66 lines
2.1 KiB
Python
66 lines
2.1 KiB
Python
|
from __future__ import annotations
|
||
|
|
|
||
|
|
import os
|
||
|
|
import sys
|
||
|
|
from contextlib import suppress
|
||
|
|
from errno import EACCES
|
||
|
|
from pathlib import Path
|
||
|
|
from typing import cast
|
||
|
|
|
||
|
|
from ._api import BaseFileLock
|
||
|
|
from ._util import ensure_directory_exists, raise_on_not_writable_file
|
||
|
|
|
||
|
|
if sys.platform == "win32": # pragma: win32 cover
|
||
|
|
import msvcrt
|
||
|
|
|
||
|
|
class WindowsFileLock(BaseFileLock):
|
||
|
|
"""Uses the :func:`msvcrt.locking` function to hard lock the lock file on Windows systems."""
|
||
|
|
|
||
|
|
def _acquire(self) -> None:
|
||
|
|
raise_on_not_writable_file(self.lock_file)
|
||
|
|
ensure_directory_exists(self.lock_file)
|
||
|
|
flags = (
|
||
|
|
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, flags, self._context.mode)
|
||
|
|
except OSError as exception:
|
||
|
|
if exception.errno != EACCES: # has no access to this lock
|
||
|
|
raise
|
||
|
|
else:
|
||
|
|
try:
|
||
|
|
msvcrt.locking(fd, msvcrt.LK_NBLCK, 1)
|
||
|
|
except OSError as exception:
|
||
|
|
os.close(fd) # close file first
|
||
|
|
if exception.errno != EACCES: # file is already locked
|
||
|
|
raise
|
||
|
|
else:
|
||
|
|
self._context.lock_file_fd = fd
|
||
|
|
|
||
|
|
def _release(self) -> None:
|
||
|
|
fd = cast(int, self._context.lock_file_fd)
|
||
|
|
self._context.lock_file_fd = None
|
||
|
|
msvcrt.locking(fd, msvcrt.LK_UNLCK, 1)
|
||
|
|
os.close(fd)
|
||
|
|
|
||
|
|
with suppress(OSError): # Probably another instance of the application hat acquired the file lock.
|
||
|
|
Path(self.lock_file).unlink()
|
||
|
|
|
||
|
|
else: # pragma: win32 no cover
|
||
|
|
|
||
|
|
class WindowsFileLock(BaseFileLock):
|
||
|
|
"""Uses the :func:`msvcrt.locking` function to hard lock the lock file on Windows systems."""
|
||
|
|
|
||
|
|
def _acquire(self) -> None:
|
||
|
|
raise NotImplementedError
|
||
|
|
|
||
|
|
def _release(self) -> None:
|
||
|
|
raise NotImplementedError
|
||
|
|
|
||
|
|
|
||
|
|
__all__ = [
|
||
|
|
"WindowsFileLock",
|
||
|
|
]
|