在Tornado中“超时”处理请求的正确方法

在Tornado中“超时”处理请求的正确方法

当客户端断开连接时，Tornado不会自动关闭请求处理程序。但是，您可以重写

on_connection_close

以在客户端断开时收到警报，这将使您最终取消连接。上下文管理器（或装饰器）可用于处理设置超时以处理请求。用于

tornado.ioloop.IOLoop.add_timeout

安排一些方法，该方法会使请求

timeout

作为

__enter__

上下文管理器的一部分超时，然后

__exit__

在上下文管理器的块中取消该回调。这是一个演示这两个想法的示例：

import timeimport contextlibfrom tornado.ioloop import IOLoopimport tornado.webfrom tornado import gen@gen.coroutinedef async_sleep(timeout):    yield gen.Task(IOLoop.instance().add_timeout, time.time() + timeout)@contextlib.contextmanagerdef auto_timeout(self, timeout=2): # Seconds    handle = IOLoop.instance().add_timeout(time.time() + timeout, self.timed_out)    try:        yield handle    except Exception as e:        print("Caught %s" % e)    finally:        IOLoop.instance().remove_timeout(handle)        if not self._timed_out: self.finish()        else: raise Exception("Request timed out") # Don't continue on passed this pointclass TimeoutableHandler(tornado.web.RequestHandler):    def initialize(self):        self._timed_out = False    def timed_out(self):        self._timed_out = True        self.write("Request timed out!n")        self.finish()  # Connection to client closes here.        # You might want to do other clean up here.class MainHandler(TimeoutableHandler):    @gen.coroutine    def get(self):        with auto_timeout(self): # We'll timeout after 2 seconds spent in this block. self.sleeper = async_sleep(5) yield self.sleeper        print("writing")  # get will abort before we reach here if we timed out.        self.write("heyn")    def on_connection_close(self):        # This isn't the greatest way to cancel a future, since it will not actually        # stop the work being done asynchronously. You'll need to cancel that some        # other way. Should be pretty straightforward with a DB connection (close        # the cursor/connection, maybe?)        self.sleeper.set_exception(Exception("cancelled"))application = tornado.web.Application([    (r"/test", MainHandler),])application.listen(8888)IOLoop.instance().start()