introduce global event sink to trigger updates across threads

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| {}));
+    }
+}