mirror of https://github.com/rust-lang/rust
81 lines
2.4 KiB
Rust
81 lines
2.4 KiB
Rust
//! This primarily benchmarks `impl Debug for str`,
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//! and it also explicitly tests that we minimizes calls to the underlying `Write`r.
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//! While that is an implementation detail and there are no guarantees about it,
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//! we should still try to minimize those calls over time rather than regress them.
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use std::fmt::{self, Write};
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use test::{black_box, Bencher};
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#[derive(Default)]
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struct CountingWriter {
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buf: String,
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write_calls: usize,
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}
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impl Write for CountingWriter {
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fn write_str(&mut self, s: &str) -> fmt::Result {
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self.buf.push_str(s);
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self.write_calls += 1;
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Ok(())
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}
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}
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fn assert_fmt(s: &str, expected: &str, expected_write_calls: usize) {
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let mut w = CountingWriter::default();
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write!(&mut w, "{s:?}").unwrap();
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assert_eq!(s.len(), 64);
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assert_eq!(w.buf, expected);
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assert_eq!(w.write_calls, expected_write_calls);
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}
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#[bench]
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fn ascii_only(b: &mut Bencher) {
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let s = "just a bit of ascii text that has no escapes. 64 bytes exactly!!";
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assert_fmt(s, r#""just a bit of ascii text that has no escapes. 64 bytes exactly!!""#, 3);
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b.iter(|| {
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black_box(format!("{:?}", black_box(s)));
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});
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}
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#[bench]
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fn ascii_escapes(b: &mut Bencher) {
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let s = "some\tmore\tascii\ttext\nthis time with some \"escapes\", also 64 byte";
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assert_fmt(
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s,
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r#""some\tmore\tascii\ttext\nthis time with some \"escapes\", also 64 byte""#,
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15,
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);
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b.iter(|| {
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black_box(format!("{:?}", black_box(s)));
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});
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}
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#[bench]
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fn some_unicode(b: &mut Bencher) {
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let s = "egy kis szöveg néhány unicode betűvel. legyen ez is 64 byte.";
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assert_fmt(s, r#""egy kis szöveg néhány unicode betűvel. legyen ez is 64 byte.""#, 3);
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b.iter(|| {
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black_box(format!("{:?}", black_box(s)));
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});
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}
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#[bench]
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fn mostly_unicode(b: &mut Bencher) {
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let s = "предложение из кириллических букв.";
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assert_fmt(s, r#""предложение из кириллических букв.""#, 3);
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b.iter(|| {
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black_box(format!("{:?}", black_box(s)));
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});
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}
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#[bench]
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fn mixed(b: &mut Bencher) {
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let s = "\"❤️\"\n\"hűha ez betű\"\n\"кириллических букв\".";
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assert_fmt(s, r#""\"❤\u{fe0f}\"\n\"hűha ez betű\"\n\"кириллических букв\".""#, 21);
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b.iter(|| {
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black_box(format!("{:?}", black_box(s)));
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});
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}
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