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authorG S Niteesh Babu <niteesh.gs@gmail.com>2021-08-24 03:37:43 +0530
committerJohn Snow <jsnow@redhat.com>2021-09-27 12:10:29 -0400
commitaeb6b48a4714895a202e97a35c789ef7edf71665 (patch)
tree0074d705d00ecd6af64e9f58bf9fe707fe0d5aad
parent974e2f4722d719618502c43271f54cc10aec1dc7 (diff)
downloadqemu-arm-aeb6b48a4714895a202e97a35c789ef7edf71665.tar.gz
python/aqmp-tui: Add AQMP TUI
Added AQMP TUI. Implements the follwing basic features: 1) Command transmission/reception. 2) Shows events asynchronously. 3) Shows server status in the bottom status bar. 4) Automatic retries on disconnects and error conditions. Also added type annotations and necessary pylint/mypy configurations. Signed-off-by: G S Niteesh Babu <niteesh.gs@gmail.com> Message-Id: <20210823220746.28295-3-niteesh.gs@gmail.com> Signed-off-by: John Snow <jsnow@redhat.com>
-rw-r--r--python/qemu/aqmp/aqmp_tui.py620
-rw-r--r--python/setup.cfg13
2 files changed, 632 insertions, 1 deletions
diff --git a/python/qemu/aqmp/aqmp_tui.py b/python/qemu/aqmp/aqmp_tui.py
new file mode 100644
index 0000000000..ac533541d2
--- /dev/null
+++ b/python/qemu/aqmp/aqmp_tui.py
@@ -0,0 +1,620 @@
+# 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.
+"""
+AQMP TUI
+
+AQMP TUI is an asynchronous interface built on top the of the AQMP library.
+It is the successor of QMP-shell and is bought-in as a replacement for it.
+
+Example Usage: aqmp-tui <SOCKET | TCP IP:PORT>
+Full Usage: aqmp-tui --help
+"""
+
+import argparse
+import asyncio
+import json
+import logging
+from logging import Handler, LogRecord
+import signal
+from typing import (
+ List,
+ Optional,
+ Tuple,
+ Type,
+ Union,
+ cast,
+)
+
+import urwid
+import urwid_readline
+
+from ..qmp import QEMUMonitorProtocol, QMPBadPortError
+from .error import ProtocolError
+from .message import DeserializationError, Message, UnexpectedTypeError
+from .protocol import ConnectError, Runstate
+from .qmp_client import ExecInterruptedError, QMPClient
+from .util import create_task, pretty_traceback
+
+
+# The name of the signal that is used to update the history list
+UPDATE_MSG: str = 'UPDATE_MSG'
+
+
+def format_json(msg: str) -> str:
+ """
+ Formats valid/invalid multi-line JSON message into a single-line message.
+
+ Formatting is first tried using the standard json module. If that fails
+ due to an decoding error then a simple string manipulation is done to
+ achieve a single line JSON string.
+
+ Converting into single line is more asthetically pleasing when looking
+ along with error messages.
+
+ Eg:
+ Input:
+ [ 1,
+ true,
+ 3 ]
+ The above input is not a valid QMP message and produces the following error
+ "QMP message is not a JSON object."
+ When displaying this in TUI in multiline mode we get
+
+ [ 1,
+ true,
+ 3 ]: QMP message is not a JSON object.
+
+ whereas in singleline mode we get the following
+
+ [1, true, 3]: QMP message is not a JSON object.
+
+ The single line mode is more asthetically pleasing.
+
+ :param msg:
+ The message to formatted into single line.
+
+ :return: Formatted singleline message.
+ """
+ try:
+ msg = json.loads(msg)
+ return str(json.dumps(msg))
+ except json.decoder.JSONDecodeError:
+ msg = msg.replace('\n', '')
+ words = msg.split(' ')
+ words = list(filter(None, words))
+ return ' '.join(words)
+
+
+def has_handler_type(logger: logging.Logger,
+ handler_type: Type[Handler]) -> bool:
+ """
+ The Logger class has no interface to check if a certain type of handler is
+ installed or not. So we provide an interface to do so.
