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docs: add description for fuse() in handling_disconnection

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Ref #88
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surechen 2021-08-24 19:38:21 +08:00 committed by GitHub
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1 changed files with 4 additions and 3 deletions
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docs/src/tutorial/handling_disconnection.md
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@ -90,12 +90,12 @@ async fn connection_writer_loop(
let mut shutdown = shutdown.fuse();
loop { // 2
select! {
msg = messages.next().fuse() => match msg {
msg = messages.next().fuse() => match msg { // 3
Some(msg) => stream.write_all(msg.as_bytes()).await?,
None => break,
},
void = shutdown.next().fuse() => match void {
Some(void) => match void {}, // 3
Some(void) => match void {}, // 4
None => break,
}
}
@ -106,7 +106,8 @@ async fn connection_writer_loop(
1. We add shutdown channel as an argument.
2. Because of `select`, we can't use a `while let` loop, so we desugar it further into a `loop`.
3. In the shutdown case we use `match void {}` as a statically-checked `unreachable!()`.
3. Function fuse() is used to turn any `Stream` into a `FusedStream`. This is used for fusing a stream such that poll_next will never again be called once it has finished.
4. In the shutdown case we use `match void {}` as a statically-checked `unreachable!()`.
Another problem is that between the moment we detect disconnection in `connection_writer_loop` and the moment when we actually remove the peer from the `peers` map, new messages might be pushed into the peer's channel.
To not lose these messages completely, we'll return the messages channel back to the broker.