mirror of
https://github.com/SickGear/SickGear.git
synced 2024-11-25 14:25:05 +00:00
288 lines
10 KiB
Python
288 lines
10 KiB
Python
from __future__ import annotations
|
|
|
|
import contextlib
|
|
import logging
|
|
import os
|
|
import time
|
|
import warnings
|
|
from abc import ABC, abstractmethod
|
|
from dataclasses import dataclass
|
|
from threading import local
|
|
from typing import TYPE_CHECKING, Any
|
|
|
|
from ._error import Timeout
|
|
|
|
if TYPE_CHECKING:
|
|
import sys
|
|
from types import TracebackType
|
|
|
|
if sys.version_info >= (3, 11): # pragma: no cover (py311+)
|
|
from typing import Self
|
|
else: # pragma: no cover (<py311)
|
|
from typing_extensions import Self
|
|
|
|
|
|
_LOGGER = logging.getLogger("filelock")
|
|
|
|
|
|
# This is a helper class which is returned by :meth:`BaseFileLock.acquire` and wraps the lock to make sure __enter__
|
|
# is not called twice when entering the with statement. If we would simply return *self*, the lock would be acquired
|
|
# again in the *__enter__* method of the BaseFileLock, but not released again automatically. issue #37 (memory leak)
|
|
class AcquireReturnProxy:
|
|
"""A context aware object that will release the lock file when exiting."""
|
|
|
|
def __init__(self, lock: BaseFileLock) -> None:
|
|
self.lock = lock
|
|
|
|
def __enter__(self) -> BaseFileLock:
|
|
return self.lock
|
|
|
|
def __exit__(
|
|
self,
|
|
exc_type: type[BaseException] | None,
|
|
exc_value: BaseException | None,
|
|
traceback: TracebackType | None,
|
|
) -> None:
|
|
self.lock.release()
|
|
|
|
|
|
@dataclass
|
|
class FileLockContext:
|
|
"""A dataclass which holds the context for a ``BaseFileLock`` object."""
|
|
|
|
# The context is held in a separate class to allow optional use of thread local storage via the
|
|
# ThreadLocalFileContext class.
|
|
|
|
#: The path to the lock file.
|
|
lock_file: str
|
|
|
|
#: The default timeout value.
|
|
timeout: float
|
|
|
|
#: The mode for the lock files
|
|
mode: int
|
|
|
|
#: The file descriptor for the *_lock_file* as it is returned by the os.open() function, not None when lock held
|
|
lock_file_fd: int | None = None
|
|
|
|
#: The lock counter is used for implementing the nested locking mechanism.
|
|
lock_counter: int = 0 # When the lock is acquired is increased and the lock is only released, when this value is 0
|
|
|
|
|
|
class ThreadLocalFileContext(FileLockContext, local):
|
|
"""A thread local version of the ``FileLockContext`` class."""
|
|
|
|
|
|
class BaseFileLock(ABC, contextlib.ContextDecorator):
|
|
"""Abstract base class for a file lock object."""
|
|
|
|
def __init__(
|
|
self,
|
|
lock_file: str | os.PathLike[str],
|
|
timeout: float = -1,
|
|
mode: int = 0o644,
|
|
thread_local: bool = True, # noqa: FBT001, FBT002
|
|
) -> None:
|
|
"""
|
|
Create a new lock object.
|
|
|
|
:param lock_file: path to the file
|
|
:param timeout: default timeout when acquiring the lock, in seconds. It will be used as fallback value in
|
|
the acquire method, if no timeout value (``None``) is given. If you want to disable the timeout, set it
|
|
to a negative value. A timeout of 0 means, that there is exactly one attempt to acquire the file lock.
|
|
:param mode: file permissions for the lockfile.
|
|
:param thread_local: Whether this object's internal context should be thread local or not.
|
|
If this is set to ``False`` then the lock will be reentrant across threads.
|
|
"""
|
|
self._is_thread_local = thread_local
|
|
|
|
# Create the context. Note that external code should not work with the context directly and should instead use
|
|
# properties of this class.
|
|
kwargs: dict[str, Any] = {
|
|
"lock_file": os.fspath(lock_file),
|
|
"timeout": timeout,
|
|
"mode": mode,
|
|
}
|
|
self._context: FileLockContext = (ThreadLocalFileContext if thread_local else FileLockContext)(**kwargs)
|
|
|
|
def is_thread_local(self) -> bool:
|
|
""":return: a flag indicating if this lock is thread local or not"""
|
|
return self._is_thread_local
|
|
|
|
@property
|
|
def lock_file(self) -> str:
|
|
""":return: path to the lock file"""
|
|
return self._context.lock_file
|
|
|
|
@property
|
|
def timeout(self) -> float:
|
|
"""
|
|
:return: the default timeout value, in seconds
|
|
|
|
.. versionadded:: 2.0.0
|
|
"""
|
|
return self._context.timeout
|
|
|
|
@timeout.setter
|
|
def timeout(self, value: float | str) -> None:
|
|
"""
|
|
Change the default timeout value.
|
|
|
|
:param value: the new value, in seconds
|
|
"""
|
|
self._context.timeout = float(value)
|
|
|
|
@abstractmethod
|
|
def _acquire(self) -> None:
|
|
"""If the file lock could be acquired, self._context.lock_file_fd holds the file descriptor of the lock file."""
|
|
raise NotImplementedError
|
|
|
|
@abstractmethod
|
|
def _release(self) -> None:
|
|
"""Releases the lock and sets self._context.lock_file_fd to None."""
|
|
raise NotImplementedError
|
|
|
|
@property
|
|
def is_locked(self) -> bool:
|
|
"""
|
|
|
|
:return: A boolean indicating if the lock file is holding the lock currently.
