Reload services on debounced file edits and replacement saves

great_ai/deploy/reload_event_handler.py

@@ -0,0 +1,46 @@
+from threading import RLock, Timer
+from typing import Callable, Optional
+
+from watchdog.events import FileSystemEvent, PatternMatchingEventHandler
+
+
+class ReloadEventHandler(PatternMatchingEventHandler):
+    """Debounce edit and replacement events emitted by supported OS observers."""
+
+    def __init__(
+        self, restart: Callable[[], None], debounce_seconds: float = 0.3
+    ) -> None:
+        super().__init__(patterns=["*.py", "*.ipynb"], ignore_patterns=["__*.py"])
+        self._restart = restart
+        self._debounce_seconds = debounce_seconds
+        self._lock = RLock()
+        self._timer: Optional[Timer] = None
+        self._closed = False
+
+    def on_any_event(self, event: FileSystemEvent) -> None:
+        if event.is_directory or event.event_type not in {
+            "created",
+            "modified",
+            "moved",
+            "closed",
+        }:
+            return
+        with self._lock:
+            if self._closed:
+                return
+            if self._timer is not None:
+                self._timer.cancel()
+            self._timer = Timer(self._debounce_seconds, self._run_restart)
+            self._timer.daemon = True
+            self._timer.start()
+
+    def _run_restart(self) -> None:
+        with self._lock:
+            if not self._closed:
+                self._restart()
+
+    def close(self) -> None:
+        with self._lock:
+            self._closed = True
+            if self._timer is not None:
+                self._timer.cancel()