mirror of
https://github.com/kovidgoyal/calibre.git
synced 2025-07-09 03:04:10 -04:00
Simplify windows exclusive file implementation by using msvcrt.locking as a fcntl substitute
This commit is contained in:
Kovid Goyal
parent
ebe67702fd
commit
0fdf23de8b
@ -66,6 +66,8 @@ def find_tests(which_tests=None):
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a(find_tests())
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from calibre.utils.shared_file import find_tests
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a(find_tests())
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from calibre.utils.test_lock import find_tests
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a(find_tests())
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if ok('dbcli'):
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from calibre.db.cli.tests import find_tests
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a(find_tests())
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@ -10,7 +10,7 @@ from functools import partial
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from collections import defaultdict
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from copy import deepcopy
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from calibre.utils.lock import LockError, ExclusiveFile
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from calibre.utils.lock import ExclusiveFile
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from calibre.constants import config_dir, CONFIG_DIR_MODE
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plugin_dir = os.path.join(config_dir, 'plugins')
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@ -278,30 +278,23 @@ class Config(ConfigInterface):
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def parse(self):
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src = ''
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if os.path.exists(self.config_file_path):
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try:
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with ExclusiveFile(self.config_file_path) as f:
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try:
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src = f.read().decode('utf-8')
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except ValueError:
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print "Failed to parse", self.config_file_path
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traceback.print_exc()
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except LockError:
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raise IOError('Could not lock config file: %s'%self.config_file_path)
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return self.option_set.parse_string(src)
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def as_string(self):
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if not os.path.exists(self.config_file_path):
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return ''
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try:
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with ExclusiveFile(self.config_file_path) as f:
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return f.read().decode('utf-8')
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except LockError:
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raise IOError('Could not lock config file: %s'%self.config_file_path)
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def set(self, name, val):
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if not self.option_set.has_option(name):
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raise ValueError('The option %s is not defined.'%name)
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try:
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if not os.path.exists(config_dir):
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make_config_dir()
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with ExclusiveFile(self.config_file_path) as f:
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@ -315,8 +308,6 @@ class Config(ConfigInterface):
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if isinstance(src, unicode):
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src = src.encode('utf-8')
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f.write(src)
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except LockError:
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raise IOError('Could not lock config file: %s'%self.config_file_path)
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class StringConfig(ConfigInterface):
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@ -5,202 +5,107 @@ __docformat__ = 'restructuredtext en'
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Secure access to locked files from multiple processes.
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'''
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from calibre.constants import iswindows, __appname__, islinux, ishaiku, win32api, win32event, winerror, fcntl
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import time, atexit, os, stat, errno
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import atexit
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import errno
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import os
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import stat
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import time
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class LockError(Exception):
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pass
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class WindowsExclFile(object):
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def __init__(self, path, timeout=20):
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self.name = path
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import win32file as w
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import pywintypes
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while timeout > 0:
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timeout -= 1
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try:
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self._handle = w.CreateFile(
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path,
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w.GENERIC_READ | w.GENERIC_WRITE, # Open for reading and writing
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0, # Open exclusive
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None, # No security attributes, ensures handle is not inherited by children
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w.OPEN_ALWAYS, # If file does not exist, create it
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w.FILE_ATTRIBUTE_NORMAL, # Normal attributes
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None, # No template file
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from calibre.constants import (
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__appname__, fcntl, filesystem_encoding, ishaiku, islinux, iswindows, win32api,
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win32event, winerror
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)
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break
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except pywintypes.error as err:
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if getattr(err, 'args', [-1])[0] in (0x20, 0x21):
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time.sleep(1)
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continue
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from calibre.utils.monotonic import monotonic
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if iswindows:
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excl_file_mode = stat.S_IREAD | stat.S_IWRITE
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import msvcrt
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else:
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raise
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if not hasattr(self, '_handle'):
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raise LockError('Failed to open exclusive file: %s' % path)
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def seek(self, amt, frm=0):
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import win32file as w
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if frm not in (0, 1, 2):
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raise ValueError('Invalid from for seek: %s' % frm)
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frm = {0: w.FILE_BEGIN, 1: w.FILE_CURRENT, 2: w.FILE_END}[frm]
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if frm is w.FILE_END:
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amt = 0 - amt
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w.SetFilePointer(self._handle, amt, frm)
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def tell(self):
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import win32file as w
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return w.SetFilePointer(self._handle, 0, w.FILE_CURRENT)
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def flush(self):
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import win32file as w
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w.FlushFileBuffers(self._handle)
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def close(self):
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if self._handle is not None:
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import win32file as w
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self.flush()
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w.CloseHandle(self._handle)
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self._handle = None
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def read(self, bytes=-1):
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import win32file as w
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sz = w.GetFileSize(self._handle)
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max = sz - self.tell()
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if bytes < 0:
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bytes = max
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bytes = min(max, bytes)
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if bytes < 1:
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return ''
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hr, ans = w.ReadFile(self._handle, bytes, None)
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if hr != 0:
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raise IOError('Error reading file: %s' % hr)
