api: use proper connection shutdown for downstream services

api/src/dooris_api/mqtt_client.py

@@ -1,9 +1,9 @@
 #
 # This whole implementation is adapted from the upstream GitHub example
 # https://github.com/eclipse-paho/paho.mqtt.python/blob/master/examples/loop_asyncio.py
-# 
+#
 
-from typing import Any
+from typing import Any, List, Set, Iterable
 import logging
 import asyncio
 import socket
@@ -16,7 +16,7 @@ logger = logging.getLogger(__name__)
 
 class AsyncLooper:
     """
-    Helper class to implement loopgin with asyncio for the underlying mqtt IO  
+    Helper class to implement loopgin with asyncio for the underlying mqtt IO
     """
 
     def __init__(self, loop: asyncio.AbstractEventLoop, client: mqtt.Client):
@@ -58,9 +58,14 @@ class AsyncLooper:
 
 class AsyncMqttClient:
     loop: asyncio.AbstractEventLoop
-    
+    connection_string: str
+    looper: AsyncLooper
+    client: mqtt.Client
+    active_subscriptions: Set[str]
+
     def __init__(self, connection_string: str, username: str, password: str):
         self.connection_string = connection_string
+        self.active_subscriptions = set()
         self.client = mqtt.Client(mqtt.CallbackAPIVersion.VERSION2, client_id="dooris")
         self.client.username = username
         self.client.password = password
@@ -68,25 +73,75 @@ class AsyncMqttClient:
         self.client.on_message = self.on_message
         self.client.on_disconnect = self.on_disconnect
 
-    def on_connect(self, client: mqtt.Client, userdata: Any, flags: mqtt.ConnectFlags, reason_code, properties: mqtt.Properties):
+    def on_connect(
+        self,
+        client: mqtt.Client,
+        userdata: Any,
+        flags: mqtt.ConnectFlags,
+        reason_code,
+        properties: mqtt.Properties,
+    ):
         logger.debug(f"mqtt client connected with message '{reason_code}'")
+        self.fut_connected.set_result(None)
 
-    def on_disconnect(self, client: mqtt.Client, userdata: Any, flags: mqtt.DisconnectFlags, reason_code, properties: mqtt.Properties):
-        logger.debug("mqtt client disconnected")
-        print("flags", type(flags), flags)
-        print("reason_code", type(reason_code), reason_code)
-        print("properties", type(properties), properties)
+    def on_disconnect(
+        self,
+        client: mqtt.Client,
+        userdata: Any,
+        flags: mqtt.DisconnectFlags,
+        reason_code,
+        properties: mqtt.Properties,
+    ):
+        logger.debug(f"mqtt client disconnected with message '{reason_code}'")
+        if self.fut_disconnect:
+            self.fut_disconnect.set_result(None)
 
-    def on_message(self, client: mqtt.Client, userdata: Any, msg):
+    def on_message(self, client: mqtt.Client, userdata: Any, msg: mqtt.MQTTMessage):
         logger.debug("mqtt client got message")
         print("msg", type(msg), msg)
 
+    def on_subscribe(self, client, userdata, mid, reason_code, properties):
+        logger.debug(f"mqtt client subscribed to topics with message '{reason_code}'")
+        self.fut_subscribe.set_result(None)
+
+    def on_unsubscribe(self, client, userdata, mid, reason_code, properties):
+        logger.debug(f"mqtt client unsubscribed from topics with message '{reason_code}'")
+        self.fut_unsubscribe.set_result(None)
+
+    async def update_subscriptions(self, topics: Iterable[str]):
+        """
+        Update MQTT subscriptions so that the client is subscribed to exactly the given list of topics 
+        """
+
+        to_add = topics.difference(self.active_subscriptions)
+        if to_add:
+            logger.info(f"mqtt client subscribing to topics {', '.join(to_add)}")
+            qos = 2
+            self.fut_subscribe = asyncio.get_running_loop().create_future()
+            self.client.subscribe([(i, qos) for i in to_add])
+            await self.fut_subscribe
+
+        to_remove = self.active_subscriptions.difference(topics)
+        if to_remove:
+            logger.info(f"mqtt client unsubscribing from topics {','.join(to_remove)}")
+            self.fut_unsubscribe = asyncio.get_running_loop().create_future()
+            self.client.unsubscribe(list(to_remove))
+            await self.fut_unsubscribe
+
     async def connect(self):
         server_host, server_port = self.connection_string.rsplit(":", maxsplit=1)
-        
-        looper = AsyncLooper(asyncio.get_running_loop(), self.client)
+
+        self.looper = AsyncLooper(asyncio.get_running_loop(), self.client)
 
         logger.info("Connecting to mqtt server at %s:%s", server_host, server_port)
+        self.fut_connected = asyncio.get_running_loop().create_future()
         self.client.connect(server_host, int(server_port))
-        self.client.socket().setsockopt(socket.SOL_SOCKET, socket.SO_SNDBUF, 2048)    
+        self.client.socket().setsockopt(socket.SOL_SOCKET, socket.SO_SNDBUF, 2048)
 
+        await self.fut_connected
+
+    async def disconnect(self):
+        logger.info("Disconnecting mqtt client from broker")
+        self.fut_disconnect = asyncio.get_running_loop().create_future()
+        self.client.disconnect()
+        await self.fut_disconnect