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|
use criterion::{
black_box, criterion_group,
measurement::{Measurement, ValueFormatter},
Criterion, Throughput,
};
use std::time::{Duration, Instant};
struct HalfSecFormatter;
impl ValueFormatter for HalfSecFormatter {
fn format_value(&self, value: f64) -> String {
// The value will be in nanoseconds so we have to convert to half-seconds.
format!("{} s/2", value * 2f64 * 10f64.powi(-9))
}
fn format_throughput(&self, throughput: &Throughput, value: f64) -> String {
match *throughput {
Throughput::Bytes(bytes) | Throughput::BytesDecimal(bytes) => {
format!("{} b/s/2", (bytes as f64) / (value * 2f64 * 10f64.powi(-9)))
}
Throughput::Elements(elems) => format!(
"{} elem/s/2",
(elems as f64) / (value * 2f64 * 10f64.powi(-9))
),
}
}
fn scale_values(&self, _typical: f64, values: &mut [f64]) -> &'static str {
for val in values {
*val *= 2f64 * 10f64.powi(-9);
}
"s/2"
}
fn scale_throughputs(
&self,
_typical: f64,
throughput: &Throughput,
values: &mut [f64],
) -> &'static str {
match *throughput {
Throughput::Bytes(bytes) | Throughput::BytesDecimal(bytes) => {
for val in values {
*val = (bytes as f64) / (*val * 2f64 * 10f64.powi(-9))
}
"b/s/2"
}
Throughput::Elements(elems) => {
for val in values {
*val = (elems as f64) / (*val * 2f64 * 10f64.powi(-9))
}
"elem/s/2"
}
}
}
fn scale_for_machines(&self, values: &mut [f64]) -> &'static str {
for val in values {
*val *= 2f64 * 10f64.powi(-9);
}
"s/2"
}
}
const NANOS_PER_SEC: u64 = 1_000_000_000;
/// Silly "measurement" that is really just wall-clock time reported in half-seconds.
struct HalfSeconds;
impl Measurement for HalfSeconds {
type Intermediate = Instant;
type Value = Duration;
fn start(&self) -> Self::Intermediate {
Instant::now()
}
fn end(&self, i: Self::Intermediate) -> Self::Value {
i.elapsed()
}
fn add(&self, v1: &Self::Value, v2: &Self::Value) -> Self::Value {
*v1 + *v2
}
fn zero(&self) -> Self::Value {
Duration::from_secs(0)
}
fn to_f64(&self, val: &Self::Value) -> f64 {
let nanos = val.as_secs() * NANOS_PER_SEC + u64::from(val.subsec_nanos());
nanos as f64
}
fn formatter(&self) -> &dyn ValueFormatter {
&HalfSecFormatter
}
}
fn fibonacci_slow(n: u64) -> u64 {
match n {
0 | 1 => 1,
n => fibonacci_slow(n - 1) + fibonacci_slow(n - 2),
}
}
fn fibonacci_cycles(criterion: &mut Criterion<HalfSeconds>) {
criterion.bench_function("fibonacci_custom_measurement", |bencher| {
bencher.iter(|| fibonacci_slow(black_box(10)))
});
}
fn alternate_measurement() -> Criterion<HalfSeconds> {
Criterion::default().with_measurement(HalfSeconds)
}
criterion_group! {
name = benches;
config = alternate_measurement();
targets = fibonacci_cycles
}
|
