Merge pull request #55 from flexiblepower/implement-reconnect

Implemented optional reconnect for S2Connection & new threading model where S2Connection.start_as_rm is blocking.

examples/example_frbc_rm.py

@@ -1,6 +1,5 @@
 import logging
 import sys
-import threading
 import uuid
 import signal
 import datetime
@@ -159,20 +158,16 @@ def deactivate(self, conn: S2Connection) -> None:
         provides_forecast=False,
         provides_power_measurements=[CommodityQuantity.ELECTRIC_POWER_L1],
     ),
+    reconnect=True,
 )
 
 
-stop_event = threading.Event()
-
-
 def stop(signal_num, _current_stack_frame):
     print(f"Received signal {signal_num}. Will stop S2 connection.")
-    stop_event.set()
+    s2_conn.stop()
 
 
 signal.signal(signal.SIGINT, stop)
 signal.signal(signal.SIGTERM, stop)
 
 s2_conn.start_as_rm()
-stop_event.wait()
-s2_conn.stop()

src/s2python/s2_connection.py

@@ -1,6 +1,7 @@
 import asyncio
 import json
 import logging
+import time
 import threading
 import uuid
 from dataclasses import dataclass
@@ -180,6 +181,7 @@ def register_handler(self, msg_type: Type[S2Message], handler: S2MessageHandler)
 
 class S2Connection:  # pylint: disable=too-many-instance-attributes
     url: str
+    reconnect: bool
     reception_status_awaiter: ReceptionStatusAwaiter
     ws: Optional[WSConnection]
     s2_parser: S2Parser
@@ -195,16 +197,20 @@ class S2Connection:  # pylint: disable=too-many-instance-attributes
 
     _eventloop: asyncio.AbstractEventLoop
     _stop_event: asyncio.Event
+    _restart_connection_event: asyncio.Event
 
-    def __init__(
+    def __init__(  # pylint: disable=too-many-arguments
         self,
         url: str,
         role: EnergyManagementRole,
         control_types: List[S2ControlType],
         asset_details: AssetDetails,
+        reconnect: bool = False,
     ) -> None:
         self.url = url
+        self.reconnect = reconnect
         self.reception_status_awaiter = ReceptionStatusAwaiter()
+        self.ws = None
         self.s2_parser = S2Parser()
 
         self._handlers = MessageHandlers()
@@ -221,14 +227,13 @@ def __init__(
         self._handlers.register_handler(HandshakeResponse, self.handle_handshake_response_as_rm)
 
     def start_as_rm(self) -> None:
-        self._thread = threading.Thread(target=self._run_eventloop, daemon=False)
-        self._thread.start()
-        logger.debug("Started eventloop thread!")
+        self._run_eventloop(self._run_as_rm())
 
-    def _run_eventloop(self) -> None:
+    def _run_eventloop(self, main_task: Awaitable[None]) -> None:
+        self._thread = threading.current_thread()
         logger.debug("Starting eventloop")
         try:
-            self._eventloop.run_until_complete(self._run_as_rm())
+            self._eventloop.run_until_complete(main_task)
         except asyncio.CancelledError:
             pass
         logger.debug("S2 connection thread has stopped.")
@@ -256,52 +261,78 @@ async def _do_stop(self) -> None:
 
     async def _run_as_rm(self) -> None:
         logger.debug("Connecting as S2 resource manager.")
-        self._received_messages = asyncio.Queue()
+
         self._stop_event = asyncio.Event()
-        await self.connect_ws()
 
-        background_tasks = []
-        background_tasks.append(self._eventloop.create_task(self._receive_messages()))
-        background_tasks.append(self._eventloop.create_task(self._handle_received_messages()))
+        first_run = True
 
-        async def wait_till_stop() -> None:
-            await self._stop_event.wait()
+        while (first_run or self.reconnect) and not self._stop_event.is_set():
+            first_run = False
+            self._restart_connection_event = asyncio.Event()
+            await self._connect_and_run()
+            time.sleep(1)
 
-        background_tasks.append(self._eventloop.create_task(wait_till_stop()))
+        logger.debug("Finished S2 connection eventloop.")
 
