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167 lines
4.3 KiB
167 lines
4.3 KiB
import time
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import errno
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import threading
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import weakref
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__all__ = ["lock_file"]
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try:
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import fcntl
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except ImportError:
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try:
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import msvcrt
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except ImportError:
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raise ImportError("Platform not supported (failed to import fcntl, msvcrt)")
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else:
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_lock_file_blocking_available = False
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def _lock_file_non_blocking(file_):
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try:
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msvcrt.locking(file_.fileno(), msvcrt.LK_NBLCK, 1)
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return True
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# TODO: check errno
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except IOError:
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return False
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def _unlock_file(file_):
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msvcrt.locking(file_.fileno(), msvcrt.LK_UNLCK, 1)
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else:
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_lock_file_blocking_available = True
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def _lock_file_blocking(file_):
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fcntl.flock(file_.fileno(), fcntl.LOCK_EX)
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def _lock_file_non_blocking(file_):
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try:
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fcntl.flock(file_.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB)
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return True
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except IOError as error:
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if error.errno in [errno.EACCES, errno.EAGAIN]:
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return False
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else:
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raise
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def _unlock_file(file_):
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fcntl.flock(file_.fileno(), fcntl.LOCK_UN)
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_locks_lock = threading.Lock()
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_locks = weakref.WeakValueDictionary()
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def lock_file(path, **kwargs):
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_locks_lock.acquire()
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try:
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lock = _locks.get(path)
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if lock is None:
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lock = _create_lock_file(path, **kwargs)
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_locks[path] = lock
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return lock
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finally:
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_locks_lock.release()
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def _create_lock_file(path, **kwargs):
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thread_lock = _ThreadLock(path, **kwargs)
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file_lock = _LockFile(path, **kwargs)
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return _LockSet([thread_lock, file_lock])
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class LockError(Exception):
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pass
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def _acquire_non_blocking(acquire, timeout, retry_period, path):
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if retry_period is None:
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retry_period = 0.05
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start_time = time.time()
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while True:
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success = acquire()
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if success:
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return
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elif (timeout is not None and
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time.time() - start_time > timeout):
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raise LockError("Couldn't lock {0}".format(path))
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else:
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time.sleep(retry_period)
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class _LockSet(object):
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def __init__(self, locks):
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self._locks = locks
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def acquire(self):
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acquired_locks = []
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try:
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for lock in self._locks:
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lock.acquire()
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acquired_locks.append(lock)
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except:
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for acquired_lock in reversed(acquired_locks):
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# TODO: handle exceptions
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acquired_lock.release()
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raise
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def release(self):
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for lock in reversed(self._locks):
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# TODO: Handle exceptions
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lock.release()
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def __enter__(self):
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self.acquire()
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return self
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def __exit__(self, *args):
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self.release()
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class _ThreadLock(object):
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def __init__(self, path, timeout=None, retry_period=None):
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self._path = path
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self._timeout = timeout
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self._retry_period = retry_period
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self._lock = threading.Lock()
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def acquire(self):
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if self._timeout is None:
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self._lock.acquire()
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else:
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_acquire_non_blocking(
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acquire=lambda: self._lock.acquire(False),
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timeout=self._timeout,
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retry_period=self._retry_period,
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path=self._path,
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)
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def release(self):
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self._lock.release()
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class _LockFile(object):
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def __init__(self, path, timeout=None, retry_period=None):
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self._path = path
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self._timeout = timeout
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self._retry_period = retry_period
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self._file = None
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self._thread_lock = threading.Lock()
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def acquire(self):
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if self._file is None:
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self._file = open(self._path, "w")
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if self._timeout is None and _lock_file_blocking_available:
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_lock_file_blocking(self._file)
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else:
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_acquire_non_blocking(
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acquire=lambda: _lock_file_non_blocking(self._file),
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timeout=self._timeout,
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retry_period=self._retry_period,
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path=self._path,
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)
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def release(self):
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_unlock_file(self._file)
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self._file.close()
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self._file = None
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