"""A Tracer implementation that records to LangChain endpoint."""
from __future__ import annotations
import logging
import weakref
from concurrent.futures import Future, ThreadPoolExecutor, wait
from datetime import datetime, timezone
from typing import TYPE_CHECKING, Any, Callable, Dict, List, Optional, Union
from uuid import UUID
from langsmith import Client
from langsmith import utils as ls_utils
from tenacity import (
Retrying,
retry_if_exception_type,
stop_after_attempt,
wait_exponential_jitter,
)
from langchain_core.env import get_runtime_environment
from langchain_core.load import dumpd
from langchain_core.tracers.base import BaseTracer
from langchain_core.tracers.schemas import Run
if TYPE_CHECKING:
from langchain_core.messages import BaseMessage
logger = logging.getLogger(__name__)
_LOGGED = set()
_TRACERS: weakref.WeakSet[LangChainTracer] = weakref.WeakSet()
_CLIENT: Optional[Client] = None
_EXECUTOR: Optional[ThreadPoolExecutor] = None
[docs]def log_error_once(method: str, exception: Exception) -> None:
"""Log an error once."""
global _LOGGED
if (method, type(exception)) in _LOGGED:
return
_LOGGED.add((method, type(exception)))
logger.error(exception)
[docs]def wait_for_all_tracers() -> None:
"""Wait for all tracers to finish."""
global _TRACERS
for tracer in list(_TRACERS):
if tracer is not None:
tracer.wait_for_futures()
[docs]def get_client() -> Client:
"""Get the client."""
global _CLIENT
if _CLIENT is None:
_CLIENT = Client()
return _CLIENT
def _get_executor() -> ThreadPoolExecutor:
"""Get the executor."""
global _EXECUTOR
if _EXECUTOR is None:
_EXECUTOR = ThreadPoolExecutor()
return _EXECUTOR
def _copy(run: Run) -> Run:
"""Copy a run."""
try:
return run.copy(deep=True)
except TypeError:
# Fallback in case the object contains a lock or other
# non-pickleable object
return run.copy()
[docs]class LangChainTracer(BaseTracer):
"""An implementation of the SharedTracer that POSTS to the langchain endpoint."""
[docs] def __init__(
self,
example_id: Optional[Union[UUID, str]] = None,
project_name: Optional[str] = None,
client: Optional[Client] = None,
tags: Optional[List[str]] = None,
use_threading: bool = True,
**kwargs: Any,
) -> None:
"""Initialize the LangChain tracer."""
super().__init__(**kwargs)
self.example_id = (
UUID(example_id) if isinstance(example_id, str) else example_id
)
self.project_name = project_name or ls_utils.get_tracer_project()
self.client = client or get_client()
self._futures: weakref.WeakSet[Future] = weakref.WeakSet()
self.tags = tags or []
self.executor = _get_executor() if use_threading else None
self.latest_run: Optional[Run] = None
global _TRACERS
_TRACERS.add(self)
[docs] def on_chat_model_start(
self,
serialized: Dict[str, Any],
messages: List[List[BaseMessage]],
*,
run_id: UUID,
tags: Optional[List[str]] = None,
parent_run_id: Optional[UUID] = None,
metadata: Optional[Dict[str, Any]] = None,
name: Optional[str] = None,
**kwargs: Any,
) -> Run:
"""Start a trace for an LLM run."""
parent_run_id_ = str(parent_run_id) if parent_run_id else None
execution_order = self._get_execution_order(parent_run_id_)
start_time = datetime.now(timezone.utc)
if metadata:
kwargs.update({"metadata": metadata})
chat_model_run = Run(
id=run_id,
parent_run_id=parent_run_id,
serialized=serialized,
inputs={"messages": [[dumpd(msg) for msg in batch] for batch in messages]},
extra=kwargs,
events=[{"name": "start", "time": start_time}],
start_time=start_time,
execution_order=execution_order,
child_execution_order=execution_order,
run_type="llm",
tags=tags,
name=name,
)
self._start_trace(chat_model_run)
self._on_chat_model_start(chat_model_run)
return chat_model_run
def _persist_run(self, run: Run) -> None:
run_ = run.copy()
run_.reference_example_id = self.example_id
self.latest_run = run_
[docs] def get_run_url(self) -> str:
"""Get the LangSmith root run URL"""
if not self.latest_run:
raise ValueError("No traced run found.")
