DAN-60 Add streaming for chat model (#46)

backend/danswer/configs/model_configs.py

@@ -20,6 +20,6 @@ BATCH_SIZE_ENCODE_CHUNKS = 8
 
 # QA Model API Configs
 # https://platform.openai.com/docs/models/model-endpoint-compatibility
-INTERNAL_MODEL_VERSION = os.environ.get("INTERNAL_MODEL", "openai-completion")
-OPENAPI_MODEL_VERSION = os.environ.get("OPENAI_MODEL_VERSION", "text-davinci-003")
+INTERNAL_MODEL_VERSION = os.environ.get("INTERNAL_MODEL", "openai-chat-completion")
+OPENAPI_MODEL_VERSION = os.environ.get("OPENAI_MODEL_VERSION", "gpt-4")
 OPENAI_MAX_OUTPUT_TOKENS = 512

backend/danswer/direct_qa/qa_prompts.py

@@ -6,17 +6,12 @@ ANSWER_PAT = "Answer:"
 UNCERTAINTY_PAT = "?"
 QUOTE_PAT = "Quote:"
 
-SYSTEM_ROLE = "You are a Question Answering system that answers queries based on provided documents. "
-
 BASE_PROMPT = (
     f"Answer the query based on provided documents and quote relevant sections. "
     f"Respond with a json containing a concise answer and up to three most relevant quotes from the documents. "
     f"The quotes must be EXACT substrings from the documents.\n"
 )
 
-UNABLE_TO_FIND_JSON_MSG = (
-    "If the query cannot be answered based on the documents, respond with {}. "
-)
 
 SAMPLE_QUESTION = "Where is the Eiffel Tower?"
 
@@ -106,12 +101,21 @@ def freeform_processor(question: str, documents: list[str]) -> str:
 
 
 def json_chat_processor(question: str, documents: list[str]) -> list[dict[str, str]]:
-    role_msg = (
-        SYSTEM_ROLE
-        + 'Start by reading the following documents and responding with "Acknowledged"'
+    intro_msg = (
+        "You are a Question Answering assistant that answers queries based on provided documents.\n"
+        'Start by reading the following documents and responding with "Acknowledged".'
     )
 
-    messages = [{"role": "system", "content": role_msg}]
+    task_msg = (
+        "Now answer the next user query based on documents above and quote relevant sections.\n"
+        "Respond with a JSON containing the answer and up to three most relevant quotes from the documents.\n"
+        "If the query cannot be answered based on the documents, do not provide an answer.\n"
+        "All quotes MUST be EXACT substrings from provided documents.\n"
+        "Your responses should be informative and concise.\n"
+        "You MUST prioritize information from provided documents over internal knowledge.\n"
+        f"Sample response:\n{json.dumps(SAMPLE_JSON_RESPONSE)}"
+    )
+    messages = [{"role": "system", "content": intro_msg}]
 
     for document in documents:
         messages.extend(
@@ -123,18 +127,10 @@ def json_chat_processor(question: str, documents: list[str]) -> list[dict[str, s
                 {"role": "assistant", "content": "Acknowledged"},
             ]
         )
-    sample_msg = (
-        f"Now answer the user query based on documents above and quote relevant sections. "
-        f"Respond with a json containing a concise answer and up to three most relevant quotes from the documents.\n"
-        f"Sample response: {json.dumps(SAMPLE_JSON_RESPONSE)}"
-    )
-    messages.append({"role": "system", "content": sample_msg})
+    messages.append({"role": "system", "content": task_msg})
 
     messages.append({"role": "user", "content": f"{QUESTION_PAT}\n{question}\n"})
 
-    # Note that the below will be dropped in reflexion if used
-    messages.append({"role": "assistant", "content": "Answer Json:\n"})
-
     return messages
 
 

backend/danswer/direct_qa/question_answer.py

@@ -324,10 +324,57 @@ class OpenAIChatCompletionQA(QAModel):
         answer, quotes_dict = process_answer(model_output, context_docs)
         return answer, quotes_dict
 
-    @log_function_time()
     def answer_question_stream(
         self, query: str, context_docs: list[InferenceChunk]
-    ) -> Any:
-        raise NotImplementedError(
-            "Danswer with chat completion does not support streaming yet"
-        )
+    ) -> Generator[dict[str, Any] | None, None, None]:
+        top_contents = [ranked_chunk.content for ranked_chunk in context_docs]
+        messages = self.prompt_processor(query, top_contents)
+        logger.debug(messages)
+
+        try:
+            response = openai.ChatCompletion.create(
+                messages=messages,
+                temperature=0,
+                top_p=1,
+                frequency_penalty=0,
+                presence_penalty=0,
+                model=self.model_version,
+                max_tokens=self.max_output_tokens,
+                stream=True,
+            )
+
+            model_output = ""
+            found_answer_start = False
+            found_answer_end = False
+            for event in response:
+                event_dict = event["choices"][0]["delta"]
+                if (
+                    "content" not in event_dict
+                ):  # could be a role message or empty termination
+                    continue
+                event_text = event_dict["content"]
+                model_previous = model_output
+                model_output += event_text
+
+                if not found_answer_start and '{"answer":"' in model_output.replace(
+                    " ", ""
+                ).replace("\n", ""):
+                    found_answer_start = True
+                    continue
+
+                if found_answer_start and not found_answer_end:
+                    if stream_answer_end(model_previous, event_text):
+                        found_answer_end = True
+                        continue
+                    yield {"answer_data": event_text}
+
+        except Exception as e:
+            logger.exception(e)
+            model_output = "Model Failure"
+
+        logger.debug(model_output)
+
+        answer, quotes_dict = process_answer(model_output, context_docs)
+        logger.info(answer)
+
+        yield quotes_dict