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author | Russell Brenner <russellbrenner@google.com> | 2010-11-18 17:33:13 -0800 |
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committer | Russell Brenner <russellbrenner@google.com> | 2010-12-02 13:47:21 -0800 |
commit | 6b70adc33054f8aee8c54d0f460458a9df11b8a5 (patch) | |
tree | 103a13998c33944d6ab3b8318c509a037e639460 /WebKitTools/Scripts/webkitpy/common/system/file_lock.py | |
parent | bdf4ebc8e70b2d221b6ee7a65660918ecb1d33aa (diff) | |
download | external_webkit-6b70adc33054f8aee8c54d0f460458a9df11b8a5.zip external_webkit-6b70adc33054f8aee8c54d0f460458a9df11b8a5.tar.gz external_webkit-6b70adc33054f8aee8c54d0f460458a9df11b8a5.tar.bz2 |
Merge WebKit at r72274: Initial merge by git.
Change-Id: Ie51f0b4a16da82942bd516dce59cfb79ebbe25fb
Diffstat (limited to 'WebKitTools/Scripts/webkitpy/common/system/file_lock.py')
-rw-r--r-- | WebKitTools/Scripts/webkitpy/common/system/file_lock.py | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/WebKitTools/Scripts/webkitpy/common/system/file_lock.py b/WebKitTools/Scripts/webkitpy/common/system/file_lock.py new file mode 100644 index 0000000..7296958 --- /dev/null +++ b/WebKitTools/Scripts/webkitpy/common/system/file_lock.py @@ -0,0 +1,83 @@ +#!/usr/bin/env python +# Copyright (C) 2010 Gabor Rapcsanyi (rgabor@inf.u-szeged.hu), University of Szeged +# +# All rights reserved. +# +# Redistribution and use in source and binary forms, with or without +# modification, are permitted provided that the following conditions +# are met: +# 1. Redistributions of source code must retain the above copyright +# notice, this list of conditions and the following disclaimer. +# 2. Redistributions in binary form must reproduce the above copyright +# notice, this list of conditions and the following disclaimer in the +# documentation and/or other materials provided with the distribution. +# +# THIS SOFTWARE IS PROVIDED BY UNIVERSITY OF SZEGED ``AS IS'' AND ANY +# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR +# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL UNIVERSITY OF SZEGED OR +# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, +# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, +# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR +# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY +# OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +"""This class helps to lock files exclusively across processes.""" + +import logging +import os +import sys +import time + + +_log = logging.getLogger("webkitpy.common.system.file_lock") + + +class FileLock(object): + + def __init__(self, lock_file_path, max_wait_time_sec=20): + self._lock_file_path = lock_file_path + self._lock_file_descriptor = None + self._max_wait_time_sec = max_wait_time_sec + + def _create_lock(self): + if sys.platform in ('darwin', 'linux2', 'cygwin'): + import fcntl + fcntl.flock(self._lock_file_descriptor, fcntl.LOCK_EX | fcntl.LOCK_NB) + elif sys.platform == 'win32': + import msvcrt + msvcrt.locking(self._lock_file_descriptor, msvcrt.LK_NBLCK, 32) + + def _remove_lock(self): + if sys.platform in ('darwin', 'linux2', 'cygwin'): + import fcntl + fcntl.flock(self._lock_file_descriptor, fcntl.LOCK_UN) + elif sys.platform == 'win32': + import msvcrt + msvcrt.locking(self._lock_file_descriptor, msvcrt.LK_UNLCK, 32) + + def acquire_lock(self): + self._lock_file_descriptor = os.open(self._lock_file_path, os.O_TRUNC | os.O_CREAT) + start_time = time.time() + while True: + try: + self._create_lock() + return True + except IOError: + if time.time() - start_time > self._max_wait_time_sec: + _log.debug("File locking failed: %s" % str(sys.exc_info())) + os.close(self._lock_file_descriptor) + self._lock_file_descriptor = None + return False + + def release_lock(self): + try: + if self._lock_file_descriptor: + self._remove_lock() + os.close(self._lock_file_descriptor) + self._lock_file_descriptor = None + os.unlink(self._lock_file_path) + except (IOError, OSError): + _log.debug("Warning in release lock: %s" % str(sys.exc_info())) |