fix: handle socket connection closed error in _signal_exit

[roerohan]

Proposed changes

In the _listening function, when there's a WebSocketException, the following line runs as a part of the error handling procedure.

deepgram-python-sdk/deepgram/clients/live/v1/async_client.py

Line 371 in d2c4334

await self._signal_exit()

Now, the WebSocketException might also be caused due to the socket connection breaking. In this case, an error is thrown of the following form

future: <Task finished name='Task-291' coro=<AsyncLiveClient._listening() done, defined at /usr/local/lib/python3.12/dist-packages/deepgram/clients/live/v1/async_client.py:171> exception=ConnectionClosedError(Close(code=1011, reason='Deepgram did not receive audio data or a text message within the timeout window. See https://dpgr.am/net0001'), Close(code=1011, reason='Deepgram did not receive audio data or a text message within the timeout window. See https://dpgr.am/net0001'), True)>

While handling this exception, the _signal_exit function is called, which has the following lines

deepgram-python-sdk/deepgram/clients/live/v1/async_client.py

Lines 483 to 496 in d2c4334

	async def _signal_exit(self) -> None:
	# send close event
	self.logger.verbose("closing socket...")
	if self._socket is not None:
	self.logger.verbose("send CloseStream...")
	await self._socket.send(json.dumps({"type": "CloseStream"}))
	await asyncio.sleep(0.5)
	# push close event
	await self._emit(
	LiveTranscriptionEvents.Close,
	CloseResponse(type=LiveTranscriptionEvents.Close.value),
	)

In line 488, we're doing a self._socket.send, which is bound to fail because the socket connection is closed. This throws an error from the _signal_exit method. Since _signal_exit is not wrapped in a try except, the _listening method also throws an error and exits. The following is a sample traceback.

Traceback (most recent call last):
  File "/usr/local/lib/python3.12/dist-packages/deepgram/clients/live/v1/async_client.py", line 287, in _listening
    await self._signal_exit()
  File "/usr/local/lib/python3.12/dist-packages/deepgram/clients/live/v1/async_client.py", line 478, in _signal_exit
    await self._socket.send(json.dumps({"type": "CloseStream"}))
  File "/usr/local/lib/python3.12/dist-packages/websockets/legacy/protocol.py", line 635, in send
    await self.ensure_open()
  File "/usr/local/lib/python3.12/dist-packages/websockets/legacy/protocol.py", line 939, in ensure_open
    raise self.connection_closed_exc()

In this PR, I've added a try except only around the self._socket.send. It might be necessary to add exception handling wherever _signal_exit is being called as well, as when _signal_exit throws an error, the while True loop will exit, and the listen_thread will not exist anymore. Therefore any transcripts will not be received for that connection.

Closes #356

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Further comments

[davidvonthenen]

Ooooh very nice catch!

This needs to also be done for the sync client here, if you can add that would be great:
https://github.com/deepgram/deepgram-python-sdk/blob/main/deepgram/clients/live/v1/client.py#L476

If you could replace this exception handling with this to provide more detail on the error, that would be great as well:

                except websockets.exceptions.ConnectionClosedOK as e:
                    self.logger.notice(f"_signal_exit  - connection closed: {e.code}")
                except websockets.exceptions.WebSocketException as e:
                    self.logger.error("_signal_exit - WebSocketException: {str(e)}")
                except Exception as e:
                    self.logger.error("_signal_exit - Exception: {str(e)}")

Thanks for finding this issue!

[roerohan]

@dvonthenen thanks for the swift response!

I've updated the PR, please take a look and let me know if I should make any other changes too.

[davidvonthenen]

This looks great! I appreciate finding and fixing this issue!