Make trainer.state a read-only property (#3109)

* Make trainer.state a read-only property

* Update states.py

Co-authored-by: Jirka Borovec <Borda@users.noreply.github.com>

pytorch_lightning/trainer/states.py

@@ -42,20 +42,17 @@ def trainer_state(*, entering: Optional[TrainerState] = None, exiting: Optional[
             if not isinstance(self, pytorch_lightning.Trainer):
                 return fn(self, *args, **kwargs)
 
-            state_before = self.state
+            state_before = self._state
             if entering is not None:
-                self.state = entering
+                self._state = entering
             result = fn(self, *args, **kwargs)
 
             # The INTERRUPTED state can be set inside the run function. To indicate that run was interrupted
             # we retain INTERRUPTED state
-            if self.state == TrainerState.INTERRUPTED:
+            if self._state == TrainerState.INTERRUPTED:
                 return result
 
-            if exiting is not None:
-                self.state = exiting
-            else:
-                self.state = state_before
+            self._state = exiting if exiting is not None else state_before
             return result
 
         return wrapped_fn

pytorch_lightning/trainer/trainer.py

@@ -402,7 +402,7 @@ class Trainer(
         self.interrupted = False
         self.should_stop = False
         self.running_sanity_check = False
-        self.state = TrainerState.INITIALIZING
+        self._state = TrainerState.INITIALIZING
 
         self._default_root_dir = default_root_dir or os.getcwd()
         self._weights_save_path = weights_save_path or self._default_root_dir
@@ -611,6 +611,10 @@ class Trainer(
         # Callback system
         self.on_init_end()
 
+    @property
+    def state(self) -> TrainerState:
+        return self._state
+
     @property
     def is_global_zero(self) -> bool:
         return self.global_rank == 0

pytorch_lightning/trainer/training_loop.py

@@ -255,7 +255,7 @@ class TrainerTrainLoopMixin(ABC):
     terminate_on_nan: bool
     tpu_id: int
     interactive_ddp_procs: ...
-    state: TrainerState
+    _state: TrainerState
     amp_backend: AMPType
     on_tpu: bool
     accelerator_backend: ...
@@ -418,7 +418,7 @@ class TrainerTrainLoopMixin(ABC):
             # user could press ctrl+c many times... only shutdown once
             if not self.interrupted:
                 self.interrupted = True
-                self.state = TrainerState.INTERRUPTED
+                self._state = TrainerState.INTERRUPTED
                 self.on_keyboard_interrupt()
 
                 self.run_training_teardown()

tests/trainer/test_states.py

@@ -31,7 +31,6 @@ def test_state_decorator_nothing_passed(tmpdir):
         return self.state
 
     trainer = Trainer(default_root_dir=tmpdir)
-    trainer.state = TrainerState.INITIALIZING
 
     snapshot_state = test_method(trainer)
 
@@ -47,7 +46,6 @@ def test_state_decorator_entering_only(tmpdir):
         return self.state
 
     trainer = Trainer(default_root_dir=tmpdir)
-    trainer.state = TrainerState.INITIALIZING
 
     snapshot_state = test_method(trainer)
 
@@ -63,7 +61,6 @@ def test_state_decorator_exiting_only(tmpdir):
         return self.state
 
     trainer = Trainer(default_root_dir=tmpdir)
-    trainer.state = TrainerState.INITIALIZING
 
     snapshot_state = test_method(trainer)
 
@@ -79,7 +76,6 @@ def test_state_decorator_entering_and_exiting(tmpdir):
         return self.state
 
     trainer = Trainer(default_root_dir=tmpdir)
-    trainer.state = TrainerState.INITIALIZING
 
     snapshot_state = test_method(trainer)
 
@@ -92,10 +88,9 @@ def test_state_decorator_interrupt(tmpdir):
 
     @trainer_state(exiting=TrainerState.FINISHED)
     def test_method(self):
-        self.state = TrainerState.INTERRUPTED
+        self._state = TrainerState.INTERRUPTED
 
     trainer = Trainer(default_root_dir=tmpdir)
-    trainer.state = TrainerState.INITIALIZING
 
     test_method(trainer)
     assert trainer.state == TrainerState.INTERRUPTED