[Twisted-Python] Blocking?

Chad Rosenberg chad at idrankwhat.net
Mon Nov 15 17:49:13 EST 2004


I've run into a problem that requires some form of blocking.  I've got a
method that's compiled from a cheetah template and that gets called as the
result of a reactor callback.  The cheetah method needs to be able to make
a PB call to fetch some data and block until the results arrive.
Something like this:

-----------
    def reactorCallback(self):
        self.callCheetahCompiledMethod()

  ...

    def cheetahCompiledMethod(self):
        print self.utilClass.lookup(foo)

  ...

class UtilClass:
    def lookup(self, whatToLookup):
        pbDeferred = self.pbCall(whatToLookup)
        # Some way to block until results are gotten
        return results
-----------

"cheetahCompiledMethod", itself, cannot use callbacks.  The call to
"lookup" can't be done before "cheetahCompiledMethod" is called since it
is unknown at that time what "cheetahCompiledMethod" will require.  I was
looking over Christopher Armstrong's gthreadless.py
(http://radix.twistedmatrix.com/archives/000099.html) and it looks
promising, but I am a little concerned about the stability of greenlets.
I also noticed twisted.trial.util.wait.  What is the best way to handle
situations like this when they come up?

Thanks,

Chad







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