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actix-web/actix-http/benches/write-camel-case.rs
Thales a0c0bff944
Don't create a slice to potential uninit data on h1 encoder (#2364)
Co-authored-by: Rob Ede <robjtede@icloud.com>
2021-08-13 18:41:19 +01:00

93 lines
2.7 KiB
Rust

use criterion::{black_box, criterion_group, criterion_main, BenchmarkId, Criterion};
fn bench_write_camel_case(c: &mut Criterion) {
let mut group = c.benchmark_group("write_camel_case");
let names = ["connection", "Transfer-Encoding", "transfer-encoding"];
for &i in &names {
let bts = i.as_bytes();
group.bench_with_input(BenchmarkId::new("Original", i), bts, |b, bts| {
b.iter(|| {
let mut buf = black_box([0; 24]);
_original::write_camel_case(black_box(bts), &mut buf)
});
});
group.bench_with_input(BenchmarkId::new("New", i), bts, |b, bts| {
b.iter(|| {
let mut buf = black_box([0; 24]);
let len = black_box(bts.len());
_new::write_camel_case(black_box(bts), buf.as_mut_ptr(), len)
});
});
}
group.finish();
}
criterion_group!(benches, bench_write_camel_case);
criterion_main!(benches);
mod _new {
pub fn write_camel_case(value: &[u8], buf: *mut u8, len: usize) {
// first copy entire (potentially wrong) slice to output
let buffer = unsafe {
std::ptr::copy_nonoverlapping(value.as_ptr(), buf, len);
std::slice::from_raw_parts_mut(buf, len)
};
let mut iter = value.iter();
// first character should be uppercase
if let Some(c @ b'a'..=b'z') = iter.next() {
buffer[0] = c & 0b1101_1111;
}
// track 1 ahead of the current position since that's the location being assigned to
let mut index = 2;
// remaining characters after hyphens should also be uppercase
while let Some(&c) = iter.next() {
if c == b'-' {
// advance iter by one and uppercase if needed
if let Some(c @ b'a'..=b'z') = iter.next() {
buffer[index] = c & 0b1101_1111;
}
}
index += 1;
}
}
}
mod _original {
pub fn write_camel_case(value: &[u8], buffer: &mut [u8]) {
let mut index = 0;
let key = value;
let mut key_iter = key.iter();
if let Some(c) = key_iter.next() {
if *c >= b'a' && *c <= b'z' {
buffer[index] = *c ^ b' ';
index += 1;
}
} else {
return;
}
while let Some(c) = key_iter.next() {
buffer[index] = *c;
index += 1;
if *c == b'-' {
if let Some(c) = key_iter.next() {
if *c >= b'a' && *c <= b'z' {
buffer[index] = *c ^ b' ';
index += 1;
}
}
}
}
}
}