Make tracing_subscriber::span::{Data, Store, etc} public

[anp]

Feature Request

Crates

tracing-subscriber

Motivation

I'm implementing a Subscriber similar to Formatter in many ways and would like to reuse the span allocation it makes use of in span::Store.

Proposal

Is it safe to expose these types as directly usable? That would probably be my preference to avoid having to implement my own slab/locking/etc setup.

Alternatives

Is it possible to imagine a version of the crate where all I/O is done in layers separately from the span and metadata management?

Maybe Subscriber could be blanket impl'd for structs that implement some smaller trait, named something like Storage?

[davidbarsky]

@anp If I'm not mistaken, the LookupSpan trait + Registry struct should address your issue. However, you'd implement a Layer instead of Subscriber. Here's a basic one done by @tobz: https://github.com/metrics-rs/metrics-tracing-test/blob/master/src/layer.rs.

[anp]

Huzzah! I think this is perfect actually, I would like all of my code to live in layers and to have the subscriber just act as the registry.

I'm tempted to rephrase this as a docs/tutorial request but I'm not well-versed enough in the subscriber crate yet to know where would be the best place.

[davidbarsky]

@anp you're right, this does need to be documented and it's not yet documented. it really does.