+
+ :param logger:
+ Logger object
+ :param handler_type:
+ The type of the handler to be checked.
+
+ :return: returns True if handler of type `handler_type`.
+ """
+ for handler in logger.handlers:
+ if isinstance(handler, handler_type):
+ return True
+ return False
+
+
+class App(QMPClient):
+ """
+ Implements the AQMP TUI.
+
+ Initializes the widgets and starts the urwid event loop.
+
+ :param address:
+ Address of the server to connect to.
+ :param num_retries:
+ The number of times to retry before stopping to reconnect.
+ :param retry_delay:
+ The delay(sec) before each retry
+ """
+ def __init__(self, address: Union[str, Tuple[str, int]], num_retries: int,
+ retry_delay: Optional[int]) -> None:
+ urwid.register_signal(type(self), UPDATE_MSG)
+ self.window = Window(self)
+ self.address = address
+ self.aloop: Optional[asyncio.AbstractEventLoop] = None
+ self.num_retries = num_retries
+ self.retry_delay = retry_delay if retry_delay else 2
+ self.retry: bool = False
+ self.exiting: bool = False
+ super().__init__()
+
+ def add_to_history(self, msg: str, level: Optional[str] = None) -> None:
+ """
+ Appends the msg to the history list.
+
+ :param msg:
+ The raw message to be appended in string type.
+ """
+ urwid.emit_signal(self, UPDATE_MSG, msg, level)
+
+ def _cb_outbound(self, msg: Message) -> Message:
+ """
+ Callback: outbound message hook.
+
+ Appends the outgoing messages to the history box.
+
+ :param msg: raw outbound message.
+ :return: final outbound message.
+ """
+ str_msg = str(msg)
+
+ if not has_handler_type(logging.getLogger(), TUILogHandler):
+ logging.debug('Request: %s', str_msg)
+ self.add_to_history('<-- ' + str_msg)
+ return msg
+
+ def _cb_inbound(self, msg: Message) -> Message:
+ """
+ Callback: outbound message hook.
+
+ Appends the incoming messages to the history box.
+
+ :param msg: raw inbound message.
+ :return: final inbound message.
+ """
+ str_msg = str(msg)
+
+ if not has_handler_type(logging.getLogger(), TUILogHandler):
+ logging.debug('Request: %s', str_msg)
+ self.add_to_history('--> ' + str_msg)
+ return msg
+
+ async def _send_to_server(self, msg: Message) -> None:
+ """
+ This coroutine sends the message to the server.
+ The message has to be pre-validated.
+
+ :param msg:
+ Pre-validated message to be to sent to the server.
+
+ :raise Exception: When an unhandled exception is caught.
+ """
+ try:
+ await self._raw(msg, assign_id='id' not in msg)
+ except ExecInterruptedError as err:
+ logging.info('Error server disconnected before reply %s', str(err))
+ self.add_to_history('Server disconnected before reply', 'ERROR')
+ except Exception as err:
+ logging.error('Exception from _send_to_server: %s', str(err))
+ raise err
+
+ def cb_send_to_server(self, raw_msg: str) -> None:
+ """
+ Validates and sends the message to the server.
+ The raw string message is first converted into a Message object
+ and is then sent to the server.
+
+ :param raw_msg:
+ The raw string message to be sent to the server.
+
+ :raise Exception: When an unhandled exception is caught.
+ """
+ try:
+ msg = Message(bytes(raw_msg, encoding='utf-8'))
+ create_task(self._send_to_server(msg))
+ except (DeserializationError, UnexpectedTypeError) as err:
+ raw_msg = format_json(raw_msg)
+ logging.info('Invalid message: %s', err.error_message)
+ self.add_to_history(f'{raw_msg}: {err.error_message}', 'ERROR')
+
+ def unhandled_input(self, key: str) -> None:
+ """
+ Handle's keys which haven't been handled by the child widgets.
