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https://github.com/evilhero/mylar
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141 lines
3.7 KiB
Python
Executable file
141 lines
3.7 KiB
Python
Executable file
# portalocker.py - Cross-platform (posix/nt) API for flock-style file locking.
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# Requires python 1.5.2 or better.
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"""Cross-platform (posix/nt) API for flock-style file locking.
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Synopsis:
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import portalocker
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file = open("somefile", "r+")
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portalocker.lock(file, portalocker.LOCK_EX)
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file.seek(12)
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file.write("foo")
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file.close()
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If you know what you're doing, you may choose to
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portalocker.unlock(file)
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before closing the file, but why?
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Methods:
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lock( file, flags )
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unlock( file )
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Constants:
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LOCK_EX
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LOCK_SH
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LOCK_NB
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Exceptions:
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LockException
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Notes:
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For the 'nt' platform, this module requires the Python Extensions for Windows.
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Be aware that this may not work as expected on Windows 95/98/ME.
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History:
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I learned the win32 technique for locking files from sample code
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provided by John Nielsen <nielsenjf@my-deja.com> in the documentation
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that accompanies the win32 modules.
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Author: Jonathan Feinberg <jdf@pobox.com>,
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Lowell Alleman <lalleman@mfps.com>,
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Rick van Hattem <Rick.van.Hattem@Fawo.nl>
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Version: 0.3
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URL: https://github.com/WoLpH/portalocker
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"""
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__all__ = [
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"lock",
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"unlock",
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"LOCK_EX",
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"LOCK_SH",
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"LOCK_NB",
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"LockException",
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]
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import os
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class LockException(Exception):
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# Error codes:
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LOCK_FAILED = 1
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if os.name == 'nt':
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import win32con
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import win32file
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import pywintypes
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LOCK_EX = win32con.LOCKFILE_EXCLUSIVE_LOCK
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LOCK_SH = 0 # the default
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LOCK_NB = win32con.LOCKFILE_FAIL_IMMEDIATELY
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# is there any reason not to reuse the following structure?
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__overlapped = pywintypes.OVERLAPPED()
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elif os.name == 'posix':
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import fcntl
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LOCK_EX = fcntl.LOCK_EX
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LOCK_SH = fcntl.LOCK_SH
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LOCK_NB = fcntl.LOCK_NB
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else:
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raise RuntimeError("PortaLocker only defined for nt and posix platforms")
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if os.name == 'nt':
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def lock(file, flags):
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hfile = win32file._get_osfhandle(file.fileno())
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try:
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win32file.LockFileEx(hfile, flags, 0, -0x10000, __overlapped)
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except pywintypes.error, exc_value:
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# error: (33, 'LockFileEx', 'The process cannot access the file because another process has locked a portion of the file.')
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if exc_value[0] == 33:
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raise LockException(LockException.LOCK_FAILED, exc_value[2])
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else:
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# Q: Are there exceptions/codes we should be dealing with here?
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raise
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def unlock(file):
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hfile = win32file._get_osfhandle(file.fileno())
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try:
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win32file.UnlockFileEx(hfile, 0, -0x10000, __overlapped)
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except pywintypes.error, exc_value:
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if exc_value[0] == 158:
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# error: (158, 'UnlockFileEx', 'The segment is already unlocked.')
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# To match the 'posix' implementation, silently ignore this error
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pass
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else:
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# Q: Are there exceptions/codes we should be dealing with here?
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raise
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elif os.name == 'posix':
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def lock(file, flags):
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try:
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fcntl.flock(file.fileno(), flags)
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except IOError, exc_value:
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# The exception code varies on different systems so we'll catch
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# every IO error
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raise LockException(*exc_value)
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def unlock(file):
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fcntl.flock(file.fileno(), fcntl.LOCK_UN)
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if __name__ == '__main__':
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from time import time, strftime, localtime
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import sys
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import portalocker
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log = open('log.txt', "a+")
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portalocker.lock(log, portalocker.LOCK_EX)
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timestamp = strftime("%m/%d/%Y %H:%M:%S\n", localtime(time()))
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log.write( timestamp )
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print "Wrote lines. Hit enter to release lock."
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dummy = sys.stdin.readline()
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log.close()
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