Controlling request demand with subscriber

[cottoncammy]

I'm trying to use a subscriber in Mutiny that allows me to control the request demand from within my reactive pipeline, but it seems like there aren't any base subscribers in the library to do this besides AssertSubscriber (unless I've missed it).

My use case is that I have an abstraction with a UnicastProcessor that allows queuing web requests and when subscribed to, submits these web requests to a rate limited API. The API's endpoints return headers that determine how many requests can be sent in a specific period, so I want to limit my request demand like this dynamically by requesting 1 item then parsing the headers, allowing n items, then after delaying for the given period if the max number of items is processed, allow 1 item again, parse the response headers and allow n items again.

So, I guess my overall question would be what subscriber can I instantiate that allows me to control the request demand? And then request more items from within my pipeline based on some conditions? Would AssertSubscriber be my only option or is there anything else?

[jponge]

You can easily create your own subscriber implementation.
I do not recomment using AssertSubscriber outside tests.

onSubscribe will be called when a subscription is given to you, and from here you will be able to request elements when it's appropriate to do so.

You might look at an example like https://github.com/smallrye/smallrye-mutiny-zero/blob/main/mutiny-zero-vertx-publishers/src/test/java/docsamples/UrbanObservatoryHttpClient.java

[cottoncammy]

Thanks!