258 lines
8.8 KiB
Python
258 lines
8.8 KiB
Python
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"""MQTT client integration (paho-mqtt 2.x).
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Provides :class:`MqttManager`: a long-lived MQTT client that runs paho's
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loop in a background thread. Designed to be started in FastAPI's lifespan
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and shared across the application as a module-level singleton (``mqtt_manager``).
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Key design decisions
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--------------------
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- **paho 2.x API**: ``Client`` requires ``CallbackAPIVersion.VERSION2`` as the
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first positional argument. VERSION2 on_connect callback receives
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``(client, userdata, connect_flags, reason_code, properties)`` — not the
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older RC int.
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- **Background thread**: ``loop_start()`` spawns a daemon thread; ``loop_stop()``
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joins it cleanly on shutdown.
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- **Never crash the process**: all paho operations are wrapped in try/except;
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connection failure is logged but does not propagate to the caller.
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- **Password safety**: the MQTT password is never passed to ``logger`` calls.
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- **Reconnect**: ``reconnect(settings)`` tears down the old client and
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establishes a fresh connection with the new settings. Callers (e.g. PUT
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/api/config) call this after saving MQTT-related config values.
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"""
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from __future__ import annotations
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import logging
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import threading
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from typing import TYPE_CHECKING
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import paho.mqtt.client as mqtt
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if TYPE_CHECKING:
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from app.config import Settings
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logger = logging.getLogger(__name__)
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# MQTT settings keys that, when changed, should trigger a reconnect.
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MQTT_SETTINGS_KEYS = {
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"mqtt_enabled",
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"mqtt_broker_host",
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"mqtt_broker_port",
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"mqtt_username",
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"mqtt_password",
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"mqtt_tls_enabled",
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}
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def _is_configured(settings: Settings) -> bool:
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"""Return True if MQTT is enabled *and* the broker host is set."""
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return bool(settings.mqtt_enabled and settings.mqtt_broker_host)
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class MqttManager:
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"""Long-lived MQTT client wrapper.
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Lifecycle
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---------
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1. ``connect(settings)`` — start background loop + connect to broker.
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2. ``publish(...)`` — publish messages while connected.
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3. ``disconnect()`` — graceful teardown (called on app shutdown).
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4. ``reconnect(settings)`` — disconnect then re-connect with new settings
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(called after saving updated MQTT configuration).
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When MQTT is not enabled or not configured, all methods are no-ops.
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Connection failures are caught and logged; they do not raise.
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"""
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def __init__(self) -> None:
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self._client: mqtt.Client | None = None
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self._lock = threading.Lock()
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self._connected = False
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# ------------------------------------------------------------------
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# Public properties
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# ------------------------------------------------------------------
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@property
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def is_connected(self) -> bool:
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"""True if the underlying paho client is currently connected."""
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return self._connected
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# ------------------------------------------------------------------
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# Public interface
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# ------------------------------------------------------------------
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def is_configured(self, settings: Settings) -> bool:
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"""Return True if MQTT is enabled and broker host is configured."""
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return _is_configured(settings)
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def connect(self, settings: Settings) -> None:
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"""Connect to the MQTT broker and start the background loop thread.
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No-op if MQTT is not enabled or broker host is not set.
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Connection errors are logged but do not raise.
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"""
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if not _is_configured(settings):
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logger.debug("MQTT not configured or not enabled — skipping connect.")
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return
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with self._lock:
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self._start_client(settings)
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def disconnect(self) -> None:
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"""Disconnect from the broker and stop the background loop thread.
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No-op if no client is active.
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"""
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with self._lock:
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self._stop_client()
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def reconnect(self, settings: Settings) -> None:
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"""Disconnect the current client (if any) and reconnect with *settings*.
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Call this after saving updated MQTT configuration values.
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No-op if MQTT is not enabled or broker host is not set.
