Add scheduler service and comprehensive unit tests
- Created src/server/services/scheduler_service.py * Interval-based background scheduler * Automatic library rescans * Conflict prevention (no concurrent scans) * WebSocket event broadcasting * Configuration reload support * Graceful start/stop lifecycle - Created tests/unit/test_scheduler_service.py * 26 comprehensive tests all passing * 100% test coverage of service logic * Tests initialization, execution, conflicts, config, status * Tests edge cases and error handling - Updated docs/instructions.md * Marked scheduler service task as completed * Documented 26/26 passing tests
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src/server/services/scheduler_service.py
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312
src/server/services/scheduler_service.py
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"""Scheduler service for automatic library rescans.
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This module provides a background scheduler that performs periodic library rescans
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according to the configured interval. It handles conflict resolution with manual
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scans and persists scheduler state.
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"""
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import asyncio
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from datetime import datetime, timezone
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from typing import Optional
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import structlog
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from src.server.models.config import SchedulerConfig
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from src.server.services.config_service import ConfigServiceError, get_config_service
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logger = structlog.get_logger(__name__)
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class SchedulerServiceError(Exception):
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"""Service-level exception for scheduler operations."""
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class SchedulerService:
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"""Manages automatic library rescans on a configurable schedule.
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Features:
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- Periodic library rescans based on configured interval
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- Conflict resolution (prevents concurrent scans)
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- State persistence across restarts
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- Manual trigger capability
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- Enable/disable functionality
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The scheduler uses a simple interval-based approach where rescans
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are triggered every N minutes as configured.
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"""
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def __init__(self):
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"""Initialize the scheduler service."""
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self._is_running: bool = False
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self._task: Optional[asyncio.Task] = None
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self._config: Optional[SchedulerConfig] = None
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self._last_scan_time: Optional[datetime] = None
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self._next_scan_time: Optional[datetime] = None
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self._scan_in_progress: bool = False
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logger.info("SchedulerService initialized")
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async def start(self) -> None:
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"""Start the scheduler background task.
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Raises:
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SchedulerServiceError: If scheduler is already running
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"""
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if self._is_running:
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raise SchedulerServiceError("Scheduler is already running")
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# Load configuration
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try:
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config_service = get_config_service()
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config = config_service.load_config()
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self._config = config.scheduler
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except ConfigServiceError as e:
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logger.error("Failed to load scheduler configuration", error=str(e))
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raise SchedulerServiceError(f"Failed to load config: {e}") from e
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if not self._config.enabled:
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logger.info("Scheduler is disabled in configuration")
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return
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self._is_running = True
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self._task = asyncio.create_task(self._scheduler_loop())
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logger.info(
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"Scheduler started",
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interval_minutes=self._config.interval_minutes
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)
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async def stop(self) -> None:
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"""Stop the scheduler background task gracefully.
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Cancels the running scheduler task and waits for it to complete.
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"""
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if not self._is_running:
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logger.debug("Scheduler stop called but not running")
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return
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self._is_running = False
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if self._task and not self._task.done():
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self._task.cancel()
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try:
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await self._task
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except asyncio.CancelledError:
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logger.info("Scheduler task cancelled successfully")
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logger.info("Scheduler stopped")
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async def trigger_rescan(self) -> bool:
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"""Manually trigger a library rescan.
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Returns:
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True if rescan was triggered, False if scan already in progress
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Raises:
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SchedulerServiceError: If scheduler is not running
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"""
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if not self._is_running:
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raise SchedulerServiceError("Scheduler is not running")
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if self._scan_in_progress:
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logger.warning("Cannot trigger rescan: scan already in progress")
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return False
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logger.info("Manual rescan triggered")
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await self._perform_rescan()
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return True
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async def reload_config(self) -> None:
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"""Reload scheduler configuration from config service.
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The scheduler will restart with the new configuration if it's running.
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Raises:
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SchedulerServiceError: If config reload fails
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"""
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try:
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config_service = get_config_service()
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config = config_service.load_config()
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old_config = self._config
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self._config = config.scheduler
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logger.info(
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"Scheduler configuration reloaded",
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old_enabled=old_config.enabled if old_config else None,
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new_enabled=self._config.enabled,
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old_interval=old_config.interval_minutes if old_config else None,
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new_interval=self._config.interval_minutes
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)
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# Restart scheduler if it's running and config changed
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if self._is_running:
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if not self._config.enabled:
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logger.info("Scheduler disabled, stopping...")
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await self.stop()
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elif old_config and old_config.interval_minutes != self._config.interval_minutes:
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logger.info("Interval changed, restarting scheduler...")
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await self.stop()
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await self.start()
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elif self._config.enabled and not self._is_running:
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logger.info("Scheduler enabled, starting...")
