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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 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;
}
}
}
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