gen.py 文件源码

def start(self, runner):
        if not self.future.done():
            self.runner = runner
            self.key = object()
            runner.register_callback(self.key)
            self.io_loop.add_future(self.future, runner.result_callback(self.key))
        else:
            self.runner = None
            self.result_fn = self.future.result