Fix macOS threading deadlock in _event_generator (issue #61)

mpv.py

@@ -685,11 +685,59 @@ def _make_node_str_map(d):
 
 
 def _event_generator(handle):
-    while True:
-        event = _mpv_wait_event(handle, -1).contents
-        if event.event_id.value == MpvEventID.NONE:
-            raise StopIteration()
-        yield event
+    """Yield events from the mpv event queue.
+
+    Uses a pipe-based wakeup mechanism to avoid deadlocks on macOS where
+    ``mpv_wait_event`` with an infinite timeout can block forever when the
+    Cocoa main-loop is blocked (see issue #61).
+    """
+    import select as _select
+
+    # Create a self-pipe for wakeup signaling.
+    _wakeup_fd_r, _wakeup_fd_w = os.pipe()
+
+    # Keep a reference to the callback so the GC doesn't reclaim it while
+    # libmpv still holds a pointer to it.
+    @WakeupCallback
+    def _wakeup_cb(_userdata):
+        try:
+            os.write(_wakeup_fd_w, b'\x00')
+        except OSError:
+            pass
+
+    _mpv_set_wakeup_callback(handle, _wakeup_cb, None)
+
+    try:
+        while True:
+            # Wait for either a wakeup byte or a 100 ms timeout.
+            try:
+                _ready, _, _ = _select.select([_wakeup_fd_r], [], [], 0.1)
+            except (OSError, ValueError):
+                break
+
+            if _ready:
+                # Drain the pipe.
+                try:
+                    os.read(_wakeup_fd_r, 4096)
+                except OSError:
+                    break
+
+            # Drain all pending mpv events without blocking.
+            while True:
+                event = _mpv_wait_event(handle, 0).contents
+                if event.event_id.value == MpvEventID.NONE:
+                    break
+                yield event
+    finally:
+        # Clean up: close the pipe and unregister the wakeup callback.
+        # The handle may already be destroyed if we're cleaning up after a
+        # SHUTDOWN event, so guard the unregister call.
+        os.close(_wakeup_fd_r)
+        os.close(_wakeup_fd_w)
+        try:
+            _mpv_set_wakeup_callback(handle, WakeupCallback(), None)
+        except Exception:
+            pass
 
 
 def _create_null_term_cmd_arg_array(name, args):