Created
December 2, 2016 07:59
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"timeout” a Request in Tornado.
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| import time | |
| import contextlib | |
| from tornado.ioloop import IOLoop | |
| import tornado.web | |
| from tornado import gen | |
| @gen.coroutine | |
| def async_sleep(timeout): | |
| yield gen.Task(IOLoop.instance().add_timeout, time.time() + timeout) | |
| @contextlib.contextmanager | |
| def 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 point | |
| class 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("hey\n") | |
| 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() |
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