"""A tracer that runs evaluators over completed runs."""
from __future__ import annotations
import logging
import threading
import weakref
from collections.abc import Sequence
from concurrent.futures import Future, ThreadPoolExecutor, wait
from typing import Any, Optional, Union, cast
from uuid import UUID
import langsmith
from langsmith.evaluation.evaluator import EvaluationResult, EvaluationResults
from langchain_core.tracers import langchain as langchain_tracer
from langchain_core.tracers.base import BaseTracer
from langchain_core.tracers.context import tracing_v2_enabled
from langchain_core.tracers.langchain import _get_executor
from langchain_core.tracers.schemas import Run
logger = logging.getLogger(__name__)
_TRACERS: weakref.WeakSet[EvaluatorCallbackHandler] = weakref.WeakSet()
[docs]
def wait_for_all_evaluators() -> None:
"""Wait for all tracers to finish."""
global _TRACERS
for tracer in list(_TRACERS):
if tracer is not None:
tracer.wait_for_futures()
[docs]
class EvaluatorCallbackHandler(BaseTracer):
"""Tracer that runs a run evaluator whenever a run is persisted.
Parameters
----------
evaluators : Sequence[RunEvaluator]
The run evaluators to apply to all top level runs.
client : LangSmith Client, optional
The LangSmith client instance to use for evaluating the runs.
If not specified, a new instance will be created.
example_id : Union[UUID, str], optional
The example ID to be associated with the runs.
project_name : str, optional
The LangSmith project name to be organize eval chain runs under.
Attributes
----------
example_id : Union[UUID, None]
The example ID associated with the runs.
client : Client
The LangSmith client instance used for evaluating the runs.
evaluators : Sequence[RunEvaluator]
The sequence of run evaluators to be executed.
executor : ThreadPoolExecutor
The thread pool executor used for running the evaluators.
futures : Set[Future]
The set of futures representing the running evaluators.
skip_unfinished : bool
Whether to skip runs that are not finished or raised
an error.
project_name : Optional[str]
The LangSmith project name to be organize eval chain runs under.
"""
name: str = "evaluator_callback_handler"
[docs]
def __init__(
self,
evaluators: Sequence[langsmith.RunEvaluator],
client: Optional[langsmith.Client] = None,
example_id: Optional[Union[UUID, str]] = None,
skip_unfinished: bool = True,
project_name: Optional[str] = "evaluators",
max_concurrency: Optional[int] = None,
**kwargs: Any,
) -> None:
super().__init__(**kwargs)
self.example_id = (
UUID(example_id) if isinstance(example_id, str) else example_id
)
self.client = client or langchain_tracer.get_client()
self.evaluators = evaluators
if max_concurrency is None:
self.executor: Optional[ThreadPoolExecutor] = _get_executor()
elif max_concurrency > 0:
self.executor = ThreadPoolExecutor(max_workers=max_concurrency)
weakref.finalize(
self,
lambda: cast(ThreadPoolExecutor, self.executor).shutdown(wait=True),
)
else:
self.executor = None
self.futures: weakref.WeakSet[Future] = weakref.WeakSet()
self.skip_unfinished = skip_unfinished
self.project_name = project_name
self.logged_eval_results: dict[tuple[str, str], list[EvaluationResult]] = {}
self.lock = threading.Lock()
global _TRACERS
_TRACERS.add(self)
def _evaluate_in_project(self, run: Run, evaluator: langsmith.RunEvaluator) -> None:
"""Evaluate the run in the project.
Args:
----------
run : Run
The run to be evaluated.
evaluator : RunEvaluator
The evaluator to use for evaluating the run.
"""
try:
if self.project_name is None:
eval_result = self.client.evaluate_run(run, evaluator)
eval_results = [eval_result]
with tracing_v2_enabled(
project_name=self.project_name, tags=["eval"], client=self.client
) as cb:
reference_example = (
self.client.read_example(run.reference_example_id)
if run.reference_example_id
else None
)
evaluation_result = evaluator.evaluate_run(
# This is subclass, but getting errors for some reason
run, # type: ignore
example=reference_example,
)
eval_results = self._log_evaluation_feedback(
evaluation_result,
run,
source_run_id=cb.latest_run.id if cb.latest_run else None,
)
except Exception as e:
logger.error(
f"Error evaluating run {run.id} with "
f"{evaluator.__class__.__name__}: {repr(e)}",
exc_info=True,
)
raise e
example_id = str(run.reference_example_id)
with self.lock:
for res in eval_results:
run_id = str(getattr(res, "target_run_id", run.id))
self.logged_eval_results.setdefault((run_id, example_id), []).append(
res
)
def _select_eval_results(
self,
results: Union[EvaluationResult, EvaluationResults],
) -> list[EvaluationResult]:
if isinstance(results, EvaluationResult):
results_ = [results]
elif isinstance(results, dict) and "results" in results:
results_ = cast(list[EvaluationResult], results["results"])
else:
msg = (
f"Invalid evaluation result type {type(results)}."
" Expected EvaluationResult or EvaluationResults."
)
raise TypeError(msg)
return results_
def _log_evaluation_feedback(
self,
evaluator_response: Union[EvaluationResult, EvaluationResults],
run: Run,
source_run_id: Optional[UUID] = None,
) -> list[EvaluationResult]:
results = self._select_eval_results(evaluator_response)
for res in results:
source_info_: dict[str, Any] = {}
if res.evaluator_info:
source_info_ = {**res.evaluator_info, **source_info_}
run_id_ = getattr(res, "target_run_id", None)
if run_id_ is None:
run_id_ = run.id
self.client.create_feedback(
run_id_,
res.key,
score=res.score,
value=res.value,
comment=res.comment,
correction=res.correction,
source_info=source_info_,
source_run_id=res.source_run_id or source_run_id,
feedback_source_type=langsmith.schemas.FeedbackSourceType.MODEL,
)
return results
def _persist_run(self, run: Run) -> None:
"""Run the evaluator on the run.
Args:
----------
run : Run
The run to be evaluated.
"""
if self.skip_unfinished and not run.outputs:
logger.debug(f"Skipping unfinished run {run.id}")
return
run_ = run.copy()
run_.reference_example_id = self.example_id
for evaluator in self.evaluators:
if self.executor is None:
self._evaluate_in_project(run_, evaluator)
else:
self.futures.add(
self.executor.submit(self._evaluate_in_project, run_, evaluator)
)
[docs]
def wait_for_futures(self) -> None:
"""Wait for all futures to complete."""
wait(self.futures)
