我正在清空队列后尝试取消间隔(interval_timer
),但不确定什么是正确的策略。
let mut some_vars = vec![1, 2, 3, 4, 5, 6, 7, 8];
let interval_timer = tokio_timer::Timer::default();
let timer = interval_timer
.interval(Duration::from_millis(1000))
.map_err(|_| {
println!("Errored out");
});
let s = timer.for_each(move |_| {
println!("Woke up");
let item = some_vars.pop().unwrap();
let f = futures::future::ok(item).map(|x| {
println!("{:?}", x);
});
tokio::spawn(f)
});
tokio::run(s);
我尝试过在[g0]中建议的drop
,但最终出现错误:
let mut some_vars = vec![1, 2, 3, 4, 5, 6, 7, 8];
let mut interval_timer = tokio_timer::Timer::default();
let timer = interval_timer
.interval(Duration::from_millis(1000))
.map_err(|_| {
println!("Errored out");
});
let s = timer.for_each(move |_| {
println!("Woke up");
if some_vars.len() == 1 {
drop(interval_timer);
}
let item = some_vars.pop().unwrap();
let f = futures::future::ok(item).map(|x| {
println!("{:?}", x);
});
tokio::spawn(f)
});
tokio::run(s);
错误:
error[E0507]: cannot move out of captured outer variable in an `FnMut` closure
--> src/main.rs:72:22
|
60 | let mut interval_timer = tokio_timer::Timer::default();
| ------------------ captured outer variable
...
72 | drop(interval_timer);
| ^^^^^^^^^^^^^^ cannot move out of captured outer variable in an `FnMut` closure
关于要从流的外部中取消流的情况,请参见stream-cancel。>>
对于您的特定情况,最简单的方法是将您的收藏集转换为流并将其与间隔计时器压缩在一起。这样,当集合为空时,结果流自然会停止:
use futures::{future, stream, Stream}; // 0.1.29 use std::time::Duration; use tokio; // 0.1.22 use tokio_timer::Interval; // 0.2.11 fn main() { tokio::run({ let some_vars = vec![1, 2, 3, 4, 5, 6, 7, 8]; let timer = Interval::new_interval(Duration::from_millis(100)).map_err(|e| panic!("Error: {}", e)); let some_vars = stream::iter_ok(some_vars.into_iter().rev()); let combined = timer.zip(some_vars); combined.for_each(move |(_, item)| { eprintln!("Woke up"); tokio::spawn(future::lazy(move || { println!("{:?}", item); Ok(()) })); Ok(()) }) }); }
否则,您可以通过使用
and_then
停止流,同时从集合中删除值并控制流是否应继续:
use futures::{future, Stream}; // 0.1.29
use std::time::Duration;
use tokio; // 0.1.22
use tokio_timer::Interval; // 0.2.11
fn main() {
tokio::run({
let mut some_vars = vec![1, 2, 3, 4, 5, 6, 7, 8];
let timer =
Interval::new_interval(Duration::from_millis(100)).map_err(|e| panic!("Error: {}", e));
let limited = timer.and_then(move |_| {
if some_vars.len() <= 4 {
Err(())
} else {
some_vars.pop().ok_or(())
}
});
limited.for_each(move |item| {
eprintln!("Woke up");
tokio::spawn(future::lazy(move || {
println!("{:?}", item);
Ok(())
}));
Ok(())
})
});
}
我创建了Tokio的Interval
结构的副本,添加了对我的应用程序方法的引用,以指示何时提前中断。
[tokio_timer::Interval
实现futures::Stream
,因此请尝试使用take_while
方法: