# Tracing Authors - tracing Span (Highlights)  ## Highlights - For instrumenting asynchronous code, `tracing` provides the [`Future::instrument` combinator](https://docs.rs/tracing/latest/tracing/struct.Span.html/trait.Instrument.html) for attaching a span to a future (async function or block). This will enter the span *every* time the future is polled, and exit it whenever the future yields. ([View Highlight](https://read.readwise.io/read/01kdpkct3grgcf2c68zze9cc90)) ^971449544 - The [`#[instrument]` attribute macro](https://docs.rs/tracing/latest/tracing/struct.Span.html/attr.instrument.html) can automatically generate correct code when used on an async function ([View Highlight](https://read.readwise.io/read/01kdpkddnntkvf7da78rnwnky5)) ^971449559