A simple acknowledger that sends a message back to a caller.

If you want to use this acknowledger in messages produced by your Broadway.Producer, you can get its configuration by calling the init/0 function. For example, you can use it in Broadway.test_message/3:

some_ref = make_ref()

Broadway.test_message(
  MyPipeline,
  "some data",
  acknowledger: Broadway.CallerAcknowledger.init({self(), some_ref}, :ignored)
)

The first parameter is a tuple with the PID to receive the messages and a unique identifier (usually a reference). Such unique identifier is then included in the messages sent to the PID. The second parameter, which is per message, is ignored.

It sends a message in the format:

{:ack, ref, successful_messages, failed_messages}

If Broadway.Message.configure_ack/2 is called on a message that uses this acknowledger, then the following message is sent:

{:configure, ref, options}