[Twisted-Python] async code structure question

[Itamar Shtull-Trauring]

On Thu, 2005-02-10 at 09:44 -0800, snacktime wrote:
> Thanks for the info Mary.  Now that I've gotten a bit further I have
> another design issue that I really don't know how to deal with.
> 
> The below code is my main server loop.  When data is received I call a
> non blocking method (Do()).  So far so good.  Inside Do() I have a
> number of reactor.callLater's that fire off blocking database calls
> inside adbapi and are chained using callbacks.  Do() returns
> immediately. 

Do() should return a Deferred that has result when processing is done,
and then you can Do().addCallback(lambda: self.transport.write("hello"))
or something.

e.g.

def Do():
    d = deferToThread(foo)
    d.addCallback(processResult)
    return d

or

def Do():
    # processing in this case is waiting for one second
    d = Deferred()
    reactor.callLater(d.callback, 1)
    return d