Cache chunked responses

[tanguilp]

The author hasn't find a way to cache chunked responses, as their content cannot be retrieved before sending (because sending is done directly through the adapter).

Implementing this could require some changes in the Plug library or even in adapters. A discussion with author of this libraries could be useful.

[LostKobrakai]

There's going to be a register_before_chunk in plug 1.15 (currently only on main) elixir-plug/plug#1154

[tanguilp]

Thanks for the information! Not clear yet how to accumulate these chunks to get the final response.

[tanguilp]

We probably don't want to accumulate chunks in memory to rebuild the response, because chunked responses are usually used to stream large responses.

Instead we should consider transforming chunks to 206 Partial Content and let http_cache cache these (unsupported right now) and even combining these chunks to rebuild the initial response (even less supported). This would be particularly interesting when disk backend is used and disk capacity surpasses largely memory capacity.