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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.Qpid.Framing;
namespace Apache.Qpid.Client.Protocol.Listener
{
public abstract class BlockingMethodFrameListener : IAMQMethodListener
{
private ManualResetEvent _resetEvent;
public abstract bool ProcessMethod(ushort channelId, AMQMethodBody frame);
/// <summary>
/// This is set if there is an exception thrown from processCommandFrame and the
/// exception is rethrown to the caller of blockForFrame()
/// </summary>
private volatile Exception _error;
protected ushort _channelId;
protected AMQMethodEvent _doneEvt = null;
public BlockingMethodFrameListener(ushort channelId)
{
_channelId = channelId;
_resetEvent = new ManualResetEvent(false);
}
/// <summary>
/// This method is called by the MINA dispatching thread. Note that it could
/// be called before BlockForFrame() has been called.
/// </summary>
/// <param name="evt">the frame event</param>
/// <returns>true if the listener has dealt with this frame</returns>
/// <exception cref="AMQException"></exception>
public bool MethodReceived(AMQMethodEvent evt)
{
AMQMethodBody method = evt.Method;
try
{
bool ready = (evt.ChannelId == _channelId) && ProcessMethod(evt.ChannelId, method);
if (ready)
{
_doneEvt = evt;
_resetEvent.Set();
}
return ready;
}
catch (AMQException e)
{
Error(e);
// we rethrow the error here, and the code in the frame dispatcher will go round
// each listener informing them that an exception has been thrown
throw e;
}
}
/// <summary>
/// This method is called by the thread that wants to wait for a frame.
/// </summary>
/// <param name="timeout">Set the number of milliseconds to wait</param>
public AMQMethodEvent BlockForFrame(int timeout)
{
_resetEvent.WaitOne(timeout, true);
//at this point the event will have been signalled. The error field might or might not be set
// depending on whether an error occurred
if (_error != null)
{
throw _error;
}
return _doneEvt;
}
/// <summary>
/// This is a callback, called by the MINA dispatcher thread only. It is also called from within this
/// class to avoid code repetition but again is only called by the MINA dispatcher thread.
/// </summary>
/// <param name="e">the exception that caused the error</param>
public void Error(Exception e)
{
// set the error so that the thread that is blocking (in BlockForFrame())
// can pick up the exception and rethrow to the caller
_error = e;
_resetEvent.Set();
}
}
}
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