Source code for qcodes.monitor.monitor

#! /usr/bin/env python
# vim:fenc=utf-8
# Copyright © 2017 unga <>
# Distributed under terms of the MIT license.
Monitor a set of parameters in a background thread
stream output over websocket

To start monitor, run this file, or if qcodes is installed as a module:

``% python -m qcodes.monitor.monitor``

Add parameters to monitor in your measurement by creating a new monitor with a
list of parameters to monitor:

``monitor = qcodes.Monitor(param1, param2, param3, ...)``
from __future__ import annotations

import asyncio
import json
import logging
import os
import socketserver
import time
import webbrowser
from asyncio import CancelledError
from collections import defaultdict
from contextlib import suppress
from threading import Event, Thread
from typing import Any, Awaitable, Callable, Sequence

import websockets
import websockets.exceptions
import websockets.server

from qcodes.parameters import Parameter


log = logging.getLogger(__name__)

def _get_metadata(
    *parameters: Parameter, use_root_instrument: bool = True
) -> dict[str, Any]:
    Return a dictionary that contains the parameter metadata grouped by the
    instrument it belongs to.
    metadata_timestamp = time.time()
    # group metadata by instrument
    metas: dict[Any, Any] = defaultdict(list)
    for parameter in parameters:
        # Get the latest value from the parameter,
        # respecting the max_val_age parameter
        meta: dict[str, float | str | None] = {}
        meta["value"] = str(parameter.get_latest())
        timestamp = parameter.get_latest.get_timestamp()
        if timestamp is not None:
            meta["ts"] = timestamp.timestamp()
            meta["ts"] = None
        meta["name"] = parameter.label or
        meta["unit"] = parameter.unit

        # find the base instrument that this parameter belongs to
        if use_root_instrument:
            baseinst = parameter.root_instrument
            baseinst = parameter.instrument
        if baseinst is None:
            metas["Unbound Parameter"].append(meta)

    # Create list of parameters, grouped by instrument
    parameters_out = []
    for instrument in metas:
        temp = {"instrument": instrument, "parameters": metas[instrument]}

    state = {"ts": metadata_timestamp, "parameters": parameters_out}
    return state

def _handler(
    parameters: Sequence[Parameter], interval: float, use_root_instrument: bool = True
) -> Callable[[websockets.server.WebSocketServerProtocol, str], Awaitable[None]]:
    Return the websockets server handler.

    async def server_func(
        websocket: websockets.server.WebSocketServerProtocol, _: str
    ) -> None:
        Create a websockets handler that sends parameter values to a listener
        every "interval" seconds.
        while True:
                # Update the parameter values
                    meta = _get_metadata(
                        *parameters, use_root_instrument=use_root_instrument
                except ValueError:
                    log.exception("Error getting parameters")
                log.debug("sending.. to %r", websocket)
                await websocket.send(json.dumps(meta))
                # Wait for interval seconds and then send again
                await asyncio.sleep(interval)
            except (CancelledError, websockets.exceptions.ConnectionClosed):
                log.debug("Got CancelledError or ConnectionClosed",
        log.debug("Closing websockets connection")

    return server_func

[docs]class Monitor(Thread): """ QCodes Monitor - WebSockets server to monitor qcodes parameters. """ running = None def __init__( self, *parameters: Parameter, interval: float = 1, use_root_instrument: bool = True, ): """ Monitor qcodes parameters. Args: *parameters: Parameters to monitor. interval: How often one wants to refresh the values. use_root_instrument: Defines if parameters are grouped according to parameter.root_instrument or parameter.instrument """ super().__init__() # Check that all values are valid parameters for parameter in parameters: if not isinstance(parameter, Parameter): raise TypeError(f"We can only monitor QCodes " f"Parameters, not {type(parameter)}") self.loop: asyncio.AbstractEventLoop | None = None self._stop_loop_future: asyncio.Future | None = None self._parameters = parameters self.loop_is_closed = Event() self.server_is_started = Event() self.handler = _handler( parameters, interval=interval, use_root_instrument=use_root_instrument ) log.debug("Start monitoring thread") if Monitor.running: # stop the old server log.debug("Stopping and restarting server") Monitor.running.stop() self.start() # Wait until the loop is running self.server_is_started.wait(timeout=5) if not self.server_is_started.is_set(): raise RuntimeError("Failed to start server") Monitor.running = self
[docs] def run(self) -> None: """ Start the event loop and run forever. """ log.debug("Running Websocket server") async def run_loop() -> None: self.loop = asyncio.get_running_loop() self._stop_loop_future = self.loop.create_future() async with websockets.server.serve( self.handler, "", WEBSOCKET_PORT, close_timeout=1 ): self.server_is_started.set() try: await self._stop_loop_future except asyncio.CancelledError: log.debug("Websocket server thread shutting down") try: finally: self.loop_is_closed.set()
[docs] def update_all(self) -> None: """ Update all parameters in the monitor. """ for parameter in self._parameters: # call get if it can be called without arguments with suppress(TypeError): parameter.get()
[docs] def stop(self) -> None: """ Shutdown the server, close the event loop and join the thread. Setting active Monitor to ``None``. """ self.join() Monitor.running = None
[docs] def join(self, timeout: float | None = None) -> None: """ Overwrite ``Thread.join`` to make sure server is stopped before joining avoiding a potential deadlock. """ log.debug("Shutting down server") if not self.is_alive(): # we run this check before trying to run to prevent a cryptic # error message log.debug("monitor is dead") return try: if self.loop is not None and self._stop_loop_future is not None: log.debug("Instructing server to stop event loop.") self.loop.call_soon_threadsafe(self._stop_loop_future.cancel) else: log.debug("No event loop found. Cannot stop event loop.") except RuntimeError: # the above may throw a runtime error if the loop is already # stopped in which case there is nothing more to do log.exception("Could not close loop") self.loop_is_closed.wait(timeout=5) if not self.loop_is_closed.is_set(): raise RuntimeError("Failed to join loop") log.debug("Loop reported closed") super().join(timeout=timeout) log.debug("Monitor Thread has joined")
[docs] @staticmethod def show() -> None: """ Overwrite this method to show/raise your monitor GUI F.ex. :: import webbrowser url = "localhost:3000" # Open URL in new window, raising the window if possible. webbrowser.open_new(url) """"http://localhost:{SERVER_PORT}")
def main() -> None: import http.server # If this file is run, create a simple webserver that serves a simple # website that can be used to view monitored parameters. static_dir = os.path.join(os.path.dirname(__file__), "dist") os.chdir(static_dir) try:"Starting HTTP Server at http://localhost:%i", SERVER_PORT) with socketserver.TCPServer(("", SERVER_PORT), http.server.SimpleHTTPRequestHandler) as httpd: log.debug("serving directory %s", static_dir)"http://localhost:{SERVER_PORT}") httpd.serve_forever() except KeyboardInterrupt:"Shutting Down HTTP Server") if __name__ == "__main__": main()