decorations.py 文件源码

def singleton_contextmanager(func):
    class CtxManager():
        def __init__(self, func):
            self.count = 0
            self.func_cm = contextmanager(func)
            self._lock = RLock()

        def __enter__(self):
            with self._lock:
                if self.count == 0:
                    self.ctm = self.func_cm()
                    self.obj = self.ctm.__enter__()
                self.count += 1

        def __exit__(self, *args):
            with self._lock:
                self.count -= 1
                if self.count > 0:
                    return
                self.ctm.__exit__(*sys.exc_info())
                del self.ctm
                del self.obj

    return CtxManager(func)