mirror of
https://github.com/clearml/clearml
synced 2025-02-01 01:26:49 +00:00
311 lines
9.3 KiB
Python
311 lines
9.3 KiB
Python
import os
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import time
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import atexit
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import tempfile
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import contextlib
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from multiprocessing import RLock as ProcessRLock
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from . import exceptions
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from . import constants
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from . import portalocker
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current_time = getattr(time, "monotonic", time.time)
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DEFAULT_TIMEOUT = 10 ** 8
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DEFAULT_CHECK_INTERVAL = 0.25
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LOCK_METHOD = constants.LOCK_EX | constants.LOCK_NB
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__all__ = [
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'Lock',
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'RLock',
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'open_atomic',
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]
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@contextlib.contextmanager
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def open_atomic(filename, binary=True):
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'''Open a file for atomic writing. Instead of locking this method allows
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you to write the entire file and move it to the actual location. Note that
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this makes the assumption that a rename is atomic on your platform which
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is generally the case but not a guarantee.
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http://docs.python.org/library/os.html#os.rename
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>>> filename = 'test_file.txt'
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>>> if os.path.exists(filename):
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... os.remove(filename)
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>>> with open_atomic(filename) as fh:
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... written = fh.write(b'test')
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>>> assert os.path.exists(filename)
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>>> os.remove(filename)
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'''
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assert not os.path.exists(filename), '%r exists' % filename
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path, name = os.path.split(filename)
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# Create the parent directory if it doesn't exist
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if path and not os.path.isdir(path): # pragma: no cover
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os.makedirs(path)
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temp_fh = tempfile.NamedTemporaryFile(
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mode=binary and 'wb' or 'w',
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dir=path,
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delete=False,
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)
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yield temp_fh
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temp_fh.flush()
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os.fsync(temp_fh.fileno())
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temp_fh.close()
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try:
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os.rename(temp_fh.name, filename)
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finally:
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try:
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os.remove(temp_fh.name)
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except Exception:
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pass
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class Lock(object):
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def __init__(
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self, filename, mode='a', timeout=DEFAULT_TIMEOUT,
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check_interval=DEFAULT_CHECK_INTERVAL, fail_when_locked=False,
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flags=LOCK_METHOD, **file_open_kwargs):
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'''Lock manager with build-in timeout
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filename -- filename
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mode -- the open mode, 'a' or 'ab' should be used for writing
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truncate -- use truncate to emulate 'w' mode, None is disabled, 0 is
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truncate to 0 bytes
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timeout -- timeout when trying to acquire a lock
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check_interval -- check interval while waiting
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fail_when_locked -- after the initial lock failed, return an error
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or lock the file
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**file_open_kwargs -- The kwargs for the `open(...)` call
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fail_when_locked is useful when multiple threads/processes can race
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when creating a file. If set to true than the system will wait till
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the lock was acquired and then return an AlreadyLocked exception.
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Note that the file is opened first and locked later. So using 'w' as
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mode will result in truncate _BEFORE_ the lock is checked.
