Watch file system updates with gevent

fswatch.py

import os, os.path, collections
import gevent, gevent.pool, gevent.queue

import platform
if platform.system() == "Windows" :
    # see https://github.com/gevent/gevent/issues/459
    import socket

event = collections.namedtuple("event", ["name", "path", "isdir"])

class DirWatcher (object) :
    def __init__ (self, root) :
        self.root = os.path.abspath(root)
        self.pool = gevent.pool.Pool()
        self.q = gevent.queue.Queue()
        self.w = {}
        self.add(root, "crawl")
    def get (self) :
        return self.q.get()
    def add (self, path, evt="create") :
        if os.path.isdir(path) :
            for name in os.listdir(path) :
                self.add(os.path.join(path, name), evt)
        self.pool.spawn(self.watch, path)
        self.q.put(event(evt, path, os.path.isdir(path)))
    def watch (self, path) :
        hub = gevent.get_hub()
        watcher = hub.loop.stat(path, 1)
        self.w[path] = watcher
        isdir = os.path.isdir(path)
        if isdir :
            old = set(os.listdir(path))
        while path in self.w :
            try :
                with gevent.Timeout(2) :
                    hub.wait(watcher)
            except :
                continue
            if os.path.isdir(path) :
                new = set(os.listdir(path))
                for name in new - old :
                    self.add(os.path.join(path, name))
                old = new
            elif os.path.exists(path) :
                self.q.put(event("update", path, isdir))
            else :
                break
        if isdir :
            for name in old :
                self.w.pop(os.path.join(path, name), None)
        self.w.pop(path, None)
        self.q.put(event("delete", path, isdir))

if __name__ == "__main__" :
    if not os.path.isdir(",test") :
        os.mkdir(",test")
    d = DirWatcher(",test")
    while True :
        print "{event.name} {event.isdir} {event.path}".format(event=d.get())