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return ans
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def readlines(self, sizehint=-1):
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return self.read().splitlines()
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def write(self, bytes):
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if isinstance(bytes, unicode):
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bytes = bytes.encode('utf-8')
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import win32file as w
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w.WriteFile(self._handle, bytes, None)
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def truncate(self, size=None):
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import win32file as w
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pos = self.tell()
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if size is None:
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size = pos
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t = min(size, pos)
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self.seek(t)
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w.SetEndOfFile(self._handle)
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self.seek(pos)
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def isatty(self):
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return False
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@property
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def closed(self):
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return self._handle is None
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excl_file_mode = stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP | stat.S_IROTH
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def unix_open(path):
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# We cannot use open(a+b) directly because Fedora apparently ships with a
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# broken libc that causes seek(0) followed by truncate() to not work for
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# files with O_APPEND set. We also use O_CLOEXEC when it is available,
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# to ensure there are no races.
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flags = os.O_RDWR | os.O_CREAT
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from calibre.constants import plugins
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speedup = plugins['speedup'][0]
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has_cloexec = False
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if hasattr(speedup, 'O_CLOEXEC'):
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try:
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fd = os.open(
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path, flags | speedup.O_CLOEXEC, stat.S_IRUSR | stat.S_IWUSR |
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stat.S_IRGRP | stat.S_IROTH
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)
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fd = os.open(path, flags | speedup.O_CLOEXEC, excl_file_mode)
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has_cloexec = True
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except EnvironmentError as err:
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if getattr(err, 'errno', None) == errno.EINVAL:
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# Kernel does not support O_CLOEXEC
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fd = os.open(
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path, flags, stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP |
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stat.S_IROTH
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)
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else:
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# Kernel may not support O_CLOEXEC
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if err.errno != errno.EINVAL:
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raise
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else:
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fd = os.open(
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path, flags, stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP | stat.S_IROTH
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)
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if not has_cloexec:
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fd = os.open(path, flags, excl_file_mode)
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fcntl.fcntl(fd, fcntl.F_SETFD, fcntl.FD_CLOEXEC)
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return os.fdopen(fd, 'r+b')
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def windows_open(path):
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flags = os.O_RDWR | os.O_CREAT | os.O_NOINHERIT | os.O_BINARY
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fd = os.open(path, flags, excl_file_mode)
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return os.fdopen(fd, 'r+bN')
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class TimeoutError(Exception):
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pass
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def retry_for_a_time(timeout, sleep_time, func, *args):
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limit = monotonic() + timeout
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last_error = None
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while monotonic() <= limit:
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try:
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return func(*args)
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except EnvironmentError as err:
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last_error = err.args
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if monotonic() > limit:
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break
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time.sleep(sleep_time)
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raise TimeoutError(*last_error)
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class ExclusiveFile(object):
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def __init__(self, path, timeout=15):
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def __init__(self, path, timeout=15, sleep_time=0.2):
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if iswindows:
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if isinstance(path, bytes):
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path = path.decode(filesystem_encoding)
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self.path = path
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self.timeout = timeout
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self.sleep_time = sleep_time
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def __enter__(self):
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self.file = WindowsExclFile(self.path, self.timeout
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) if iswindows else unix_open(self.path)
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self.file.seek(0)
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timeout = self.timeout
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if not iswindows:
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while self.timeout < 0 or timeout >= 0:
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try:
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fcntl.flock(self.file.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB)
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break
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except IOError:
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time.sleep(1)
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timeout -= 1
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if timeout < 0 and self.timeout >= 0:
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self.file.close()
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raise LockError('Failed to lock')
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if iswindows:
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f = windows_open(self.path)
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retry_for_a_time(
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self.timeout, self.sleep_time, msvcrt.locking,
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f.fileno(), msvcrt.LK_NBLCK, 1
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)
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else:
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f = unix_open(self.path)
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retry_for_a_time(
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self.timeout, self.sleep_time, fcntl.flock,
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f.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB
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)
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self.file = f
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except TimeoutError as err:
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raise OSError(*(list(err.args)[:2] + [self.path]))
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return self.file
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def __exit__(self, type, value, traceback):
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if iswindows:
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try:
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msvcrt.locking(self.file.fileno(), msvcrt.LK_UNLCK, 1)
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except EnvironmentError:
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pass
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self.file.close()
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def test_exclusive_file(path=None):
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if path is None:
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import tempfile
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f = os.path.join(tempfile.gettempdir(), 'test-exclusive-file')
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with ExclusiveFile(f):
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# Try same process lock
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try:
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with ExclusiveFile(f, timeout=1):
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raise LockError(
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"ExclusiveFile failed to prevent multiple uses in the same process!"
