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from __future__ import division, print_function, absolute_import
import threading
import scipy._lib.decorator
__all__ = ['ReentrancyError', 'ReentrancyLock', 'non_reentrant']
class ReentrancyError(RuntimeError):
pass
class ReentrancyLock(object):
"""
Threading lock that raises an exception for reentrant calls.
Calls from different threads are serialized, and nested calls from the
same thread result to an error.
The object can be used as a context manager, or to decorate functions
via the decorate() method.
"""
def __init__(self, err_msg):
self._rlock = threading.RLock()
self._entered = False
self._err_msg = err_msg
def __enter__(self):
self._rlock.acquire()
if self._entered:
self._rlock.release()
raise ReentrancyError(self._err_msg)
self._entered = True
def __exit__(self, type, value, traceback):
self._entered = False
self._rlock.release()
def decorate(self, func):
def caller(func, *a, **kw):
with self:
return func(*a, **kw)
return scipy._lib.decorator.decorate(func, caller)
def non_reentrant(err_msg=None):
"""
Decorate a function with a threading lock and prevent reentrant calls.
"""
def decorator(func):
msg = err_msg
if msg is None:
msg = "%s is not re-entrant" % func.__name__
lock = ReentrancyLock(msg)
return lock.decorate(func)
return decorator
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