;
+            m_log.WarnFormat("[TOKENS] {3}: Actual={0},Request={1},TotalRequest={2}",tb.DripRate,tb.RequestedDripRate,tb.TotalDripRequest,"  CLIENT");
+
+            tb = m_throttleCategory;
+            m_log.WarnFormat("[TOKENS] {3}: Actual={0},Request={1},TotalRequest={2}",tb.DripRate,tb.RequestedDripRate,tb.TotalDripRequest,"    CATEGORY");
+
+            for (int i = 0; i < THROTTLE_CATEGORY_COUNT; i++)
+            {
+                tb = m_throttleCategories[i];
+                m_log.WarnFormat("[TOKENS] {4} <{0}:{1}>: Actual={2},Requested={3}",AgentID,i,tb.DripRate,tb.RequestedDripRate,"      BUCKET");
+            }
+                
+///</mic>
+
             // TODO: This data structure is wrong in so many ways. Locking and copying the entire lists
             // of pending and needed ACKs for every client every time some method wants information about
             // this connection is a recipe for poor performance
@@ -223,13 +250,14 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             info.pendingAcks = new Dictionary<uint, uint>();
             info.needAck = new Dictionary<uint, byte[]>();
 
-            info.resendThrottle = m_throttleCategories[(int)ThrottleOutPacketType.Resend].DripRate;
-            info.landThrottle = m_throttleCategories[(int)ThrottleOutPacketType.Land].DripRate;
-            info.windThrottle = m_throttleCategories[(int)ThrottleOutPacketType.Wind].DripRate;
-            info.cloudThrottle = m_throttleCategories[(int)ThrottleOutPacketType.Cloud].DripRate;
-            info.taskThrottle = m_throttleCategories[(int)ThrottleOutPacketType.State].DripRate + m_throttleCategories[(int)ThrottleOutPacketType.Task].DripRate;
-            info.assetThrottle = m_throttleCategories[(int)ThrottleOutPacketType.Asset].DripRate;
-            info.textureThrottle = m_throttleCategories[(int)ThrottleOutPacketType.Texture].DripRate;
+            info.resendThrottle = (int)m_throttleCategories[(int)ThrottleOutPacketType.Resend].DripRate;
+            info.landThrottle = (int)m_throttleCategories[(int)ThrottleOutPacketType.Land].DripRate;
+            info.windThrottle = (int)m_throttleCategories[(int)ThrottleOutPacketType.Wind].DripRate;
+            info.cloudThrottle = (int)m_throttleCategories[(int)ThrottleOutPacketType.Cloud].DripRate;
+            // info.taskThrottle = m_throttleCategories[(int)ThrottleOutPacketType.State].DripRate + m_throttleCategories[(int)ThrottleOutPacketType.Task].DripRate;
+            info.taskThrottle = (int)m_throttleCategories[(int)ThrottleOutPacketType.Task].DripRate;
+            info.assetThrottle = (int)m_throttleCategories[(int)ThrottleOutPacketType.Asset].DripRate;
+            info.textureThrottle = (int)m_throttleCategories[(int)ThrottleOutPacketType.Texture].DripRate;
             info.totalThrottle = info.resendThrottle + info.landThrottle + info.windThrottle + info.cloudThrottle +
                 info.taskThrottle + info.assetThrottle + info.textureThrottle;
 
@@ -317,8 +345,9 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             int texture = (int)(BitConverter.ToSingle(adjData, pos) * 0.125f); pos += 4;
             int asset = (int)(BitConverter.ToSingle(adjData, pos) * 0.125f);
             // State is a subcategory of task that we allocate a percentage to
-            int state = (int)((float)task * STATE_TASK_PERCENTAGE);
-            task -= state;
+            int state = 0;
+            // int state = (int)((float)task * STATE_TASK_PERCENTAGE);
+            // task -= state;
 
             // Make sure none of the throttles are set below our packet MTU,
             // otherwise a throttle could become permanently clogged
@@ -339,40 +368,32 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             // Update the token buckets with new throttle values
             TokenBucket bucket;
 
