langchain/libs/core/langchain_core/tracers/context.py

from __future__ import annotations

from contextlib import contextmanager
from contextvars import ContextVar
from typing import (
    TYPE_CHECKING,
    Any,
    Generator,
    List,
    Optional,
    Tuple,
    Type,
    Union,
    cast,
)
from uuid import UUID

from langsmith import utils as ls_utils
from langsmith.run_helpers import get_run_tree_context

from langchain_core.tracers.langchain import LangChainTracer
from langchain_core.tracers.run_collector import RunCollectorCallbackHandler
from langchain_core.tracers.schemas import TracerSessionV1
from langchain_core.utils.env import env_var_is_set

if TYPE_CHECKING:
    from langsmith import Client as LangSmithClient

    from langchain_core.callbacks.base import BaseCallbackHandler, Callbacks
    from langchain_core.callbacks.manager import AsyncCallbackManager, CallbackManager

# for backwards partial compatibility if this is imported by users but unused
tracing_callback_var: Any = None
tracing_v2_callback_var: ContextVar[Optional[LangChainTracer]] = ContextVar(
    "tracing_callback_v2", default=None
)  # noqa: E501
run_collector_var: ContextVar[Optional[RunCollectorCallbackHandler]] = ContextVar(
    "run_collector", default=None
)  # noqa: E501


@contextmanager
def tracing_enabled(
    session_name: str = "default",
) -> Generator[TracerSessionV1, None, None]:
    """Throws an error because this has been replaced by tracing_v2_enabled."""
    raise RuntimeError(
        "tracing_enabled is no longer supported. Please use tracing_enabled_v2 instead."
    )


@contextmanager
def tracing_v2_enabled(
    project_name: Optional[str] = None,
    *,
    example_id: Optional[Union[str, UUID]] = None,
    tags: Optional[List[str]] = None,
    client: Optional[LangSmithClient] = None,
) -> Generator[LangChainTracer, None, None]:
    """Instruct LangChain to log all runs in context to LangSmith.

    Args:
        project_name (str, optional): The name of the project.
            Defaults to "default".
        example_id (str or UUID, optional): The ID of the example.
            Defaults to None.
        tags (List[str], optional): The tags to add to the run.
            Defaults to None.
        client (LangSmithClient, optional): The client of the langsmith.
            Defaults to None.

    Returns:
        None

    Example:
        >>> with tracing_v2_enabled():
        ...     # LangChain code will automatically be traced

        You can use this to fetch the LangSmith run URL:

        >>> with tracing_v2_enabled() as cb:
        ...     chain.invoke("foo")
        ...     run_url = cb.get_run_url()
    """
    if isinstance(example_id, str):
        example_id = UUID(example_id)
    cb = LangChainTracer(
        example_id=example_id,
        project_name=project_name,
        tags=tags,
        client=client,
    )
    try:
        tracing_v2_callback_var.set(cb)
        yield cb
    finally:
        tracing_v2_callback_var.set(None)


@contextmanager
def collect_runs() -> Generator[RunCollectorCallbackHandler, None, None]:
    """Collect all run traces in context.

    Returns:
        run_collector.RunCollectorCallbackHandler: The run collector callback handler.

    Example:
        >>> with collect_runs() as runs_cb:
                chain.invoke("foo")
                run_id = runs_cb.traced_runs[0].id
    """
    cb = RunCollectorCallbackHandler()
    run_collector_var.set(cb)
    yield cb
    run_collector_var.set(None)


def _get_trace_callbacks(
    project_name: Optional[str] = None,
    example_id: Optional[Union[str, UUID]] = None,
    callback_manager: Optional[Union[CallbackManager, AsyncCallbackManager]] = None,
) -> Callbacks:
    if _tracing_v2_is_enabled():
        project_name_ = project_name or _get_tracer_project()
        tracer = tracing_v2_callback_var.get() or LangChainTracer(
            project_name=project_name_,
            example_id=example_id,
        )
        if callback_manager is None:
            from langchain_core.callbacks.base import Callbacks

            cb = cast(Callbacks, [tracer])
        else:
            if not any(
                isinstance(handler, LangChainTracer)
                for handler in callback_manager.handlers
            ):
                callback_manager.add_handler(tracer, True)
                # If it already has a LangChainTracer, we don't need to add another one.
                # this would likely mess up the trace hierarchy.
            cb = callback_manager
    else:
        cb = None
    return cb


def _tracing_v2_is_enabled() -> bool:
    return (
        env_var_is_set("LANGCHAIN_TRACING_V2")
        or env_var_is_set("LANGSMITH_TRACING")
        or env_var_is_set("LANGSMITH_TRACING_V2")
        or tracing_v2_callback_var.get() is not None
        or get_run_tree_context() is not None
    )


def _get_tracer_project() -> str:
    run_tree = get_run_tree_context()
    return getattr(
        run_tree,
        "session_name",
        getattr(
            # Note, if people are trying to nest @traceable functions and the
            # tracing_v2_enabled context manager, this will likely mess up the
            # tree structure.
            tracing_v2_callback_var.get(),
            "project",
            # Have to set this to a string even though it always will return
            # a string because `get_tracer_project` technically can return
            # None, but only when a specific argument is supplied.
            # Therefore, this just tricks the mypy type checker
            str(ls_utils.get_tracer_project()),
        ),
    )


_configure_hooks: List[
    Tuple[
        ContextVar[Optional[BaseCallbackHandler]],
        bool,
        Optional[Type[BaseCallbackHandler]],
        Optional[str],
    ]
] = []


def register_configure_hook(
    context_var: ContextVar[Optional[Any]],
    inheritable: bool,
    handle_class: Optional[Type[BaseCallbackHandler]] = None,
    env_var: Optional[str] = None,
) -> None:
    """Register a configure hook.

    Args:
        context_var (ContextVar[Optional[Any]]): The context variable.
        inheritable (bool): Whether the context variable is inheritable.
        handle_class (Optional[Type[BaseCallbackHandler]], optional):
          The callback handler class. Defaults to None.
        env_var (Optional[str], optional): The environment variable. Defaults to None.

    Raises:
        ValueError: If env_var is set, handle_class must also be set
          to a non-None value.
    """
    if env_var is not None and handle_class is None:
        raise ValueError(
            "If env_var is set, handle_class must also be set to a non-None value."
        )
    from langchain_core.callbacks.base import BaseCallbackHandler

    _configure_hooks.append(
        (
            # the typings of ContextVar do not have the generic arg set as covariant
            # so we have to cast it
            cast(ContextVar[Optional[BaseCallbackHandler]], context_var),
            inheritable,
            handle_class,
            env_var,
        )
    )


register_configure_hook(run_collector_var, False)