# Tracing Authors - tracing Span (Highlights) ![rw-book-cover|256](https://readwise-assets.s3.amazonaws.com/static/images/article1.be68295a7e40.png) ## Metadata **Review**:: [readwise.io](https://readwise.io/bookreview/57200855) **Source**:: #from/readwise #from/reader **Zettel**:: #zettel/fleeting **Status**:: #x **Authors**:: [[Tracing Authors]] **Full Title**:: tracing Span **Category**:: #articles #readwise/articles **Category Icon**:: 📰 **URL**:: [docs.rs](https://docs.rs/tracing/latest/tracing/struct.Span.html) **Host**:: [[docs.rs]] **Highlighted**:: [[2025-12-30]] **Created**:: [[2026-01-03]] ## 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