On Fri, Jul 30, 2021 at 4:19 PM G S Niteesh Babu <niteesh.gs@gmail.com>
wrote:

> Added a draft of AQMP TUI.
>
> Implements the follwing basic features:
> 1) Command transmission/reception.
> 2) Shows events asynchronously.
> 3) Shows server status in the bottom status bar.
>
> Also added necessary pylint, mypy configurations
>
> Signed-off-by: G S Niteesh Babu <niteesh.gs@gmail.com>
> ---
>  python/qemu/aqmp/aqmp_tui.py | 333 +++++++++++++++++++++++++++++++++++
>  python/setup.cfg             |  16 +-
>  2 files changed, 348 insertions(+), 1 deletion(-)
>  create mode 100644 python/qemu/aqmp/aqmp_tui.py
>
> diff --git a/python/qemu/aqmp/aqmp_tui.py b/python/qemu/aqmp/aqmp_tui.py
> new file mode 100644
> index 0000000000..ec9eba0aa7
> --- /dev/null
> +++ b/python/qemu/aqmp/aqmp_tui.py
> @@ -0,0 +1,333 @@
> +# Copyright (c) 2021
> +#
> +# Authors:
> +#  Niteesh Babu G S <niteesh.gs@gmail.com>
> +#
> +# This work is licensed under the terms of the GNU GPL, version 2 or
> +# later.  See the COPYING file in the top-level directory.
> +
> +import argparse
> +import asyncio
> +import logging
> +from logging import Handler
> +import signal
> +
> +import urwid
> +import urwid_readline
> +
> +from ..qmp import QEMUMonitorProtocol, QMPBadPortError
> +from .message import DeserializationError, Message, UnexpectedTypeError
> +from .protocol import ConnectError
> +from .qmp_client import ExecInterruptedError, QMPClient
> +from .util import create_task, pretty_traceback
> +
> +
> +UPDATE_MSG = 'UPDATE_MSG'
> +
> +# Using root logger to enable all loggers under qemu and asyncio
> +LOGGER = logging.getLogger()
> +
> +
> +def format_json(msg):
> +    """
> +    Formats given multiline JSON message into a single line message.
> +    Converting into single line is more asthetically pleasing when looking
> +    along with error messages compared to multiline JSON.
> +    """
> +    # FIXME: Use better formatting mechanism. Might break at more complex
> JSON
> +    # data.
> +    msg = msg.replace('\n', '')
> +    words = msg.split(' ')
> +    words = [word for word in words if word != '']
> +    return ' '.join(words)
> +
> +
> +class App(QMPClient):
> +    def __init__(self, address):
> +        urwid.register_signal(type(self), UPDATE_MSG)
> +        self.window = Window(self)
> +        self.address = address
> +        self.aloop = None
> +        super().__init__()
> +
> +    def add_to_history(self, msg):
> +        urwid.emit_signal(self, UPDATE_MSG, msg)
> +
> +    def _cb_outbound(self, msg):
> +        # FIXME: I think the ideal way to omit these messages during
> in-TUI
> +        # logging will be to add a filter to the logger. We can use regex
> to
> +        # filter out messages starting with 'Request:' or 'Response:' but
> I
> +        # think a better approach will be encapsulate the message in an
> object
> +        # and filter based on the object. Encapsulation of the message
> will
> +        # also be necessary when we want different formatting of messages
> +        # inside TUI.
> +        handler = LOGGER.handlers[0]
> +        if not isinstance(handler, TUILogHandler):
> +            LOGGER.debug('Request: %s', str(msg))
> +        self.add_to_history('<-- ' + str(msg))
> +        return msg
> +
> +    def _cb_inbound(self, msg):
> +        handler = LOGGER.handlers[0]
> +        if not isinstance(handler, TUILogHandler):
> +            LOGGER.debug('Response: %s', str(msg))
> +        self.add_to_history('--> ' + str(msg))
> +        return msg
> +
> +    async def wait_for_events(self):
> +        async for event in self.events:
> +            self.handle_event(event)
> +
> +    async def _send_to_server(self, raw_msg):
> +        # FIXME: Format the raw_msg in history view to one line. It is not
> +        # pleasing to see multiple lines JSON object with an error
> statement.
