"""A simple progress bar for the console."""
import threading
from collections.abc import Sequence
from typing import Any, Optional
from uuid import UUID
from langchain_core.callbacks import base as base_callbacks
from langchain_core.documents import Document
from langchain_core.outputs import LLMResult
[docs]
class ProgressBarCallback(base_callbacks.BaseCallbackHandler):
"""A simple progress bar for the console."""
[docs]
def __init__(
self, total: int, ncols: int = 50, end_with: str = "\n", **kwargs: Any
):
"""Initialize the progress bar.
Args:
total: int, the total number of items to be processed.
ncols: int, the character width of the progress bar.
end_with: str, last string to print after progress bar reaches end.
"""
self.total = total
self.ncols = ncols
self.end_with = end_with
self.counter = 0
self.lock = threading.Lock()
self._print_bar()
[docs]
def increment(self) -> None:
"""Increment the counter and update the progress bar."""
with self.lock:
self.counter += 1
self._print_bar()
def _print_bar(self) -> None:
"""Print the progress bar to the console."""
progress = self.counter / self.total
arrow = "-" * int(round(progress * self.ncols) - 1) + ">"
spaces = " " * (self.ncols - len(arrow))
end = "" if self.counter < self.total else self.end_with
print(f"\r[{arrow + spaces}] {self.counter}/{self.total}", end=end) # noqa: T201
[docs]
def on_chain_error(
self,
error: BaseException,
*,
run_id: UUID,
parent_run_id: Optional[UUID] = None,
**kwargs: Any,
) -> Any:
if parent_run_id is None:
self.increment()
[docs]
def on_chain_end(
self,
outputs: dict[str, Any],
*,
run_id: UUID,
parent_run_id: Optional[UUID] = None,
**kwargs: Any,
) -> Any:
if parent_run_id is None:
self.increment()
[docs]
def on_retriever_error(
self,
error: BaseException,
*,
run_id: UUID,
parent_run_id: Optional[UUID] = None,
**kwargs: Any,
) -> Any:
if parent_run_id is None:
self.increment()
[docs]
def on_retriever_end(
self,
documents: Sequence[Document],
*,
run_id: UUID,
parent_run_id: Optional[UUID] = None,
**kwargs: Any,
) -> Any:
if parent_run_id is None:
self.increment()
[docs]
def on_llm_error(
self,
error: BaseException,
*,
run_id: UUID,
parent_run_id: Optional[UUID] = None,
**kwargs: Any,
) -> Any:
if parent_run_id is None:
self.increment()
[docs]
def on_llm_end(
self,
response: LLMResult,
*,
run_id: UUID,
parent_run_id: Optional[UUID] = None,
**kwargs: Any,
) -> Any:
if parent_run_id is None:
self.increment()