-            bucket = m_throttle;
-            bucket.MaxBurst = total;
+            bucket = m_throttleCategory;
+            bucket.RequestedDripRate = total;
 
             bucket = m_throttleCategories[(int)ThrottleOutPacketType.Resend];
-            bucket.DripRate = resend;
-            bucket.MaxBurst = resend;
+            bucket.RequestedDripRate = resend;
 
             bucket = m_throttleCategories[(int)ThrottleOutPacketType.Land];
-            bucket.DripRate = land;
-            bucket.MaxBurst = land;
+            bucket.RequestedDripRate = land;
 
             bucket = m_throttleCategories[(int)ThrottleOutPacketType.Wind];
-            bucket.DripRate = wind;
-            bucket.MaxBurst = wind;
+            bucket.RequestedDripRate = wind;
 
             bucket = m_throttleCategories[(int)ThrottleOutPacketType.Cloud];
-            bucket.DripRate = cloud;
-            bucket.MaxBurst = cloud;
+            bucket.RequestedDripRate = cloud;
 
             bucket = m_throttleCategories[(int)ThrottleOutPacketType.Asset];
-            bucket.DripRate = asset;
-            bucket.MaxBurst = asset;
+            bucket.RequestedDripRate = asset;
 
             bucket = m_throttleCategories[(int)ThrottleOutPacketType.Task];
-            bucket.DripRate = task + state;
-            bucket.MaxBurst = task + state;
+            bucket.RequestedDripRate = task;
 
             bucket = m_throttleCategories[(int)ThrottleOutPacketType.State];
-            bucket.DripRate = state;
-            bucket.MaxBurst = state;
+            bucket.RequestedDripRate = state;
 
             bucket = m_throttleCategories[(int)ThrottleOutPacketType.Texture];
-            bucket.DripRate = texture;
-            bucket.MaxBurst = texture;
+            bucket.RequestedDripRate = texture;
 
             // Reset the packed throttles cached data
             m_packedThrottles = null;
@@ -387,14 +408,13 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                 data = new byte[7 * 4];
                 int i = 0;
 
-                Buffer.BlockCopy(Utils.FloatToBytes((float)m_throttleCategories[(int)ThrottleOutPacketType.Resend].DripRate), 0, data, i, 4); i += 4;
-                Buffer.BlockCopy(Utils.FloatToBytes((float)m_throttleCategories[(int)ThrottleOutPacketType.Land].DripRate), 0, data, i, 4); i += 4;
-                Buffer.BlockCopy(Utils.FloatToBytes((float)m_throttleCategories[(int)ThrottleOutPacketType.Wind].DripRate), 0, data, i, 4); i += 4;
-                Buffer.BlockCopy(Utils.FloatToBytes((float)m_throttleCategories[(int)ThrottleOutPacketType.Cloud].DripRate), 0, data, i, 4); i += 4;
-                Buffer.BlockCopy(Utils.FloatToBytes((float)(m_throttleCategories[(int)ThrottleOutPacketType.Task].DripRate) +
-                                                            m_throttleCategories[(int)ThrottleOutPacketType.State].DripRate), 0, data, i, 4); i += 4;
-                Buffer.BlockCopy(Utils.FloatToBytes((float)m_throttleCategories[(int)ThrottleOutPacketType.Texture].DripRate), 0, data, i, 4); i += 4;
-                Buffer.BlockCopy(Utils.FloatToBytes((float)m_throttleCategories[(int)ThrottleOutPacketType.Asset].DripRate), 0, data, i, 4); i += 4;
+                Buffer.BlockCopy(Utils.FloatToBytes((float)m_throttleCategories[(int)ThrottleOutPacketType.Resend].RequestedDripRate), 0, data, i, 4); i += 4;
+                Buffer.BlockCopy(Utils.FloatToBytes((float)m_throttleCategories[(int)ThrottleOutPacketType.Land].RequestedDripRate), 0, data, i, 4); i += 4;
+                Buffer.BlockCopy(Utils.FloatToBytes((float)m_throttleCategories[(int)ThrottleOutPacketType.Wind].RequestedDripRate), 0, data, i, 4); i += 4;
+                Buffer.BlockCopy(Utils.FloatToBytes((float)m_throttleCategories[(int)ThrottleOutPacketType.Cloud].RequestedDripRate), 0, data, i, 4); i += 4;
+                Buffer.BlockCopy(Utils.FloatToBytes((float)m_throttleCategories[(int)ThrottleOutPacketType.Task].RequestedDripRate), 0, data, i, 4); i += 4;
+                Buffer.BlockCopy(Utils.FloatToBytes((float)m_throttleCategories[(int)ThrottleOutPacketType.Texture].RequestedDripRate), 0, data, i, 4); i += 4;
+                Buffer.BlockCopy(Utils.FloatToBytes((float)m_throttleCategories[(int)ThrottleOutPacketType.Asset].RequestedDripRate), 0, data, i, 4); i += 4;
 
                 m_packedThrottles = data;
             }
diff --git a/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs b/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs
index 583214c..d08b25f 100644
--- a/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs
+++ b/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs
@@ -228,7 +228,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
            }
            #endregion BinaryStats
 
