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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
using System;
using System.Threading;
using Apache.NMS.Stomp.Commands;
namespace Apache.NMS.Stomp.Transport
{
/// <summary>
/// A Transport which guards access to the next transport using a mutex.
/// </summary>
public class MutexTransport : TransportFilter
{
private readonly object transmissionLock = new object();
private void GetTransmissionLock(int timeout)
{
if(timeout > 0)
{
DateTime timeoutTime = DateTime.Now + TimeSpan.FromMilliseconds(timeout);
int waitCount = 1;
while(true)
{
if(Monitor.TryEnter(transmissionLock))
{
break;
}
if(DateTime.Now > timeoutTime)
{
throw new IOException(string.Format("Oneway timed out after {0} milliseconds.", timeout));
}
// Back off from being overly aggressive. Having too many threads
// aggressively trying to get the lock pegs the CPU.
Thread.Sleep(3 * (waitCount++));
}
}
else
{
Monitor.Enter(transmissionLock);
}
}
public MutexTransport(ITransport next) : base(next)
{
}
public override void Oneway(Command command)
{
GetTransmissionLock(this.next.Timeout);
try
{
base.Oneway(command);
}
finally
{
Monitor.Exit(transmissionLock);
}
}
public override FutureResponse AsyncRequest(Command command)
{
GetTransmissionLock(this.next.AsyncTimeout);
try
{
return base.AsyncRequest(command);
}
finally
{
Monitor.Exit(transmissionLock);
}
}
public override Response Request(Command command, TimeSpan timeout)
{
GetTransmissionLock((int) timeout.TotalMilliseconds);
try
{
return base.Request(command, timeout);
}
finally
{
Monitor.Exit(transmissionLock);
}
}
}
}