fix(server): fix has_position_ids (#395)

Fix #389

server/text_generation_server/models/causal_lm.py

@@ -496,11 +496,6 @@ class CausalLM(Model):
             else:
                 tokenizer.add_special_tokens({"pad_token": "[PAD]"})
 
-        self.has_position_ids = (
-            inspect.signature(model.forward).parameters.get("position_ids", None)
-            is not None
-        )
-
         super(CausalLM, self).__init__(
             model=model,
             tokenizer=tokenizer,

server/text_generation_server/models/model.py

+import inspect
 import torch
 
 from abc import ABC, abstractmethod
@@ -29,6 +30,12 @@ class Model(ABC):
         self.device = device
         self.rank = rank
         self.world_size = world_size
+
+        self.has_position_ids = (
+            inspect.signature(model.forward).parameters.get("position_ids", None)
+            is not None
+        )
+
         self.check_initialized()
 
     @property