如何通过期货:: Sink发送物品清单？

让我们回到API文档......

fn send(self, item: Self::SinkItem) -> Send
where
    Self: Sized, 

从这里,我们可以看到Send消耗接收器并返回一个Future对象.那很奇怪,不是吗!实际上并没有那么奇怪,一旦你看到Future实现Future- 将某些内容推送到流中可能会阻塞流是否已满; 这是背压的概念.结果是a Send是如何知道项目何时实际添加到流中.实施Item = S了Sink有wait,具体类型的Sink::send_all.因此,一种解决方案是将未来推向完成以获得回收,其中一种方法是调用Stream:

use futures::Future; // 0.1.26
use std::fmt;

fn thing(mut sink: S)
where
    S: futures::Sink,
    S::SinkError: fmt::Debug,
{
    let mut all_the_things = vec![1, 2, 3, 4, 5];

    while let Some(v) = all_the_things.pop() {
        let f = sink.send(v);
        sink = f.wait().expect("Something bad happened while sending");
    }
}

use futures::Future; // 0.1.26
use std::fmt;

fn thing(sink: S)
where
    S: futures::Sink,
    S::SinkError: fmt::Debug,
{
    let all_the_things = vec![1, 2, 3, 4, 5];

    sink.send_all(futures::stream::iter_ok(all_the_things))
        .wait()
        .expect("Something bad happened while sending");
}