root_listeners.py — langchain Source File

Source Code

"""Tracers that call listeners."""

from collections.abc import Awaitable, Callable
from typing import TYPE_CHECKING

from langchain_core.runnables.config import (
    RunnableConfig,
    acall_func_with_variable_args,
    call_func_with_variable_args,
)
from langchain_core.tracers.base import AsyncBaseTracer, BaseTracer
from langchain_core.tracers.schemas import Run

if TYPE_CHECKING:
    from uuid import UUID

Listener = Callable[[Run], None] | Callable[[Run, RunnableConfig], None]
AsyncListener = (
    Callable[[Run], Awaitable[None]] | Callable[[Run, RunnableConfig], Awaitable[None]]
)


class RootListenersTracer(BaseTracer):
    """Tracer that calls listeners on run start, end, and error."""

    log_missing_parent = False
    """Whether to log a warning if the parent is missing."""

    def __init__(
        self,
        *,
        config: RunnableConfig,
        on_start: Listener | None,
        on_end: Listener | None,
        on_error: Listener | None,
    ) -> None:
        """Initialize the tracer.

        Args:
            config: The runnable config.
            on_start: The listener to call on run start.
            on_end: The listener to call on run end.
            on_error: The listener to call on run error
        """
        super().__init__(_schema_format="original+chat")

        self.config = config
        self._arg_on_start = on_start
        self._arg_on_end = on_end
        self._arg_on_error = on_error
        self.root_id: UUID | None = None

    def _persist_run(self, run: Run) -> None:
        # This is a legacy method only called once for an entire run tree
        # therefore not useful here
        pass

    def _on_run_create(self, run: Run) -> None:
        if self.root_id is not None:
            return
// ... (71 more lines)