Python:锁定目录 [英] Python: Lock directory

问题描述

AFAIK此代码可用于锁定目录:

AFAIK this code can be used to lock a directory:

class LockDirectory(object):
    def __init__(self, directory):
        assert os.path.exists(directory)
        self.directory = directory

    def __enter__(self):
        self.dir_fd = os.open(self.directory, os.O_RDONLY)
        try:
            fcntl.flock(self.dir_fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
        except IOError as ex:
            if ex.errno != errno.EAGAIN:
                raise
            raise Exception('Somebody else is locking %r - quitting.' % self.directory)

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

但是根据此问题的答案，无法锁定目录: Python:锁定目录

But according to the answers of this question locking a directoy is not possible: Python: Lock a directory

上面的代码有什么问题?

What is wrong with above code?

我只需要支持当前的linux版本.没有Windows，Mac或其他Unix.

I only need to support current linux version. No Windows, Mac or other unix.

推荐答案

我稍稍更改了代码，像大多数上下文管理一样添加了return self，然后使用dup()，第二个上下文管理将失败.很简单，取消注释fcntl.flock(self.dir_fd,fcntl.LOCK_UN)

I change your code a bit,add return self like most context manage do,then with dup(),the second context manage will fail.and the solution is simple,uncommentfcntl.flock(self.dir_fd,fcntl.LOCK_UN)

用于打开文件的模式与群集无关.

The mode used to open the file doesn't matter to flock.

并且您无法聚集在NFS上.

and you cannot flock on NFS.

import os
import fcntl
import time
class LockDirectory(object):
    def __init__(self, directory):
        assert os.path.exists(directory)
        self.directory = directory

    def __enter__(self):
        self.dir_fd = os.open(self.directory, os.O_RDONLY)
        try:
            fcntl.flock(self.dir_fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
        except IOError as ex:             
            raise Exception('Somebody else is locking %r - quitting.' % self.directory)
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        # fcntl.flock(self.dir_fd,fcntl.LOCK_UN)
        os.close(self.dir_fd)

def main():
    with LockDirectory("test") as lock:
        newfd = os.dup(lock.dir_fd)
    with LockDirectory("test") as lock2:
        pass

if __name__ == '__main__':
    main()

这篇关于Python:锁定目录的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！