gistfile1.rs

extern crate test;

const TEXT: &'static str = "Hello World!";
const LONG_TEXT: &'static str = "
There are not many persons who know what wonders are opened to them in the
stories and visions of their youth; for when as children we listen and dream,
we think but half-formed thoughts, and when as men we try to remember, we are
dulled and prosaic with the poison of life. But some of us awake in the night
with strange phantasms of enchanted hills and gardens, of fountains that sing
in the sun, of golden cliffs overhanging murmuring seas, of plains that stretch
down to sleeping cities of bronze and stone, and of shadowy companies of heroes
that ride caparisoned white horses along the edges of thick forests; and then
we know that we have looked back through the ivory gates into that world of
wonder which was ours before we were wise and unhappy.";

fn bench_direct(b: &mut test::Bencher, string: &str) {
    b.iter(|| {
        test::black_box(string.into_string());
    });
    b.bytes = string.as_bytes().len().to_u64().unwrap();
}

fn bench_via_format(b: &mut test::Bencher, string: &str) {
    b.iter(|| {
        test::black_box(string.to_string());
    });
    b.bytes = string.as_bytes().len().to_u64().unwrap();
}

fn very_long_string() -> String {
    let mut s = String::with_capacity(LONG_TEXT.len() * 1000);
    for _ in range(0u32, 1000) {
        s.push_str(LONG_TEXT);
    }
    s
}

#[bench] fn bench_short_direct(b: &mut test::Bencher) { bench_direct(b, TEXT); }
#[bench] fn bench_short_via_format(b: &mut test::Bencher) { bench_via_format(b, TEXT); }

#[bench] fn bench_medium_direct(b: &mut test::Bencher) { bench_direct(b, LONG_TEXT); }
#[bench] fn bench_medium_via_format(b: &mut test::Bencher) { bench_via_format(b, LONG_TEXT); }

#[bench] fn bench_long_direct(b: &mut test::Bencher) { bench_direct(b, very_long_string().as_slice()); }
#[bench] fn bench_long_via_format(b: &mut test::Bencher) { bench_via_format(b, very_long_string().as_slice()); }

gistfile2.txt

running 6 tests
test bench_long_direct       ... bench:    191766 ns/iter (+/- 4034) = 3941 MB/s
test bench_long_via_format   ... bench:    586749 ns/iter (+/- 12841) = 1288 MB/s
test bench_medium_direct     ... bench:        37 ns/iter (+/- 2) = 20432 MB/s
test bench_medium_via_format ... bench:       664 ns/iter (+/- 19) = 1138 MB/s
test bench_short_direct      ... bench:        20 ns/iter (+/- 0) = 600 MB/s
test bench_short_via_format  ... bench:        65 ns/iter (+/- 2) = 184 MB/s

test result: ok. 0 passed; 0 failed; 0 ignored; 6 measured

gistfile3.txt

Samples: 61K of event 'cycles', Event count (approx.): 58774277955
 52.06%  foo  [kernel.kallsyms]   [k] 0xffffffff8104f45a
 27.65%  foo  foo                 [.] str::is_utf8::h6996a9c8a713fcb5Z8r
 12.31%  foo  foo                 [.] bench_direct::closure.1422
  2.76%  foo  foo                 [.] vec::Vec$LT$u8$GT$.fmt..FormatWriter::write::h3
  2.24%  foo  foo                 [.] je_sdallocx
  1.06%  foo  foo                 [.] je_mallocx
  0.29%  foo  foo                 [.] vec::Vec$LT$T$GT$::reserve::h593269131940607514
  0.29%  foo  foo                 [.] very_long_string::h3f95259094d8730eBba
  0.27%  foo  foo                 [.] fmt::write::he5559dc0465fcb0cerA
  0.26%  foo  foo                 [.] bench_via_format::closure.1848
  0.20%  foo  foo                 [.] fmt::Formatter$LT$$x27a$GT$::run::h8d9aa2ee4516
  0.10%  foo  foo                 [.] fmt::str.Show::fmt::h410e1aecf309504aUJA
  0.09%  foo  foo                 [.] fmt::Formatter$LT$$x27a$GT$::pad::h7fd3397e8a51
  0.09%  foo  foo                 [.] arena_purge_stashed
  0.08%  foo  foo                 [.] Bencher::iter::closure.1391
  0.07%  foo  foo                 [.] fmt::_$BP$$x27a$x20T.Show::fmt::h65382186988000
  0.03%  foo  libc-2.19.so        [.] __madvise
  0.02%  foo  libpthread-2.19.so  [.] pthread_mutex_lock
  0.02%  foo  foo                 [.] vec::alloc_or_realloc::h4819189490705178488
  0.02%  foo  libpthread-2.19.so  [.] pthread_mutex_unlock
  0.01%  foo  foo                 [.] arena_avail_tree_remove
  0.01%  foo  foo                 [.] je_pages_purge