|
|
|
|
.. versionchanged:: 2.0.0
|
|
|
|
This was previously a method and is now a property.
|
|
"""
|
|
return self._context.lock_file_fd is not None
|
|
|
|
@property
|
|
def lock_counter(self) -> int:
|
|
""":return: The number of times this lock has been acquired (but not yet released)."""
|
|
return self._context.lock_counter
|
|
|
|
def acquire(
|
|
self,
|
|
timeout: float | None = None,
|
|
poll_interval: float = 0.05,
|
|
*,
|
|
poll_intervall: float | None = None,
|
|
blocking: bool = True,
|
|
) -> AcquireReturnProxy:
|
|
"""
|
|
Try to acquire the file lock.
|
|
|
|
:param timeout: maximum wait time for acquiring the lock, ``None`` means use the default :attr:`~timeout` is and
|
|
if ``timeout < 0``, there is no timeout and this method will block until the lock could be acquired
|
|
:param poll_interval: interval of trying to acquire the lock file
|
|
:param poll_intervall: deprecated, kept for backwards compatibility, use ``poll_interval`` instead
|
|
:param blocking: defaults to True. If False, function will return immediately if it cannot obtain a lock on the
|
|
first attempt. Otherwise, this method will block until the timeout expires or the lock is acquired.
|
|
:raises Timeout: if fails to acquire lock within the timeout period
|
|
:return: a context object that will unlock the file when the context is exited
|
|
|
|
.. code-block:: python
|
|
|
|
# You can use this method in the context manager (recommended)
|
|
with lock.acquire():
|
|
pass
|
|
|
|
# Or use an equivalent try-finally construct:
|
|
lock.acquire()
|
|
try:
|
|
pass
|
|
finally:
|
|
lock.release()
|
|
|
|
.. versionchanged:: 2.0.0
|
|
|
|
This method returns now a *proxy* object instead of *self*,
|
|
so that it can be used in a with statement without side effects.
|
|
|
|
"""
|
|
# Use the default timeout, if no timeout is provided.
|
|
if timeout is None:
|
|
timeout = self._context.timeout
|
|
|
|
if poll_intervall is not None:
|
|
msg = "use poll_interval instead of poll_intervall"
|
|
warnings.warn(msg, DeprecationWarning, stacklevel=2)
|
|
poll_interval = poll_intervall
|
|
|
|
# Increment the number right at the beginning. We can still undo it, if something fails.
|
|
self._context.lock_counter += 1
|
|
|
|
lock_id = id(self)
|
|
lock_filename = self.lock_file
|
|
start_time = time.perf_counter()
|
|
try:
|
|
while True:
|
|
if not self.is_locked:
|
|
_LOGGER.debug("Attempting to acquire lock %s on %s", lock_id, lock_filename)
|
|
self._acquire()
|
|
if self.is_locked:
|
|
_LOGGER.debug("Lock %s acquired on %s", lock_id, lock_filename)
|
|
break
|
|
if blocking is False:
|
|
_LOGGER.debug("Failed to immediately acquire lock %s on %s", lock_id, lock_filename)
|
|
raise Timeout(lock_filename) # noqa: TRY301
|
|
if 0 <= timeout < time.perf_counter() - start_time:
|
|
_LOGGER.debug("Timeout on acquiring lock %s on %s", lock_id, lock_filename)
|
|
raise Timeout(lock_filename) # noqa: TRY301
|
|
msg = "Lock %s not acquired on %s, waiting %s seconds ..."
|
|
_LOGGER.debug(msg, lock_id, lock_filename, poll_interval)
|
|
time.sleep(poll_interval)
|
|
except BaseException: # Something did go wrong, so decrement the counter.
|
|
self._context.lock_counter = max(0, self._context.lock_counter - 1)
|
|
raise
|
|
return AcquireReturnProxy(lock=self)
|
|
|
|
def release(self, force: bool = False) -> None: # noqa: FBT001, FBT002
|
|
"""
|
|
Releases the file lock. Please note, that the lock is only completely released, if the lock counter is 0. Also
|
|
note, that the lock file itself is not automatically deleted.
|
|
|
|
:param force: If true, the lock counter is ignored and the lock is released in every case/
|
|
"""
|
|
if self.is_locked:
|
|
self._context.lock_counter -= 1
|
|
|
|
if self._context.lock_counter == 0 or force:
|
|
lock_id, lock_filename = id(self), self.lock_file
|
|
|
|
_LOGGER.debug("Attempting to release lock %s on %s", lock_id, lock_filename)
|
|
self._release()
|
|
self._context.lock_counter = 0
|
|
_LOGGER.debug("Lock %s released on %s", lock_id, lock_filename)
|
|
|
|
def __enter__(self) -> Self:
|
|
"""
|
|
Acquire the lock.
|
|
|
|
:return: the lock object
|
|
"""
|
|
self.acquire()
|
|
return self
|
|
|
|
def __exit__(
|
|
self,
|
|
exc_type: type[BaseException] | None,
|
|
exc_value: BaseException | None,
|
|
traceback: TracebackType | None,
|
|
) -> None:
|
|
"""
|
|
Release the lock.
|
|
|
|
:param exc_type: the exception type if raised
|
|
:param exc_value: the exception value if raised
|
|
:param traceback: the exception traceback if raised
|
|
"""
|
|
self.release()
|
|
|
|
def __del__(self) -> None:
|
|
"""Called when the lock object is deleted."""
|
|
self.release(force=True)
|
|
|
|
|
|
__all__ = [
|
|
"BaseFileLock",
|
|
"AcquireReturnProxy",
|
|
]
|