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use crate::cmp::{max, min};
use crate::io::*;
#[test]
fn copy_copies() {
let mut r = repeat(0).take(4);
let mut w = sink();
assert_eq!(copy(&mut r, &mut w).unwrap(), 4);
let mut r = repeat(0).take(1 << 17);
assert_eq!(copy(&mut r as &mut dyn Read, &mut w as &mut dyn Write).unwrap(), 1 << 17);
}
struct ShortReader {
cap: usize,
read_size: usize,
observed_buffer: usize,
}
impl Read for ShortReader {
fn read(&mut self, buf: &mut [u8]) -> Result<usize> {
let bytes = min(self.cap, self.read_size);
self.cap -= bytes;
self.observed_buffer = max(self.observed_buffer, buf.len());
Ok(bytes)
}
}
struct WriteObserver {
observed_buffer: usize,
}
impl Write for WriteObserver {
fn write(&mut self, buf: &[u8]) -> Result<usize> {
self.observed_buffer = max(self.observed_buffer, buf.len());
Ok(buf.len())
}
fn flush(&mut self) -> Result<()> {
Ok(())
}
}
#[test]
fn copy_specializes_bufwriter() {
let cap = 117 * 1024;
let buf_sz = 16 * 1024;
let mut r = ShortReader { cap, observed_buffer: 0, read_size: 1337 };
let mut w = BufWriter::with_capacity(buf_sz, WriteObserver { observed_buffer: 0 });
assert_eq!(
copy(&mut r, &mut w).unwrap(),
cap as u64,
"expected the whole capacity to be copied"
);
assert_eq!(r.observed_buffer, buf_sz, "expected a large buffer to be provided to the reader");
assert!(w.get_mut().observed_buffer > DEFAULT_BUF_SIZE, "expected coalesced writes");
}
#[test]
fn copy_specializes_bufreader() {
let mut source = vec![0; 768 * 1024];
source[1] = 42;
let mut buffered = BufReader::with_capacity(256 * 1024, Cursor::new(&mut source));
let mut sink = Vec::new();
assert_eq!(crate::io::copy(&mut buffered, &mut sink).unwrap(), source.len() as u64);
assert_eq!(source.as_slice(), sink.as_slice());
let buf_sz = 71 * 1024;
assert!(buf_sz > DEFAULT_BUF_SIZE, "test precondition");
let mut buffered = BufReader::with_capacity(buf_sz, Cursor::new(&mut source));
let mut sink = WriteObserver { observed_buffer: 0 };
assert_eq!(crate::io::copy(&mut buffered, &mut sink).unwrap(), source.len() as u64);
assert_eq!(
sink.observed_buffer, buf_sz,
"expected a large buffer to be provided to the writer"
);
}
#[cfg(unix)]
mod io_benches {
use crate::fs::File;
use crate::fs::OpenOptions;
use crate::io::prelude::*;
use crate::io::BufReader;
use test::Bencher;
#[bench]
fn bench_copy_buf_reader(b: &mut Bencher) {
let mut file_in = File::open("/dev/zero").expect("opening /dev/zero failed");
// use dyn to avoid specializations unrelated to readbuf
let dyn_in = &mut file_in as &mut dyn Read;
let mut reader = BufReader::with_capacity(256 * 1024, dyn_in.take(0));
let mut writer =
OpenOptions::new().write(true).open("/dev/null").expect("opening /dev/null failed");
const BYTES: u64 = 1024 * 1024;
b.bytes = BYTES;
b.iter(|| {
reader.get_mut().set_limit(BYTES);
crate::io::copy(&mut reader, &mut writer).unwrap()
});
}
}
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