commit: f73e60a7df4dfe91bc43fd0bb9cbb481fe9dc294 Author: Devan Franchini <twitch153 <AT> gentoo <DOT> org> AuthorDate: Wed May 13 19:59:13 2015 +0000 Commit: Devan Franchini <twitch153 <AT> gentoo <DOT> org> CommitDate: Wed May 13 19:59:13 2015 +0000 URL: https://gitweb.gentoo.org/proj/layman.git/commit/?id=f73e60a7
flocker.py: Adds file locking utility class layman/flocker.py | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 66 insertions(+) diff --git a/layman/flocker.py b/layman/flocker.py new file mode 100644 index 0000000..d40925d --- /dev/null +++ b/layman/flocker.py @@ -0,0 +1,66 @@ +#!/usr/bin/python +# -*- coding: utf-8 -*- +# File: flocker.py +# +# Handles all file locking. +# +# Copyright: +# (c) 2015 Devan Franchini +# Distributed under the terms of the GNU General Public License v2 +# +# Author(s): +# Michał Górny <[email protected]> +# Devan Franchini <[email protected]> +# + +#=============================================================================== +# +# Dependencies +# +#------------------------------------------------------------------------------- +import fcntl + +from layman.compatibility import fileopen + + +class FileLocker(object): + + def __init__(self): + self.files = {} + self.locked = set() + + + def lock_file(self, path, exclusive=False): + '''Lock the file located at path.''' + file_mode = 'r' + lock_mode = fcntl.LOCK_SH + + if exclusive: + file_mode = 'w+' + lock_mode = fcntl.LOCK_EX + + assert path not in self.locked + + self.locked.add(path) + fcntl.flock(self.get_file(path, file_mode).fileno(), lock_mode) + + + def unlock_file(self, path): + '''Unlock the file located at path.''' + assert path in self.locked + + fcntl.flock(self.get_file(path).fileno(), fcntl.LOCK_UN) + self.locked.discard(path) + + + def get_file(self, path, mode='r'): + '''Obtains file object for given path''' + assert mode in ('r', 'w+') + + if path not in self.files: + self.files[path] = fileopen(path, mode) + + f = self.files[path] + f.seek(0) + + return f
