Add retries, close connection on timeout (fix #6)
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@ -28,11 +28,12 @@ class NeoHubConnectionError(Error):
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class NeoHub:
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def __init__(self, host='Neo-Hub', port=4242, request_timeout=5):
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def __init__(self, host='Neo-Hub', port=4242, request_timeout=5, request_attempts=1):
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self._logger = logging.getLogger('neohub')
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self._host = host
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self._port = port
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self._request_timeout = request_timeout
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self._request_attempts = request_attempts
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async def _send_message(self, reader: asyncio.StreamReader, writer: asyncio.StreamWriter, message: str):
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encoded_message = bytearray(json.dumps(message) + "\0\r", "utf-8")
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@ -49,39 +50,39 @@ class NeoHub:
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return data
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async def _send(self, message, expected_reply=None):
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try:
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reader, writer = await asyncio.open_connection(self._host, self._port)
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except (socket.gaierror, ConnectionRefusedError) as e:
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err = f'Could not connect to NeoHub at {self._host}: {e}'
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self._logger.error(err)
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raise NeoHubConnectionError from e
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last_exception = None
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for attempt in range(1, self._request_attempts+1):
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try:
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reader, writer = await asyncio.open_connection(self._host, self._port)
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data = await asyncio.wait_for(
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self._send_message(reader, writer, message), timeout=self._request_timeout)
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json_string = data.decode('utf-8')
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self._logger.debug(f"Received message: {json_string}")
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reply = json.loads(json_string, object_hook=lambda d: SimpleNamespace(**d))
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try:
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data = await asyncio.wait_for(
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self._send_message(reader, writer, message), timeout=self._request_timeout)
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except asyncio.TimeoutError as e:
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self._logger.error(f'Timeout talking to NeoHub: {e}')
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return False
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if expected_reply is None:
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return reply
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if reply.__dict__ == expected_reply:
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return True
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self._logger.error(f"[{attempt}] Unexpected reply: {reply}")
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except (socket.gaierror, ConnectionRefusedError) as e:
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last_exception = NeoHubConnectionError(e)
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self._logger.error(f"[{attempt}] Could not connect to NeoHub at {self._host}: {e}")
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except asyncio.TimeoutError as e:
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last_exception = e
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self._logger.error(f"[{attempt}] Timed out while sending a message to {self._host}")
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if writer is not None:
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writer.close()
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except json.decoder.JSONDecodeError as e:
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last_exception = e
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self._logger.error(f"[{attempt}] Could not decode JSON: {e}")
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# Wait for 1/2 of the timeout value before retrying.
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if self._request_attempts > 1 and attempt < self._request_attempts:
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await asyncio.sleep(self._request_timeout / 2)
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json_string = data.decode('utf-8')
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self._logger.debug(f"Received message: {json_string}")
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try:
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reply = json.loads(json_string, object_hook=lambda d: SimpleNamespace(**d))
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except json.decoder.JSONDecodeError as e:
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if expected_reply is None:
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raise(e)
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else:
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return False
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if expected_reply is None:
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return reply
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else:
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if reply.__dict__ == expected_reply:
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return True
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else:
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self._logger.error(f"Unexpected reply: {reply}")
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return False
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if expected_reply is None and last_exception is not None:
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raise(last_exception)
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return False
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async def firmware(self):
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"""
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@ -1,6 +1,7 @@
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import asyncio
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import json
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import pytest
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import time
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from types import SimpleNamespace
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import neohubapi
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@ -15,7 +16,8 @@ class FakeProtocol(asyncio.Protocol):
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def data_received(self, data):
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input = data.decode()
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# self.handler() is set by create_protocol below.
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# self.server and self.handler are set by create_protocol below.
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self.server.inputs.append(input)
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output = self.handler(input).encode() + b'\0'
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self.transport.write(output)
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self.transport.close()
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@ -25,11 +27,13 @@ class FakeServer:
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def __init__(self, loop, port):
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self.port = port
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self.loop = loop
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self.inputs = []
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async def start(self, handler):
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def create_protocol():
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fake_protocol = FakeProtocol()
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fake_protocol.handler = handler
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fake_protocol.server = self
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return fake_protocol
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self.server = await self.loop.create_server(create_protocol, HOST, self.port)
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@ -75,7 +79,35 @@ async def test_send_invalid_json(fakeserver):
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# expected_reply is set, function returns False.
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assert await hub._send('test', {'message': 'ok'}) is False
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assert len(fakeserver.inputs) == 1 # by default there are no retries.
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# expected_reply is not set, function raises exception.
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with pytest.raises(json.decoder.JSONDecodeError):
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await hub._send('test')
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@pytest.mark.asyncio
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async def test_send_timeout(fakeserver):
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def handler(input):
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time.sleep(0.2)
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return '{"message": "ok"}'
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await fakeserver.start(handler)
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hub = neohubapi.neohub.NeoHub(host=HOST, port=fakeserver.port, request_timeout=0.1)
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with pytest.raises(asyncio.TimeoutError):
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await hub._send('test')
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@pytest.mark.asyncio
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async def test_send_retries(fakeserver):
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def handler(input):
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return '{"message": "error"}'
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await fakeserver.start(handler)
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hub = neohubapi.neohub.NeoHub(
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host=HOST, port=fakeserver.port, request_attempts=3, request_timeout=0.1)
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# after 3 attempts the result is still incorrect.
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assert await hub._send('test', {'message': 'ok'}) is False
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assert len(fakeserver.inputs) == 3
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