-            m_throttle = new TokenBucket(null, sceneThrottleBps, sceneThrottleBps);
+            m_throttle = new TokenBucket(null, sceneThrottleBps);
             ThrottleRates = new ThrottleRates(configSource);
         }
 
diff --git a/OpenSim/Region/ClientStack/LindenUDP/TokenBucket.cs b/OpenSim/Region/ClientStack/LindenUDP/TokenBucket.cs
index 0a8331f..e4d59ff 100644
--- a/OpenSim/Region/ClientStack/LindenUDP/TokenBucket.cs
+++ b/OpenSim/Region/ClientStack/LindenUDP/TokenBucket.cs
@@ -26,6 +26,10 @@
  */
 
 using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Reflection;
+using log4net;
 
 namespace OpenSim.Region.ClientStack.LindenUDP
 {
@@ -35,89 +39,126 @@ namespace OpenSim.Region.ClientStack.LindenUDP
     /// </summary>
     public class TokenBucket
     {
-        /// <summary>Parent bucket to this bucket, or null if this is a root
-        /// bucket</summary>
-        TokenBucket parent;
-        /// <summary>Size of the bucket in bytes. If zero, the bucket has 
-        /// infinite capacity</summary>
-        int maxBurst;
-        /// <summary>Rate that the bucket fills, in bytes per millisecond. If
-        /// zero, the bucket always remains full</summary>
-        int tokensPerMS;
-        /// <summary>Number of tokens currently in the bucket</summary>
-        int content;
+        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
+        private static Int32 m_counter = 0;
+        
+        private Int32 m_identifier;
+        
+        /// <summary>
+        /// Number of ticks (ms) per quantum, drip rate and max burst
+        /// are defined over this interval.
+        /// </summary>
+        private const Int32 m_ticksPerQuantum = 1000;
+
+        /// <summary>
+        /// This is the number of quantums worth of packets that can
+        /// be accommodated during a burst
+        /// </summary>
+        private const Double m_quantumsPerBurst = 1.5;
+                
+        /// <summary>
+        /// </summary>
+        private const Int32 m_minimumDripRate = 1400;
+        
         /// <summary>Time of the last drip, in system ticks</summary>
-        int lastDrip;
+        private Int32 m_lastDrip;
+
+        /// <summary>
+        /// The number of bytes that can be sent at this moment. This is the
+        /// current number of tokens in the bucket
+        /// </summary>
+        private Int64 m_tokenCount;
 
-        #region Properties
+        /// <summary>
+        /// Map of children buckets and their requested maximum burst rate
+        /// </summary>
+        private Dictionary<TokenBucket,Int64> m_children = new Dictionary<TokenBucket,Int64>();
+        
+#region Properties
 
         /// <summary>
         /// The parent bucket of this bucket, or null if this bucket has no
         /// parent. The parent bucket will limit the aggregate bandwidth of all
         /// of its children buckets
         /// </summary>
+        private TokenBucket m_parent;
         public TokenBucket Parent
         {
-            get { return parent; }
+            get { return m_parent; }
+            set { m_parent = value; }
         }
 
         /// <summary>
         /// Maximum burst rate in bytes per second. This is the maximum number
-        /// of tokens that can accumulate in the bucket at any one time
+        /// of tokens that can accumulate in the bucket at any one time. This 
+        /// also sets the total request for leaf nodes
         /// </summary>
-        public int MaxBurst
+        private Int64 m_burstRate;
+        public Int64 RequestedBurstRate
         {
-            get { return maxBurst; }
-            set { maxBurst = (value >= 0 ? value : 0); }
+            get { return m_burstRate; }
+            set { m_burstRate = (value < 0 ? 0 : value); }
         }
 
+        public Int64 BurstRate
+        {
+            get {
+                double rate = RequestedBurstRate * BurstRateModifier();
+                if (rate < m_minimumDripRate * m_quantumsPerBurst)
+                    rate = m_minimumDripRate * m_quantumsPerBurst;
+                
+                return (Int64) rate;
+            }
+        }
+               
         /// <summary>
         /// The speed limit of this bucket in bytes per second. This is the
-        /// number of tokens that are added to the bucket per second
+        /// number of tokens that are added to the bucket per quantum
         /// </summary>
         /// <remarks>Tokens are added to the bucket any time 
         /// <seealso cref="RemoveTokens"/> is called, at the granularity of
         /// the system tick interval (typically around 15-22ms)</remarks>
-        public int DripRate
+        private Int64 m_dripRate;
+        public Int64 RequestedDripRate
         {
-            get { return tokensPerMS * 1000; }
-            set
-            {
-                if (value == 0)
-                    tokensPerMS = 0;
-                else
-                {
-                    int bpms = (int)((float)value / 1000.0f);
-
-                    if (bpms <= 0)
-                        tokensPerMS = 1; // 1 byte/ms is the minimum granularity
-                    else
-                        tokensPerMS = bpms;
-                }
+            get { return (m_dripRate == 0 ? m_totalDripRequest : m_dripRate); }
+            set {
+                m_dripRate = (value < 0 ? 0 : value);
+                m_burstRate = (Int64)((double)m_dripRate * m_quantumsPerBurst);
+                m_totalDripRequest = m_dripRate;
+                if (m_parent != null)
+                    m_parent.RegisterRequest(this,m_dripRate);
             }
         }
 
