MaxKB/apps/common/lock/impl/file_lock.py

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# coding=utf-8
"""
@project: MaxKB
@Author
@file file_lock.py
@date2024/8/20 10:48
@desc:
"""
import errno
import hashlib
import os
import time
import six
from common.lock.base_lock import BaseLock
from maxkb.const import PROJECT_DIR
def key_to_lock_name(key):
"""
Combine part of a key with its hash to prevent very long filenames
"""
MAX_LENGTH = 50
key_hash = hashlib.md5(six.b(key)).hexdigest()
lock_name = key[:MAX_LENGTH - len(key_hash) - 1] + '_' + key_hash
return lock_name
class FileLock(BaseLock):
"""
File locking backend.
"""
def __init__(self, settings=None):
if settings is None:
settings = {}
self.location = settings.get('location')
if self.location is None:
self.location = os.path.join(PROJECT_DIR, 'data', 'lock')
try:
os.makedirs(self.location)
except OSError as error:
# Directory exists?
if error.errno != errno.EEXIST:
# Re-raise unexpected OSError
raise
def _get_lock_path(self, key):
lock_name = key_to_lock_name(key)
return os.path.join(self.location, lock_name)
def try_lock(self, key, timeout):
lock_path = self._get_lock_path(key)
try:
# 创建锁文件,如果没创建成功则拿不到
fd = os.open(lock_path, os.O_CREAT | os.O_EXCL)
except OSError as error:
if error.errno == errno.EEXIST:
# File already exists, check its modification time
mtime = os.path.getmtime(lock_path)
ttl = mtime + timeout - time.time()
if ttl > 0:
return False
else:
# 如果超时时间已到,直接上锁成功继续执行
os.utime(lock_path, None)
return True
else:
return False
else:
os.close(fd)
return True
def un_lock(self, key):
lock_path = self._get_lock_path(key)
os.remove(lock_path)