# -*- coding: utf-8 -*-
# -----------------------------------------------------------------------------
# Copyright 2015-2018 by Exopy Authors, see AUTHORS for more details.
#
# Distributed under the terms of the BSD license.
#
# The full license is in the file LICENCE, distributed with this software.
# -----------------------------------------------------------------------------
"""Thread safe bit flag with convenient interface.
"""
from threading import Event, RLock
[docs]class BitFlag(object):
"""Bit flag conveniency class providing thread safety facilities.
Parameters
----------
flags : iterable[unicode]
Name of the flags that this flag understand.
"""
__slots__ = ('flags', '_lock', '_flags', '_events', '_state')
def __new__(cls, flags):
self = object.__new__(cls)
self.flags = flags
self._flags = {f: 2**i for i, f in enumerate(flags)}
self._events = {}
self._lock = RLock()
self._state = 0
return self
[docs] def set(self, *flags):
"""Set specified flags.
If a flag is already set this is a no-op. If a thread is waiting on a
flag, it gets notified.
"""
with self._lock:
for f in flags:
self._state |= self._flags[f]
if f in self._events:
self._events[f].set()
del self._events[f]
[docs] def clear(self, *flags):
"""Clear the specified flags.
If a flag is already cleared this is a no-op.
"""
flags = flags if flags else self.flags
with self._lock:
for f in flags:
self._state &= ~self._flags[f]
[docs] def test(self, *flags):
"""Test is all specified flags are set.
"""
res = True
with self._lock:
for f in flags:
res &= bool(self._state & self._flags[f])
return res
[docs] def wait(self, timeout, *flags):
"""Wait till some flags are set.
Parameters
----------
timeout : float|None
Maximum time to wait. If None waits forever.
flags : iterable[unicode]
Flags upon which to wait.
Returns
-------
result : bool
False if the method returned because of the timeout.
"""
events = []
with self._lock:
for f in flags:
if not self.test(f):
if f not in self._events:
self._events[f] = Event()
events.append(self._events[f])
res = True
for e in events:
res &= e.wait(timeout)
return res