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

from time import time, sleep
from watchdog.observers import Observer
from watchdog.events import FileSystemEventHandler

from tfw.networking.event_handlers.server_connector import ServerUplinkConnector

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


class WebideReloadEventHandler(FileSystemEventHandler):
    def __init__(self, rate_per_second):
        super().__init__()
        self.uplink = ServerUplinkConnector()

        self.min_interval = 1 / float(rate_per_second)
        self.last_call = time()

    def on_modified(self, event):
        self.limit_rate()

        log.debug(event)
        anchor = 'anchor_webide'
        self.uplink.send(anchor, {'anchor': anchor,
                                  'data': {'command': 'reload'}})

    def limit_rate(self):   #TODO: pls review me :3
        since_last_call = time() - self.last_call
        to_next_call = self.min_interval - since_last_call
        self.last_call = time()
        if to_next_call > 0:
            sleep(to_next_call)


class DirectoryMonitor:
    def __init__(self, directory):
        self.observer = Observer()
        self.observer.schedule(WebideReloadEventHandler(rate_per_second=5), directory, recursive=True)

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

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