核心回调类#

class CallbackManager(BaseCallbackHandler, ABC):
    """
    Callback manager that handles callbacks for events within LlamaIndex.

    The callback manager provides a way to call handlers on event starts/ends.

    Additionally, the callback manager traces the current stack of events.
    It does this by using a few key attributes.
    - trace_stack - The current stack of events that have not ended yet.
                    When an event ends, it's removed from the stack.
                    Since this is a contextvar, it is unique to each
                    thread/task.
    - trace_map - A mapping of event ids to their children events.
                  On the start of events, the bottom of the trace stack
                  is used as the current parent event for the trace map.
    - trace_id - A simple name for the current trace, usually denoting the
                 entrypoint (query, index_construction, insert, etc.)

    Args:
        handlers (List[BaseCallbackHandler]): list of handlers to use.

    Usage:
        with callback_manager.event(CBEventType.QUERY) as event:
            event.on_start(payload={key, val})
            ...
            event.on_end(payload={key, val})

    """

    def __init__(self, handlers: Optional[List[BaseCallbackHandler]] = None):
        """Initialize the manager with a list of handlers."""
        from llama_index.core import global_handler

        handlers = handlers or []

        # add eval handlers based on global defaults
        if global_handler is not None:
            new_handler = global_handler
            # go through existing handlers, check if any are same type as new handler
            # if so, error
            for existing_handler in handlers:
                if isinstance(existing_handler, type(new_handler)):
                    raise ValueError(
                        "Cannot add two handlers of the same type "
                        f"{type(new_handler)} to the callback manager."
                    )
            handlers.append(new_handler)

        # if we passed in no handlers, use the global default
        if len(handlers) == 0:
            from llama_index.core.settings import Settings

            # hidden var access to prevent recursion in getter
            cb_manager = Settings._callback_manager
            if cb_manager is not None:
                handlers = cb_manager.handlers

        self.handlers: List[BaseCallbackHandler] = handlers
        self._trace_map: Dict[str, List[str]] = defaultdict(list)

    def on_event_start(
        self,
        event_type: CBEventType,
        payload: Optional[Dict[str, Any]] = None,
        event_id: Optional[str] = None,
        parent_id: Optional[str] = None,
        **kwargs: Any,
    ) -> str:
        """Run handlers when an event starts and return id of event."""
        event_id = event_id or str(uuid.uuid4())

        # if no trace is running, start a default trace
        try:
            parent_id = parent_id or global_stack_trace.get()[-1]
        except IndexError:
            self.start_trace("llama-index")
            parent_id = global_stack_trace.get()[-1]
        parent_id = cast(str, parent_id)
        self._trace_map[parent_id].append(event_id)
        for handler in self.handlers:
            if event_type not in handler.event_starts_to_ignore:
                handler.on_event_start(
                    event_type,
                    payload,
                    event_id=event_id,
                    parent_id=parent_id,
                    **kwargs,
                )

        if event_type not in LEAF_EVENTS:
            # copy the stack trace to prevent conflicts with threads/coroutines
            current_trace_stack = global_stack_trace.get().copy()
            current_trace_stack.append(event_id)
            global_stack_trace.set(current_trace_stack)

        return event_id

    def on_event_end(
        self,
        event_type: CBEventType,
        payload: Optional[Dict[str, Any]] = None,
        event_id: Optional[str] = None,
        **kwargs: Any,
    ) -> None:
        """Run handlers when an event ends."""
        event_id = event_id or str(uuid.uuid4())
        for handler in self.handlers:
            if event_type not in handler.event_ends_to_ignore:
                handler.on_event_end(event_type, payload, event_id=event_id, **kwargs)

        if event_type not in LEAF_EVENTS:
            # copy the stack trace to prevent conflicts with threads/coroutines
            current_trace_stack = global_stack_trace.get().copy()
            current_trace_stack.pop()
            global_stack_trace.set(current_trace_stack)

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

    @contextmanager
    def event(
        self,
        event_type: CBEventType,
        payload: Optional[Dict[str, Any]] = None,
        event_id: Optional[str] = None,
    ) -> Generator["EventContext", None, None]:
        """
        Context manager for lanching and shutdown of events.

