Add more connection state

It's now possible to known when client is connecting/connected
and disconnecting/disconnected.
The difference between the two state is mostly whether the connection
is opened or not.
This will allow to avoid a reconnection while a reconnection is ongoing.

src/paho/mqtt/client.py

@@ -145,12 +145,6 @@ class _OutPacket(TypedDict):
 CONNACK_REFUSED_BAD_USERNAME_PASSWORD = ConnackCode.CONNACK_REFUSED_BAD_USERNAME_PASSWORD
 CONNACK_REFUSED_NOT_AUTHORIZED = ConnackCode.CONNACK_REFUSED_NOT_AUTHORIZED
 
-# Connection state
-mqtt_cs_new = ConnectionState.MQTT_CS_NEW
-mqtt_cs_connected = ConnectionState.MQTT_CS_CONNECTED
-mqtt_cs_disconnecting = ConnectionState.MQTT_CS_DISCONNECTING
-mqtt_cs_connect_async = ConnectionState.MQTT_CS_CONNECT_ASYNC
-
 # Message state
 mqtt_ms_invalid = MessageState.MQTT_MS_INVALID
 mqtt_ms_publish = MessageState.MQTT_MS_PUBLISH
@@ -688,7 +682,7 @@ def __init__(
         self._reconnect_on_failure = reconnect_on_failure
         self._ping_t = 0.0
         self._last_mid = 0
-        self._state = mqtt_cs_new
+        self._state = ConnectionState.MQTT_CS_NEW
         self._out_messages: collections.OrderedDict[
             int, MQTTMessage
         ] = collections.OrderedDict()
@@ -1329,7 +1323,7 @@ def connect_async(
         self._bind_port = bind_port
         self._clean_start = clean_start
         self._connect_properties = properties
-        self._state = mqtt_cs_connect_async
+        self._state = ConnectionState.MQTT_CS_CONNECT_ASYNC
 
     def reconnect_delay_set(self, min_delay: int = 1, max_delay: int = 120) -> None:
         """ Configure the exponential reconnect delay
@@ -1364,7 +1358,7 @@ def reconnect(self) -> MQTTErrorCode:
         }
 
         self._ping_t = 0.0
-        self._state = mqtt_cs_new
+        self._state = ConnectionState.MQTT_CS_CONNECTING
 
         self._sock_close()
 
@@ -1470,13 +1464,13 @@ def _loop(self, timeout: float = 1.0) -> MQTTErrorCode:
             # call _loop(). We still want to break that loop by returning an
             # rc != MQTT_ERR_SUCCESS and we don't want state to change from
             # mqtt_cs_disconnecting.
-            if self._state != ConnectionState.MQTT_CS_DISCONNECTING:
+            if self._state not in (ConnectionState.MQTT_CS_DISCONNECTING, ConnectionState.MQTT_CS_DISCONNECTED):
                 self._state = ConnectionState.MQTT_CS_CONNECTION_LOST
             return MQTTErrorCode.MQTT_ERR_CONN_LOST
         except ValueError:
             # Can occur if we just reconnected but rlist/wlist contain a -1 for
             # some reason.
-            if self._state != ConnectionState.MQTT_CS_DISCONNECTING:
+            if self._state not in (ConnectionState.MQTT_CS_DISCONNECTING, ConnectionState.MQTT_CS_DISCONNECTED):
                 self._state = ConnectionState.MQTT_CS_CONNECTION_LOST
             return MQTTErrorCode.MQTT_ERR_CONN_LOST
         except Exception:
@@ -1663,7 +1657,7 @@ def is_connected(self) -> bool:
         True if connection exists
         False if connection is closed
         """
-        return self._state == mqtt_cs_connected
+        return self._state == ConnectionState.MQTT_CS_CONNECTED
 
     def disconnect(
         self,
@@ -1677,10 +1671,11 @@ def disconnect(
         properties: (MQTT v5.0 only) a Properties instance setting the MQTT v5.0 properties
         to be included. Optional - if not set, no properties are sent.
         """
-        self._state = mqtt_cs_disconnecting
-
         if self._sock is None:
+            self._state = ConnectionState.MQTT_CS_DISCONNECTED
             return MQTT_ERR_NO_CONN
+        else:
+            self._state = ConnectionState.MQTT_CS_DISCONNECTING
 
         return self._send_disconnect(reasoncode, properties)
 
@@ -1944,7 +1939,8 @@ def loop_misc(self) -> MQTTErrorCode:
             # This hasn't happened in the keepalive time so we should disconnect.
             self._sock_close()
 
-            if self._state == mqtt_cs_disconnecting:
+            if self._state in (ConnectionState.MQTT_CS_DISCONNECTING, ConnectionState.MQTT_CS_DISCONNECTED):
+                self._state = ConnectionState.MQTT_CS_DISCONNECTED
                 rc = MQTTErrorCode.MQTT_ERR_SUCCESS
             else:
                 self._state = ConnectionState.MQTT_CS_CONNECTION_LOST
@@ -2069,7 +2065,7 @@ def loop_forever(
             if self._thread_terminate is True:
                 break
 
