/// <summary>
/// Tries to fail-over the connection, if the connection policy will permit it, and the fail-over process has not yet been
/// started. If the connection does not allow fail-over then an exception will be raised. If a fail-over is already in progress
/// this method allows it to continue to run and will do nothing.
///
/// <p/>This method should only be called when the connection has been remotely closed.
/// </summary>
///
/// <returns>The fail-over state at the end of this attempt.</returns>
private FailoverState AttemptFailover()
{
_log.Debug("private void AttemptFailover(): called");
_log.Debug("_failoverState = " + _failoverState);
// Ensure that the connection stops sending heart beats, if it still is.
_connection.StopHeartBeatThread();
// Check that the connection policy allows fail-over to be attempted.
if (!_connection.IsFailoverAllowed)
{
_log.Debug("Connection does not allowed to failover");
_connection.ExceptionReceived(
new AMQDisconnectedException("Broker closed connection and reconnection is not permitted."));
}
// Check if connection was closed deliberately by the application, in which case no fail-over is attempted.
if (_connection.Closed)
{
return(_failoverState);
}
// If the connection allows fail-over and fail-over has not yet been started, then it is started and the fail-over state is
// advanced to 'in progress'
if (_failoverState == FailoverState.NOT_STARTED && _connection.IsFailoverAllowed)
{
_log.Info("Starting the fail-over process.");
_failoverState = FailoverState.IN_PROGRESS;
StartFailoverThread();
}
return(_failoverState);
}
/// <summary>
/// Receives notification of any IO exceptions on the connection.
///
/// <p/>Upon receipt of a connection closed exception or any IOException, the fail-over process is attempted. If the fail-over fails, then
/// all method listeners and the application connection object are notified of the connection failure exception.
///
/// <p/>All other exception types are propagated to all method listeners.
/// </summary>
public void OnException(Exception cause)
{
_log.Warn("public void OnException(Exception cause = " + cause + "): called");
// Ensure that the method listener set cannot be changed whilst this exception is propagated to all listeners. This also
// ensures that this exception is fully propagated to all listeners, before another one can be processed.
lock (_lock)
{
if (cause is AMQConnectionClosedException || cause is System.IO.IOException)
{
// Try a fail-over because the connection has failed.
FailoverState failoverState = AttemptFailover();
// Check if the fail-over has failed, in which case notify all method listeners of the exception.
// The application connection object is also notified of the failure of the connection with the exception.
if (failoverState == FailoverState.FAILED)
{
_log.Debug("Fail-over has failed. Notifying all method listeners of the exception.");
AMQException amqe = new AMQException("Protocol handler error: " + cause, cause);
PropagateExceptionToWaiters(amqe);
_connection.ExceptionReceived(cause);
}
}
// Notify all method listeners of the exception.
else
{
PropagateExceptionToWaiters(cause);
_connection.ExceptionReceived(cause);
}
}
}
/// <summary>
/// Tries to fail-over the connection, if the connection policy will permit it, and the fail-over process has not yet been
/// started. If the connection does not allow fail-over then an exception will be raised. If a fail-over is already in progress
/// this method allows it to continue to run and will do nothing.
///
/// <p/>This method should only be called when the connection has been remotely closed.
/// </summary>
///
/// <returns>The fail-over state at the end of this attempt.</returns>
private FailoverState AttemptFailover()
{
_log.Debug("private void AttemptFailover(): called");
_log.Debug("_failoverState = " + _failoverState);
// Ensure that the connection stops sending heart beats, if it still is.
_connection.StopHeartBeatThread();
// Check that the connection policy allows fail-over to be attempted.
if (!_connection.IsFailoverAllowed)
{
_log.Debug("Connection does not allowed to failover");
_connection.ExceptionReceived(
new AMQDisconnectedException("Broker closed connection and reconnection is not permitted."));
}
// Check if connection was closed deliberately by the application, in which case no fail-over is attempted.
if (_connection.Closed)
{
return _failoverState;
}
// If the connection allows fail-over and fail-over has not yet been started, then it is started and the fail-over state is
// advanced to 'in progress'
if (_failoverState == FailoverState.NOT_STARTED && _connection.IsFailoverAllowed)
{
_log.Info("Starting the fail-over process.");
_failoverState = FailoverState.IN_PROGRESS;
StartFailoverThread();
}
return _failoverState;
}