+
+ :param key:
+ Unhandled key
+ """
+ if key == 'esc':
+ self.kill_app()
+
+ def kill_app(self) -> None:
+ """
+ Initiates killing of app. A bridge between asynchronous and synchronous
+ code.
+ """
+ create_task(self._kill_app())
+
+ async def _kill_app(self) -> None:
+ """
+ This coroutine initiates the actual disconnect process and calls
+ urwid.ExitMainLoop() to kill the TUI.
+
+ :raise Exception: When an unhandled exception is caught.
+ """
+ self.exiting = True
+ await self.disconnect()
+ logging.debug('Disconnect finished. Exiting app')
+ raise urwid.ExitMainLoop()
+
+ async def disconnect(self) -> None:
+ """
+ Overrides the disconnect method to handle the errors locally.
+ """
+ try:
+ await super().disconnect()
+ except (OSError, EOFError) as err:
+ logging.info('disconnect: %s', str(err))
+ self.retry = True
+ except ProtocolError as err:
+ logging.info('disconnect: %s', str(err))
+ except Exception as err:
+ logging.error('disconnect: Unhandled exception %s', str(err))
+ raise err
+
+ def _set_status(self, msg: str) -> None:
+ """
+ Sets the message as the status.
+
+ :param msg:
+ The message to be displayed in the status bar.
+ """
+ self.window.footer.set_text(msg)
+
+ def _get_formatted_address(self) -> str:
+ """
+ Returns a formatted version of the server's address.
+
+ :return: formatted address
+ """
+ if isinstance(self.address, tuple):
+ host, port = self.address
+ addr = f'{host}:{port}'
+ else:
+ addr = f'{self.address}'
+ return addr
+
+ async def _initiate_connection(self) -> Optional[ConnectError]:
+ """
+ Tries connecting to a server a number of times with a delay between
+ each try. If all retries failed then return the error faced during
+ the last retry.
+
+ :return: Error faced during last retry.
+ """
+ current_retries = 0
+ err = None
+
+ # initial try
+ await self.connect_server()
+ while self.retry and current_retries < self.num_retries:
+ logging.info('Connection Failed, retrying in %d', self.retry_delay)
+ status = f'[Retry #{current_retries} ({self.retry_delay}s)]'
+ self._set_status(status)
+
+ await asyncio.sleep(self.retry_delay)
+
+ err = await self.connect_server()
+ current_retries += 1
+ # If all retries failed report the last error
+ if err:
+ logging.info('All retries failed: %s', err)
+ return err
+ return None
+
+ async def manage_connection(self) -> None:
+ """
+ Manage the connection based on the current run state.
+
+ A reconnect is issued when the current state is IDLE and the number
+ of retries is not exhausted.
+ A disconnect is issued when the current state is DISCONNECTING.
+ """
+ while not self.exiting:
+ if self.runstate == Runstate.IDLE:
+ err = await self._initiate_connection()
+ # If retry is still true then, we have exhausted all our tries.
+ if err:
+ self._set_status(f'[Error: {err.error_message}]')
+ else:
+ addr = self._get_formatted_address()
+ self._set_status(f'[Connected {addr}]')
+ elif self.runstate == Runstate.DISCONNECTING:
+ self._set_status('[Disconnected]')
+ await self.disconnect()
+ # check if a retry is needed
+ if self.runstate == Runstate.IDLE:
+ continue
+ await self.runstate_changed()
+
+ async def connect_server(self) -> Optional[ConnectError]:
+ """
+ Initiates a connection to the server at address `self.address`
+ and in case of a failure, sets the status to the respective error.
+ """
+ try:
+ await self.connect(self.address)
+ self.retry = False
+ except ConnectError as err:
+ logging.info('connect_server: ConnectError %s', str(err))
+ self.retry = True
+ return err
+ return None
+
+ def run(self, debug: bool = False) -> None:
+ """
+ Starts the long running co-routines and the urwid event loop.
