38 lines
1.2 KiB
Python
38 lines
1.2 KiB
Python
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from eventlet import hubs
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from eventlet.semaphore import Semaphore
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class Lock(Semaphore):
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"""A lock.
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This is API-compatible with :class:`threading.Lock`.
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It is a context manager, and thus can be used in a with block::
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lock = Lock()
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with lock:
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do_some_stuff()
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"""
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def release(self, blocking=True):
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"""Modify behaviour vs :class:`Semaphore` to raise a RuntimeError
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exception if the value is greater than zero. This corrects behaviour
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to realign with :class:`threading.Lock`.
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"""
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if self.counter > 0:
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raise RuntimeError("release unlocked lock")
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# Consciously *do not* call super().release(), but instead inline
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# Semaphore.release() here. We've seen issues with logging._lock
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# deadlocking because garbage collection happened to run mid-release
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# and eliminating the extra stack frame should help prevent that.
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# See https://github.com/eventlet/eventlet/issues/742
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self.counter += 1
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if self._waiters:
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hubs.get_hub().schedule_call_global(0, self._do_acquire)
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return True
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def _at_fork_reinit(self):
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self.counter = 1
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self._waiters.clear()
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