[Feature] Collectors' getattr_policy and getattr_env

ghstack-source-id: bd63914
Pull-Request: #3171

Author: vmoens

torchrl/collectors/collectors.py

@@ -1817,6 +1817,13 @@ def get_policy_version(self) -> str | int | None:
         """
         return self.policy_version
 
+    def getattr_policy(self, attr):
+        # send command to policy to return the attr
+        return getattr(self.policy, attr)
+
+    def getattr_env(self, attr):
+        # send command to env to return the attr
+        return getattr(self.env, attr)
 
 
 class _MultiDataCollector(DataCollectorBase):
@@ -2782,6 +2789,57 @@ def get_policy_version(self) -> str | int | None:
         """
         return self.policy_version
 
+    def getattr_policy(self, attr):
+        """Get an attribute from the policy of the first worker.
+
+        Args:
+            attr (str): The attribute name to retrieve from the policy.
+
+        Returns:
+            The attribute value from the policy of the first worker.
+
+        Raises:
+            AttributeError: If the attribute doesn't exist on the policy.
+        """
+        _check_for_faulty_process(self.procs)
+
+        # Send command to first worker (index 0)
+        self.pipes[0].send((attr, "getattr_policy"))
+        result, msg = self.pipes[0].recv()
+        if msg != "getattr_policy":
+            raise RuntimeError(f"Expected msg='getattr_policy', got {msg}")
+
+        # If the worker returned an AttributeError, re-raise it
+        if isinstance(result, AttributeError):
+            raise result
+
+        return result
+
+    def getattr_env(self, attr):
+        """Get an attribute from the environment of the first worker.
+
+        Args:
+            attr (str): The attribute name to retrieve from the environment.
+
+        Returns:
+            The attribute value from the environment of the first worker.
+
+        Raises:
+            AttributeError: If the attribute doesn't exist on the environment.
+        """
+        _check_for_faulty_process(self.procs)
+
+        # Send command to first worker (index 0)
+        self.pipes[0].send((attr, "getattr_env"))
+        result, msg = self.pipes[0].recv()
+        if msg != "getattr_env":
+            raise RuntimeError(f"Expected msg='getattr_env', got {msg}")
+
+        # If the worker returned an AttributeError, re-raise it
+        if isinstance(result, AttributeError):
+            raise result
+
+        return result
 
 
 @accept_remote_rref_udf_invocation
@@ -3947,6 +4005,25 @@ def cast_tensor(x, MPS_ERROR=MPS_ERROR):
             has_timed_out = False
             continue
 
+        elif msg == "getattr_policy":
+            attr_name = data_in
+            try:
+                result = getattr(inner_collector.policy, attr_name)
+                pipe_child.send((result, "getattr_policy"))
+            except AttributeError as e:
+                pipe_child.send((e, "getattr_policy"))
+            has_timed_out = False
+            continue
+
+        elif msg == "getattr_env":
+            attr_name = data_in
+            try:
+                result = getattr(inner_collector.env, attr_name)
+                pipe_child.send((result, "getattr_env"))
+            except AttributeError as e:
+                pipe_child.send((e, "getattr_env"))
+            has_timed_out = False
+            continue
 
         elif msg == "close":
             del collected_tensordict, data, next_data, data_in