+
+ :param debug:
+ Enables/Disables asyncio event loop debugging
+ """
+ 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.manage_connection(), self.aloop)
+ try:
+ main_loop.run()
+ except Exception as err:
+ logging.error('%s\n%s\n', str(err), pretty_traceback())
+ raise err
+
+
+class StatusBar(urwid.Text):
+ """
+ A simple statusbar modelled using the Text widget. The status can be
+ set using the set_text function. All text set is aligned to right.
+
+ :param text: Initial text to be displayed. Default is empty str.
+ """
+ def __init__(self, text: str = ''):
+ super().__init__(text, align='right')
+
+
+class Editor(urwid_readline.ReadlineEdit):
+ """
+ A simple editor modelled using the urwid_readline.ReadlineEdit widget.
+ Mimcs GNU readline shortcuts and provides history support.
+
+ The readline shortcuts can be found below:
+ https://github.com/rr-/urwid_readline#features
+
+ Along with the readline features, this editor also has support for
+ history. Pressing the 'up'/'down' switches between the prev/next messages
+ available in the history.
+
+ Currently there is no support to save the history to a file. The history of
+ previous commands is lost on exit.
+
+ :param parent: Reference to the TUI object.
+ """
+ def __init__(self, parent: App) -> None:
+ super().__init__(caption='> ', multiline=True)
+ self.parent = parent
+ self.history: List[str] = []
+ self.last_index: int = -1
+ self.show_history: bool = False
+
+ def keypress(self, size: Tuple[int, int], key: str) -> Optional[str]:
+ """
+ Handles the keypress on this widget.
+
+ :param size:
+ The current size of the widget.
+ :param key:
+ The key to be handled.
+
+ :return: Unhandled key if any.
+ """
+ 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.
+ if not self.history:
+ return None
+ self.show_history = True
+ last_msg = self.history[self.last_index]
+ self.set_edit_text(last_msg)
+ self.edit_pos = len(last_msg)
+ elif key == 'up' and self.show_history:
+ self.last_index = max(self.last_index - 1, -len(self.history))
+ self.set_edit_text(self.history[self.last_index])
+ self.edit_pos = len(self.history[self.last_index])
+ elif key == 'down' and self.show_history:
+ if self.last_index == -1:
+ self.set_edit_text('')
+ self.show_history = False
+ else:
+ self.last_index += 1
+ self.set_edit_text(self.history[self.last_index])
+ self.edit_pos = len(self.history[self.last_index])
+ 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.parent.cb_send_to_server(msg)
+ self.history.append(msg)
+ self.set_edit_text('')
+ self.last_index = -1
+ self.show_history = False
+ else:
+ self.show_history = False
+ self.last_index = -1
+ return cast(Optional[str], super().keypress(size, key))
+ return None
+
+
+class EditorWidget(urwid.Filler):
+ """
+ Wrapper around the editor widget.
+
+ The Editor is a flow widget and has to wrapped inside a box widget.
+ This class wraps the Editor inside filler widget.
+
+ :param parent: Reference to the TUI object.
+ """
+ def __init__(self, parent: App) -> None:
+ super().__init__(Editor(parent), valign='top')
+
+
+class HistoryBox(urwid.ListBox):
+ """
+ This widget is modelled using the ListBox widget, contains the list of
+ all messages both QMP messages and log messsages to be shown in the TUI.
+
+ The messages are urwid.Text widgets. On every append of a message, the
+ focus is shifted to the last appended message.
+
+ :param parent: Reference to the TUI object.
+ """
+ def __init__(self, parent: App) -> None:
+ self.parent = parent
+ self.history = urwid.SimpleFocusListWalker([])
+ super().__init__(self.history)
+
+ def add_to_history(self, history: str) -> None:
+ """
+ Appends a message to the list and set the focus to the last appended
+ message.
+
+ :param history:
+ The history item(message/event) to be appended to the list.
