Context switch from enqueue_event() to get_event() directly

src/platform/macos/events_loop.rs

@@ -53,10 +53,15 @@ impl Shared {
     pub fn enqueue_event(&self, event: Event) {
         self.pending_events.lock().unwrap().push_back(event);
 
-        // attempt to wake the runloop
-        self.timer.trigger();
-        unsafe {
-            runloop::CFRunLoopWakeUp(runloop::CFRunLoopGetMain());
+        // attempt to hop back
+        if unsafe { super::send_event::try_resume(1) } {
+            // success!
+        } else {
+            // attempt to wake the runloop
+            self.timer.trigger();
+            unsafe {
+                runloop::CFRunLoopWakeUp(runloop::CFRunLoopGetMain());
+            }
         }
     }
 

src/platform/macos/send_event.rs

@@ -1,6 +1,10 @@
 use cocoa;
 use cocoa::appkit::{NSApp,NSApplication};
 
+pub unsafe fn try_resume(value: usize) -> bool {
+    false
+}
+
 // The `SendEvent` struct encapsulates the idea of calling [NSApp sendEvent:event].
 // This is a separate struct because, in the case of resize events, dispatching an event can enter
 // an internal runloop, and we don't want to get stuck there.

src/platform/macos/send_event_context.rs

@@ -28,6 +28,8 @@ unsafe fn resume(value: usize) {
     }
 }
 
+// Attempt to hop back to the "normal" stack frame, yielding `value`. Returns false if we're not
+// inside a coroutine.
 pub unsafe fn try_resume(value: usize) -> bool {
     if let Some(context) = INNER_CONTEXT.with(|c| { c.take() }) {
         // resume it, getting a new context

src/platform/macos/timer.rs

@@ -10,19 +10,13 @@ pub struct Timer {
     timer: CFRunLoopTimerRef,
 }
 
-#[cfg(feature="context")]
 extern "C" fn timer_callback(_timer: CFRunLoopTimerRef, _info: *mut c_void) {
     // attempt to yield back to the caller
-    use super::send_event_context::try_resume;
     unsafe {
-        try_resume(1);
+        super::send_event::try_resume(1);
     }
 }
 
-#[cfg(not(feature="context"))]
-extern "C" fn timer_callback(timer: CFRunLoopTimerRef, info: *mut c_void) {
-    // nothing to do
-}
 
 impl Timer {
     pub fn new() -> Timer {