Log total, ttft chat response time on start, end llm_response events

- Deduplicate code to collect chat telemetry by relying on
  end_llm_response event
- Log time to first token and total chat response time for latency
  analysis of Khoj as an agent. Not just the latency of the LLM
- Remove duplicate timer in the image generation path

src/khoj/routers/api_chat.py

@@ -1,6 +1,7 @@
 import asyncio
 import json
 import logging
+import time
 from datetime import datetime
 from functools import partial
 from typing import Any, Dict, List, Optional
@@ -22,11 +23,7 @@ from khoj.database.adapters import (
     aget_user_name,
 )
 from khoj.database.models import KhojUser
-from khoj.processor.conversation.prompts import (
+from khoj.processor.conversation.prompts import help_message, no_entries_found
-    help_message,
-    no_entries_found,
-    no_notes_found,
-)
 from khoj.processor.conversation.utils import save_to_conversation_log
 from khoj.processor.speech.text_to_speech import generate_text_to_speech
 from khoj.processor.tools.online_search import read_webpages, search_online
@@ -34,7 +31,6 @@ from khoj.routers.api import extract_references_and_questions
 from khoj.routers.helpers import (
     ApiUserRateLimiter,
     CommonQueryParams,
-    CommonQueryParamsClass,
     ConversationCommandRateLimiter,
     agenerate_chat_response,
     aget_relevant_information_sources,
@@ -547,22 +543,27 @@ async def chat(
     ),
 ):
     async def event_generator(q: str):
+        start_time = time.perf_counter()
+        ttft = None
+        chat_metadata: dict = {}
         connection_alive = True
         user: KhojUser = request.user.object
         q = unquote(q)
 
         async def send_event(event_type: str, data: str | dict):
-            nonlocal connection_alive
+            nonlocal connection_alive, ttft
             if not connection_alive or await request.is_disconnected():
                 connection_alive = False
                 logger.warn(f"User {user} disconnected from {common.client} client")
                 return
             try:
+                if event_type == "end_llm_response":
+                    collect_telemetry()
+                if event_type == "start_llm_response":
+                    ttft = time.perf_counter() - start_time
                 if event_type == "message":
                     yield data
-                elif event_type == "references":
+                elif event_type == "references" or stream:
-                    yield json.dumps({"type": event_type, "data": data})
-                elif stream:
                     yield json.dumps({"type": event_type, "data": data})
             except asyncio.CancelledError:
                 connection_alive = False
@@ -581,12 +582,36 @@ async def chat(
             async for result in send_event("end_llm_response", ""):
                 yield result
 
+        def collect_telemetry():
+            # Gather chat response telemetry
+            nonlocal chat_metadata
+            latency = time.perf_counter() - start_time
+            cmd_set = set([cmd.value for cmd in conversation_commands])
+            chat_metadata = chat_metadata or {}
+            chat_metadata["conversation_command"] = cmd_set
+            chat_metadata["agent"] = conversation.agent.slug if conversation.agent else None
+            chat_metadata["latency"] = f"{latency:.3f}"
+            chat_metadata["ttft_latency"] = f"{ttft:.3f}"
+
+            logger.info(f"Chat response time to first token: {ttft:.3f} seconds")
+            logger.info(f"Chat response total time: {latency:.3f} seconds")
+            update_telemetry_state(
+                request=request,
+                telemetry_type="api",
+                api="chat",
+                client=request.user.client_app,
+                user_agent=request.headers.get("user-agent"),
+                host=request.headers.get("host"),
+                metadata=chat_metadata,
+            )
+
         conversation = await ConversationAdapters.aget_conversation_by_user(
             user, client_application=request.user.client_app, conversation_id=conversation_id, title=title
         )
         if not conversation:
-            async for result in send_llm_response(f"No Conversation id: {conversation_id}  not found"):
+            async for result in send_llm_response(f"Conversation {conversation_id} not found"):
                 yield result
+            return
 
         await is_ready_to_chat(user)
 
@@ -684,12 +709,6 @@ async def chat(
                 client_application=request.user.client_app,
                 conversation_id=conversation_id,
             )
-            update_telemetry_state(
-                request=request,
-                telemetry_type="api",
-                api="chat",
-                metadata={"conversation_command": conversation_commands[0].value},
-            )
             return
 
         custom_filters = []
@@ -732,17 +751,6 @@ async def chat(
                 inferred_queries=[query_to_run],
                 automation_id=automation.id,
             )
-            common = CommonQueryParamsClass(
-                client=request.user.client_app,
-                user_agent=request.headers.get("user-agent"),
-                host=request.headers.get("host"),
-            )
-            update_telemetry_state(
-                request=request,
-                telemetry_type="api",
-                api="chat",
-                **common.__dict__,
-            )
             async for result in send_llm_response(llm_response):
                 yield result
             return
@@ -839,12 +847,6 @@ async def chat(
         # Generate Output
         ## Generate Image Output
         if ConversationCommand.Image in conversation_commands:
-            update_telemetry_state(
-                request=request,
-                telemetry_type="api",
-                api="chat",
-                metadata={"conversation_command": conversation_commands[0].value},
-            )
             async for result in text_to_image(
                 q,
                 user,
@@ -913,17 +915,6 @@ async def chat(
             user_name,
         )
 
-        cmd_set = set([cmd.value for cmd in conversation_commands])
-        chat_metadata["conversation_command"] = cmd_set
-        chat_metadata["agent"] = conversation.agent.slug if conversation.agent else None
-
-        update_telemetry_state(
-            request=request,
-            telemetry_type="api",
-            api="chat",
-            metadata=chat_metadata,
-        )
-
         # Send Response
         async for result in send_event("start_llm_response", ""):
             yield result

src/khoj/routers/helpers.py

@@ -780,7 +780,6 @@ async def text_to_image(
             chat_history += f"Q: Prompt: {chat['intent']['query']}\n"
             chat_history += f"A: Improved Prompt: {chat['intent']['inferred-queries'][0]}\n"
 
-    with timer("Improve the original user query", logger):
     if send_status_func:
         async for event in send_status_func("**✍🏽 Enhancing the Painting Prompt**"):
             yield {"status": event}