# If this is the first run in a project, the project may not yet be created.
# This method is only really useful for debugging flows, so we will assume
# there is some tolerace for latency.
for attempt in Retrying(
stop=stop_after_attempt(5),
wait=wait_exponential_jitter(),
retry=retry_if_exception_type(ls_utils.LangSmithError),
):
with attempt:
return self.client.get_run_url(
run=self.latest_run, project_name=self.project_name
)
raise ValueError("Failed to get run URL.")
def _get_tags(self, run: Run) -> List[str]:
"""Get combined tags for a run."""
tags = set(run.tags or [])
tags.update(self.tags or [])
return list(tags)
def _persist_run_single(self, run: Run) -> None:
"""Persist a run."""
run_dict = run.dict(exclude={"child_runs"})
run_dict["tags"] = self._get_tags(run)
extra = run_dict.get("extra", {})
extra["runtime"] = get_runtime_environment()
run_dict["extra"] = extra
try:
self.client.create_run(**run_dict, project_name=self.project_name)
except Exception as e:
# Errors are swallowed by the thread executor so we need to log them here
log_error_once("post", e)
raise
def _update_run_single(self, run: Run) -> None:
"""Update a run."""
try:
run_dict = run.dict()
run_dict["tags"] = self._get_tags(run)
self.client.update_run(run.id, **run_dict)
except Exception as e:
# Errors are swallowed by the thread executor so we need to log them here
log_error_once("patch", e)
raise
def _submit(self, function: Callable[[Run], None], run: Run) -> None:
"""Submit a function to the executor."""
if self.executor is None:
function(run)
else:
self._futures.add(self.executor.submit(function, run))
def _on_llm_start(self, run: Run) -> None:
"""Persist an LLM run."""
if run.parent_run_id is None:
run.reference_example_id = self.example_id
self._submit(self._persist_run_single, _copy(run))
def _on_chat_model_start(self, run: Run) -> None:
"""Persist an LLM run."""
if run.parent_run_id is None:
run.reference_example_id = self.example_id
self._submit(self._persist_run_single, _copy(run))
def _on_llm_end(self, run: Run) -> None:
"""Process the LLM Run."""
self._submit(self._update_run_single, _copy(run))
def _on_llm_error(self, run: Run) -> None:
"""Process the LLM Run upon error."""
self._submit(self._update_run_single, _copy(run))
def _on_chain_start(self, run: Run) -> None:
"""Process the Chain Run upon start."""
if run.parent_run_id is None:
run.reference_example_id = self.example_id
self._submit(self._persist_run_single, _copy(run))
def _on_chain_end(self, run: Run) -> None:
"""Process the Chain Run."""
self._submit(self._update_run_single, _copy(run))
def _on_chain_error(self, run: Run) -> None:
"""Process the Chain Run upon error."""
self._submit(self._update_run_single, _copy(run))
def _on_tool_start(self, run: Run) -> None:
"""Process the Tool Run upon start."""
if run.parent_run_id is None:
run.reference_example_id = self.example_id
self._submit(self._persist_run_single, _copy(run))
def _on_tool_end(self, run: Run) -> None:
"""Process the Tool Run."""
self._submit(self._update_run_single, _copy(run))
def _on_tool_error(self, run: Run) -> None:
"""Process the Tool Run upon error."""
self._submit(self._update_run_single, _copy(run))
def _on_retriever_start(self, run: Run) -> None:
"""Process the Retriever Run upon start."""
if run.parent_run_id is None:
run.reference_example_id = self.example_id
self._submit(self._persist_run_single, _copy(run))
def _on_retriever_end(self, run: Run) -> None:
"""Process the Retriever Run."""
self._submit(self._update_run_single, _copy(run))
def _on_retriever_error(self, run: Run) -> None:
"""Process the Retriever Run upon error."""
self._submit(self._update_run_single, _copy(run))
[docs] def wait_for_futures(self) -> None:
"""Wait for the given futures to complete."""
wait(self._futures)