cargo-bench-aoc

cargo bench-aoc

A command-line tool to benchmark my solutions to the Advent of Code.

The tool uses Divan under the hood to provide accurate and reproducible benchmark results. I/O (i.e. reading input files and printing the answers to the terminal) is excluded.

Since all my solutions are self-contained programs, bench-aoc uses a little bit of trickery to temporarily convert a project to a benchmark:

• The tool copies the project to the temporary subdirectory target/bench-aoc.
• It then modifies the Cargo.toml in the temporary directory to add Divan as a dependency and to configure cargo bench.
• Further, it patches the temporary main.rs file as follows:
  • It adds boilerplate code to benchmark the main function with Divan.
  • It replaces fs::read_to_string statements with the contents of the puzzle's input file.
  • It replaces println! with format! so the answers will not be printed to the terminal anymore. Formatting still happens, though, as it might be part of the solution.
• Finally, the tool calls cargo bench from the temporary directory.

Note that the tool does not delete the temporary directory. This is useful as it allows you to modify the original program, run the benchmark, and see how the modifications have affected the performance. It also avoids unnecessary recompilation.

Installation

To install the tool, run the following command in the cargo-bench-aoc directory:

cargo install --path .

Usage

After installing, change into the project directory you want to benchmark and simply run

cargo bench-aoc .

You may also provide the path to the directory as the first parameter

cargo bench-aoc 2025/day01

or benchmark several projects (sequentially)

cargo bench-aoc 2025/day01 2025/day02 2025/day03