Viewing file:  _windows.py (1.36 KB) -rw-r--r--
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import os
from errno import ENOENT
from ._api import BaseFileLock
from ._util import raise_on_exist_ro_file
try:
import msvcrt
except ImportError:
msvcrt = None
class WindowsFileLock(BaseFileLock):
"""Uses the :func:`msvcrt.locking` function to hard lock the lock file on windows systems."""
def _acquire(self):
raise_on_exist_ro_file(self._lock_file)
mode = (
os.O_RDWR # open for read and write
| os.O_CREAT # create file if not exists
| os.O_TRUNC # truncate file if not empty
)
try:
fd = os.open(self._lock_file, mode)
except OSError as exception:
if exception.errno == ENOENT: # No such file or directory
raise
else:
try:
msvcrt.locking(fd, msvcrt.LK_NBLCK, 1)
except (OSError, IOError): # noqa: B014 # IOError is not OSError on python 2
os.close(fd)
else:
self._lock_file_fd = fd
def _release(self):
fd = self._lock_file_fd
self._lock_file_fd = None
msvcrt.locking(fd, msvcrt.LK_UNLCK, 1)
os.close(fd)
try:
os.remove(self._lock_file)
# Probably another instance of the application hat acquired the file lock.
except OSError:
pass
__all__ = [
"WindowsFileLock",
]
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