> +        try:
> +            msg = Message(bytes(raw_msg, encoding='utf-8'))
> +            # Format multiline json into a single line JSON, since it is
> more
> +            # pleasing to look along with err message in TUI.
> +            raw_msg = self.format_json(raw_msg)
> +            await self._raw(msg, assign_id='id' not in msg)
> +        except (ValueError, TypeError) as err:
> +            LOGGER.info('Invalid message: %s', str(err))
> +            self.add_to_history(f'{raw_msg}: {err}')
> +        except (DeserializationError, UnexpectedTypeError) as err:
> +            LOGGER.info('Invalid message: %s', err.error_message)
> +            self.add_to_history(f'{raw_msg}: {err.error_message}')
> +        except ExecInterruptedError:
> +            LOGGER.info('Error server disconnected before reply')
> +            urwid.emit_signal(self, UPDATE_MSG,
> +                              '{"error": "Server disconnected before
> reply"}')
> +            self._set_status("Server disconnected")
> +        except Exception as err:
> +            LOGGER.error('Exception from _send_to_server: %s', str(err))
> +            raise err
> +
> +    def cb_send_to_server(self, msg):
> +        create_task(self._send_to_server(msg))
> +
> +    def unhandled_input(self, key):
> +        if key == 'esc':
> +            self.kill_app()
> +
> +    def kill_app(self):
> +        # TODO: Work on the disconnect logic
> +        create_task(self._kill_app())
> +
> +    async def _kill_app(self):
> +        # It is ok to call disconnect even in disconnect state
> +        try:
> +            await self.disconnect()
> +            LOGGER.debug('Disconnect finished. Exiting app')
> +        except Exception as err:
> +            LOGGER.info('_kill_app: %s', str(err))
> +            # Let the app crash after providing a proper stack trace
> +            raise err
> +        raise urwid.ExitMainLoop()
> +
> +    def handle_event(self, event):
> +        # FIXME: Consider all states present in qapi/run-state.json
> +        if event['event'] == 'SHUTDOWN':
> +            self._set_status('Server shutdown')
> +
> +    def _set_status(self, msg: str) -> None:
> +        self.window.footer.set_text(msg)
> +
> +    def _get_formatted_address(self) -> str:
> +        addr = f'{self.address}'
> +        if isinstance(self.address, tuple):
> +            host, port = self.address
> +            addr = f'{host}:{port}'
> +        return addr
> +
> +    async def connect_server(self):
> +        try:
> +            await self.connect(self.address)
> +            addr = self._get_formatted_address()
> +            self._set_status(f'Connected to {addr}')
> +        except ConnectError as err:
> +            LOGGER.info('connect_server: ConnectError %s', str(err))
> +            self._set_status('Server shutdown')
> +
> +    def run(self, debug=False):
> +        self.aloop = asyncio.get_event_loop()
> +        self.aloop.set_debug(debug)
> +
> +        # Gracefully handle SIGTERM and SIGINT signals
> +        cancel_signals = [signal.SIGTERM, signal.SIGINT]
> +        for sig in cancel_signals:
> +            self.aloop.add_signal_handler(sig, self.kill_app)
> +
> +        event_loop = urwid.AsyncioEventLoop(loop=self.aloop)
> +        main_loop = urwid.MainLoop(urwid.AttrMap(self.window,
> 'background'),
> +                                   unhandled_input=self.unhandled_input,
> +                                   handle_mouse=True,
> +                                   event_loop=event_loop)
> +
> +        create_task(self.wait_for_events(), self.aloop)
> +        create_task(self.connect_server(), self.aloop)
> +        try:
> +            main_loop.run()
> +        except Exception as err:
> +            LOGGER.error('%s\n%s\n', str(err), pretty_traceback())
> +            raise err
> +
> +
> +class StatusBar(urwid.Text):
> +    """
> +    A simple Text widget that currently only shows connection status.
