/* * 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 OpenSimulator 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(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; } } }