Lukas
52f237d5d4
CRITICAL FIX: Background tasks (especially blocklist_import) crashed mid-execution, leaving partial state. On retry, the same bans were applied again, causing duplicates. Solution: Content-hash based operation tracking for blocklist imports: - Added import_runs table (migration 6) to track operations by source + content hash - Before banning, check if this exact content has already been imported - If completed: skip banning (already done), optionally re-warm cache - If new or failed: proceed with ban and mark as completed or failed Changes: - Database: Migration 6 adds import_runs table with operation state tracking - Model: Added ImportRunEntry for import run records - Repository: New import_run_repo module with CRUD operations - Workflow: Updated blocklist_import_workflow to check operation history before banning - Dependencies: Registered import_run_repo for dependency injection - Tests: Added test_import_source_idempotent_on_retry and test_import_source_different_content_not_reused - Documentation: Added Task Idempotency section to Backend-Development.md Verification: - All 7 import tests pass (5 existing + 2 new idempotency tests) - Type checking: mypy --strict ✅ - Linting: ruff ✅ - No API changes, backwards compatible via automatic migration Fixes: Background tasks not idempotent #CRITICAL Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
93 lines
3.0 KiB
Python
93 lines
3.0 KiB
Python
"""Scheduler lock heartbeat background task.
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Registers an APScheduler job that periodically updates the scheduler lock's
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heartbeat timestamp. This prevents the lock from being considered stale
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if the running instance experiences temporary delays or high load.
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Without this heartbeat, stale lock detection (based on TTL) could incorrectly
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determine that the scheduler instance has crashed when it's merely busy, and
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a new instance could take over.
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"""
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from __future__ import annotations
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from typing import TYPE_CHECKING
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import structlog
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from app.tasks.db import task_db
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from app.tasks.timeout_utils import run_with_timeout
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from app.utils.runtime_state import get_effective_settings
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from app.utils.scheduler_lock import update_scheduler_lock_heartbeat
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if TYPE_CHECKING:
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from fastapi import FastAPI
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from app.config import Settings
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log: structlog.stdlib.BoundLogger = structlog.get_logger()
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#: How often the heartbeat job fires (seconds). Must be less than the lock TTL.
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SCHEDULER_LOCK_HEARTBEAT_INTERVAL: int = 10
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#: Stable APScheduler job ID — ensures re-registration replaces, not duplicates.
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JOB_ID: str = "scheduler_lock_heartbeat"
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#: Maximum seconds to allow for scheduler lock heartbeat to complete.
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TASK_TIMEOUT_SECONDS: int = 5
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async def _update_heartbeat_with_resources(settings: Settings) -> None:
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"""Update the scheduler lock heartbeat timestamp.
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If the heartbeat update fails (e.g., we no longer hold the lock), log
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a warning but don't crash the scheduler. This allows the running
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application to continue even if something went wrong.
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Args:
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settings: The resolved application settings used for database access.
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"""
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async def _do_update() -> None:
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async with task_db(settings) as db:
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success = await update_scheduler_lock_heartbeat(db)
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if success:
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log.debug("scheduler_lock_heartbeat_updated")
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else:
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log.warning(
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"scheduler_lock_heartbeat_failed",
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message="Failed to update heartbeat; we may have lost the lock.",
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)
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await run_with_timeout("scheduler_lock_heartbeat", _do_update(), TASK_TIMEOUT_SECONDS)
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async def _update_heartbeat(app: FastAPI) -> None:
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await _update_heartbeat_with_resources(get_effective_settings(app))
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def register(app: FastAPI) -> None:
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"""Add (or replace) the scheduler lock heartbeat job.
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Must be called after the scheduler has been started (i.e., inside the
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lifespan handler, after ``scheduler.start()``).
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Args:
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app: The :class:`fastapi.FastAPI` application instance whose
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``app.state.scheduler`` will receive the job.
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"""
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settings = get_effective_settings(app)
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app.state.scheduler.add_job(
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_update_heartbeat_with_resources,
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trigger="interval",
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seconds=SCHEDULER_LOCK_HEARTBEAT_INTERVAL,
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kwargs={"settings": settings},
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id=JOB_ID,
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replace_existing=True,
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)
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log.info(
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"scheduler_lock_heartbeat_scheduled",
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interval_seconds=SCHEDULER_LOCK_HEARTBEAT_INTERVAL,
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)
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