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)
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except LockError:
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pass
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# Try different process lock
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from calibre.utils.ipc.simple_worker import fork_job
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err = fork_job('calibre.utils.lock', 'test_exclusive_file',
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(f, ))['result']
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if err is not None:
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raise LockError('ExclusiveFile failed with error: %s' % err)
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else:
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try:
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with ExclusiveFile(path, timeout=1):
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raise Exception(
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'ExclusiveFile failed to prevent multiple uses in different processes!'
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)
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except LockError:
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pass
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except Exception as err:
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return str(err)
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def _clean_lock_file(file):
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try:
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file.close()
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87
src/calibre/utils/test_lock.py
Normal file
87
src/calibre/utils/test_lock.py
Normal file
@ -0,0 +1,87 @@
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#!/usr/bin/env python2
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# vim:fileencoding=utf-8
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# License: GPLv3 Copyright: 2017, Kovid Goyal <kovid at kovidgoyal.net>
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from __future__ import absolute_import, division, print_function, unicode_literals
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import fcntl
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import os
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import shutil
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import subprocess
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import tempfile
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import unittest
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from threading import Thread
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from calibre.constants import iswindows
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from calibre.debug import run_calibre_debug
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from calibre.utils.lock import ExclusiveFile, unix_open
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def FastFailEF(name):
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return ExclusiveFile(name, sleep_time=0.01, timeout=0.05)
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class Other(Thread):
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daemon = True
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locked = None
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def run(self):
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try:
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with FastFailEF('test'):
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self.locked = True
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except EnvironmentError:
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self.locked = False
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class IPCLockTest(unittest.TestCase):
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def setUp(self):
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self.cwd = os.getcwd()
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self.tdir = tempfile.mkdtemp()
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os.chdir(self.tdir)
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def tearDown(self):
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os.chdir(self.cwd)
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shutil.rmtree(self.tdir)
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def test_exclusive_file_same_process(self):
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with ExclusiveFile('test'):
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ef = FastFailEF('test')
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self.assertRaises(EnvironmentError, ef.__enter__)
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t = Other()
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t.start(), t.join()
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self.assertIs(t.locked, False)
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if not iswindows:
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with unix_open('test') as f:
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self.assertEqual(
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1, fcntl.fcntl(f.fileno(), fcntl.F_GETFD) & fcntl.FD_CLOEXEC
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)
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def test_exclusive_file_other_process(self):
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child = run_calibre_debug(
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'-c',
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'from calibre.utils.test_lock import other1; other1()',
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stdout=subprocess.PIPE
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)
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ready = child.stdout.readline()
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self.assertEqual(ready.strip(), b'ready')
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ef = FastFailEF('test')
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self.assertRaises(EnvironmentError, ef.__enter__)
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child.kill()
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self.assertIsNotNone(child.wait())
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with ExclusiveFile('test'):
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pass
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def other1():
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import sys, time
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e = ExclusiveFile('test')
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with e:
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print('ready')
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sys.stdout.close()
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sys.stderr.close()
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time.sleep(30)
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def find_tests():
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return unittest.defaultTestLoader.loadTestsFromTestCase(IPCLockTest)
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