-        await self.connect_as_rm()
-        (done, pending) = await asyncio.wait(background_tasks, return_when=asyncio.FIRST_COMPLETED)
-        for task in done:
-            try:
-                await task
-            except asyncio.CancelledError:
-                pass
-            except websockets.ConnectionClosedError:
-                logger.info("The other party closed the websocket connection.c")
+    async def _connect_and_run(self) -> None:
+        self._received_messages = asyncio.Queue()
+        await self._connect_ws()
+        if self.ws:
 
-        for task in pending:
-            try:
-                task.cancel()
-                await task
-            except asyncio.CancelledError:
-                pass
+            async def wait_till_stop() -> None:
+                await self._stop_event.wait()
+
+            async def wait_till_connection_restart() -> None:
+                await self._restart_connection_event.wait()
+
+            background_tasks = [
+                self._eventloop.create_task(self._receive_messages()),
+                self._eventloop.create_task(wait_till_stop()),
+                self._eventloop.create_task(self._connect_as_rm()),
+                self._eventloop.create_task(wait_till_connection_restart()),
+            ]
+
+            (done, pending) = await asyncio.wait(
+                background_tasks, return_when=asyncio.FIRST_COMPLETED
+            )
+            if self._current_control_type:
+                self._current_control_type.deactivate(self)
+                self._current_control_type = None
+
+            for task in done:
+                try:
+                    await task
+                except asyncio.CancelledError:
+                    pass
+                except (websockets.ConnectionClosedError, websockets.ConnectionClosedOK):
+                    logger.info("The other party closed the websocket connection.")
+
+            for task in pending:
+                try:
+                    task.cancel()
+                    await task
+                except asyncio.CancelledError:
+                    pass
 
-        if self.ws:
             await self.ws.close()
             await self.ws.wait_closed()
-        logger.debug("Finished S2 connection eventloop.")
 
-    async def connect_ws(self) -> None:
-        self.ws = await ws_connect(uri=self.url)
+    async def _connect_ws(self) -> None:
+        try:
+            self.ws = await ws_connect(uri=self.url)
+        except (EOFError, OSError) as e:
+            logger.info("Could not connect due to: %s", str(e))
 
-    async def connect_as_rm(self) -> None:
+    async def _connect_as_rm(self) -> None:
         await self.send_msg_and_await_reception_status_async(
             Handshake(
                 message_id=uuid.uuid4(), role=self.role, supported_protocol_versions=[S2_VERSION]
             )
         )
         logger.debug("Send handshake to CEM. Expecting Handshake and HandshakeResponse from CEM.")
 
+        await self._handle_received_messages()
+
     async def handle_handshake(
         self, _: "S2Connection", message: S2Message, send_okay: Awaitable[None]
     ) -> None:
@@ -427,7 +458,11 @@ async def _send_and_forget(self, s2_msg: S2Message) -> None:
 
         json_msg = s2_msg.to_json()
         logger.debug("Sending message %s", json_msg)
-        await self.ws.send(json_msg)
+        try:
+            await self.ws.send(json_msg)
+        except websockets.ConnectionClosedError as e:
+            logger.error("Unable to send message %s due to %s", s2_msg, str(e))
+            self._restart_connection_event.set()
 
     async def respond_with_reception_status(
         self, subject_message_id: str, status: ReceptionStatusValues, diagnostic_label: str
@@ -458,9 +493,17 @@ async def send_msg_and_await_reception_status_async(
             s2_msg.message_id,  # type: ignore[attr-defined]
             timeout_reception_status,
         )
-        reception_status = await self.reception_status_awaiter.wait_for_reception_status(
-            s2_msg.message_id, timeout_reception_status  # type: ignore[attr-defined]
-        )
+        try:
+            reception_status = await self.reception_status_awaiter.wait_for_reception_status(
+                s2_msg.message_id, timeout_reception_status  # type: ignore[attr-defined]
+            )
+        except TimeoutError:
+            logger.error(
+                "Did not receive a reception status on time for %s",
+                s2_msg.message_id,  # type: ignore[attr-defined]
+            )
+            self._stop_event.set()
+            raise
 
         if reception_status.status != ReceptionStatusValues.OK and raise_on_error:
             raise RuntimeError(f"ReceptionStatus was not OK but rather {reception_status.status}")