Merge origin/main (561b053f79) into simp/forwardport: forward-port 220 main commits into the simplified tree

tools/file_state.py

@@ -64,16 +64,29 @@ class FileStateRegistry:
         self._reads: Dict[str, Dict[str, ReadStamp]] = defaultdict(dict)
         self._last_writer: Dict[str, Tuple[str, float]] = {}
         self._path_locks: Dict[str, threading.Lock] = {}
+        self._path_lock_users: Dict[str, int] = {}
         self._meta_lock = threading.Lock()  # guards _path_locks
         self._state_lock = threading.Lock()  # guards _reads + _last_writer
 
     @contextmanager
     def lock_path(self, resolved: str):
-        """Per-path lock: threads on the same path serialize, different paths proceed."""
+        """Per-path lock: threads on the same path serialize, different paths proceed.
+        The lock entry is dropped once the last holder/waiter exits."""
         with self._meta_lock:
             lock = self._path_locks.setdefault(resolved, threading.Lock())
-        with lock:
+            self._path_lock_users[resolved] = self._path_lock_users.get(resolved, 0) + 1
+        lock.acquire()
+        try:
             yield
+        finally:
+            lock.release()
+            with self._meta_lock:
+                users = self._path_lock_users[resolved] - 1
+                if users:
+                    self._path_lock_users[resolved] = users
+                else:
+                    self._path_lock_users.pop(resolved, None)
+                    self._path_locks.pop(resolved, None)
 
     def _stamp(self, task_id: str, resolved: str, mtime: float, now: float, partial: bool) -> None:
         """Caller holds ``_state_lock``."""
@@ -177,6 +190,11 @@ class FileStateRegistry:
         with self._state_lock:
             return list(self._reads.get(task_id, {}).keys())
 
+    def forget_task(self, task_id: str) -> None:
+        """Release read stamps owned by a task after its lifecycle ends."""
+        with self._state_lock:
+            self._reads.pop(task_id, None)
+
     def clear(self) -> None:
         """Reset all state. Intended for tests only."""
         with self._state_lock:
@@ -184,6 +202,7 @@ class FileStateRegistry:
             self._last_writer.clear()
         with self._meta_lock:
             self._path_locks.clear()
+            self._path_lock_users.clear()
 
 
 _registry = FileStateRegistry()