* Refactor: Genericise request limit strategies and move to OpenSim.Framework.Communications.Limit

2 files changed, 181 insertions, 0 deletions

diff --git a/OpenSim/Framework/Communications/Limit/IRequestLimitStrategy.cs b/OpenSim/Framework/Communications/Limit/IRequestLimitStrategy.cs
new file mode 100644
index 0000000..ded9ffc
--- /dev/null
+++ b/OpenSim/Framework/Communications/Limit/IRequestLimitStrategy.cs
@@ -0,0 +1,68 @@
+/*
+ * 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;
+
+namespace OpenSim.Framework.Communications.Limit
+{
+    /// <summary>
+    /// Interface for strategies that can limit requests from the client.  Currently only used in the
+    /// texture modules to deal with repeated requests for certain textures.  However, limiting strategies
+    /// could be used with other requests.
+    /// </summary>    
+    public interface IRequestLimitStrategy<TId>
+    {           
+        /// <summary>
+        /// Should the request be allowed?  If the id is not monitored, then the request is always allowed.
+        /// Otherwise, the strategy criteria will be applied.
+        /// </summary>
+        /// <param name="id"></param>
+        /// <returns></returns>
+        bool AllowRequest(TId id);
+        
+        /// <summary>
+        /// Has the request been refused just once?
+        /// </summary>
+        /// <returns>False if the request has not yet been refused, or if the request has been refused more
+        /// than once.</returns>
+        bool IsFirstRefusal(TId id);
+        
+        /// <summary>
+        /// Start monitoring for future AllowRequest calls.  If the id is already monitored, then monitoring
+        /// continues.
+        /// </summary>
+        /// <param name="id"></param>
+        void MonitorRequests(TId id);
+        
+        /// <summary>
+        /// Is the id being monitored?
+        /// </summary>
+        /// <param name="uuid"> </param>
+        /// <returns></returns>
+        bool IsMonitoringRequests(TId id);
+    }
+}
diff --git a/OpenSim/Framework/Communications/Limit/RepeatLimitStrategy.cs b/OpenSim/Framework/Communications/Limit/RepeatLimitStrategy.cs
new file mode 100644
index 0000000..6dd0fa1
--- /dev/null
+++ b/OpenSim/Framework/Communications/Limit/RepeatLimitStrategy.cs
@@ -0,0 +1,113 @@
+/*
+ * 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 them after they've been repeated a certain number of times.
+    /// </summary>    
+    public class RepeatLimitStrategy<TId> : IRequestLimitStrategy<TId>
+    {
+        private static readonly log4net.ILog m_log 
+            = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
+        
+        /// <summary>
+        /// Record each asset request that we're notified about.
+        /// </summary>
+        private readonly Dictionary<TId, int> requestCounts = new Dictionary<TId, int>();
+        
+        /// <summary>
+        /// The maximum number of requests that can be made before we drop subsequent requests.
+        /// </summary>
+        private readonly int m_maxRequests;
+        public int MaxRequests
+        {
+            get { return m_maxRequests; }
+        }
+       
+        /// <summary></summary>
+        /// <param name="maxRequests">The maximum number of requests that may be served before all further
+        /// requests are dropped.</param>
+        public RepeatLimitStrategy(int maxRequests)
+        {
+            m_maxRequests = maxRequests;
+        }
+        
+        /// <summary>
+        /// <see cref="IRequestLimitStrategy"/>
+        /// </summary>
+        public bool AllowRequest(TId id)
+        {                 
+            if (requestCounts.ContainsKey(id))
+            {
+                requestCounts[id] += 1;
+                
+                if (requestCounts[id] > m_maxRequests)
+                {                    
+                    return false;
+                }                                                         
+            }
+            
+            return true;
+        }
+        
+        /// <summary>
+        /// <see cref="IRequestLimitStrategy"/>
+        /// </summary>        
+        public bool IsFirstRefusal(TId id)
+        {
+            if (m_maxRequests + 1 == requestCounts[id])
+            {
+                return true;
+            }            
+            
+            return false;
+        }
+        
+        /// <summary>
+        /// <see cref="IRequestLimitStrategy"/>
+        /// </summary>        
+        public void MonitorRequests(TId id)
+        {
+            if (!IsMonitoringRequests(id))
+            {
+                requestCounts.Add(id, 1);
+            }            
+        }  
+        
+        /// <summary>
+        /// <see cref="IRequestLimitStrategy"/>
+        /// </summary>         
+        public bool IsMonitoringRequests(TId id)
+        {
+            return requestCounts.ContainsKey(id);
+        }
+    }
+}