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"""
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with self._lock:
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self._stop_client()
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self.connect(settings)
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def publish(
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self,
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topic: str,
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payload: str | bytes | None,
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*,
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retain: bool = False,
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qos: int = 0,
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) -> None:
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"""Publish a message to *topic*.
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If the client is not connected the call is silently skipped.
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Errors are logged but do not raise.
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"""
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with self._lock:
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client = self._client
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if client is None or not self._connected:
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logger.debug("MQTT publish skipped — not connected (topic=%s).", topic)
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return
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try:
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client.publish(topic, payload=payload, qos=qos, retain=retain)
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except Exception:
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logger.exception("MQTT publish error (topic=%s).", topic)
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# ------------------------------------------------------------------
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# Internal helpers — must be called with self._lock held
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# ------------------------------------------------------------------
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def _start_client(self, settings: Settings) -> None:
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"""Build a fresh paho Client, configure it, and call loop_start + connect."""
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client = mqtt.Client(
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callback_api_version=mqtt.CallbackAPIVersion.VERSION2,
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client_id="home-automation",
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)
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# Callbacks — VERSION2 on_connect signature:
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# (client, userdata, connect_flags, reason_code, properties)
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def _on_connect(
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_client: mqtt.Client,
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_userdata: object,
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_flags: mqtt.ConnectFlags,
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reason_code: mqtt.ReasonCode,
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_properties: mqtt.Properties | None,
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) -> None:
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if reason_code.is_failure:
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logger.warning("MQTT connection refused: %s", reason_code)
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self._connected = False
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else:
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logger.info("MQTT connected (reason_code=%s).", reason_code)
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self._connected = True
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# VERSION2 on_disconnect signature:
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# (client, userdata, disconnect_flags, reason_code, properties)
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def _on_disconnect(
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_client: mqtt.Client,
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_userdata: object,
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_disconnect_flags: mqtt.DisconnectFlags,
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reason_code: mqtt.ReasonCode,
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_properties: mqtt.Properties | None,
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) -> None:
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self._connected = False
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if reason_code.is_failure:
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logger.warning("MQTT disconnected unexpectedly (reason_code=%s).", reason_code)
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else:
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logger.info("MQTT disconnected cleanly.")
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client.on_connect = _on_connect
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client.on_disconnect = _on_disconnect
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# TLS
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if settings.mqtt_tls_enabled:
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try:
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client.tls_set()
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except Exception:
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logger.exception("MQTT TLS setup failed.")
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return
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# Credentials — never log the password
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if settings.mqtt_username:
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client.username_pw_set(
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username=settings.mqtt_username,
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password=settings.mqtt_password or None,
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)
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# Start background loop thread *before* connect so paho can handle
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# the connection handshake asynchronously.
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client.loop_start()
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try:
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client.connect(
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host=settings.mqtt_broker_host,
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port=settings.mqtt_broker_port,
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keepalive=60,
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)
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except Exception:
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# Log without leaking the password
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logger.exception(
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"MQTT connect failed (host=%s, port=%s). Stopping loop.",
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settings.mqtt_broker_host,
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settings.mqtt_broker_port,
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)
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try:
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client.loop_stop()
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except Exception:
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pass
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return
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self._client = client
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logger.info(
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"MQTT client started (host=%s, port=%s).",
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settings.mqtt_broker_host,
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settings.mqtt_broker_port,
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)
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def _stop_client(self) -> None:
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"""Disconnect and stop the background loop. Idempotent."""
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client = self._client
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if client is None:
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return
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self._client = None
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self._connected = False
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try:
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client.disconnect()
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except Exception:
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logger.debug("MQTT disconnect raised (ignoring).", exc_info=True)
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try:
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client.loop_stop()
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except Exception:
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logger.debug("MQTT loop_stop raised (ignoring).", exc_info=True)
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logger.info("MQTT client stopped.")
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# ---------------------------------------------------------------------------
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# Module-level singleton — shared across lifespan and route handlers
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# ---------------------------------------------------------------------------
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mqtt_manager = MqttManager()
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