LockFile文件-解决并发写入日志的问题

import threading
import os


class LockedFile(object):
    SETUP_LOGGER_LOCK = threading.Lock()
    LOGFILES = {}

@classmethod
def open(cls, fn):
    with cls.SETUP_LOGGER_LOCK:
        if fn not in cls.LOGFILES:
            if os.path.exists(os.path.dirname(fn)):
                os.mkdir(os.path.dirname(fn))
                cls.LOGFILES[fn] = cls(fn)
        rv = cls.LOGFILES[fn]
        rv.users += 1
    return rv

def __init__(self, fn):
    self._filename = fn
    self._f = None
    self.users = 0
    self._lock = threading.Lock()

def __enter__(self):
    return self

def __exit__(self, exc_type, exc_val, exc_tb):
    self.close()

def write(self, data):
    with self._lock:
        if self._f is None:
            self._f = open(self._filename, 'ab')
        self._f.write(data)
        self._f.flush()

def close(self):
    with self.SETUP_LOGGER_LOCK:
        self.users -= 1
        if self.users == 0:
            if self._f:
                self._f.close()
            self.LOGFILES.pop(self._filename)