88 lines
1.6 KiB
Rust
88 lines
1.6 KiB
Rust
// Watchers on the wall was the last good episode of Game of Thrones
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use std::{
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collections::*,
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sync::Arc,
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time::Duration,
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};
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use futures::channel::oneshot;
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use tokio::{
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sync::Mutex,
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time::delay_for,
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};
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pub struct Watchers <T> {
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pub senders: HashMap <String, oneshot::Sender <T>>,
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}
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impl <T> Default for Watchers <T> {
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fn default () -> Self {
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Self {
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senders: Default::default (),
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}
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}
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}
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impl <T: 'static + Clone + Send + Sync> Watchers <T> {
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pub fn add_watcher_with_id (&mut self, s: oneshot::Sender <T>, id: String) {
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self.senders.insert (id, s);
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}
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pub fn remove_watcher (&mut self, id: &str) {
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self.senders.remove (id);
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}
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/*
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fn wake_all (&mut self, msg: T) {
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let waiters = {
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std::mem::take (&mut self.senders)
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};
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for (_id, waiter) in waiters.into_iter () {
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waiter.send (msg.clone ()).ok ();
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}
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}
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*/
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pub fn wake_one (&mut self, msg: T, id: &str) -> bool {
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println! ("wake_one {}", id);
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if let Some (waiter) = self.senders.remove (id) {
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waiter.send (msg).ok ();
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true
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}
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else {
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false
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}
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}
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pub fn num_watchers (&self) -> usize {
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self.senders.len ()
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}
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pub async fn long_poll (that: Arc <Mutex <Self>>, id: String) -> Option <T> {
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println! ("long_poll {}", id);
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let (s, r) = oneshot::channel ();
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let timeout = Duration::from_secs (5);
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let id_2 = id.clone ();
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{
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let mut that = that.lock ().await;
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that.add_watcher_with_id (s, id_2)
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}
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tokio::spawn (async move {
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delay_for (timeout).await;
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let mut that = that.lock ().await;
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that.remove_watcher (&id);
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});
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if let Ok (message) = r.await {
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Some (message)
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}
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else {
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None
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}
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}
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}
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