Python 如何在ContextDecorator中引发Tornado超时异常？

我希望：

• 制作一个自定义计时器包装器，用于日志记录/其他计时目的
• 如果包装的操作超过预定义的时间长度，则包括抢先退出

这就是我到目前为止所做的：

from contextlib import ContextDecorator
import datetime

from tornado import gen, ioloop
from tornado.concurrent import Future


class timing_logger(ContextDecorator):
    def __init__(self, allowed_ms):
        self.allowed_ms = allowed_ms
        self.f = Future()
        # this exception is not bubbled up by Tornado but fires
        gen.with_timeout(datetime.timedelta(seconds=1+allowed_ms/1000), self.f)

    def __enter__(self):
        self.start_time = datetime.datetime.now()
        return self

    def __exit__(self, exc_type, exc_val, traceback):
        self.f.set_result(True)
        elapsed_time_ms = (datetime.datetime.now() - self.start_time).total_seconds() * 1000

        if exc_type == gen.TimeoutError:
            raise TimeoutError('ruh oh, this is reeeally bad')

        if elapsed_time_ms > self.allowed_ms:
            raise TimeoutError('took {actual} ms, but was only allowed {allowed}.'.format(
                 actual=elapsed_time_ms, allowed=self.allowed_ms))

        else:
            print('worked. nothing to see here...')
        return False


@gen.coroutine
def main():

    with timing_logger(1000):
        # real application may be a variety of coroutines
        # and regular function calls, some of which may hang
        # for a long time
        for i in range(25):
            yield gen.sleep(0.1)


if __name__ == "__main__":
    ioloop.IOLoop.current().run_sync(
        lambda: main())

我在这里遇到的问题是，因为我没有生成具有_timeoutfuture的

gen

$python test.py 
ERROR:tornado.application:Future <tornado.concurrent.Future object at 0x10c7cb668> exception was never retrieved: tornado.gen.TimeoutError: Timeout
Traceback (most recent call last):
  File "test.py", line 48, in <module>
    lambda: main())
<snip>
    yielded = self.gen.send(value)
  File "test.py", line 43, in main
    yield gen.sleep(0.1)
  File "test.py", line 28, in __exit__
    actual=elapsed_time_ms, allowed=self.allowed_ms))
TimeoutError: took 2606.2940000000003 ms, but was only allowed 1000.

但我希望将上述内容包含到我的ContextDecorator中，因为必须将其复制到我想要使用的
计时记录器
的所有内容中，这将变得既乏味又容易出错

如何实现所需的功能以允许ContextDecorator将超时作为其功能的一部分

使用Python 3.6.1和最新的Tornado（4.5.1）。
您可以使用中断并触发此异常，而不是使用Tornado超时：

这将适当引发异常，从而生成完整的ContextDecorator，如下所示：

from contextlib import ContextDecorator
import datetime

from tornado import gen, ioloop
from tornado.concurrent import Future


class timing_logger(ContextDecorator):
    def __init__(self, allowed_ms):
        self.allowed_ms = allowed_ms
        self.f = Future()
        # this exception is not bubbled up by Tornado but fires
        gen.with_timeout(datetime.timedelta(seconds=1+allowed_ms/1000), self.f)

    def __enter__(self):
        self.start_time = datetime.datetime.now()
        def timeout_handler(signum, frame):
            raise gen.TimeoutError()  # could be any type of exception

        self.signal = signal.signal(signal.SIGALRM, timeout_handler)
        signal.alarm(1 + self.allowed_ms // 1000)

        return self

    def __exit__(self, exc_type, exc_val, traceback):
        signal.alarm(0)
        self.f.set_result(True)
        elapsed_time_ms = (datetime.datetime.now() - self.start_time).total_seconds() * 1000

        if exc_type == gen.TimeoutError:
            raise TimeoutError('ruh oh, this is reeeally bad')

        if elapsed_time_ms > self.allowed_ms:
            raise TimeoutError('took {actual} ms, but was only allowed {allowed}.'.format(
                 actual=elapsed_time_ms, allowed=self.allowed_ms))

        else:
            print('worked. nothing to see here...')
        return False

请注意，您需要在
\uuuu退出\uuuu>中重置警报，否则它将在稍后的代码中触发。
您可以使用中断并触发此异常，而不是使用龙卷风超时：

这将适当引发异常，从而生成完整的ContextDecorator，如下所示：

from contextlib import ContextDecorator
import datetime

from tornado import gen, ioloop
from tornado.concurrent import Future


class timing_logger(ContextDecorator):
    def __init__(self, allowed_ms):
        self.allowed_ms = allowed_ms
        self.f = Future()
        # this exception is not bubbled up by Tornado but fires
        gen.with_timeout(datetime.timedelta(seconds=1+allowed_ms/1000), self.f)

    def __enter__(self):
        self.start_time = datetime.datetime.now()
        def timeout_handler(signum, frame):
            raise gen.TimeoutError()  # could be any type of exception

        self.signal = signal.signal(signal.SIGALRM, timeout_handler)
        signal.alarm(1 + self.allowed_ms // 1000)

        return self

    def __exit__(self, exc_type, exc_val, traceback):
        signal.alarm(0)
        self.f.set_result(True)
        elapsed_time_ms = (datetime.datetime.now() - self.start_time).total_seconds() * 1000

        if exc_type == gen.TimeoutError:
            raise TimeoutError('ruh oh, this is reeeally bad')

        if elapsed_time_ms > self.allowed_ms:
            raise TimeoutError('took {actual} ms, but was only allowed {allowed}.'.format(
                 actual=elapsed_time_ms, allowed=self.allowed_ms))

        else:
            print('worked. nothing to see here...')
        return False

请注意，您需要重置
\uuuuu出口\uuuuu
中的警报，否则它将在稍后的代码中触发

from contextlib import ContextDecorator
import datetime

from tornado import gen, ioloop
from tornado.concurrent import Future


class timing_logger(ContextDecorator):
    def __init__(self, allowed_ms):
        self.allowed_ms = allowed_ms
        self.f = Future()
        # this exception is not bubbled up by Tornado but fires
        gen.with_timeout(datetime.timedelta(seconds=1+allowed_ms/1000), self.f)

    def __enter__(self):
        self.start_time = datetime.datetime.now()
        def timeout_handler(signum, frame):
            raise gen.TimeoutError()  # could be any type of exception

        self.signal = signal.signal(signal.SIGALRM, timeout_handler)
        signal.alarm(1 + self.allowed_ms // 1000)

        return self

    def __exit__(self, exc_type, exc_val, traceback):
        signal.alarm(0)
        self.f.set_result(True)
        elapsed_time_ms = (datetime.datetime.now() - self.start_time).total_seconds() * 1000

        if exc_type == gen.TimeoutError:
            raise TimeoutError('ruh oh, this is reeeally bad')

        if elapsed_time_ms > self.allowed_ms:
            raise TimeoutError('took {actual} ms, but was only allowed {allowed}.'.format(
                 actual=elapsed_time_ms, allowed=self.allowed_ms))

        else:
            print('worked. nothing to see here...')
        return False