2a345bbcc1
This is much nicer for callers who want to short-circuit real I/O errors
with `?`, because they can write this
if let Some(status) = foo.try_wait()? {
...
} else {
...
}
instead of this
match foo.try_wait() {
Ok(status) => {
...
}
Err(err) if err.kind() == io::ErrorKind::WouldBlock => {
...
}
Err(err) => return Err(err),
}
The original design of `try_wait` was patterned after the `Read` and
`Write` traits, which support both blocking and non-blocking
implementations in a single API. But since `try_wait` is never blocking,
it makes sense to optimize for the non-blocking case.
Tracking issue: https://github.com/rust-lang/rust/issues/38903
66 lines
1.9 KiB
Rust
66 lines
1.9 KiB
Rust
// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// ignore-emscripten
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#![feature(process_try_wait)]
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use std::env;
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use std::process::Command;
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use std::thread;
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use std::time::Duration;
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fn main() {
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let args = env::args().collect::<Vec<_>>();
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if args.len() != 1 {
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match &args[1][..] {
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"sleep" => thread::sleep(Duration::new(1_000, 0)),
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_ => {}
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}
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return
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}
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let mut me = Command::new(env::current_exe().unwrap())
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.arg("sleep")
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.spawn()
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.unwrap();
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let maybe_status = me.try_wait().unwrap();
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assert!(maybe_status.is_none());
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let maybe_status = me.try_wait().unwrap();
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assert!(maybe_status.is_none());
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me.kill().unwrap();
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me.wait().unwrap();
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let status = me.try_wait().unwrap().unwrap();
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assert!(!status.success());
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let status = me.try_wait().unwrap().unwrap();
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assert!(!status.success());
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let mut me = Command::new(env::current_exe().unwrap())
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.arg("return-quickly")
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.spawn()
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.unwrap();
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loop {
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match me.try_wait() {
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Ok(Some(res)) => {
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assert!(res.success());
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break
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}
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Ok(None) => {
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thread::sleep(Duration::from_millis(1));
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}
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Err(e) => panic!("error in try_wait: {}", e),
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}
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}
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let status = me.try_wait().unwrap().unwrap();
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assert!(status.success());
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}
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