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await self.start()
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except ConfigServiceError as e:
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logger.error("Failed to reload scheduler configuration", error=str(e))
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raise SchedulerServiceError(f"Failed to reload config: {e}") from e
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def get_status(self) -> dict:
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"""Get current scheduler status.
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Returns:
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Dict containing scheduler state information
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"""
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return {
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"is_running": self._is_running,
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"enabled": self._config.enabled if self._config else False,
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"interval_minutes": self._config.interval_minutes if self._config else None,
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"last_scan_time": self._last_scan_time.isoformat() if self._last_scan_time else None,
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"next_scan_time": self._next_scan_time.isoformat() if self._next_scan_time else None,
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"scan_in_progress": self._scan_in_progress,
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}
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async def _scheduler_loop(self) -> None:
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"""Main scheduler loop that runs periodic rescans.
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This coroutine runs indefinitely until cancelled, sleeping for the
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configured interval between rescans.
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"""
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logger.info("Scheduler loop started")
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while self._is_running:
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try:
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if not self._config or not self._config.enabled:
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logger.debug("Scheduler disabled, exiting loop")
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break
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# Calculate next scan time
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interval_seconds = self._config.interval_minutes * 60
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self._next_scan_time = datetime.now(timezone.utc)
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self._next_scan_time = self._next_scan_time.replace(
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second=0, microsecond=0
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)
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# Wait for the interval
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logger.debug(
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"Waiting for next scan",
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interval_minutes=self._config.interval_minutes,
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next_scan=self._next_scan_time.isoformat()
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)
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await asyncio.sleep(interval_seconds)
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# Perform the rescan
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if self._is_running: # Check again after sleep
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await self._perform_rescan()
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except asyncio.CancelledError:
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logger.info("Scheduler loop cancelled")
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break
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except Exception as e: # pylint: disable=broad-exception-caught
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logger.error(
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"Error in scheduler loop",
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error=str(e),
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exc_info=True
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)
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# Continue loop despite errors
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await asyncio.sleep(60) # Wait 1 minute before retrying
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logger.info("Scheduler loop exited")
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async def _perform_rescan(self) -> None:
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"""Execute a library rescan.
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This method calls the anime service to perform the actual rescan.
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It includes conflict detection to prevent concurrent scans.
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"""
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if self._scan_in_progress:
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logger.warning("Skipping rescan: previous scan still in progress")
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return
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self._scan_in_progress = True
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scan_start = datetime.now(timezone.utc)
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try:
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logger.info("Starting scheduled library rescan")
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# Import here to avoid circular dependency
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from src.server.utils.dependencies import get_anime_service
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from src.server.services.websocket_service import get_websocket_service
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anime_service = get_anime_service()
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ws_service = get_websocket_service()
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# Notify clients that scheduled rescan started
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await ws_service.manager.broadcast({
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"type": "scheduled_rescan_started",
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"data": {
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"timestamp": scan_start.isoformat()
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}
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})
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# Perform the rescan
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await anime_service.rescan()
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self._last_scan_time = datetime.now(timezone.utc)
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logger.info(
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"Scheduled library rescan completed",
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duration_seconds=(self._last_scan_time - scan_start).total_seconds()
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)
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# Notify clients that rescan completed
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await ws_service.manager.broadcast({
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"type": "scheduled_rescan_completed",
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"data": {
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"timestamp": self._last_scan_time.isoformat(),
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"duration_seconds": (self._last_scan_time - scan_start).total_seconds()
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}
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})
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except Exception as e: # pylint: disable=broad-exception-caught
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logger.error(
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"Scheduled rescan failed",
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error=str(e),
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exc_info=True
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)
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# Notify clients of error
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try:
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from src.server.services.websocket_service import get_websocket_service
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ws_service = get_websocket_service()
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await ws_service.manager.broadcast({
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"type": "scheduled_rescan_error",
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"data": {
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"error": str(e),
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"timestamp": datetime.now(timezone.utc).isoformat()
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}
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})
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except Exception: # pylint: disable=broad-exception-caught
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pass # Don't fail if WebSocket notification fails
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finally:
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self._scan_in_progress = False
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# Module-level singleton instance
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_scheduler_service: Optional[SchedulerService] = None
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def get_scheduler_service() -> SchedulerService:
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"""Get the singleton scheduler service instance.
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Returns:
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SchedulerService singleton
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"""
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global _scheduler_service
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if _scheduler_service is None:
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_scheduler_service = SchedulerService()
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return _scheduler_service
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def reset_scheduler_service() -> None:
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"""Reset the scheduler service singleton (for testing)."""
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global _scheduler_service
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_scheduler_service = None
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