M5-T04: add Modbus poll service and APScheduler polling job
This commit is contained in:
@@ -41,6 +41,9 @@ class Settings(BaseSettings):
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auth_trust_forwarded_for: bool = False
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auth_totp_issuer: str = "" # defaults to app_name when empty
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# Modbus polling — global kill-switch; T08 will wire this into CONFIG_FIELDS/UI.
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modbus_polling_enabled: bool = True
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model_config = SettingsConfigDict(
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env_file=".env",
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env_file_encoding="utf-8",
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+18
@@ -25,6 +25,7 @@ from app.config import get_settings
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from app.services.auth import AuthBootstrapError, initialize_auth_schema
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from app.services.config_page import seed_missing_config_from_bootstrap, sync_app_hostname_from_bootstrap
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from app.services.public_ip import check_public_ipv4_and_notify
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from app.services.modbus_poll import poll_all_enabled_devices, BASE_POLL_TICK_SECONDS
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from scripts.app_db_adopt import AppDatabaseAdoptionError, validate_app_runtime_db
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logger = logging.getLogger(__name__)
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@@ -48,6 +49,15 @@ def _run_scheduled_public_ip_check() -> None:
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session.close()
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def _run_scheduled_modbus_poll() -> None:
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session_local = get_session_local()
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session: Session = session_local()
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try:
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poll_all_enabled_devices(session, bootstrap_settings=get_settings())
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finally:
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session.close()
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def ensure_auth_db_ready() -> None:
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session_local = get_session_local()
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session: Session = session_local()
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@@ -83,6 +93,14 @@ async def lifespan(_: FastAPI):
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max_instances=1,
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coalesce=True,
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)
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scheduler.add_job(
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_run_scheduled_modbus_poll,
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trigger=IntervalTrigger(seconds=BASE_POLL_TICK_SECONDS),
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id="modbus-poll",
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replace_existing=True,
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max_instances=1,
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coalesce=True,
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)
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scheduler.start()
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yield
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scheduler.shutdown(wait=False)
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@@ -0,0 +1,184 @@
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"""Modbus polling service — periodic read-and-store for enabled Modbus devices.
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Design notes
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------------
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- ``poll_device`` loads the device's YAML profile, calls the driver to bulk-read
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all register blocks in a single TCP connection, decodes the raw registers into
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an engineering-value dict via the profile, and persists one ``ModbusReading``
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row. It also stamps ``last_poll_at`` / ``last_poll_ok`` on the device.
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- All exceptions are caught and logged inside ``poll_device``; the function
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never re-raises. This prevents a single broken device from aborting the
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sweep for all other devices.
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- ``poll_all_enabled_devices`` respects per-device ``poll_interval_s``: it skips
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a device whose ``last_poll_at`` is recent enough. This lets the APScheduler
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job run on a short base tick (e.g. 5 s) while each device self-regulates its
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own cadence.
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- The global ``modbus_polling_enabled`` flag from ``Settings`` (merged with any
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DB overrides via ``build_runtime_settings``) gates the entire sweep as a
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no-op. T08 will expose this flag in CONFIG_FIELDS/UI; for now it is
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controlled by the ``MODBUS_POLLING_ENABLED`` env var (or the default True).
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"""
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from __future__ import annotations
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import logging
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from datetime import UTC, datetime
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from sqlalchemy import select
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from sqlalchemy.orm import Session
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from app.config import Settings
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from app.integrations.modbus import driver, profiles
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from app.models.modbus import ModbusDevice, ModbusReading
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from app.services.config_page import build_runtime_settings
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logger = logging.getLogger(__name__)
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# Base polling tick in seconds (used by APScheduler; each device checks its own interval).
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BASE_POLL_TICK_SECONDS = 5
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def poll_device(session: Session, device: ModbusDevice) -> ModbusReading | None:
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"""Read one enabled Modbus device, decode, and persist a reading row.
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Parameters
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----------
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session:
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Open SQLAlchemy session. The caller is responsible for session
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lifecycle (open / commit / close).
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device:
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``ModbusDevice`` ORM instance to poll.
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Returns
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-------
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ModbusReading | None
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The newly-persisted reading on success, or ``None`` on any failure.
