转载http://xiaorui.cc/2014/11/26/tornado调用ioloop-tracebackfuture实现非堵塞的模块/

当然实现的方法，还是存在点问题的， 但是最少流程是跑通了。 我在用ab做测试的时候，会发现数据已经进入到ioloop里面，但是逻辑堵塞到我们调用的函数上。 

 

tornado.web.asynchronous的作用是保持长连接，也就是除非你主动调用self.finish()方法，否则requestHandler将不会返回。

tornado.gen.coroutine是使用协程的方式实现类似异步的处理效果。最新版的tornado，其实不一定需要写

 

下一步再写一个，tornado redis brpop的非堵塞模块。 

 

咱们先来看看，tornado的那个异步的装饰器@gen.coroutine，到底做了什么事情？

 

 

 

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def _make_coroutine_wrapper(func, replace_callback):     @functools.wraps(func)     def wrapper(*args, **kwargs):         runner = None         future = TracebackFuture() #创建了一个新的Future对象,这货就是Future.           if replace_callback and 'callback' in kwargs:             callback = kwargs.pop('callback')             IOLoop.current().add_future(                 future, lambda future: callback(future.result())) #当future执行完就把callback加入ioloop.           try:             result = func(*args, **kwargs) #调用被装饰函数         except (Return, StopIteration) as e:             result = getattr(e, 'value', None)         except Exception:             future.set_exc_info(sys.exc_info())             return future         else:             if isinstance(result, types.GeneratorType): #如果被装饰函数被调用后产生一个Generator就用一个Runner来让future调用result.                 runner = Runner(result, future)                 runner.run()                 return future         future.set_result(result)         return future     return wrapper

 

 

这个是tornado的demo，异步的逻辑需要你用yield async来生成的。 

 

 

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import tornado.ioloop import tornado.web from tornado.gen import coroutine   import torasync import time   def test(a):     time.sleep(3)     print 'coming'     return 'ok'   class MainHandler(tornado.web.RequestHandler):     @coroutine     def get(self):         result = yield tornasync.async(test, "xiaorui.cc")         self.write("%s" % result )   application = tornado.web.Application([     (r"/", MainHandler), ])   if __name__ == "__main__":     application.listen(8888)     tornado.ioloop.IOLoop.instance().start()

 

 

 

 

 

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from tornado.concurrent import TracebackFuture from tornado.ioloop import IOLoop   def async(task, *args, **kwargs):     callback = kwargs.pop("callback", None)     if callback:         IOLoop.instance().add_future(future,                                      lambda future: callback(future.result()))     result = task(*args,**kwargs)     IOLoop.instance().add_callback(_on_result, result, future)     return future   def _on_result(result, future):     # if result is not ready, add callback function to next loop,     if result:         future.set_result(result)     else:         IOLoop.instance().add_callback(_on_result, result, future)