feat: Improve retry mechanism for _get_ai_reply and refactor method (#2113)

letta/agent.py

@@ -1,5 +1,6 @@
 import datetime
 import inspect
+import time
 import traceback
 import warnings
 from abc import ABC, abstractmethod
@@ -566,60 +567,60 @@ class Agent(BaseAgent):
         self,
         message_sequence: List[Message],
         function_call: str = "auto",
-        first_message: bool = False,  # hint
+        first_message: bool = False,
         stream: bool = False,  # TODO move to config?
-        fail_on_empty_response: bool = False,
         empty_response_retry_limit: int = 3,
+        backoff_factor: float = 0.5,  # delay multiplier for exponential backoff
+        max_delay: float = 10.0,  # max delay between retries
     ) -> ChatCompletionResponse:
-        """Get response from LLM API"""
-        # Get the allowed tools based on the ToolRulesSolver state
+        """Get response from LLM API with robust retry mechanism."""
+
         allowed_tool_names = self.tool_rules_solver.get_allowed_tool_names()
+        allowed_functions = (
+            self.functions if not allowed_tool_names else [func for func in self.functions if func["name"] in allowed_tool_names]
+        )
 
-        if not allowed_tool_names:
-            # if it's empty, any available tools are fair game
-            allowed_functions = self.functions
-        else:
-            allowed_functions = [func for func in self.functions if func["name"] in allowed_tool_names]
+        for attempt in range(1, empty_response_retry_limit + 1):
+            try:
+                response = create(
+                    llm_config=self.agent_state.llm_config,
+                    messages=message_sequence,
+                    user_id=self.agent_state.user_id,
+                    functions=allowed_functions,
+                    functions_python=self.functions_python,
+                    function_call=function_call,
+                    first_message=first_message,
+                    stream=stream,
+                    stream_interface=self.interface,
+                )
 
-        try:
-            response = create(
-                # agent_state=self.agent_state,
-                llm_config=self.agent_state.llm_config,
-                messages=message_sequence,
-                user_id=self.agent_state.user_id,
-                functions=allowed_functions,
-                functions_python=self.functions_python,
-                function_call=function_call,
-                # hint
-                first_message=first_message,
-                # streaming
-                stream=stream,
-                stream_interface=self.interface,
-            )
+                # These bottom two are retryable
+                if len(response.choices) == 0 or response.choices[0] is None:
+                    raise ValueError(f"API call returned an empty message: {response}")
 
-            if len(response.choices) == 0 or response.choices[0] is None:
-                empty_api_err_message = f"API call didn't return a message: {response}"
-                if fail_on_empty_response or empty_response_retry_limit == 0:
-                    raise Exception(empty_api_err_message)
+                if response.choices[0].finish_reason not in ["stop", "function_call", "tool_calls"]:
+                    if response.choices[0].finish_reason == "length":
+                        # This is not retryable, hence RuntimeError v.s. ValueError
+                        raise RuntimeError("Finish reason was length (maximum context length)")
+                    else:
+                        raise ValueError(f"Bad finish reason from API: {response.choices[0].finish_reason}")
+
+                return response
+
+            except ValueError as ve:
+                if attempt >= empty_response_retry_limit:
+                    warnings.warn(f"Retry limit reached. Final error: {ve}")
+                    break
                 else:
-                    # Decrement retry limit and try again
-                    warnings.warn(empty_api_err_message)
-                    return self._get_ai_reply(
-                        message_sequence, function_call, first_message, stream, fail_on_empty_response, empty_response_retry_limit - 1
-                    )
+                    delay = min(backoff_factor * (2 ** (attempt - 1)), max_delay)
+                    warnings.warn(f"Attempt {attempt} failed: {ve}. Retrying in {delay} seconds...")
+                    time.sleep(delay)
 
-            # special case for 'length'
-            if response.choices[0].finish_reason == "length":
-                raise Exception("Finish reason was length (maximum context length)")
+            except Exception as e:
+                # For non-retryable errors, exit immediately
+                raise e
 
-            # catches for soft errors
-            if response.choices[0].finish_reason not in ["stop", "function_call", "tool_calls"]:
-                raise Exception(f"API call finish with bad finish reason: {response}")
-
-            # unpack with response.choices[0].message.content
-            return response
-        except Exception as e:
-            raise e
+        raise Exception("Retries exhausted and no valid response received.")
 
     def _handle_ai_response(
         self,