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actix-web/actix-http/benches/quality-value.rs
2022-01-05 14:10:38 +00:00

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use criterion::{criterion_group, criterion_main, BenchmarkId, Criterion};
const CODES: &[u16] = &[0, 1000, 201, 800, 550];
fn bench_quality_display_impls(c: &mut Criterion) {
let mut group = c.benchmark_group("quality value display impls");
for i in CODES.iter() {
group.bench_with_input(BenchmarkId::new("New (fast?)", i), i, |b, &i| {
b.iter(|| _new::Quality(i).to_string())
});
group.bench_with_input(BenchmarkId::new("Naive", i), i, |b, &i| {
b.iter(|| _naive::Quality(i).to_string())
});
}
group.finish();
}
criterion_group!(benches, bench_quality_display_impls);
criterion_main!(benches);
mod _new {
use std::fmt;
pub struct Quality(pub(crate) u16);
impl fmt::Display for Quality {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self.0 {
0 => f.write_str("0"),
1000 => f.write_str("1"),
// some number in the range 1999
x => {
f.write_str("0.")?;
// this implementation avoids string allocation otherwise required
// for `.trim_end_matches('0')`
if x < 10 {
f.write_str("00")?;
// 0 is handled so it's not possible to have a trailing 0, we can just return
itoa_fmt(f, x)
} else if x < 100 {
f.write_str("0")?;
if x % 10 == 0 {
// trailing 0, divide by 10 and write
itoa_fmt(f, x / 10)
} else {
itoa_fmt(f, x)
}
} else {
// x is in range 101999
if x % 100 == 0 {
// two trailing 0s, divide by 100 and write
itoa_fmt(f, x / 100)
} else if x % 10 == 0 {
// one trailing 0, divide by 10 and write
itoa_fmt(f, x / 10)
} else {
itoa_fmt(f, x)
}
}
}
}
}
}
pub fn itoa_fmt<W: fmt::Write, V: itoa::Integer>(mut wr: W, value: V) -> fmt::Result {
let mut buf = itoa::Buffer::new();
wr.write_str(buf.format(value))
}
}
mod _naive {
use std::fmt;
pub struct Quality(pub(crate) u16);
impl fmt::Display for Quality {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self.0 {
0 => f.write_str("0"),
1000 => f.write_str("1"),
x => {
write!(f, "{}", format!("{:03}", x).trim_end_matches('0'))
}
}
}
}
}