        Handles sending on_evnt_start and on_event_end to handlers for specified event.

        Usage:
            with callback_manager.event(CBEventType.QUERY, payload={key, val}) as event:
                ...
                event.on_end(payload={key, val})  # optional
        """
        # create event context wrapper
        event = EventContext(self, event_type, event_id=event_id)
        event.on_start(payload=payload)

        payload = None
        try:
            yield event
        except Exception as e:
            # data already logged to trace?
            if not hasattr(e, "event_added"):
                payload = {EventPayload.EXCEPTION: e}
                e.event_added = True  # type: ignore
                if not event.finished:
                    event.on_end(payload=payload)
            raise
        finally:
            # ensure event is ended
            if not event.finished:
                event.on_end(payload=payload)

    @contextmanager
    def as_trace(self, trace_id: str) -> Generator[None, None, None]:
        """Context manager tracer for lanching and shutdown of traces."""
        self.start_trace(trace_id=trace_id)

        try:
            yield
        except Exception as e:
            # event already added to trace?
            if not hasattr(e, "event_added"):
                self.on_event_start(
                    CBEventType.EXCEPTION, payload={EventPayload.EXCEPTION: e}
                )
                e.event_added = True  # type: ignore

            raise
        finally:
            # ensure trace is ended
            self.end_trace(trace_id=trace_id)

    def start_trace(self, trace_id: Optional[str] = None) -> None:
        """Run when an overall trace is launched."""
        current_trace_stack_ids = global_stack_trace_ids.get().copy()
        if trace_id is not None:
            if len(current_trace_stack_ids) == 0:
                self._reset_trace_events()

                for handler in self.handlers:
                    handler.start_trace(trace_id=trace_id)

                current_trace_stack_ids = [trace_id]
            else:
                current_trace_stack_ids.append(trace_id)

        global_stack_trace_ids.set(current_trace_stack_ids)

    def end_trace(
        self,
        trace_id: Optional[str] = None,
        trace_map: Optional[Dict[str, List[str]]] = None,
    ) -> None:
        """Run when an overall trace is exited."""
        current_trace_stack_ids = global_stack_trace_ids.get().copy()
        if trace_id is not None and len(current_trace_stack_ids) > 0:
            current_trace_stack_ids.pop()
            if len(current_trace_stack_ids) == 0:
                for handler in self.handlers:
                    handler.end_trace(trace_id=trace_id, trace_map=self._trace_map)
                current_trace_stack_ids = []

        global_stack_trace_ids.set(current_trace_stack_ids)

    def _reset_trace_events(self) -> None:
        """Helper function to reset the current trace."""
        self._trace_map = defaultdict(list)
        global_stack_trace.set([BASE_TRACE_EVENT])

    @property
    def trace_map(self) -> Dict[str, List[str]]:
        return self._trace_map

    @classmethod
    def __get_pydantic_core_schema__(
        cls, source: Type[Any], handler: GetCoreSchemaHandler
    ) -> CoreSchema:
        return core_schema.any_schema()

    @classmethod
    def __get_pydantic_json_schema__(
        cls, core_schema: CoreSchema, handler: GetJsonSchemaHandler
    ) -> Dict[str, Any]:
        json_schema = handler(core_schema)
        return handler.resolve_ref_schema(json_schema)

class BaseCallbackHandler(ABC):
    """Base callback handler that can be used to track event starts and ends."""

    def __init__(
        self,
        event_starts_to_ignore: List[CBEventType],
        event_ends_to_ignore: List[CBEventType],
    ) -> None:
        """Initialize the base callback handler."""
        self.event_starts_to_ignore = tuple(event_starts_to_ignore)
        self.event_ends_to_ignore = tuple(event_ends_to_ignore)

    @abstractmethod
    def on_event_start(
        self,
        event_type: CBEventType,
        payload: Optional[Dict[str, Any]] = None,
        event_id: str = "",
        parent_id: str = "",
        **kwargs: Any,
    ) -> str:
        """Run when an event starts and return id of event."""

