Send input state out to clients every tick

src/net/server.rs

@@ -96,7 +96,33 @@ impl Server {
     }
 
     fn tick(&mut self, tick: Instant) {
-        trace!("Tick {:?}", tick)
+        trace!("Tick {:?}", tick);
+
+        let total_input = self
+            .players
+            .iter()
+            .map(|player| match player {
+                Some(PlayerState { input, .. }) => input.clone(),
+                None => json!([]),
+            })
+            .collect();
+
+        self.broadcast(ServerMessage::Input { total_input });
+    }
+
+    fn broadcast(&mut self, msg: ServerMessage) {
+        // iterate by index instead of iterator, because we need to call
+        // remove_player(&mut self) in the error case
+        for slot in 0..self.players.len() {
+            if let Some(ref mut player) = self.players[slot] {
+                // don't poll ready; we give the channel enough buffer that an overflow indicates
+                // the client has fallen hopelessly behind.
+                if player.sender.start_send(msg.clone()).is_err() {
+                    info!("Client#{} fell behind", slot);
+                    self.remove_player(slot);
+                }
+            }
+        }
     }
 
     pub fn remove_player(&mut self, player_id: PlayerId) {