Implement the concept of the frame dispatcher and handlers

fixeria/threads
Vadim Yanitskiy 5 months ago
parent 05c71259f6
commit af18b58e1f
  1. 122
      handlers.py
  2. 69
      peer.py

@ -0,0 +1,122 @@
# This file is a part of sedbgmux, an open source DebugMux client.
# Copyright (c) 2022 Vadim Yanitskiy <axilirator@gmail.com>
#
# SPDX-License-Identifier: GPL-3.0-or-later
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import logging as log
import threading
import queue
import enum
import abc
from typing import Any, Optional
from construct import Container
from proto import DbgMuxFrame
class DbgMuxFrameHandler(abc.ABC):
''' Abstract DebugMux frame handler '''
_tx_queue: Optional[queue.Queue] = None
def send(self, msg_type: DbgMuxFrame.MsgType, msg: Any = b''):
''' Called by child classes to send some message '''
assert self._tx_queue is not None
self._tx_queue.put((msg_type, msg))
@abc.abstractmethod
def _handle_frame(self, frame: Container) -> None:
''' Handle the given DebugMux frame '''
class ConnState(enum.Enum):
''' Connection state for DbgMuxConnHandler '''
NotEstablished = enum.auto()
Establishing = enum.auto()
Established = enum.auto()
class DbgMuxConnHandler(DbgMuxFrameHandler):
''' Abstract DebugMux connection handler '''
def __init__(self):
self.conn_state: ConnState = ConnState.NotEstablished
self.ConnRef: int = 0xffff
self.DPRef: int = 0xffff
def establish(self, DPRef: int) -> None:
assert self.conn_state == ConnState.NotEstablished
log.info("Establishing connection with DPRef=0x%04x", DPRef)
self.send(DbgMuxFrame.MsgType.ConnEstablish, dict(DPRef=DPRef))
self.conn_state = ConnState.Establishing
self.DPRef = DPRef
def send_data(self, data: bytes) -> None:
''' Called by child classes to send connection data '''
assert self.conn_state == ConnState.Established
msg = dict(ConnRef=self.ConnRef, Data=data)
self.send(DbgMuxFrame.MsgType.ConnData, msg)
def _match(self, frame: Container,
msg_type: DbgMuxFrame.MsgType,
msg_fields: dict = { }) -> bool:
if frame['MsgType'] != msg_type:
return False
for (key, val) in msg_fields.items():
if key not in frame['Msg']:
return False
if frame['Msg'][key] != val:
return False
return True
def _handle_frame(self, frame: Container) -> None:
''' Handle the given DebugMux frame '''
if self.conn_state == ConnState.Established:
fields = dict(ConnRef=self.ConnRef)
if self._match(frame, DbgMuxFrame.MsgType.ConnData, fields):
self._handle_data(frame['Msg']['Data'])
self.send(DbgMuxFrame.MsgType.Ack)
raise StopIteration
elif self._match(frame, DbgMuxFrame.MsgType.ConnTerminated, fields):
log.info('Connection terminated (DPRef=0x%04x, ConnRef=0x%04x)',
self.DPRef, self.ConnRef)
self.conn_state = ConnState.NotEstablished
self._handle_terminate()
self.send(DbgMuxFrame.MsgType.Ack)
raise StopIteration
elif self.conn_state == ConnState.Establishing:
# Match ConnEstablished with our DPRef and any ConnRef
if self._match(frame, DbgMuxFrame.MsgType.ConnEstablished, dict(DPRef=self.DPRef)):
log.info('Connection established (DPRef=0x%04x, ConnRef=0x%04x)',
self.DPRef, frame['Msg']['ConnRef'])
self.conn_state = ConnState.Established
self.ConnRef = frame['Msg']['ConnRef']
self._handle_establish()
self.send(DbgMuxFrame.MsgType.Ack)
raise StopIteration
@abc.abstractmethod
def _handle_data(self, data: bytes) -> None:
''' Called on reciept of connection data '''
@abc.abstractmethod
def _handle_establish(self) -> None:
''' Called on connection establishment '''
@abc.abstractmethod
def _handle_terminate(self) -> None:
''' Called on connection termination '''

@ -23,10 +23,73 @@ import queue
from typing import Any, Optional
from construct import Const, Container, Int16ul
from handlers import DbgMuxFrameHandler
from transport import Transport
from proto import DbgMuxFrame
class DbgMuxFrameDisp:
''' DebugMux frame dispatcher '''
def __init__(self, rxq: queue.Queue, txq: queue.Queue):
self.__hlist = list()
self._rx_queue = rxq
self._tx_queue = txq
self._thread = threading.Thread(target=self._worker,
name='DbgMuxPeer-Disp',
daemon=True)
self._shutdown = threading.Event()
def start(self) -> None:
self._shutdown.clear()
self._thread.start()
def stop(self) -> None:
self._shutdown.set()
self._thread.join()
def find_by_name(self, name: str) -> Optional[DbgMuxFrameHandler]:
for (hname, hinst) in self.__hlist:
if hname == name:
return hinst
return None
def register(self, inst: DbgMuxFrameHandler,
name: Optional[str] = None) -> None:
if name is not None and self.find_by_name(name):
raise FileExistsError
self.__hlist.append((name, inst))
# Give a handler access to the Tx queue
inst._tx_queue = self._tx_queue
def unregister(self, name: str):
inst = self.find_by_name(name)
if inst is None:
raise FileNotFoundError
self.__hlist.remove((name, inst))
def _worker(self) -> None:
while not self._shutdown.is_set():
try:
frame = self._rx_queue.get(block=True, timeout=0.5)
self._dispatch(frame)
except queue.Empty:
pass
log.debug('Thread \'%s\' is shutting down', threading.current_thread().name)
def _dispatch(self, frame: DbgMuxFrame) -> None:
for (hname, hinst) in self.__hlist:
try:
hinst._handle_frame(frame)
except StopIteration:
return
except Exception as e:
log.error("Handler '%s' raised an exception: %s", hname, e)
# TODO: remove this handler?
log.error("DebugMux message %s was not handled, dropping...", frame['Msg'])
class DbgMuxPeer:
def __init__(self, io: Transport):
self.tx_count: int = 0
@ -40,13 +103,17 @@ class DbgMuxPeer:
self._tx_thread = threading.Thread(target=self._tx_worker,
name='DbgMuxPeer-Tx',
daemon=True)
self._shutdown = threading.Event()
# Internal queues for Rx/Tx frames
self._rx_queue = queue.Queue()
self._tx_queue = queue.Queue()
# Init frame dispatcher
self.disp = DbgMuxFrameDisp(self._rx_queue,
self._tx_queue)
# TODO: self.disp.start()
def start(self) -> None:
self._shutdown.clear()
self._rx_thread.start()

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