mirror of
https://github.com/saveweb/biliarchiver.git
synced 2024-09-19 19:15:27 -07:00
92 lines
3.0 KiB
Python
92 lines
3.0 KiB
Python
import os
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import sys
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import importlib.util
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class AlreadyRunningError(Exception):
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def __init__(self, message: str=""):
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self.message = message
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super().__init__(self.message)
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def __str__(self):
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return self.message
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LOCK_FILENAME = '_uploading.lock'
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class UploadLock_Basic:
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def __init__(self, lock_dir):
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self.lock_file = os.path.join(lock_dir, LOCK_FILENAME)
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def __enter__(self):
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if os.path.exists(self.lock_file):
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with open(self.lock_file, 'r', encoding='utf-8') as f:
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print(f.read())
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print("Another instance is already running.")
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raise AlreadyRunningError('Another instance is already running.')
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else:
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with open(self.lock_file, 'w', encoding='utf-8') as f:
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f.write(f'PID: {os.getpid()}: Running')
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# print("Acquired lock, continuing.")
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def __exit__(self, exc_type, exc_val, exc_tb):
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os.remove(self.lock_file)
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# print("Released lock.")
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# decorator
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def __call__(self, func):
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def wrapper(*args, **kwargs):
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with self:
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return func(*args, **kwargs)
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return wrapper
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class UploadLock_Fcntl():
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fcntl = None
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try:
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import fcntl
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except ModuleNotFoundError:
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pass
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def __init__(self, lock_dir):
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if self.fcntl is None:
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raise(ModuleNotFoundError("No module named 'fcntl'", name='fcntl'))
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self.lock_file = os.path.join(lock_dir, LOCK_FILENAME)
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self.lock_file_fd = None
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def __enter__(self):
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assert self.fcntl is not None
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self.lock_file_fd = open(self.lock_file, 'w')
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try:
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self.fcntl.lockf(self.lock_file_fd, self.fcntl.LOCK_EX | self.fcntl.LOCK_NB)
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# print("Acquired lock, continuing.")
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except IOError:
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raise AlreadyRunningError("Another instance is already running.")
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def __exit__(self, exc_type, exc_val, exc_tb):
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assert self.fcntl is not None
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if self.lock_file_fd is None:
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raise IOError("Lock file not opened.")
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self.fcntl.lockf(self.lock_file_fd, self.fcntl.LOCK_UN)
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self.lock_file_fd.close() # lock_file_fd.close() 之后，其他进程有机会在本进程删掉锁文件之前拿到新锁
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try:
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os.remove(self.lock_file) # 删除文件不影响其他进程已持有的 inode 新锁
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except FileNotFoundError:
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# 如果抢到新锁的是本进程，删除文件的是其他进程，那么本进程再删除时自然会 FileNotFoundError，忽略就好
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pass
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# print("Released lock.")
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# decorator
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def __call__(self, func):
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def wrapper(*args, **kwargs):
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with self:
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return func(*args, **kwargs)
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return wrapper
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class UploadLock():
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def __new__(cls, lock_dir):
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fcntl_avaivable = importlib.util.find_spec('fcntl')
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if fcntl_avaivable is not None:
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return UploadLock_Fcntl(lock_dir)
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else:
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return UploadLock_Basic(lock_dir) |