+ """
+ self.history.append(urwid.Text(history))
+ self.history.set_focus(len(self.history) - 1)
+
+ def mouse_event(self, size: Tuple[int, int], _event: str, button: float,
+ _x: int, _y: int, focus: bool) -> None:
+ # Unfortunately there are no urwid constants that represent the mouse
+ # events.
+ if button == 4: # Scroll up event
+ super().keypress(size, 'up')
+ elif button == 5: # Scroll down event
+ super().keypress(size, 'down')
+
+
+class HistoryWindow(urwid.Frame):
+ """
+ This window composes the HistoryBox and EditorWidget in a horizontal split.
+ By default the first focus is given to the history box.
+
+ :param parent: Reference to the TUI object.
+ """
+ def __init__(self, parent: App) -> None:
+ self.parent = parent
+ self.editor_widget = EditorWidget(parent)
+ self.editor = urwid.LineBox(self.editor_widget)
+ self.history = HistoryBox(parent)
+ self.body = urwid.Pile([('weight', 80, self.history),
+ ('weight', 20, self.editor)])
+ super().__init__(self.body)
+ urwid.connect_signal(self.parent, UPDATE_MSG, self.cb_add_to_history)
+
+ def cb_add_to_history(self, msg: str, level: Optional[str] = None) -> None:
+ """
+ Appends a message to the history box
+
+ :param msg:
+ The message to be appended to the history box.
+ """
+ if level:
+ msg = f'[{level}]: {msg}'
+ self.history.add_to_history(msg)
+
+
+class Window(urwid.Frame):
+ """
+ This window is the top most widget of the TUI and will contain other
+ windows. Each child of this widget is responsible for displaying a specific
+ functionality.
+
+ :param parent: Reference to the TUI object.
+ """
+ def __init__(self, parent: App) -> None:
+ self.parent = parent
+ footer = StatusBar()
+ body = HistoryWindow(parent)
+ super().__init__(body, footer=footer)
+
+
+class TUILogHandler(Handler):
+ """
+ This handler routes all the log messages to the TUI screen.
+ It is installed to the root logger to so that the log message from all
+ libraries begin used is routed to the screen.
+
+ :param tui: Reference to the TUI object.
+ """
+ def __init__(self, tui: App) -> None:
+ super().__init__()
+ self.tui = tui
+
+ def emit(self, record: LogRecord) -> None:
+ """
+ Emits a record to the TUI screen.
+
+ Appends the log message to the TUI screen
+ """
+ level = record.levelname
+ msg = record.getMessage()
+ self.tui.add_to_history(msg, level)
+
+
+def main() -> None:
+ """
+ Driver of the whole script, parses arguments, initialize the TUI and
+ the logger.
+ """
+ parser = argparse.ArgumentParser(description='AQMP TUI')
+ parser.add_argument('qmp_server', help='Address of the QMP server. '
+ 'Format <UNIX socket path | TCP addr:port>')
+ parser.add_argument('--num-retries', type=int, default=10,
+ help='Number of times to reconnect before giving up.')
+ parser.add_argument('--retry-delay', type=int,
+ help='Time(s) to wait before next retry. '
+ 'Default action is to wait 2s between each retry.')
+ 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. '
+ '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(str(err))
+
+ app = App(address, args.num_retries, args.retry_delay)
+
+ root_logger = logging.getLogger()
+ root_logger.setLevel(logging.getLevelName(args.log_level))
+
+ if args.log_file:
+ root_logger.addHandler(logging.FileHandler(args.log_file))
+ else:
+ root_logger.addHandler(TUILogHandler(app))
+
+ app.run(args.asyncio_debug)
+
+
+if __name__ == '__main__':
+ main()
diff --git a/python/setup.cfg b/python/setup.cfg
index efcda23c48..9bc25998c1 100644
--- a/python/setup.cfg
+++ b/python/setup.cfg
@@ -81,8 +81,19 @@ namespace_packages = True
# fusepy has no type stubs:
allow_subclassing_any = True
+[mypy-qemu.aqmp.aqmp_tui]
+# 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]