Fix set goal bug (facebookresearch#772)

* Fix a bug

habitat/core/dataset.py

@@ -72,6 +72,16 @@ class Episode:
     info: Optional[Dict[str, Any]] = None
     _shortest_path_cache: Any = attr.ib(init=False, default=None)
 
+    # NB: This method is marked static despite taking self so that
+    # on_setattr=Episode._reset_shortest_path_cache_hook works as attrs
+    # will pass the instance as the first argument!
+    @staticmethod
+    def _reset_shortest_path_cache_hook(
+        self: "Episode", attribute: attr.Attribute, value: Any
+    ) -> Any:
+        self._shortest_path_cache = None
+        return value
+
     def __getstate__(self):
         return {
             k: v

habitat/core/utils.py

@@ -9,6 +9,7 @@
 import math
 from typing import Any, Dict, List, Optional
 
+import attr
 import numpy as np
 import quaternion  # noqa: F401
 
@@ -60,7 +61,7 @@ def tile_images(images: List[np.ndarray]) -> np.ndarray:
 
 
 def not_none_validator(
-    self: Any, attribute: Any, value: Optional[Any]
+    self: Any, attribute: attr.Attribute, value: Optional[Any]
 ) -> None:
     if value is None:
         raise ValueError(f"Argument '{attribute.name}' must be set")

habitat/tasks/nav/nav.py

@@ -110,7 +110,9 @@ class NavigationEpisode(Episode):
     """
 
     goals: List[NavigationGoal] = attr.ib(
-        default=None, validator=not_none_validator
+        default=None,
+        validator=not_none_validator,
+        on_setattr=Episode._reset_shortest_path_cache_hook,
     )
     start_room: Optional[str] = None
     shortest_paths: Optional[List[List[ShortestPathPoint]]] = None

test/test_dataset.py

@@ -9,6 +9,7 @@
 import pytest
 
 from habitat.core.dataset import Dataset, Episode
+from habitat.tasks.nav.nav import NavigationEpisode, NavigationGoal
 
 
 def _construct_dataset(num_episodes, num_groups=10):
@@ -359,3 +360,19 @@ def test_preserve_order():
     episode_iter = dataset.get_episode_iterator(shuffle=False, cycle=False)
 
     assert list(episode_iter) == episodes
+
+
+def test_reset_goals():
+    ep = NavigationEpisode(
+        episode_id="0",
+        scene_id="1",
+        start_position=[0, 0, 0],
+        start_rotation=[1, 0, 0, 0],
+        goals=[NavigationGoal(position=[1, 2, 3])],
+    )
+
+    ep._shortest_path_cache = "Dummy"
+    assert ep._shortest_path_cache is not None
+
+    ep.goals = [NavigationGoal(position=[3, 4, 5])]
+    assert ep._shortest_path_cache is None