71 lines
2.4 KiB
Python
71 lines
2.4 KiB
Python
"""Background BM25 refresh tasks for the web app.
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The refresh is scheduled on the event loop instead of a thread because the async psycopg
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driver only works from the loop; a bare thread cannot open a session on the async engine.
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"""
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from __future__ import annotations
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import asyncio
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import logging
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from typing import TYPE_CHECKING
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from sqlalchemy.ext.asyncio import AsyncSession
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from python.ebook_search.bm25_corpus import load_bm25_corpus, refresh_bm25_corpus
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if TYPE_CHECKING:
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from fastapi import FastAPI
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from sqlalchemy.ext.asyncio import AsyncEngine
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from python.ebook_search.config import EbookSearchConfig
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logger = logging.getLogger(__name__)
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def schedule_bm25_refresh(app: FastAPI) -> None:
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"""Schedule a delayed BM25 corpus refresh, replacing any pending refresh.
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Only called from route handlers, so a running event loop is guaranteed.
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"""
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cancel_bm25_refresh(app)
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loop = asyncio.get_running_loop()
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def start_refresh() -> None:
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app.state.bm25_refresh_task = loop.create_task(refresh_bm25_for_app(app))
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app.state.bm25_refresh_timer = loop.call_later(app.state.config.bm25_refresh_delay_seconds, start_refresh)
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logger.info(f"ebook_bm25_refresh_scheduled {app.state.config.bm25_refresh_delay_seconds=}")
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def cancel_bm25_refresh(app: FastAPI) -> None:
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"""Cancel any pending BM25 corpus refresh timer and in-flight refresh task."""
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existing_timer = getattr(app.state, "bm25_refresh_timer", None)
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if existing_timer is not None:
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existing_timer.cancel()
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app.state.bm25_refresh_timer = None
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logger.info("ebook_bm25_refresh_cancelled")
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existing_task = getattr(app.state, "bm25_refresh_task", None)
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if existing_task is not None:
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if not existing_task.done():
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existing_task.cancel()
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app.state.bm25_refresh_task = None
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async def refresh_bm25_for_app(app: FastAPI) -> None:
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"""Refresh the BM25 corpus using the app engine and config."""
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try:
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await refresh_bm25_for_engine(app.state.engine, app.state.config)
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except Exception:
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logger.exception("ebook_bm25_refresh_failed")
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async def refresh_bm25_for_engine(engine: AsyncEngine, config: EbookSearchConfig) -> None:
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"""Refresh the BM25 corpus using an async SQLAlchemy engine."""
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async with AsyncSession(engine) as session:
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await refresh_bm25_corpus(session, config)
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load_bm25_corpus.cache_clear()
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logger.info("ebook_bm25_corpus_cache_cleared_after_refresh")
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