langchain/langchain/callbacks/base.py

"""Base callback handler that can be used to handle callbacks from langchain."""

from abc import ABC, abstractmethod
from typing import Any, Dict, List

from pydantic import BaseModel

from langchain.schema import AgentAction, AgentFinish, LLMResult


class BaseCallbackHandler(BaseModel, ABC):
    """Base callback handler that can be used to handle callbacks from langchain."""

    ignore_llm: bool = False
    ignore_chain: bool = False
    ignore_agent: bool = False

    @abstractmethod
    def on_llm_start(
        self, serialized: Dict[str, Any], prompts: List[str], **kwargs: Any
    ) -> None:
        """Run when LLM starts running."""

    @abstractmethod
    def on_llm_end(
        self,
        response: LLMResult,
    ) -> None:
        """Run when LLM ends running."""

    @abstractmethod
    def on_llm_error(self, error: Exception) -> None:
        """Run when LLM errors."""

    @abstractmethod
    def on_chain_start(
        self, serialized: Dict[str, Any], inputs: Dict[str, Any], **kwargs: Any
    ) -> None:
        """Run when chain starts running."""

    @abstractmethod
    def on_chain_end(self, outputs: Dict[str, Any]) -> None:
        """Run when chain ends running."""

    @abstractmethod
    def on_chain_error(self, error: Exception) -> None:
        """Run when chain errors."""

    @abstractmethod
    def on_tool_start(
        self, serialized: Dict[str, Any], action: AgentAction, **kwargs: Any
    ) -> None:
        """Run when tool starts running."""

    @abstractmethod
    def on_tool_end(self, output: str, **kwargs: Any) -> None:
        """Run when tool ends running."""

    @abstractmethod
    def on_tool_error(self, error: Exception) -> None:
        """Run when tool errors."""

    @abstractmethod
    def on_text(self, text: str, **kwargs: Any) -> None:
        """Run on arbitrary text."""

    @abstractmethod
    def on_agent_end(self, finish: AgentFinish, **kwargs: Any) -> None:
        """Run on agent end."""


class BaseCallbackManager(BaseCallbackHandler, ABC):
    """Base callback manager that can be used to handle callbacks from LangChain."""

    @abstractmethod
    def add_handler(self, callback: BaseCallbackHandler) -> None:
        """Add a handler to the callback manager."""

    @abstractmethod
    def remove_handler(self, handler: BaseCallbackHandler) -> None:
        """Remove a handler from the callback manager."""

    @abstractmethod
    def set_handler(self, handler: BaseCallbackHandler) -> None:
        """Set handler as the only handler on the callback manager."""


class CallbackManager(BaseCallbackManager):
    """Callback manager that can be used to handle callbacks from langchain."""

    handlers: List[BaseCallbackHandler]

    def on_llm_start(
        self, serialized: Dict[str, Any], prompts: List[str], **kwargs: Any
    ) -> None:
        """Run when LLM starts running."""
        for handler in self.handlers:
            if not handler.ignore_llm:
                handler.on_llm_start(serialized, prompts, **kwargs)

    def on_llm_end(
        self,
        response: LLMResult,
    ) -> None:
        """Run when LLM ends running."""
        for handler in self.handlers:
            if not handler.ignore_llm:
                handler.on_llm_end(response)

    def on_llm_error(self, error: Exception) -> None:
        """Run when LLM errors."""
        for handler in self.handlers:
            if not handler.ignore_llm:
                handler.on_llm_error(error)

    def on_chain_start(
        self, serialized: Dict[str, Any], inputs: Dict[str, Any], **kwargs: Any
    ) -> None:
        """Run when chain starts running."""
        for handler in self.handlers:
            if not handler.ignore_chain:
                handler.on_chain_start(serialized, inputs, **kwargs)

    def on_chain_end(self, outputs: Dict[str, Any]) -> None:
        """Run when chain ends running."""
        for handler in self.handlers:
            if not handler.ignore_chain:
                handler.on_chain_end(outputs)

    def on_chain_error(self, error: Exception) -> None:
        """Run when chain errors."""
        for handler in self.handlers:
            if not handler.ignore_chain:
                handler.on_chain_error(error)

    def on_tool_start(
        self, serialized: Dict[str, Any], action: AgentAction, **kwargs: Any
    ) -> None:
        """Run when tool starts running."""
        for handler in self.handlers:
            if not handler.ignore_agent:
                handler.on_tool_start(serialized, action, **kwargs)

    def on_tool_end(self, output: str, **kwargs: Any) -> None:
        """Run when tool ends running."""
        for handler in self.handlers:
            if not handler.ignore_agent:
                handler.on_tool_end(output, **kwargs)

    def on_tool_error(self, error: Exception) -> None:
        """Run when tool errors."""
        for handler in self.handlers:
            if not handler.ignore_agent:
                handler.on_tool_error(error)

    def on_text(self, text: str, **kwargs: Any) -> None:
        """Run on additional input from chains and agents."""
        for handler in self.handlers:
            handler.on_text(text, **kwargs)

    def on_agent_end(self, finish: AgentFinish, **kwargs: Any) -> None:
        """Run on agent end."""
        for handler in self.handlers:
            if not handler.ignore_agent:
                handler.on_agent_end(finish, **kwargs)

    def add_handler(self, handler: BaseCallbackHandler) -> None:
        """Add a handler to the callback manager."""
        self.handlers.append(handler)

    def remove_handler(self, handler: BaseCallbackHandler) -> None:
        """Remove a handler from the callback manager."""
        self.handlers.remove(handler)

    def set_handler(self, handler: BaseCallbackHandler) -> None:
        """Set handler as the only handler on the callback manager."""
        self.handlers = [handler]