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Failure is logged and the device's ``last_poll_ok`` is set to ``False``.
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"""
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now = datetime.now(UTC)
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try:
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profile = profiles.load_profile(device.profile)
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registers = driver.read_blocks(
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device.host,
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device.port,
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device.unit_id,
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[{"start": b.start, "count": b.count} for b in profile.blocks],
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)
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payload = profiles.decode(profile, registers)
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reading = ModbusReading(
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device_id=device.id,
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recorded_at=now,
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payload=payload,
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)
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session.add(reading)
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device.last_poll_at = now
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device.last_poll_ok = True
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session.commit()
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logger.debug(
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"Polled device %r (id=%d): %d metrics recorded at %s",
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device.friendly_name,
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device.id,
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len(payload),
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now.isoformat(),
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)
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return reading
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except Exception: # noqa: BLE001
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logger.exception(
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"Failed to poll device %r (id=%d, host=%s:%d, unit_id=%d)",
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device.friendly_name,
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device.id,
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device.host,
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device.port,
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device.unit_id,
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)
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# Rollback first — if session.add(reading) already ran in the success
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# branch before commit() failed, that pending ModbusReading must be
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# discarded. Without rollback it would remain staged and could be
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# flushed/committed by a subsequent operation (even for a different
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# device), producing a spurious reading row for a poll that failed.
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# Rollback also expires all ORM objects; device fields are re-set below.
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try:
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session.rollback()
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except Exception: # noqa: BLE001
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logger.exception(
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"session.rollback() failed for device id=%d; session may be unusable", device.id
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)
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try:
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device.last_poll_at = now
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device.last_poll_ok = False
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session.commit()
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except Exception: # noqa: BLE001
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logger.exception(
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"Also failed to persist last_poll_ok=False for device id=%d", device.id
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)
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return None
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def poll_all_enabled_devices(
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session: Session,
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*,
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bootstrap_settings: Settings,
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) -> None:
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"""Sweep all enabled Modbus devices and poll each one whose interval has elapsed.
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Global kill-switch: if ``build_runtime_settings(...).modbus_polling_enabled``
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is ``False``, this function returns immediately without touching any device.
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Per-device interval: a device is skipped if its ``last_poll_at`` is not yet
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``poll_interval_s`` seconds in the past. This allows the APScheduler job to
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run on a short fixed tick while each device self-regulates its own cadence.
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Exceptions from individual devices are swallowed inside ``poll_device``;
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this function itself will not raise.
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Parameters
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----------
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session:
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Open SQLAlchemy session.
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bootstrap_settings:
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The bootstrap ``Settings`` instance (from ``get_settings()``), used as
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the base for ``build_runtime_settings`` to pick up any DB overrides.
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"""
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try:
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runtime_settings = build_runtime_settings(session, bootstrap_settings)
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except Exception: # noqa: BLE001
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logger.exception("Failed to build runtime settings for Modbus poll; aborting sweep")
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return
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if not runtime_settings.modbus_polling_enabled:
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logger.debug("Modbus polling is disabled (modbus_polling_enabled=False); skipping sweep")
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return
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try:
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devices = session.execute(
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select(ModbusDevice).where(ModbusDevice.enabled == True) # noqa: E712
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).scalars().all()
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except Exception: # noqa: BLE001
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logger.exception("Failed to query enabled Modbus devices; aborting sweep")
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return
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now = datetime.now(UTC)
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for device in devices:
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# Respect per-device poll interval: skip if last poll was too recent.
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if device.last_poll_at is not None:
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# SQLite may return a naive datetime despite DateTime(timezone=True) —
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# treat naive values as UTC so the comparison is safe.
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last_poll = device.last_poll_at
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if last_poll.tzinfo is None:
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last_poll = last_poll.replace(tzinfo=UTC)
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elapsed = (now - last_poll).total_seconds()
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if elapsed < device.poll_interval_s:
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logger.debug(
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"Skipping device %r (id=%d): %.1fs elapsed < %ds interval",
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device.friendly_name,
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device.id,
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elapsed,
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device.poll_interval_s,
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)
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continue
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poll_device(session, device)
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