-        /// <summary>
-        /// The speed limit of this bucket in bytes per millisecond
-        /// </summary>
-        public int DripPerMS
+        public Int64 DripRate
         {
-            get { return tokensPerMS; }
+            get {
+                if (m_parent == null)
+                    return Math.Min(RequestedDripRate,TotalDripRequest);
+                
+                double rate = (double)RequestedDripRate * m_parent.DripRateModifier();
+                if (rate < m_minimumDripRate)
+                    rate = m_minimumDripRate;
+
+                return (Int64)rate;
+            }
         }
 
         /// <summary>
-        /// The number of bytes that can be sent at this moment. This is the
-        /// current number of tokens in the bucket
-        /// <remarks>If this bucket has a parent bucket that does not have
-        /// enough tokens for a request, <seealso cref="RemoveTokens"/> will 
-        /// return false regardless of the content of this bucket</remarks>
+        /// The current total of the requested maximum burst rates of 
+        /// this bucket's children buckets.
         /// </summary>
-        public int Content
-        {
-            get { return content; }
-        }
+        private Int64 m_totalDripRequest;
+        public Int64 TotalDripRequest 
+            {
+                get { return m_totalDripRequest; }
+                set { m_totalDripRequest = value; }
+            }
+        
+#endregion Properties
 
-        #endregion Properties
+#region Constructor
 
         /// <summary>
         /// Default constructor
@@ -128,56 +169,115 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         /// zero if this bucket has no maximum capacity</param>
         /// <param name="dripRate">Rate that the bucket fills, in bytes per
         /// second. If zero, the bucket always remains full</param>
-        public TokenBucket(TokenBucket parent, int maxBurst, int dripRate)
+        public TokenBucket(TokenBucket parent, Int64 dripRate) 
         {
-            this.parent = parent;
-            MaxBurst = maxBurst;
-            DripRate = dripRate;
-            lastDrip = Environment.TickCount & Int32.MaxValue;
+            m_identifier = m_counter++;
+
+            Parent = parent;
+            RequestedDripRate = dripRate;
+            // TotalDripRequest = dripRate; // this will be overwritten when a child node registers
+            // MaxBurst = (Int64)((double)dripRate * m_quantumsPerBurst);
+            m_lastDrip = Environment.TickCount & Int32.MaxValue;
         }
 
+#endregion Constructor
+
         /// <summary>
-        /// Remove a given number of tokens from the bucket
+        /// Compute a modifier for the MaxBurst rate. This is 1.0, meaning
+        /// no modification if the requested bandwidth is less than the
+        /// max burst bandwidth all the way to the root of the throttle
+        /// hierarchy. However, if any of the parents is over-booked, then
+        /// the modifier will be less than 1.
         /// </summary>
-        /// <param name="amount">Number of tokens to remove from the bucket</param>
-        /// <returns>True if the requested number of tokens were removed from
-        /// the bucket, otherwise false</returns>
-        public bool RemoveTokens(int amount)
+        private double DripRateModifier()
+        {
+            Int64 driprate = DripRate;
+            return driprate >= TotalDripRequest ? 1.0 : (double)driprate / (double)TotalDripRequest;
+        }
+
+        /// <summary>
+        /// </summary>
+        private double BurstRateModifier()
+        {
+            // for now... burst rate is always m_quantumsPerBurst (constant)
+            // larger than drip rate so the ratio of burst requests is the
+            // same as the drip ratio
+            return DripRateModifier();
+        }
+
+        /// <summary>
+        /// Register drip rate requested by a child of this throttle. Pass the
+        /// changes up the hierarchy.
+        /// </summary>
+        public void RegisterRequest(TokenBucket child, Int64 request)
         {
-            bool dummy;
-            return RemoveTokens(amount, out dummy);
+            m_children[child] = request;
+            // m_totalDripRequest = m_children.Values.Sum();
+
+            m_totalDripRequest = 0;
+            foreach (KeyValuePair<TokenBucket, Int64> cref in m_children)
+                m_totalDripRequest += cref.Value;
+            
+            // Pass the new values up to the parent
+            if (m_parent != null)
+                m_parent.RegisterRequest(this,Math.Min(RequestedDripRate, TotalDripRequest));
         }
 
