如何在期货集中获得第一个未来的结果？
我有一堆async_std :: udpsocket，并希望将它们全部驱动到第一个人完成，然后从其相应的u8 buffer中获取结果。
我尝试过
// build sockets and buffers
let sockets = Vec::new();
let buffers = HashMap::new();
for addr in ["127.0.0.1:4000", "10.0.0.1:8080", "192.168.0.1:9000"] {
let socket = UdpSocket::bind(addr.parse().unwrap()).await?;
let buf = [0u8; 1500];
sockets.push(socket);
buffers.insert(socket.peer_addr()?, buf);
}
// create an iterator of tasks reading from each socket
let socket_tasks = sockets.into_iter().map(|socket| {
let socket_addr = socket.peer_addr().unwrap();
let buf = buffers.get_mut(&socket_addr).unwrap();
socket
.recv_from(buf)
.and_then(|_| async move { Ok(socket_addr) })
});
// wait for the first socket to return a value (DOESN'T WORK)
let buffer = try_join_all(socket_tasks)
.and_then(|socket_addr| async { Ok(buffers.get(&socket_addr)) })
.await
，但是这不起作用，因为期货:: future :: try_join_all drives 全部所有期货都可以完成，并返回vec＆lt;（socketAddr）＆gt; < /代码>。我想在A single Future完成并仅获得socketAddr - 类似于select！select！但在集合上获得的东西。
怎么办？
I have a bunch of async_std::UdpSocket and want to drive them all until the first one completes, then get the result from its corresponding u8 buffer.
I've tried
// build sockets and buffers
let sockets = Vec::new();
let buffers = HashMap::new();
for addr in ["127.0.0.1:4000", "10.0.0.1:8080", "192.168.0.1:9000"] {
let socket = UdpSocket::bind(addr.parse().unwrap()).await?;
let buf = [0u8; 1500];
sockets.push(socket);
buffers.insert(socket.peer_addr()?, buf);
}
// create an iterator of tasks reading from each socket
let socket_tasks = sockets.into_iter().map(|socket| {
let socket_addr = socket.peer_addr().unwrap();
let buf = buffers.get_mut(&socket_addr).unwrap();
socket
.recv_from(buf)
.and_then(|_| async move { Ok(socket_addr) })
});
// wait for the first socket to return a value (DOESN'T WORK)
let buffer = try_join_all(socket_tasks)
.and_then(|socket_addr| async { Ok(buffers.get(&socket_addr)) })
.await
However this does not work because futures::future::try_join_all drives all futures to completion and returns a Vec<(SocketAddr)>. I want to get the result when a single future completes and get just a SocketAddr--something akin to select! but over a collection.
How can this be done?
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如果您只需要第一个未来，也可以使用 ：未来:: select_all（） 。如果有很多期货
FuturesUnordered可能会更具性能减少工作。If you only need the first future you can also use
futures::future::select_all(). If there are many futuresFuturesUnorderedmay be more performant because it only polls future when they awake, but if there are fewselect_all()is likely to be more performant as it is doing less work.futuresunordered是一个流将以他们完成的顺序产生期货结果。您可以socket_tasks.collect（）进入此类型，然后使用next（）streamext的方法，创建一个未来，该未来将在整个未来的第一个未来时完成收集完成。FuturesUnorderedis aStreamthat will produce the results of futures in the order they complete. You cansocket_tasks.collect()into this type, and then use thenext()method ofStreamExtto create a future that will complete when the first future in the whole collection completes.