我正在尝试将Twisted与greenlets一起使用,因此可以在不使用inlineCallbacks的情况下以twisted形式编写同步外观的代码。
这是我的代码:
import time, functools
from twisted.internet import reactor, threads
from twisted.internet.defer import Deferred
from functools import wraps
import greenlet
def make_async(func):
@wraps(func)
def wrapper(*pos, **kwds):
d = Deferred()
def greenlet_func():
try:
rc = func(*pos, **kwds)
d.callback(rc)
except Exception, ex:
print ex
d.errback(ex)
g = greenlet.greenlet(greenlet_func)
g.switch()
return d
return wrapper
def sleep(t):
print "sleep(): greenelet:", greenlet.getcurrent()
g = greenlet.getcurrent()
reactor.callLater(t, g.switch)
g.parent.switch()
def wait_one(d):
print "wait_one(): greenelet:", greenlet.getcurrent()
g = greenlet.getcurrent()
active = True
def callback(result):
if not active:
g.switch(result)
else:
reactor.callLater(0, g.switch, result)
def errback(failure):
if not active:
g.throw(failure)
else:
reactor.callLater(0, g.throw, failure)
d.addCallback(callback)
d.addErrback(errback)
active = False
rc = g.parent.switch()
return rc
@make_async
def inner():
print "inner(): greenelet:", greenlet.getcurrent()
import random, time
interval = random.random()
print "Sleeping for %s seconds..." % interval
sleep(interval)
print "done"
return interval
@make_async
def outer():
print "outer(): greenelet:", greenlet.getcurrent()
print wait_one(inner())
print "Here"
reactor.callLater(0, outer)
reactor.run()
有五个主要部分:
当我运行此代码时,我得到以下输出(注意最后两行的错误):
outer(): greenelet: <greenlet.greenlet object at 0xb729cc5c>
inner(): greenelet: <greenlet.greenlet object at 0xb729ce3c>
Sleeping for 0.545666723422 seconds...
sleep(): greenelet: <greenlet.greenlet object at 0xb729ce3c>
wait_one(): greenelet: <greenlet.greenlet object at 0xb729cc5c>
done
0.545666723422
Here
Exception twisted.python.failure.Failure: <twisted.python.failure.Failure <class 'greenlet.GreenletExit'>> in <greenlet.greenlet object at 0xb729ce3c> ignored
GreenletExit did not kill <greenlet.greenlet object at 0xb729ce3c>
经过一些研究,我发现:
我在调试它时遇到了麻烦,因为我无法访问GreenletExit
或twisted.python.failure.Failure
异常来获取其堆栈跟踪。
有谁知道我在做什么错,或者我如何调试正在抛出的异常?
另一个数据点:如果我修改wait_one()使其立即返回(并且不对延迟传递的任何内容进行注册),则错误会消失。:-/
wait_one
像这样重写您的错误回调:
def errback(failure):
## new code
if g.dead:
return
##
if not active:
g.throw(failure)
else:
reactor.callLater(0, g.throw, failure)
如果greenlet已死(运行结束),则没有任何异常抛出。
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我来说两句