> ## Documentation Index
> Fetch the complete documentation index at: https://codspeed.io/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# criterion.rs compatibility layer documentation
> A compatibility layer for `criterion.rs`
export const BuildkiteIcon = props => ;
export const GitLabIcon = props => ;
export const GitHubIcon = props => ;
## Overview
`codspeed-criterion-compat` is a Criterion.rs compatibility layer for CodSpeed
that allows you to seamlessly integrate existing Criterion benchmarks with
CodSpeed performance measurement.
This crate acts as a drop-in replacement for Criterion, maintaining your
existing benchmark code while enabling CodSpeed integration.
## Installation
```sh theme={null}
cargo add --dev codspeed-criterion-compat --rename criterion
```
This will install the `codspeed-criterion-compat` crate and rename it to `criterion` in your `Cargo.toml`.
This way, you can keep your existing imports and the compatibility layer will take care of the rest.
Using the compatibility layer won't change the behavior of your benchmark suite
and criterion will still run it as usual.
If you prefer, you can also install `codspeed-criterion-compat` as is and change
your imports to use this new crate name.
## Usage
Let's start with the example from the
[Criterion.rs documentation](https://bheisler.github.io/criterion.rs/book/getting_started.html),
creating a benchmark suite for the Fibonacci function (in
`benches/my_benchmark.rs`):
```rust theme={null}
use criterion::{black_box, criterion_group, criterion_main, Criterion};
fn fibonacci(n: u64) -> u64 {
match n {
0 => 1,
1 => 1,
n => fibonacci(n-1) + fibonacci(n-2),
}
}
pub fn criterion_benchmark(c: &mut Criterion) {
c.bench_function("fib 20", |b| b.iter(|| fibonacci(black_box(20))));
}
criterion_group!(benches, criterion_benchmark);
criterion_main!(benches);
```
The last step in creating the Criterion benchmark is to add the new benchmark
target in your `Cargo.toml`:
```toml title="Cargo.toml" theme={null}
[[bench]]
name = "my_benchmark"
harness = false
```
And that's it! You can now run your benchmark suite with `cargo-codspeed`:
```shellsession title=terminal icon="square-terminal" theme={null}
$ cargo codspeed build
Finished release [optimized] target(s) in 0.12s
Finished built 1 benchmark suite(s)
$ cargo codspeed run
Collected 1 benchmark suite(s) to run
Running my_benchmark
Using codspeed-criterion-compat v1.0.0 compatibility layer
NOTICE: codspeed is enabled, but no performance measurement will be made since it's running in an unknown environment.
Checked: benches/bencher_example.rs::fib_20 (group: benches)
Done running bencher_example
Finished running 1 benchmark suite(s)
```
## Compatibility
### Not (yet) supported
* `iter_custom`
* `with_filter`
## Resources
* [Official criterion.rs documentation](https://bheisler.github.io/criterion.rs/book/index.html)
* [Official criterion.rs GitHub repository](https://github.com/bheisler/criterion.rs)
