Mastering Rust - Second Edition

Built-in micro-benchmark harness

Rust's built-in benchmarking framework measures the performance of code by running it through several iterations and reports the average time taken for the operation in question. This is facilitated by two things:

• The #[bench] annotation on a function. This marks the function as a benchmark test.
• The internal compiler crate libtest with a Bencher type, which the benchmark function uses for running the same benchmark code in several iterations. This type resides under the test crate, which is internal to the compiler.

Now, we'll write and run a simple benchmark test. Let's create a new Cargo project by running cargo new --lib bench_example. No changes to Cargo.toml are needed for this. The contents of src/lib.rs ...