Reload services on debounced file edits and replacement saves

great_ai/__main__.py

@@ -11,7 +11,6 @@ import uvicorn
 from uvicorn._subprocess import get_subprocess
 from uvicorn.config import LOGGING_CONFIG, Config
 from uvicorn.supervisors import BaseReload, Multiprocess
-from watchdog.events import FileSystemEvent, PatternMatchingEventHandler
 from watchdog.observers import Observer
 
 from great_ai.constants import SERVER_NAME
@@ -20,6 +19,7 @@ from great_ai.deploy import GreatAI
 from great_ai.errors import ArgumentValidationError, MissingArgumentError
 from great_ai.utilities import get_logger
 
+from .deploy.reload_event_handler import ReloadEventHandler
 from .parse_arguments import parse_arguments
 
 logger = get_logger(SERVER_NAME)
@@ -83,18 +83,12 @@ def serve() -> None:
                     pass
     else:
 
-        class EventHandler(PatternMatchingEventHandler):
+        class EventHandler(ReloadEventHandler):
             def __init__(self) -> None:
-                super().__init__(
-                    patterns=["*.py", "*.ipynb"], ignore_patterns=["__*.py"]
-                )
+                super().__init__(self.restart)
                 self.server: Optional[GreatAIReload] = None
                 self.restart()
 
-            def on_closed(self, event: FileSystemEvent) -> None:
-                logger.warning(f"File {event.src_path} has triggered a restart")
-                self.restart()
-
             def restart(self) -> None:
                 file_name = get_script_name(args.file_name)
                 app = find_app(file_name)
@@ -124,6 +118,7 @@ def serve() -> None:
             Event().wait()
         finally:
             observer.stop()
+            restart_handler.close()
             restart_handler.stop_server()
             if args.file_name.endswith(".ipynb"):
                 try:

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()

tests/test_cli_regressions.py

@@ -0,0 +1,27 @@
+from threading import Event
+
+from watchdog.events import FileClosedEvent, FileModifiedEvent, FileMovedEvent
+
+from great_ai.deploy.reload_event_handler import ReloadEventHandler
+
+
+def test_reload_debounces_edit_and_replacement_events() -> None:
+    completed = Event()
+    calls = []
+
+    def restart() -> None:
+        calls.append("restart")
+        completed.set()
+
+    handler = ReloadEventHandler(restart, debounce_seconds=0.02)
+    try:
+        handler.dispatch(FileModifiedEvent("service.py"))
+        handler.dispatch(FileClosedEvent("service.py"))
+        handler.dispatch(FileMovedEvent("temporary", "service.py"))
+        assert completed.wait(timeout=2)
+        assert calls == ["restart"]
+        handler.dispatch(FileModifiedEvent("__service__.py"))
+    finally:
+        handler.close()
+    handler.dispatch(FileModifiedEvent("service.py"))
+    assert calls == ["restart"]