/// <summary>
/// Convenience for "at-most once delivery" semantics. Each message is acked to RabbitMQ
/// before it is emitted downstream.
/// </summary>
/// <param name="settings"></param>
/// <param name="bufferSize"></param>
/// <returns></returns>
public static Source <IncomingMessage, NotUsed> AtMostOnceSource(IAmqpSourceSettings settings, int bufferSize)
{
return(CommittableSource(settings, bufferSize)
.SelectAsync(1, async cm =>
{
await cm.Ack();
return cm.Message;
}));
}
public AmqpSourceStageLogic(AmqpSourceStage <T> stage, Attributes attributes) : base(stage.Shape)
{
_outlet = stage.Out;
_amqpSourceSettings = stage.AmqpSourceSettings;
_receiver = stage.AmqpSourceSettings.GetReceiverLink();
_decider = attributes.GetDeciderOrDefault();
SetHandler(_outlet, () =>
{
if (_queue.TryDequeue(out var msg))
{
PushMessage(msg);
}
}, onDownstreamFinish: CompleteStage);
/// <summary>
/// The `committableSource` makes it possible to commit (ack/nack) messages to RabbitMQ.
/// This is useful when "at-least once delivery" is desired, as each message will likely be
/// delivered one time but in failure cases could be duplicated.
/// If you commit the offset before processing the message you get "at-most once delivery" semantics,
/// and for that there is a <see cref="AtMostOnceSource"/>.
/// Compared to auto-commit, this gives exact control over when a message is considered consumed.
/// </summary>
/// <param name="settings"></param>
/// <param name="bufferSize"></param>
/// <returns>TBD</returns>
public static Source <CommittableIncomingMessage, NotUsed> CommittableSource(IAmqpSourceSettings settings, int bufferSize)
{
return(Source.FromGraph(new AmqpSourceStage(settings, bufferSize)));
}
/// <summary>
/// Constructor
/// </summary>
/// <param name="settings">The source settings</param>
/// <param name="bufferSize">The max number of elements to prefetch and buffer at any given time.</param>
public AmqpSourceStage(IAmqpSourceSettings settings, int bufferSize)
{
Settings = settings;
BufferSize = bufferSize;
}
public static Source <T, NotUsed> Create <T>(IAmqpSourceSettings <T> sourceSettings)
{
return(Source.FromGraph(new AmqpSourceStage <T>(sourceSettings)));
}
public AmqpSourceStage(IAmqpSourceSettings <T> amqpSourceSettings)
{
Out = new Outlet <T>("AmqpSource.Out");
Shape = new SourceShape <T>(Out);
AmqpSourceSettings = amqpSourceSettings;
}