-            if self._state == mqtt_cs_connect_async:
+            if self._state == ConnectionState.MQTT_CS_CONNECT_ASYNC:
                 try:
                     self.reconnect()
                 except OSError:
@@ -2098,7 +2094,7 @@ def loop_forever(
 
             def should_exit() -> bool:
                 return (
-                    self._state == mqtt_cs_disconnecting or
+                    self._state in (ConnectionState.MQTT_CS_DISCONNECTING, ConnectionState.MQTT_CS_DISCONNECTED) or
                     run is False or  # noqa: B023 (uses the run variable from the outer scope on purpose)
                     self._thread_terminate is True
                 )
@@ -2751,7 +2747,8 @@ def _loop_rc_handle(
         if rc:
             self._sock_close()
 
-            if self._state == mqtt_cs_disconnecting:
+            if self._state in (ConnectionState.MQTT_CS_DISCONNECTING, ConnectionState.MQTT_CS_DISCONNECTED):
+                self._state = ConnectionState.MQTT_CS_DISCONNECTED
                 rc = MQTTErrorCode.MQTT_ERR_SUCCESS
 
             self._do_on_disconnect(rc, properties)
@@ -2921,6 +2918,11 @@ def _packet_write(self) -> MQTTErrorCode:
 
                         self._do_on_disconnect(MQTTErrorCode.MQTT_ERR_SUCCESS)
                         self._sock_close()
+                        # Only change to disconnected if the disconnection was wanted
+                        # by the client (== state was disconnecting). If the broker disconnected
+                        # use unilaterally don't change the state and client may reconnect.
+                        if self._state == ConnectionState.MQTT_CS_DISCONNECTING:
+                            self._state = ConnectionState.MQTT_CS_DISCONNECTED
                         return MQTTErrorCode.MQTT_ERR_SUCCESS
 
                 else:
@@ -2957,7 +2959,7 @@ def _check_keepalive(self) -> None:
             last_msg_in = self._last_msg_in
 
         if self._sock is not None and (now - last_msg_out >= self._keepalive or now - last_msg_in >= self._keepalive):
-            if self._state == mqtt_cs_connected and self._ping_t == 0:
+            if self._state == ConnectionState.MQTT_CS_CONNECTED and self._ping_t == 0:
                 try:
                     self._send_pingreq()
                 except Exception:
@@ -2970,7 +2972,8 @@ def _check_keepalive(self) -> None:
             else:
                 self._sock_close()
 
-                if self._state == mqtt_cs_disconnecting:
+                if self._state in (ConnectionState.MQTT_CS_DISCONNECTING, ConnectionState.MQTT_CS_DISCONNECTED):
+                    self._state = ConnectionState.MQTT_CS_DISCONNECTED
                     rc = MQTTErrorCode.MQTT_ERR_SUCCESS
                 else:
                     rc = MQTTErrorCode.MQTT_ERR_KEEPALIVE
@@ -3568,7 +3571,7 @@ def _handle_connack(self) -> MQTTErrorCode:
                 return self.reconnect()
 
         if result == 0:
-            self._state = mqtt_cs_connected
+            self._state = ConnectionState.MQTT_CS_CONNECTED
             self._reconnect_delay = None
 
         if self._protocol == MQTTv5:
@@ -4092,7 +4095,7 @@ def _reconnect_wait(self) -> None:
             target_time = now + self._reconnect_delay
 
         remaining = target_time - now
-        while (self._state != mqtt_cs_disconnecting
+        while (self._state not in (ConnectionState.MQTT_CS_DISCONNECTING, ConnectionState.MQTT_CS_DISCONNECTED)
                 and not self._thread_terminate
                 and remaining > 0):
 

src/paho/mqtt/enums.py

@@ -63,12 +63,14 @@ class ConnackCode(enum.IntEnum):
     CONNACK_REFUSED_NOT_AUTHORIZED = 5
 
 
-class ConnectionState(enum.IntEnum):
-    MQTT_CS_NEW = 0
-    MQTT_CS_CONNECTED = 1
-    MQTT_CS_DISCONNECTING = 2
-    MQTT_CS_CONNECT_ASYNC = 3
-    MQTT_CS_CONNECTION_LOST = 4
+class ConnectionState(enum.Enum):
+    MQTT_CS_NEW = enum.auto()
+    MQTT_CS_CONNECT_ASYNC = enum.auto()
+    MQTT_CS_CONNECTING = enum.auto()
+    MQTT_CS_CONNECTED = enum.auto()
+    MQTT_CS_CONNECTION_LOST = enum.auto()
+    MQTT_CS_DISCONNECTING = enum.auto()
+    MQTT_CS_DISCONNECTED = enum.auto()
 
 
 class MessageState(enum.IntEnum):