> +    """
> +    def __init__(self, text=''):
> +        super().__init__(text, align='right')
> +
> +
> +class Editor(urwid_readline.ReadlineEdit):
> +    """
> +    Support urwid_readline features along with
> +    history support which lacks in urwid_readline
> +    """
> +    def __init__(self, master):
> +        super().__init__(caption='> ', multiline=True)
> +        self.master = master
> +        self.history = []
> +        self.last_index = -1
> +        self.show_history = False
> +
> +    def keypress(self, size, key):
> +        # TODO: Add some logic for down key and clean up logic if
> possible.
> +        # Returning None means the key has been handled by this widget
> +        # which otherwise is propogated to the parent widget to be
> +        # handled
> +        msg = self.get_edit_text()
> +        if key == 'up' and not msg:
> +            # Show the history when 'up arrow' is pressed with no input
> text.
> +            # NOTE: The show_history logic is necessary because in
> 'multiline'
> +            # mode (which we use) 'up arrow' is used to move between
> lines.
> +            self.show_history = True
> +            last_msg = self.history[self.last_index] if self.history else
> ''
> +            self.set_edit_text(last_msg)
> +            self.edit_pos = len(last_msg)
> +            self.last_index += 1
> +        elif key == 'up' and self.show_history:
> +            if self.last_index < len(self.history):
> +                self.set_edit_text(self.history[self.last_index])
> +                self.edit_pos = len(self.history[self.last_index])
> +                self.last_index += 1
> +        elif key == 'meta enter':
> +            # When using multiline, enter inserts a new line into the
> editor
> +            # send the input to the server on alt + enter
> +            self.master.cb_send_to_server(msg)
>

cb_send_to_server calls create_task(App._send_to_server(msg)) at which
point in the coroutine you finally do msg = Message(bytes(raw_msg,
encoding='utf-8')). However, you can do your message conversion *first*,
here in the Editor.

That way, you can avoid erasing the editor bar when the message is garbled
and the user has a chance to fix the corrupted message *first* before we
dispatch to the callback-async-machine. That should reduce quite a lot of
the error cases in _send_to_server and helps separate out the two kinds of
errors we expect to see here:

1. The user typed something that's garbage, and we didn't actually even
send it (because we couldn't), and
2. We sent (or tried to send) the message; but a failure occurred.


> +            self.history.insert(0, msg)
> +            self.set_edit_text('')
> +            self.last_index = 0
> +            self.show_history = False
> +        else:
> +            self.show_history = False
> +            self.last_index = 0
> +            return super().keypress(size, key)
> +        return None
> +
> +
> +class EditorWidget(urwid.Filler):
> +    """
> +    Wraps CustomEdit
> +    """
> +    def __init__(self, master):
> +        super().__init__(Editor(master), valign='top')
> +
> +
> +class HistoryBox(urwid.ListBox):
> +    """
> +    Shows all the QMP message transmitted/received
> +    """
> +    def __init__(self, master):
> +        self.master = master
> +        self.history = urwid.SimpleFocusListWalker([])
> +        super().__init__(self.history)
> +
> +    def add_to_history(self, history):
> +        self.history.append(urwid.Text(history))
> +        if self.history:
> +            self.history.set_focus(len(self.history) - 1)
> +
> +
> +class HistoryWindow(urwid.Frame):
> +    """
> +    Composes the HistoryBox and EditorWidget
> +    """
> +    def __init__(self, master):
