/// <summary>
/// Receives the messages in an asynchronous loop and closes the session once there are no more messages.
/// </summary>
private void ReceiveMessagesAndCloseSession(MessageSession session, CancellationToken cancellationToken)
{
CountdownEvent unreleasedMessages = new CountdownEvent(1);
Action <bool> closeSession = (bool success) =>
{
Action doClose = () =>
{
try
{
unreleasedMessages.Signal();
if (!unreleasedMessages.Wait(15000, cancellationToken))
{
Trace.TraceWarning("Waited for pending unreleased messages before closing session in subscription {0} but they did not complete in time", this.subscription);
}
}
catch (OperationCanceledException)
{
}
finally
{
unreleasedMessages.Dispose();
}
this.receiveRetryPolicy.ExecuteAction(
cb => session.BeginClose(cb, null),
session.EndClose,
() =>
{
this.instrumentation.SessionEnded();
if (success)
{
this.dynamicThrottling.NotifyWorkCompleted();
}
else
{
this.dynamicThrottling.NotifyWorkCompletedWithError();
}
},
ex =>
{
this.instrumentation.SessionEnded();
Trace.TraceError("An unrecoverable error occurred while trying to close a session in subscription {1}:\r\n{0}", ex, this.subscription);
this.dynamicThrottling.NotifyWorkCompletedWithError();
});
};
if (this.requiresSequentialProcessing)
{
doClose.Invoke();
}
else
{
// Allow some time for releasing the messages before closing. Also, continue in a non I/O completion thread in order to block.
TaskEx.Delay(200).ContinueWith(t => doClose());
}
};
// Declare an action to receive the next message in the queue or closes the session if cancelled.
Action receiveNext = null;
// Declare an action acting as a callback whenever a non-transient exception occurs while receiving or processing messages.
Action <Exception> recoverReceive = null;
// Declare an action responsible for the core operations in the message receive loop.
Action receiveMessage = (() =>
{
// Use a retry policy to execute the Receive action in an asynchronous and reliable fashion.
this.receiveRetryPolicy.ExecuteAction
(
cb =>
{
// Start receiving a new message asynchronously.
// Does not wait for new messages to arrive in a session. If no further messages we will just close the session.
session.BeginReceive(TimeSpan.Zero, cb, null);
},
// Complete the asynchronous operation. This may throw an exception that will be handled internally by retry policy.
session.EndReceive,
msg =>
{
// Process the message once it was successfully received
// Check if we actually received any messages.
if (msg != null)
{
var roundtripStopwatch = Stopwatch.StartNew();
long schedulingElapsedMilliseconds = 0;
long processingElapsedMilliseconds = 0;
unreleasedMessages.AddCount();
Task.Factory.StartNew(() =>
{
var releaseAction = MessageReleaseAction.AbandonMessage;
try
{
this.instrumentation.MessageReceived();
schedulingElapsedMilliseconds = roundtripStopwatch.ElapsedMilliseconds;
// Make sure the process was told to stop receiving while it was waiting for a new message.
if (!cancellationToken.IsCancellationRequested)
{
try
{
try
{
// Process the received message.
releaseAction = this.InvokeMessageHandler(msg);
processingElapsedMilliseconds = roundtripStopwatch.ElapsedMilliseconds - schedulingElapsedMilliseconds;
this.instrumentation.MessageProcessed(releaseAction.Kind == MessageReleaseActionKind.Complete, processingElapsedMilliseconds);
}
catch
{
processingElapsedMilliseconds = roundtripStopwatch.ElapsedMilliseconds - schedulingElapsedMilliseconds;
this.instrumentation.MessageProcessed(false, processingElapsedMilliseconds);
throw;
}
}
finally
{
if (roundtripStopwatch.Elapsed > TimeSpan.FromSeconds(45))
{
this.dynamicThrottling.Penalize();
}
}
}
}
finally
{
// Ensure that any resources allocated by a BrokeredMessage instance are released.
if (this.requiresSequentialProcessing)
{
this.ReleaseMessage(msg, releaseAction, () => { receiveNext(); }, () => { closeSession(false); }, unreleasedMessages, processingElapsedMilliseconds, schedulingElapsedMilliseconds, roundtripStopwatch);
}
else
{
// Receives next without waiting for the message to be released.
this.ReleaseMessage(msg, releaseAction, () => { }, () => { this.dynamicThrottling.Penalize(); }, unreleasedMessages, processingElapsedMilliseconds, schedulingElapsedMilliseconds, roundtripStopwatch);
receiveNext.Invoke();
}
}
});
}
else
{
// no more messages in the session, close it and do not continue receiving
closeSession(true);
}
},
ex =>
{
// Invoke a custom action to indicate that we have encountered an exception and
// need further decision as to whether to continue receiving messages.
recoverReceive.Invoke(ex);
});
});
// Initialize an action to receive the next message in the queue or closes the session if cancelled.
receiveNext = () =>
{
if (!cancellationToken.IsCancellationRequested)
{
// Continue receiving and processing new messages until told to stop.
receiveMessage.Invoke();
}
else
{
closeSession(true);
}
};
// Initialize a custom action acting as a callback whenever a non-transient exception occurs while receiving or processing messages.
recoverReceive = ex =>
{
// Just log an exception. Do not allow an unhandled exception to terminate the message receive loop abnormally.
Trace.TraceError("An unrecoverable error occurred while trying to receive a new message from subscription {1}:\r\n{0}", ex, this.subscription);
// Cannot continue to receive messages from this session.
closeSession(false);
};
// Start receiving messages asynchronously for the session.
receiveNext.Invoke();
}
/// <summary>
/// Receives the messages in an asynchronous loop and closes the session once there are no more messages.
