Module `Trace_thread_local_storage`

use thread-local-storage to store ambient spans.

This doesn't work with cooperative concurrency (Eio, Lwt, etc) but is fine in a threaded context.

val k_span : Trace_core.span Thread_local_storage.t

Key to access the current span

val provider : Trace_core.Ambient_span_provider.t

val setup : unit -> unit

Install the provider