> +        self.master = master
> +        self.editor_widget = EditorWidget(master)
> +        self.editor = urwid.LineBox(self.editor_widget)
> +        self.history = HistoryBox(master)
> +        self.body = urwid.Pile([('weight', 80, self.history),
> +                                ('weight', 20, self.editor)])
> +        super().__init__(self.body)
> +        urwid.connect_signal(self.master, UPDATE_MSG,
> self.cb_add_to_history)
> +
> +    def cb_add_to_history(self, msg):
> +        self.history.add_to_history(msg)
> +
> +
> +class Window(urwid.Frame):
> +    """
> +    This is going to be the main window that is going to compose other
> +    windows. In this stage it is unnecesssary but will be necessary in
> +    future when we will have multiple windows and want to the switch
> between
> +    them and display overlays
> +    """
> +    def __init__(self, master):
> +        self.master = master
> +        footer = StatusBar()
> +        body = HistoryWindow(master)
> +        super().__init__(body, footer=footer)
> +
> +
> +class TUILogHandler(Handler):
> +    def __init__(self, tui):
> +        super().__init__()
> +        self.tui = tui
> +
> +    def emit(self, record):
> +        level = record.levelname
> +        msg = record.getMessage()
> +        msg = f'[{level}]: {msg}'
> +        self.tui.add_to_history(msg)
> +
> +
> +def main():
> +    parser = argparse.ArgumentParser(description='AQMP TUI')
> +    parser.add_argument('qmp_server', help='Address of the QMP server'
> +                        '< UNIX socket path | TCP addr:port >')
> +    parser.add_argument('--log-file', help='The Log file name')
> +    parser.add_argument('--log-level', default='WARNING',
> +                        help='Log level
> <CRITICAL|ERROR|WARNING|INFO|DEBUG|>')
> +    parser.add_argument('--asyncio-debug', action='store_true',
> +                        help='Enable debug mode for asyncio loop'
> +                        'Generates lot of output, makes TUI unusable when'
> +                        'logs are logged in the TUI itself.'
> +                        'Use only when logging to a file')
> +    args = parser.parse_args()
> +
> +    try:
> +        address = QEMUMonitorProtocol.parse_address(args.qmp_server)
> +    except QMPBadPortError as err:
> +        parser.error(err)
> +
> +    app = App(address)
> +
> +    if args.log_file:
> +        LOGGER.addHandler(logging.FileHandler(args.log_file))
> +    else:
> +        LOGGER.addHandler(TUILogHandler(app))
> +
> +    log_level = logging.getLevelName(args.log_level)
> +    # getLevelName returns 'Level {log_level}' when a invalid level is
> passed.
> +    if log_level == f'Level {args.log_level}':
> +        parser.error('Invalid log level')
> +    LOGGER.setLevel(log_level)
> +
> +    app.run(args.asyncio_debug)
> +
> +
> +if __name__ == '__main__':
> +    main()  # type: ignore
> diff --git a/python/setup.cfg b/python/setup.cfg
> index d106a0ed7a..50f9894468 100644
> --- a/python/setup.cfg
> +++ b/python/setup.cfg
> @@ -81,8 +81,22 @@ namespace_packages = True
>  # fusepy has no type stubs:
>  allow_subclassing_any = True
>
> +[mypy-qemu.aqmp.aqmp_tui]
> +disallow_untyped_defs = False
> +disallow_incomplete_defs = False
> +check_untyped_defs = False
> +# urwid and urwid_readline have no type stubs:
> +allow_subclassing_any = True
> +
> +# The following missing import directives are because these libraries do
> not
> +# provide type stubs. Allow them on an as-needed basis for mypy.
>  [mypy-fuse]
> -# fusepy has no type stubs:
> +ignore_missing_imports = True
> +
> +[mypy-urwid]
> +ignore_missing_imports = True
> +
> +[mypy-urwid_readline]
>  ignore_missing_imports = True
>
>  [pylint.messages control]
> --
> 2.17.1
>
>