Avoid leaking Windows by storing Weak pointers in EventsLoop

src/platform/macos/events_loop.rs

@@ -6,7 +6,7 @@ use std;
 
 
 pub struct EventsLoop {
-    pub windows: std::sync::Mutex<Vec<std::sync::Arc<Window>>>,
+    pub windows: std::sync::Mutex<Vec<std::sync::Weak<Window>>>,
     pub pending_events: std::sync::Mutex<std::collections::VecDeque<Event>>,
     modifiers: std::sync::Mutex<Modifiers>,
     interrupted: std::sync::atomic::AtomicBool,
@@ -236,8 +236,6 @@ impl EventsLoop {
         let event_type = ns_event.eventType();
         let ns_window = ns_event.window();
         let window_id = super::window::get_window_id(ns_window);
-        let windows = self.windows.lock().unwrap();
-        let maybe_window = windows.iter().find(|window| window_id == window.id());
 
         // FIXME: Document this. Why do we do this? Seems like it passes on events to window/app.
         // If we don't do this, window does not become main for some reason.
@@ -246,16 +244,23 @@ impl EventsLoop {
             _ => appkit::NSApp().sendEvent_(ns_event),
         }
 
+        let windows = self.windows.lock().unwrap();
+        let maybe_window = windows.iter()
+            .filter_map(std::sync::Weak::upgrade)
+            .find(|window| window_id == window.id());
+
         let into_event = |window_event| Event::WindowEvent {
             window_id: ::WindowId(window_id),
             event: window_event,
         };
 
         // Returns `Some` window if one of our windows is the key window.
-        let maybe_key_window = || windows.iter().find(|window| {
-            let is_key_window: cocoa::base::BOOL = msg_send![*window.window, isKeyWindow];
-            is_key_window == cocoa::base::YES
-        });
+        let maybe_key_window = || windows.iter()
+            .filter_map(std::sync::Weak::upgrade)
+            .find(|window| {
+                let is_key_window: cocoa::base::BOOL = msg_send![*window.window, isKeyWindow];
+                is_key_window == cocoa::base::YES
+            });
 
         match event_type {
 
@@ -586,4 +591,4 @@ fn event_mods(event: cocoa::base::id) -> ModifiersState {
         alt: flags.contains(appkit::NSAlternateKeyMask),
         logo: flags.contains(appkit::NSCommandKeyMask),
     }
-}
+}

src/platform/macos/mod.rs

@@ -26,7 +26,8 @@ impl Window2 {
     {
         let weak_events_loop = ::std::sync::Arc::downgrade(&events_loop);
         let window = ::std::sync::Arc::new(try!(Window::new(weak_events_loop, attributes, pl_attribs)));
-        events_loop.windows.lock().unwrap().push(window.clone());
+        let weak_window = ::std::sync::Arc::downgrade(&window);
+        events_loop.windows.lock().unwrap().push(weak_window);
         Ok(Window2 { window: window })
     }
 

src/platform/macos/window.rs

@@ -174,7 +174,10 @@ impl Drop for Window {
         let id = self.id();
         if let Some(ev) = self.delegate.state.events_loop.upgrade() {
             let mut windows = ev.windows.lock().unwrap();
-            windows.retain(|w| w.id() != id)
+            windows.retain(|w| match w.upgrade() {
+                Some(w) => w.id() != id,
+                None => true,
+            })
         }
     }
 }