introduce global event sink to trigger updates across threads

Cargo.toml

@@ -5,6 +5,7 @@ authors = ["Henrik Friedrichsen <henrik@affekt.org>"]
 
 [dependencies]
 cursive = "0.10"
+crossbeam-channel = "0.3.8"
 env_logger = "0.5.13"
 failure = "0.1.3"
 futures = "0.1"

src/events.rs

@@ -0,0 +1,39 @@
+use crossbeam_channel::{unbounded, Sender, Receiver, TryIter};
+use cursive::{Cursive, CbFunc};
+
+pub enum Event {
+    QueueUpdate,
+}
+
+pub type EventSender = Sender<Event>;
+
+pub struct EventManager {
+    tx: EventSender,
+    rx: Receiver<Event>,
+    cursive_sink: Sender<Box<dyn CbFunc>>,
+}
+
+impl EventManager {
+    pub fn new(cursive_sink: Sender<Box<dyn CbFunc>>) -> EventManager {
+        let (tx, rx) = unbounded();
+
+        EventManager {
+            tx: tx,
+            rx: rx,
+            cursive_sink: cursive_sink,
+        }
+    }
+
+    pub fn msg_iter(&self) -> TryIter<Event> {
+        self.rx.try_iter()
+    }
+
+    pub fn sink(&mut self) -> EventSender {
+        self.tx.clone()
+    }
+
+    pub fn trigger(&self) {
+        // send a no-op to trigger event loop processing
+        self.cursive_sink.send(Box::new(|_s: &mut Cursive| {}));
+    }
+}

src/main.rs

@@ -1,3 +1,4 @@
+extern crate crossbeam_channel;
 extern crate cursive;
 extern crate failure;
 extern crate futures;
@@ -23,15 +24,19 @@ use std::sync::Arc;
 use std::sync::Mutex;
 
 use cursive::event::Key;
+use cursive::view::ScrollStrategy;
 use cursive::views::*;
 use cursive::Cursive;
 
 mod config;
+mod events;
 mod queue;
 mod spotify;
 mod theme;
 mod ui;
 
+use events::{Event, EventManager};
+
 fn init_logger(content: TextContent) {
     let mut builder = env_logger::Builder::from_default_env();
     {
@@ -65,6 +70,8 @@ fn main() {
     init_logger(logbuf);
 
     let mut cursive = Cursive::default();
+    let mut event_manager = EventManager::new(cursive.cb_sink().clone());
+
     cursive.add_global_callback('q', |s| s.quit());
     cursive.set_theme(theme::default());
 
@@ -77,7 +84,7 @@ fn main() {
     };
 
     let cfg = config::load(path.to_str().unwrap()).expect("could not load configuration file");
-    let queue = Arc::new(Mutex::new(queue::Queue::new()));
+    let queue = Arc::new(Mutex::new(queue::Queue::new(event_manager.sink())));
 
     let spotify = Arc::new(spotify::Spotify::new(
         cfg.username,
@@ -86,6 +93,10 @@ fn main() {
         queue.clone(),
     ));
 
+    let track = TextView::new("Track Title");
+    let pos = TextView::new("[0:00/0:00]");
+    let status = LinearLayout::horizontal().child(track).child(pos);
+
     let searchscreen = cursive.active_screen();
     let search = ui::search::SearchView::new(spotify.clone(), queue.clone());
     cursive.add_fullscreen_layer(search.view);
@@ -103,10 +114,13 @@ fn main() {
         s.set_screen(logscreen);
     });
 
