baseimage-tutorial-framework/lib/tfw/components/directory_monitor.py

from watchdog.observers import Observer
from watchdog.events import FileSystemEventHandler as FileSystemWatchdogEventHandler

from tfw.networking.event_handlers.server_connector import ServerUplinkConnector
from tfw.components.decorators import RateLimiter

from tfw.config.logs import logging
log = logging.getLogger(__name__)


class DirectoryMonitor:
    def __init__(self, directory):
        self.observer = Observer()
        self.eventhandler = WebideReloadWatchdogEventHandler()
        self.observer.schedule(self.eventhandler, directory, recursive=True)
        self.pause, self.resume = self.eventhandler.pause, self.eventhandler.resume

    def watch(self):
        self.observer.start()

    def stop(self):
        self.observer.stop()
        self.observer.join()

    @property
    def ignore(self):
        return self.eventhandler.ignore

    @ignore.setter
    def ignore(self, value):
        self.eventhandler.ignore = value if value >= 0 else 0

    @property
    def pauser(self):
        return DirectoryMonitor.Pauser(self)

    class Pauser:
        def __init__(self, directory_monitor):
            self.directorymonitor = directory_monitor
        def __enter__(self):
            self.directorymonitor.pause()
        def __exit__(self, exc_type, exc_val, exc_tb):
            self.directorymonitor.resume()


class WebideReloadWatchdogEventHandler(FileSystemWatchdogEventHandler):
    def __init__(self):
        super().__init__()
        self.uplink = ServerUplinkConnector()
        self._paused = False
        self.ignore = 0

    def pause(self):
        self._paused = True

    def resume(self):
        self._paused = False

    @RateLimiter(rate_per_second=2)
    def on_modified(self, event):
        if self._paused: return
        if self.ignore > 0:
            self.ignore = self.ignore - 1
            return
        log.debug(event)
        key = 'webide'
        self.uplink.send(key, {'data': {'command': 'reload'}})