criterion 0.2.0

extern crate criterion;
extern crate walkdir;

use criterion::{Benchmark, Criterion, Fun, ParameterizedBenchmark, Throughput};
use std::time::Duration;
use std::path::Path;
use walkdir::WalkDir;
use std::rc::Rc;
use std::cell::RefCell;
use std::process::{Command, Stdio};

/*
 * Please note that these tests are not complete examples of how to use
 * Criterion.rs. See the benches folder for actual examples.
 */

// Configure a Criterion struct to perform really fast benchmarks. This is not
// recommended for real benchmarking, only for testing.
fn short_benchmark() -> Criterion {
    Criterion::default()
        .warm_up_time(Duration::from_millis(250))
        .measurement_time(Duration::from_millis(500))
        .nresamples(1000)
}

#[derive(Clone)]
struct Counter {
    counter: Rc<RefCell<usize>>,
}
impl Counter {
    fn count(&self) {
        *(*self.counter).borrow_mut() += 1;
    }

    fn read(&self) -> usize {
        *(*self.counter).borrow()
    }
}
impl Default for Counter {
    fn default() -> Counter {
        Counter {
            counter: Rc::new(RefCell::new(0)),
        }
    }
}

fn create_command(depth: usize) -> Command {
    let mut command = Command::new("python3");
    command
        .arg("tests/external_process.py")
        .arg(format!("{}", depth));
    command
}

fn create_command_without_arg() -> Command {
    let mut command = Command::new("python3");
    command.arg("tests/external_process.py");
    command
}

fn has_python3() -> bool {
    Command::new("python3")
        .arg("--version")
        .stdout(Stdio::null())
        .stderr(Stdio::null())
        .output()
        .is_ok()
}

#[test]
fn test_creates_directory() {
    short_benchmark().bench_function("test_creates_directory", |b| b.iter(|| 10));
    assert!(Path::new("target/criterion/test_creates_directory").is_dir());
}

#[test]
fn test_without_plots() {
    short_benchmark()
        .without_plots()
        .bench_function("test_without_plots", |b| b.iter(|| 10));

    for entry in WalkDir::new("target/criterion/test_without_plots") {
        let entry = entry.ok();
        let is_svg = entry
            .as_ref()
            .and_then(|entry| entry.path().extension())
            .and_then(|ext| ext.to_str())
            .map(|ext| ext == "svg")
            .unwrap_or(false);
        assert!(
            !is_svg,
            "Found SVG file ({:?}) in output directory with plots disabled",
            entry.unwrap().file_name()
        );
    }
}

#[test]
fn test_sample_size() {
    let counter = Counter::default();

    let clone = counter.clone();
    short_benchmark()
        .sample_size(50)
        .bench_function("test_sample_size", move |b| {
            clone.count();
            b.iter(|| 10)
        });

    // This function will be called more than sample_size times because of the
    // warmup.
    assert!(counter.read() > 50);
}

#[test]
fn test_warmup_time() {
    let counter1 = Counter::default();

    let clone = counter1.clone();
    short_benchmark()
        .warm_up_time(Duration::from_millis(100))
        .bench_function("test_warmup_time_1", move |b| {
            clone.count();
            b.iter(|| 10)
        });

    let counter2 = Counter::default();
    let clone = counter2.clone();
    short_benchmark()
        .warm_up_time(Duration::from_millis(1000))
        .bench_function("test_warmup_time_2", move |b| {
            clone.count();
            b.iter(|| 10)
        });

    assert!(counter1.read() < counter2.read());
}

#[test]
fn test_measurement_time() {
    let counter1 = Counter::default();

    let clone = counter1.clone();
    short_benchmark()
        .measurement_time(Duration::from_millis(100))
        .bench_function("test_meas_time_1", move |b| b.iter(|| clone.count()));

    let counter2 = Counter::default();
    let clone = counter2.clone();
    short_benchmark()
        .measurement_time(Duration::from_millis(1000))
        .bench_function("test_meas_time_2", move |b| b.iter(|| clone.count()));

    assert!(counter1.read() < counter2.read());
}

#[test]
fn test_bench_function() {
    short_benchmark().bench_function("test_bench_function", move |b| b.iter(|| 10));
}

#[test]
fn test_bench_functions() {
    let function_1 = Fun::new("times 10", |b, i| b.iter(|| *i * 10));
    let function_2 = Fun::new("times 20", |b, i| b.iter(|| *i * 20));

    let functions = vec![function_1, function_2];

    short_benchmark().bench_functions("test_bench_functions", functions, 20);
}

#[test]
fn test_bench_function_over_inputs() {
    short_benchmark().bench_function_over_inputs(
        "test_bench_function_over_inputs",
        |b, i| b.iter(|| *i * 10),
        vec![100, 1000],
    );
}

#[test]
fn test_bench_program() {
    if !has_python3() {
        return;
    }

    short_benchmark().bench_program("test_bench_program", create_command(10));
}

#[test]
fn test_bench_program_over_inputs() {
    if !has_python3() {
        return;
    }

    // Note that bench_program_over_inputs automatically passes the input
    // as the first command-line parameter.
    short_benchmark().bench_program_over_inputs(
        "test_bench_program_over_inputs",
        create_command_without_arg,
        vec![10, 20],
    );
}

#[test]
fn test_bench_unparameterized() {
    let mut benchmark = Benchmark::new("return 10", |b| b.iter(|| 10))
        .with_function("return 20", |b| b.iter(|| 20));

    if has_python3() {
        benchmark = benchmark.with_program("external", create_command(10));
    }

    short_benchmark().bench("test_bench_unparam", benchmark);
}

#[test]
fn test_bench_parameterized() {
    let parameters = vec![5, 10];
    let mut benchmark =
        ParameterizedBenchmark::new("times 10", |b, i| b.iter(|| *i * 10), parameters)
            .with_function("times 20", |b, i| b.iter(|| *i * 20));

    if has_python3() {
        // Unlike bench_program_over_inputs, the parameter is provided as a
        // parameter to the closure here.
        benchmark = benchmark.with_program("external", |i| create_command(*i));
    }

    short_benchmark().bench("test_bench_param", benchmark);
}

#[test]
fn test_filtering() {
    let counter = Counter::default();
    let clone = counter.clone();

    short_benchmark()
        .with_filter("Foo")
        .bench_function("test_filtering", move |b| b.iter(|| clone.count()));

    assert_eq!(counter.read(), 0);
    assert!(!Path::new("target/criterion/test_filtering").is_dir());
}

#[test]
fn test_timing_loops() {
    short_benchmark().bench(
        "test_timing_loops",
        Benchmark::new("iter", |b| b.iter(|| 10))
            .with_function("iter_with_setup", |b| {
                b.iter_with_setup(|| vec![10], |v| v[0])
            })
            .with_function("iter_with_large_setup", |b| {
                b.iter_with_large_setup(|| vec![10], ::std::mem::drop)
            })
            .with_function("iter_with_large_drop", |b| {
                b.iter_with_large_drop(|| vec![10; 100])
            }),
    );
}

#[test]
fn test_throughput() {
    short_benchmark().bench(
        "test_throughput_bytes",
        Benchmark::new("strlen", |b| b.iter(|| "foo".len())).throughput(Throughput::Bytes(3)),
    );
    short_benchmark().bench(
        "test_throughput_elems",
        ParameterizedBenchmark::new(
            "veclen",
            |b, v| b.iter(|| v.len()),
            vec![vec![1], vec![1, 2, 3]],
        ).throughput(|v| Throughput::Elements(v.len() as u32)),
    );
}