/// </summary>
private void ReceiveMessagesAndCloseSession(MessageSession session, CancellationToken cancellationToken)
{
CountdownEvent unreleasedMessages = new CountdownEvent(1);
Action<bool> closeSession = (bool success) =>
{
Action doClose = () =>
{
try
{
unreleasedMessages.Signal();
if (!unreleasedMessages.Wait(15000, cancellationToken))
{
Trace.TraceWarning("Waited for pending unreleased messages before closing session in subscription {0} but they did not complete in time", this.subscription);
}
}
catch (OperationCanceledException)
{
}
finally
{
unreleasedMessages.Dispose();
}
this.receiveRetryPolicy.ExecuteAction(
cb => session.BeginClose(cb, null),
session.EndClose,
() =>
{
this.instrumentation.SessionEnded();
if (success)
{
this.dynamicThrottling.NotifyWorkCompleted();
}
else
{
this.dynamicThrottling.NotifyWorkCompletedWithError();
}
},
ex =>
{
this.instrumentation.SessionEnded();
Trace.TraceError("An unrecoverable error occurred while trying to close a session in subscription {1}:\r\n{0}", ex, this.subscription);
this.dynamicThrottling.NotifyWorkCompletedWithError();
});
};
if (this.requiresSequentialProcessing)
{
doClose.Invoke();
}
else
{
// Allow some time for releasing the messages before closing. Also, continue in a non I/O completion thread in order to block.
TaskEx.Delay(200).ContinueWith(t => doClose());
}
};
// Declare an action to receive the next message in the queue or closes the session if cancelled.
Action receiveNext = null;
// Declare an action acting as a callback whenever a non-transient exception occurs while receiving or processing messages.
Action<Exception> recoverReceive = null;
// Declare an action responsible for the core operations in the message receive loop.
Action receiveMessage = (() =>
{
// Use a retry policy to execute the Receive action in an asynchronous and reliable fashion.
this.receiveRetryPolicy.ExecuteAction
(
cb =>
{
// Start receiving a new message asynchronously.
// Does not wait for new messages to arrive in a session. If no further messages we will just close the session.
session.BeginReceive(TimeSpan.Zero, cb, null);
},
// Complete the asynchronous operation. This may throw an exception that will be handled internally by retry policy.
session.EndReceive,
msg =>
{
// Process the message once it was successfully received
// Check if we actually received any messages.
if (msg != null)
{
var roundtripStopwatch = Stopwatch.StartNew();
long schedulingElapsedMilliseconds = 0;
long processingElapsedMilliseconds = 0;
unreleasedMessages.AddCount();
Task.Factory.StartNew(() =>
{
var releaseAction = MessageReleaseAction.AbandonMessage;
try
{
this.instrumentation.MessageReceived();
schedulingElapsedMilliseconds = roundtripStopwatch.ElapsedMilliseconds;
// Make sure the process was told to stop receiving while it was waiting for a new message.
if (!cancellationToken.IsCancellationRequested)
{
try
{
try
{
// Process the received message.
releaseAction = this.InvokeMessageHandler(msg);
processingElapsedMilliseconds = roundtripStopwatch.ElapsedMilliseconds - schedulingElapsedMilliseconds;
this.instrumentation.MessageProcessed(releaseAction.Kind == MessageReleaseActionKind.Complete, processingElapsedMilliseconds);
}
catch
{
processingElapsedMilliseconds = roundtripStopwatch.ElapsedMilliseconds - schedulingElapsedMilliseconds;
this.instrumentation.MessageProcessed(false, processingElapsedMilliseconds);
throw;
}
}
finally
{
if (roundtripStopwatch.Elapsed > TimeSpan.FromSeconds(45))
{
this.dynamicThrottling.Penalize();
}
}
}
}
finally
{
// Ensure that any resources allocated by a BrokeredMessage instance are released.
if (this.requiresSequentialProcessing)
{
this.ReleaseMessage(msg, releaseAction, () => { receiveNext(); }, () => { closeSession(false); }, unreleasedMessages, processingElapsedMilliseconds, schedulingElapsedMilliseconds, roundtripStopwatch);
}
else
{
// Receives next without waiting for the message to be released.
this.ReleaseMessage(msg, releaseAction, () => { }, () => { this.dynamicThrottling.Penalize(); }, unreleasedMessages, processingElapsedMilliseconds, schedulingElapsedMilliseconds, roundtripStopwatch);
receiveNext.Invoke();
}
}
});
}
else
{
// no more messages in the session, close it and do not continue receiving
closeSession(true);
}
},
ex =>
{
// Invoke a custom action to indicate that we have encountered an exception and
// need further decision as to whether to continue receiving messages.
recoverReceive.Invoke(ex);
});
});
// Initialize an action to receive the next message in the queue or closes the session if cancelled.
receiveNext = () =>
{
if (!cancellationToken.IsCancellationRequested)
{
// Continue receiving and processing new messages until told to stop.
receiveMessage.Invoke();
}
else
{
closeSession(true);
}
};
// Initialize a custom action acting as a callback whenever a non-transient exception occurs while receiving or processing messages.
recoverReceive = ex =>
{
// Just log an exception. Do not allow an unhandled exception to terminate the message receive loop abnormally.
Trace.TraceError("An unrecoverable error occurred while trying to receive a new message from subscription {1}:\r\n{0}", ex, this.subscription);
// Cannot continue to receive messages from this session.
closeSession(false);
};
// Start receiving messages asynchronously for the session.
receiveNext.Invoke();
}