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'''
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if 'w' in mode:
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truncate = True
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mode = mode.replace('w', 'a')
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else:
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truncate = False
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self.fh = None
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self.filename = filename
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self.mode = mode
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self.truncate = truncate
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self.timeout = timeout
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self.check_interval = check_interval
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self.fail_when_locked = fail_when_locked
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self.flags = flags
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self.file_open_kwargs = file_open_kwargs
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def acquire(
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self, timeout=None, check_interval=None, fail_when_locked=None):
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'''Acquire the locked filehandle'''
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if timeout is None:
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timeout = self.timeout
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if timeout is None:
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timeout = 0
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if check_interval is None:
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check_interval = self.check_interval
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if fail_when_locked is None:
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fail_when_locked = self.fail_when_locked
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# If we already have a filehandle, return it
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fh = self.fh
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if fh:
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return fh
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# Get a new filehandler
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fh = self._get_fh()
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try:
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# Try to lock
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fh = self._get_lock(fh)
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except exceptions.LockException as exception:
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# Try till the timeout has passed
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timeoutend = current_time() + timeout
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while timeoutend > current_time():
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# Wait a bit
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time.sleep(check_interval)
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# Try again
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try:
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# We already tried to the get the lock
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# If fail_when_locked is true, then stop trying
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if fail_when_locked:
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raise exceptions.AlreadyLocked(exception)
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else: # pragma: no cover
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# We've got the lock
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fh = self._get_lock(fh)
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break
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except exceptions.LockException:
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pass
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else:
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# We got a timeout... reraising
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raise exceptions.LockException(exception)
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# Prepare the filehandle (truncate if needed)
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fh = self._prepare_fh(fh)
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self.fh = fh
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return fh
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def release(self):
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'''Releases the currently locked file handle'''
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if self.fh:
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# noinspection PyBroadException
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try:
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portalocker.unlock(self.fh)
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except Exception:
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pass
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# noinspection PyBroadException
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try:
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self.fh.close()
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except Exception:
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pass
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self.fh = None
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def _get_fh(self):
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'''Get a new filehandle'''
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return open(self.filename, self.mode, **self.file_open_kwargs)
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def _get_lock(self, fh):
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'''
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Try to lock the given filehandle
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returns LockException if it fails'''
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portalocker.lock(fh, self.flags)
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return fh
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def _prepare_fh(self, fh):
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'''
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Prepare the filehandle for usage
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If truncate is a number, the file will be truncated to that amount of
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bytes
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'''
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if self.truncate:
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fh.seek(0)
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fh.truncate(0)
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return fh
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def __enter__(self):
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return self.acquire()
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def __exit__(self, type_, value, tb):
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self.release()
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def __delete__(self, instance): # pragma: no cover
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instance.release()
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class RLock(Lock):
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"""
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A reentrant lock, functions in a similar way to threading.RLock in that it
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can be acquired multiple times. When the corresponding number of release()
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calls are made the lock will finally release the underlying file lock.
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"""
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def __init__(
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self, filename, mode='a', timeout=DEFAULT_TIMEOUT,
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check_interval=DEFAULT_CHECK_INTERVAL, fail_when_locked=False,
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flags=LOCK_METHOD):
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super(RLock, self).__init__(filename, mode, timeout, check_interval,
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fail_when_locked, flags)
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self._acquire_count = 0
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self._lock = ProcessRLock()
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self._pid = os.getpid()
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def acquire(self, timeout=None, check_interval=None, fail_when_locked=None):
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if self._lock:
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if not self._lock.acquire(block=timeout != 0, timeout=timeout):
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# We got a timeout... reraising
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raise exceptions.LockException()
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# check if we need to recreate the file lock on another subprocess
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if self._pid != os.getpid():
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self._pid = os.getpid()
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self._acquire_count = 0
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if self.fh:
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# noinspection PyBroadException
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try:
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portalocker.unlock(self.fh)
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self.fh.close()
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except Exception:
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pass
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self.fh = None
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if self._acquire_count >= 1:
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fh = self.fh
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else:
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fh = super(RLock, self).acquire(timeout, check_interval,
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fail_when_locked)
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self._acquire_count += 1
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return fh
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def release(self):
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if self._acquire_count == 0:
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raise exceptions.LockException(
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"Cannot release more times than acquired")
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if self._acquire_count == 1:
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super(RLock, self).release()
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self._acquire_count -= 1
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if self._lock:
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self._lock.release()
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def __del__(self):
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self._lock = None
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# try to remove the file when we are done
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if not os.path.isfile(self.filename):
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return
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try:
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self.acquire(timeout=0)
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try:
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os.unlink(self.filename)
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removed = True
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except Exception:
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removed = False
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self.release()
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if not removed:
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try:
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os.unlink(self.filename)
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except Exception:
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pass
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except Exception:
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pass
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class TemporaryFileLock(Lock):
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def __init__(self, filename='.lock', timeout=DEFAULT_TIMEOUT,
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check_interval=DEFAULT_CHECK_INTERVAL, fail_when_locked=True,
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flags=LOCK_METHOD):
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Lock.__init__(self, filename=filename, mode='w', timeout=timeout,
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check_interval=check_interval,
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fail_when_locked=fail_when_locked, flags=flags)
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atexit.register(self.release)
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def release(self):
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Lock.release(self)
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if os.path.isfile(self.filename): # pragma: no branch
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os.unlink(self.filename)
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