python – 具有异步响应的Twisted http服务器,其中请求必须等待数据变为可用或超时
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我正在尝试编写一个简单的http服务器来处理在数据结构中查找响应或超时的异步请求：
>请求到达
>时间<超时检查responseCollector响应(使用requestId作为键)
>如果回复,请将其退回
>如果超时,则返回超时消息
我是新手,我想知道做异步响应的最佳方法是什么.我看了some twisted Deferred docs和callLater,但我不清楚到底应该做些什么.现在我使用deferToThread运行阻塞方法并等待超时.我的延迟方法得到一个字符串不可调用的错误：
Unhandled error in Deferred:
Traceback (most recent call last):
File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/threading.py", line 497, in __bootstrap
self.__bootstrap_inner()
File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/threading.py", line 522, in __bootstrap_inner
self.run()
File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/threading.py", line 477, in run
self.__target(*self.__args, **self.__kwargs)
--- <exception caught here> ---
File "/System/Library/Frameworks/Python.framework/Versions/2.6/Extras/lib/python/twisted/python/threadpool.py", line 210, in _worker
result = context.call(ctx, function, *args, **kwargs)
File "/System/Library/Frameworks/Python.framework/Versions/2.6/Extras/lib/python/twisted/python/context.py", line 59, in callWithContext
return self.currentContext().callWithContext(ctx, func, *args, **kw)
File "/System/Library/Frameworks/Python.framework/Versions/2.6/Extras/lib/python/twisted/python/context.py", line 37, in callWithContext
return func(*args,**kw)
exceptions.TypeError: 'str' object is not callable
这是我的代码：
from twisted.web import server, resource
from twisted.internet import reactor, threads
import json
import time
connectedClients = {}
responseCollector = {}
# add fake data to the collector
class FakeData(resource.Resource):
isLeaf = True
def render_GET(self, request):
request.setHeader("content-type", "application/json")
if 'rid' in request.args and 'data' in request.args:
rid = request.args['rid'][0]
data = request.args['data'][0]
responseCollector[str(rid)] = data
return json.dumps(responseCollector)
return "{}"
class RequestHandler(resource.Resource):
isLeaf = True
def render_GET(self, request):
#request.setHeader("content-type", "application/json")
if not ('rid' in request.args and and 'json' in request.args):
return '{"success":"false","response":"invalid request"}'
rid = request.args['rid'][0]
json = request.args['id'][0]
# TODO: Wait for data to show up in the responseCollector with same rid
# as our request without blocking other requests OR timeout
d = threads.deferToThread(self.blockingMethod(rid))
d.addCallback(self.ret)
d.addErrback(self.err)
def blockingMethod(self,rid):
timeout = 5.0
timeElapsed = 0.0
while timeElapsed<timeout:
if rid in responseCollector:
return responseCollector[rid]
else:
timeElapsed+=0.01
time.sleep(0.01)
return "timeout"
def ret(self, hdata):
return hdata
def err(self, failure):
return failure
reactor.listenTCP(8080, server.Site(RequestHandler()))
reactor.listenTCP(9080, server.Site(FakeData()))
reactor.run()
发出请求(当前没有返回任何有用的内容)：
http://localhost:8080/?rid=1234&json={%22foo%22:%22bar%22}
添加一些假数据以用于请求：
http://localhost:9080/?rid=1234&data=foo
更新了工作版本
from twisted.web import server, resource
from twisted.internet import reactor, threads
import json
import time
connectedClients = {}
responseCollector = {}
# add fake data to the collector
class FakeData(resource.Resource):
isLeaf = True
def render_GET(self, request):
request.setHeader("content-type", "application/json")
if 'rid' in request.args and 'data' in request.args:
rid = request.args['rid'][0]
data = request.args['data'][0]
responseCollector[str(rid)] = data
return json.dumps(responseCollector)
return "{}"
class RequestHandler(resource.Resource):
isLeaf = True
def render_GET(self, request):
if not ('rid' in request.args and 'data' in request.args):
return '{"success":"false","response":"invalid request"}'
rid = request.args['rid'][0]
json = request.args['data'][0]
# TODO: Wait for data to show up in the responseCollector with same rid
# as our request without blocking other requests OR timeout
d = threads.deferToThread(self.blockingMethod,rid)
d.addCallback(self.ret, request)
d.addErrback(self.err)
return server.NOT_DONE_YET
def blockingMethod(self,rid):
timeout = 5.0
timeElapsed = 0.0
while timeElapsed<timeout:
if rid in responseCollector:
return responseCollector[rid]
else:
timeElapsed+=0.01
time.sleep(0.01)
return "timeout"
def ret(self, result, request):
request.write(result)
request.finish()
def err(self, failure):
return failure
reactor.listenTCP(8080, server.Site(RequestHandler()))
reactor.listenTCP(9080, server.Site(FakeData()))
reactor.run()
解决方法:
在render_GET()中,您应该返回twisted.web.server.NOT_DONE_YET.您应该将请求对象传递给ret方法：d.addCallback(self.ret,request)
然后在ret(请求)中,您应该使用request.write(hdata)编写异步数据并关闭与request.finish()的连接.
def ret(self, result, request):
request.write(result)
request.finish()
一些信息来自：http://twistedmatrix.com/documents/current/web/howto/using-twistedweb.html
Resource rendering occurs when Twisted Web locates a leaf Resource
object to handle a web request. A Resource’s render method may do
various things to produce output which will be sent back to the
browser:
- Return a string
- Request a Deferred, return server.NOT_DONE_YET,
and call request.write(“stuff”) and request.finish() later, in a
callback on the Deferred.
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