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gh-85049: Add multiprocessing.Lock.locked() #20651

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gh-85049: Add multiprocessing.Lock.locked() #20651

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6 changes: 6 additions & 0 deletions Doc/library/multiprocessing.rst
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Expand Up @@ -1301,6 +1301,12 @@ object -- see :ref:`multiprocessing-managers`.
Behavior is the same as in :meth:`threading.Lock.release` except that
when invoked on an unlocked lock, a :exc:`ValueError` is raised.

.. method:: locked()

Return true if the lock is acquired.

.. versionadded:: 3.10


.. class:: RLock()

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3 changes: 3 additions & 0 deletions Lib/multiprocessing/synchronize.py
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Expand Up @@ -161,6 +161,9 @@ class Lock(SemLock):
def __init__(self, *, ctx):
SemLock.__init__(self, SEMAPHORE, 1, 1, ctx=ctx)

def locked(self):
return self._semlock._is_zero()

def __repr__(self):
try:
if self._semlock._is_mine():
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2 changes: 2 additions & 0 deletions Lib/test/_test_multiprocessing.py
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Expand Up @@ -1230,8 +1230,10 @@ class _TestLock(BaseTestCase):
def test_lock(self):
lock = self.Lock()
self.assertEqual(lock.acquire(), True)
self.assertTrue(lock.locked())
self.assertEqual(lock.acquire(False), False)
self.assertEqual(lock.release(), None)
self.assertFalse(lock.locked())
self.assertRaises((ValueError, threading.ThreadError), lock.release)

def test_rlock(self):
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2020-06-05-15-47-43.bpo-40872.hW9afp.rst
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@@ -0,0 +1,2 @@
:class:`multiprocessing.Lock` now has a `locked()` method that returns
whether the lock is currently held. Patch contributed by Rémi Lapeyre.