    @abstractmethod
    def on_event_end(
        self,
        event_type: CBEventType,
        payload: Optional[Dict[str, Any]] = None,
        event_id: str = "",
        **kwargs: Any,
    ) -> None:
        """Run when an event ends."""

    @abstractmethod
    def start_trace(self, trace_id: Optional[str] = None) -> None:
        """Run when an overall trace is launched."""

    @abstractmethod
    def end_trace(
        self,
        trace_id: Optional[str] = None,
        trace_map: Optional[Dict[str, List[str]]] = None,
    ) -> None:
        """Run when an overall trace is exited."""

@dataclass
class CBEvent:
    """Generic class to store event information."""

    event_type: CBEventType
    payload: Optional[Dict[str, Any]] = None
    time: str = ""
    id_: str = ""

    def __post_init__(self) -> None:
        """Init time and id if needed."""
        if not self.time:
            self.time = datetime.now().strftime(TIMESTAMP_FORMAT)
        if not self.id_:
            self.id = str(uuid.uuid4())

class CBEventType(str, Enum):
    """
    Callback manager event types.

    Attributes:
        CHUNKING: Logs for the before and after of text splitting.
        NODE_PARSING: Logs for the documents and the nodes that they are parsed into.
        EMBEDDING: Logs for the number of texts embedded.
        LLM: Logs for the template and response of LLM calls.
        QUERY: Keeps track of the start and end of each query.
        RETRIEVE: Logs for the nodes retrieved for a query.
        SYNTHESIZE: Logs for the result for synthesize calls.
        TREE: Logs for the summary and level of summaries generated.
        SUB_QUESTION: Logs for a generated sub question and answer.

    """

    CHUNKING = "chunking"
    NODE_PARSING = "node_parsing"
    EMBEDDING = "embedding"
    LLM = "llm"
    QUERY = "query"
    RETRIEVE = "retrieve"
    SYNTHESIZE = "synthesize"
    TREE = "tree"
    SUB_QUESTION = "sub_question"
    TEMPLATING = "templating"
    FUNCTION_CALL = "function_call"
    RERANKING = "reranking"
    EXCEPTION = "exception"
    AGENT_STEP = "agent_step"

class EventPayload(str, Enum):
    DOCUMENTS = "documents"  # list of documents before parsing
    CHUNKS = "chunks"  # list of text chunks
    NODES = "nodes"  # list of nodes
    PROMPT = "formatted_prompt"  # formatted prompt sent to LLM
    MESSAGES = "messages"  # list of messages sent to LLM
    COMPLETION = "completion"  # completion from LLM
    RESPONSE = "response"  # message response from LLM
    QUERY_STR = "query_str"  # query used for query engine
    SUB_QUESTION = "sub_question"  # a sub question & answer + sources
    EMBEDDINGS = "embeddings"  # list of embeddings
    TOP_K = "top_k"  # top k nodes retrieved
    ADDITIONAL_KWARGS = "additional_kwargs"  # additional kwargs for event call
    SERIALIZED = "serialized"  # serialized object for event caller
    FUNCTION_CALL = "function_call"  # function call for the LLM
    FUNCTION_OUTPUT = "function_call_response"  # function call output
    TOOL = "tool"  # tool used in LLM call
    MODEL_NAME = "model_name"  # model name used in an event
    TEMPLATE = "template"  # template used in LLM call
    TEMPLATE_VARS = "template_vars"  # template variables used in LLM call
    SYSTEM_PROMPT = "system_prompt"  # system prompt used in LLM call
    QUERY_WRAPPER_PROMPT = "query_wrapper_prompt"  # query wrapper prompt used in LLM
    EXCEPTION = "exception"  # exception raised in an event