async def _command_queue_iteration(self, command):
"""
Coroutine which evaluates one item from the circuit command queue.
1. Dispatch and validate through caproto.VirtualCircuit.process_command
- Upon server failure, respond to the client with
caproto.ErrorResponse
2. Update Channel state if applicable.
"""
try:
self.circuit.process_command(command)
except ca.RemoteProtocolError:
cid, sid = self._get_ids_from_command(command)
if cid is not None:
try:
await self.send(ca.ServerDisconnResponse(cid=cid))
except Exception:
self.log.exception(
"Client broke the protocol in a recoverable way, but "
"channel disconnection of cid=%d sid=%d failed.", cid,
sid)
raise LoopExit('Recoverable protocol error failure')
else:
self.log.exception(
"Client broke the protocol in a recoverable way. "
"Disconnected channel cid=%d sid=%d but keeping the "
"circuit alive.", cid, sid)
await self._wake_new_command()
return
else:
self.log.exception(
"Client broke the protocol in an unrecoverable way.")
# TODO: Kill the circuit.
raise LoopExit('Unrecoverable protocol error')
except Exception:
self.log.exception('Circuit command queue evaluation failed')
# Internal error - ignore for now
return
if command is ca.DISCONNECTED:
raise DisconnectedCircuit
try:
response = await self._process_command(command)
return response
except Exception as ex:
if not self.connected:
if not isinstance(command, ca.ClearChannelRequest):
self.log.error(
'Server error after client '
'disconnection: %s', command)
raise LoopExit('Server error after client disconnection')
cid, sid = self._get_ids_from_command(command)
chan, _ = self._get_db_entry_from_command(command)
self.log.exception('Server failed to process command (%r): %s',
chan.name, command)
if cid is not None:
error_message = f'Python exception: {type(ex).__name__} {ex}'
return [
ca.ErrorResponse(command,
cid,
status=ca.CAStatus.ECA_INTERNAL,
error_message=error_message)
]
async def command_queue_loop(self):
"""
Coroutine which feeds from the circuit command queue.
1. Dispatch and validate through caproto.VirtualCircuit.process_command
- Upon server failure, respond to the client with
caproto.ErrorResponse
2. Update Channel state if applicable.
"""
# The write_event will be cleared when a write is scheduled and set
# when one completes.
maybe_awaitable = self.write_event.set()
# The curio backend makes this an awaitable thing.
if maybe_awaitable is not None:
await maybe_awaitable
while True:
try:
command = await self.command_queue.get()
self.circuit.process_command(command)
if command is ca.DISCONNECTED:
break
except self.TaskCancelled:
break
except ca.RemoteProtocolError as ex:
if hasattr(command, 'sid'):
sid = command.sid
cid = self.circuit.channels_sid[sid].cid
elif hasattr(command, 'cid'):
cid = command.cid
sid = self.circuit.channels[cid].sid
else:
cid, sid = None, None
if cid is not None:
try:
await self.send(ca.ServerDisconnResponse(cid=cid))
except Exception:
self.log.error(
"Client broke the protocol in a recoverable "
"way, but channel disconnection of cid=%d sid=%d "
"failed.", cid, sid,
exc_info=ex)
break
else:
self.log.error(
"Client broke the protocol in a recoverable "
"way. Disconnected channel cid=%d sid=%d "
"but keeping the circuit alive.", cid, sid,
exc_info=ex)
await self._wake_new_command()
continue
else:
self.log.error("Client broke the protocol in an "
"unrecoverable way.", exc_info=ex)
# TODO: Kill the circuit.
break
except Exception:
self.log.exception('Circuit command queue evaluation failed')
continue
try:
response_command = await self._process_command(command)
if response_command is not None:
await self.send(*response_command)
except DisconnectedCircuit:
await self._on_disconnect()
self.circuit.disconnect()
await self.context.circuit_disconnected(self)
break
except Exception as ex:
if not self.connected:
if not isinstance(command, ca.ClearChannelRequest):
self.log.error('Server error after client '
'disconnection: %s', command)
break
self.log.exception('Server failed to process command: %s',
command)
if hasattr(command, 'sid'):
cid = self.circuit.channels_sid[command.sid].cid
response_command = ca.ErrorResponse(
command, cid,
status=ca.CAStatus.ECA_INTERNAL,
error_message=('Python exception: {} {}'
''.format(type(ex).__name__, ex))
)
await self.send(response_command)
await self._wake_new_command()