         /// <summary>
+        /// Remove the rate requested by a child of this throttle. Pass the
+        /// changes up the hierarchy.
+        /// </summary>
+        public void UnregisterRequest(TokenBucket child)
+        {
+            m_children.Remove(child);
+            // m_totalDripRequest = m_children.Values.Sum();
+
+            m_totalDripRequest = 0;
+            foreach (KeyValuePair<TokenBucket, Int64> cref in m_children)
+                m_totalDripRequest += cref.Value;
+
+            // Pass the new values up to the parent
+            if (m_parent != null)
+                m_parent.RegisterRequest(this,Math.Min(RequestedDripRate, TotalDripRequest));
+        }
+        
+        /// <summary>
         /// Remove a given number of tokens from the bucket
         /// </summary>
         /// <param name="amount">Number of tokens to remove from the bucket</param>
-        /// <param name="dripSucceeded">True if tokens were added to the bucket
-        /// during this call, otherwise false</param>
         /// <returns>True if the requested number of tokens were removed from
         /// the bucket, otherwise false</returns>
-        public bool RemoveTokens(int amount, out bool dripSucceeded)
+        public bool RemoveTokens(Int64 amount)
         {
-            if (maxBurst == 0)
+            // Deposit tokens for this interval
+            Drip();
+
+            // If we have enough tokens then remove them and return
+            if (m_tokenCount - amount >= 0)
             {
-                dripSucceeded = true;
-                return true;
+                if (m_parent == null || m_parent.RemoveTokens(amount))
+                {
+                    m_tokenCount -= amount;
+                    return true;
+                }
             }
 
-            dripSucceeded = Drip();
+            return false;
+        }
 
-            if (content - amount >= 0)
-            {
-                if (parent != null && !parent.RemoveTokens(amount))
-                    return false;
+        /// <summary>
+        /// Deposit tokens into the bucket from a child bucket that did
+        /// not use all of its available tokens
+        /// </summary>
+        private void Deposit(Int64 count)
+        {
+            m_tokenCount += count;
 
-                content -= amount;
-                return true;
-            }
-            else
-            {
-                return false;
-            }
+            // Deposit the overflow in the parent bucket, this is how we share
+            // unused bandwidth
+            Int64 burstrate = BurstRate;
+            if (m_tokenCount > burstrate)
+                m_tokenCount = burstrate;
         }
 
         /// <summary>
@@ -186,37 +286,29 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         /// call to Drip
         /// </summary>
         /// <returns>True if tokens were added to the bucket, otherwise false</returns>
-        public bool Drip()
+        private void Drip()
         {
-            if (tokensPerMS == 0)
+            // This should never happen... means we are a leaf node and were created
+            // with no drip rate...
+            if (DripRate == 0)
             {
-                content = maxBurst;
-                return true;
+                m_log.WarnFormat("[TOKENBUCKET] something odd is happening and drip rate is 0");
+                return;
             }
-            else
-            {
-                int now = Environment.TickCount & Int32.MaxValue;
-                int deltaMS = now - lastDrip;
-
-                if (deltaMS <= 0)
-                {
-                    if (deltaMS < 0)
-                        lastDrip = now;
-                    return false;
-                }
+            
+            // Determine the interval over which we are adding tokens, never add
+            // more than a single quantum of tokens
+            Int32 now = Environment.TickCount & Int32.MaxValue;
+            Int32 deltaMS = Math.Min(now - m_lastDrip, m_ticksPerQuantum);
 
-                int dripAmount = deltaMS * tokensPerMS;
+            m_lastDrip = now;
 
-                content = Math.Min(content + dripAmount, maxBurst);
-                lastDrip = now;
+            // This can be 0 in the very unusual case that the timer wrapped
+            // It can be 0 if we try add tokens at a sub-tick rate
+            if (deltaMS <= 0)
+                return;
 
-                if (dripAmount < 0 || content < 0)
-                    // sim has been idle for too long, integer has overflown
-                    // previous calculation is meaningless, let's put it at correct max
-                    content = maxBurst;
-
-                return true;
-            }
+            Deposit(deltaMS * DripRate / m_ticksPerQuantum);
         }
     }
 }