1 files changed, 140 insertions, 0 deletions

diff --git a/OpenSim/Framework/Communications/Limit/TimeLimitStrategy.cs b/OpenSim/Framework/Communications/Limit/TimeLimitStrategy.cs
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+++ b/OpenSim/Framework/Communications/Limit/TimeLimitStrategy.cs
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+/*
+ * Copyright (c) Contributors, http://opensimulator.org/
+ * See CONTRIBUTORS.TXT for a full list of copyright holders.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of the OpenSim Project nor the
+ *       names of its contributors may be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+using System;
+using System.Collections.Generic;
+
+namespace OpenSim.Framework.Communications.Limit
+{
+    /// <summary>
+    /// Limit requests by discarding repeat attempts that occur within a given time period
+    /// 
+    /// XXX Don't use this for limiting texture downloading, at least not until we better handle multiple requests
+    /// for the same texture at different resolutions.
+    /// </summary>    
+    public class TimeLimitStrategy<TId> : IRequestLimitStrategy<TId>
+    {
+        /// <summary>
+        /// Record the time at which an asset request occurs.
+        /// </summary>
+        private readonly Dictionary<TId, Request> requests = new Dictionary<TId, Request>();    
+        
+        /// <summary>
+        /// The minimum time period between which requests for the same data will be serviced.
+        /// </summary>
+        private readonly TimeSpan m_repeatPeriod;
+        public TimeSpan RepeatPeriod
+        {
+            get { return m_repeatPeriod; }
+        }
+
+        /// <summary></summary>
+        /// <param name="repeatPeriod"></param>        
+        public TimeLimitStrategy(TimeSpan repeatPeriod)
+        {
+            m_repeatPeriod = repeatPeriod;
+        }
+        
+        /// <summary>
+        /// <see cref="IRequestLimitStrategy"/>
+        /// </summary>
+        public bool AllowRequest(TId id)
+        {                 
+            if (IsMonitoringRequests(id))
+            {
+                DateTime now = DateTime.Now;
+                TimeSpan elapsed = now - requests[id].Time;
+                
+                if (elapsed < RepeatPeriod)
+                {
+                    requests[id].Refusals += 1;
+                    return false;
+                }
+                
+                requests[id].Time = now; 
+            }
+            
+            return true;
+        }
+        
+        /// <summary>
+        /// <see cref="IRequestLimitStrategy"/>
+        /// </summary>        
+        public bool IsFirstRefusal(TId id)
+        {
+            if (IsMonitoringRequests(id))
+            {
+                if (1 == requests[id].Refusals)
+                {
+                    return true;
+                }
+            }           
+            
+            return false;
+        }
+        
+        /// <summary>
+        /// <see cref="IRequestLimitStrategy"/>
+        /// </summary>        
+        public void MonitorRequests(TId id)
+        {
+            if (!IsMonitoringRequests(id))
+            {
+                requests.Add(id, new Request(System.DateTime.Now));
+            }            
+        }  
+        
+        /// <summary>
+        /// <see cref="IRequestLimitStrategy"/>
+        /// </summary>         
+        public bool IsMonitoringRequests(TId id)
+        {
+            return requests.ContainsKey(id);
+        }      
+    }
+    
+    /// <summary>
+    /// Private request details.
+    /// </summary>
+    class Request
+    {
+        /// <summary>
+        /// Time of last request
+        /// </summary>
+        public DateTime Time;
+        
+        /// <summary>
+        /// Number of refusals associated with this request
+        /// </summary>
+        public int Refusals;
+        
+        public Request(DateTime time)
+        {
+            Time = time;
+        }
+    }
+}