/// <summary>
/// Sends a message to the RabbitMQ broker.
/// </summary>
/// <remarks>
/// If <see cref="RabbitPublisher.BasicProperties"/> is not set uses <see cref="BasicProperties"/> as default.
/// </remarks>
/// <param name="messageBody">The message to be sent.</param>
/// <param name="publisher">Publisher information.</param>
/// <param name="queue">Queue information.</param>
/// <example>
/// <code>
/// ...
/// var body = Encoding.UTF8.GetBytes(jsonItem);
/// handler.SendMessage(body, publisher, queue);
/// ...
/// </code>
/// </example>
public void SendMessage(
byte[] messageBody,
RabbitPublisher publisher,
RabbitQueue queue)
{
if (messageBody == default)
{
throw new ArgumentNullException(nameof(messageBody), "Message must not be null");
}
if (publisher == null)
{
throw new ArgumentNullException(nameof(publisher), "Publisher must not be null.");
}
if (queue == null)
{
throw new ArgumentNullException(nameof(queue), "Queue must not be null.");
}
using (var conn = ConnectionFactory.CreateConnection())
using (var channel = conn.CreateModel())
{
channel.QueueDeclare(queue: queue.Name,
durable: queue.Durable,
exclusive: queue.Exclusive,
autoDelete: queue.AutoDelete);
channel.BasicPublish(exchange: publisher.Exchange,
routingKey: publisher.RoutingKey,
basicProperties: publisher.BasicProperties ?? this.BasicProperties,
messageBody);
}
}
/// <summary>
/// Initiates a new thread for receiving messages.
/// </summary>
/// <remarks>
/// <para>Automatically handles acknowledged and not acknowledged responses.</para>
/// <para>Use <paramref name="messageReceived"/> to manipulate the message.</para>
/// <para>Use <paramref name="exceptionReceived"/> to manipulate exceptions.</para>
/// </remarks>
/// <param name="queue">Queue information.</param>
/// <param name="cancellationToken">Cancellation token.</param>
/// <param name="messageReceived">
/// <para>Message received treatment.</para>
/// <para>Usually message content is inside <see cref="BasicDeliverEventArgs.Body"/>.</para>
/// </param>
/// <param name="exceptionReceived">Exception treatment.</param>
/// <param name="dieOnException">If an exception is thrown should the worker dies.</param>
/// <example>
/// <code>
/// ...
/// handler.ReceiveMessages(queue, cToken,
/// messageReceived: (model, ea) =>
/// {
/// var body = ea.Body.ToArray();
/// string jsonContent = Encoding.UTF8.GetString(body);
/// ...
/// },
/// exceptionReceived: (model, ea, exc) =>
/// {
/// logger.LogError("Something happened", exc);
/// ...
/// });
/// ...
/// </code>
/// </example>
public void ReceiveMessages(
RabbitQueue queue,
CancellationTokenSource cancellationToken,
Action <object, BasicDeliverEventArgs> messageReceived,
Action <object, BasicDeliverEventArgs, Exception> exceptionReceived = null,
bool dieOnException = false)
{
if (queue == null)
{
throw new ArgumentNullException(paramName: nameof(queue), message: "Queue information must not be null.");
}
if (cancellationToken == default)
{
throw new ArgumentNullException(paramName: nameof(cancellationToken), message: "Cancellation token must not be null.");
}
if (messageReceived == null)
{
throw new ArgumentNullException(paramName: nameof(messageReceived), message: "Callback must not be null.");
}
Task.Factory.StartNew(() =>
{
using (var conn = ConnectionFactory.CreateConnection())
using (var channel = conn.CreateModel())
{
// maximum of 2 messages for each worker to receive.
channel.BasicQos(0, 2, false);
channel.QueueDeclare(queue: queue.Name,
durable: queue.Durable,
exclusive: queue.Exclusive,
autoDelete: queue.AutoDelete);
var consumer = new EventingBasicConsumer(channel);
consumer.Received += (model, evtArgs) =>
{
try
{
messageReceived.Invoke(model, evtArgs);
channel.BasicAck(evtArgs.DeliveryTag, false);
}
catch (Exception e)
{
channel.BasicNack(evtArgs.DeliveryTag, false, true);
exceptionReceived?.Invoke(model, evtArgs, e);
if (dieOnException)
{
cancellationToken.Cancel();
// TODO: find a better way to stop the thread instantaneosly
// and not waiting for it to finish.
Task.Delay(1 * 1000).Wait();
}
}
};
channel.BasicConsume(queue: queue.Name,
autoAck: false,
consumer: consumer);
// keep thread alive
while (!cancellationToken.IsCancellationRequested)
{
Task.Delay(1 * 1000).Wait();
}
}
}, cancellationToken.Token);
}