-    cursive.add_global_callback(Key::F2, move |s| {
-        s.set_screen(queuescreen);
-        queue.redraw(s);
-    });
+    {
+        let event_sink = event_manager.sink();
+        cursive.add_global_callback(Key::F2, move |s| {
+            s.set_screen(queuescreen);
+            event_sink.send(Event::QueueUpdate);
+        });
+    }
 
     cursive.add_global_callback(Key::F3, move |s| {
         s.set_screen(searchscreen);
@@ -115,5 +129,11 @@ fn main() {
     // cursive event loop
     while cursive.is_running() {
         cursive.step();
+        for event in event_manager.msg_iter() {
+            trace!("event received");
+            match event {
+                Event::QueueUpdate => queue.redraw(&mut cursive)
+            }
+        }
     }
 }

src/queue.rs

@@ -3,24 +3,44 @@ use std::collections::VecDeque;
 
 use rspotify::spotify::model::track::FullTrack;
 
+use events::{Event, EventSender};
+
 pub struct Queue {
     queue: VecDeque<FullTrack>,
+    ev_sink: EventSender,
 }
 
 impl Queue {
-    pub fn new() -> Queue {
+    pub fn new(ev_sink: EventSender) -> Queue {
         Queue {
             queue: VecDeque::new(),
+            ev_sink: ev_sink,
         }
     }
+    fn send_event(&self) {
+        self.ev_sink.send(Event::QueueUpdate);
+    }
     pub fn remove(&mut self, index: usize) -> Option<FullTrack> {
-        self.queue.remove(index)
+        match self.queue.remove(index) {
+            Some(track) => {
+                self.send_event();
+                Some(track)
+            },
+            None => None
+        }
     }
     pub fn enqueue(&mut self, track: FullTrack) {
         self.queue.push_back(track);
+        self.send_event();
     }
     pub fn dequeue(&mut self) -> Option<FullTrack> {
-        self.queue.pop_front()
+        match self.queue.pop_front() {
+            Some(track) => {
+                self.send_event();
+                Some(track)
+            },
+            None => None
+        }
     }
     pub fn iter(&self) -> Iter<FullTrack> {
         self.queue.iter()

src/ui/queue.rs

@@ -33,32 +33,34 @@ impl QueueView {
     }
 
     pub fn redraw(&self, s: &mut Cursive) {
-        let mut queuelist: ViewRef<ListView> = s.find_id("queue_list").unwrap();
-        queuelist.clear();
+        let view_ref: Option<ViewRef<ListView>> = s.find_id("queue_list");
+        if let Some(mut queuelist) = view_ref {
+            queuelist.clear();
 
-        let queue_ref = self.queue.clone();
-        let queue = self.queue.lock().unwrap();
-        for (index, track) in queue.iter().enumerate() {
-            let artists = track
-                .artists
-                .iter()
-                .map(|ref artist| artist.name.clone())
-                .collect::<Vec<String>>()
-                .join(", ");
-            let formatted = format!("{} - {}", artists, track.name);
+            let queue_ref = self.queue.clone();
+            let queue = self.queue.lock().unwrap();
+            for (index, track) in queue.iter().enumerate() {
+                let artists = track
+                    .artists
+                    .iter()
+                    .map(|ref artist| artist.name.clone())
+                    .collect::<Vec<String>>()
+                    .join(", ");
+                let formatted = format!("{} - {}", artists, track.name);
 
-            let trackid = SpotifyId::from_base62(&track.id).expect("could not load track");
-            let s = self.spotify.clone();
+                let trackid = SpotifyId::from_base62(&track.id).expect("could not load track");
+                let s = self.spotify.clone();
 
-            let queue_ref = queue_ref.clone();
-            let button = Button::new_raw(formatted, move |_cursive| {
-                s.load(trackid);
-                s.play();
-                queue_ref.lock().unwrap().remove(index);
-                // TODO: update view representation, preferably, queue changes
-                // cause a view refresh
-            });
-            queuelist.add_child("", button);
+                let queue_ref = queue_ref.clone();
+                let button = Button::new_raw(formatted, move |_cursive| {
+                    s.load(trackid);
+                    s.play();
+                    queue_ref.lock().unwrap().remove(index);
+                    // TODO: update view representation, preferably, queue changes
+                    // cause a view refresh
+                });
+                queuelist.add_child("", button);
+            }
         }
     }
 }