[ZODB-Dev] ZEO ClientStorage's use of the asyncore main loop (was [Fwd: Re: [Zope3-dev] Twisted Publisher and Zope 2])

[Jim Fulton]

Shane Hathaway wrote:
> Jim Fulton wrote:
> 
>> Tim and I have discussed this for some time.  We think an
>> asynchronous I/O approach is still appropriate, to handle
>> asynchronous messages from servers to clients, but we need
>> to get away from expecting a server to provide the asyncore
>> main loop needed by ZEO. Rather, ZEO should provide its own
>> main loop running in a separate thread. (Or, possibly, each
>> client storage should have its own thread.) Among other things,
>> this would allow us to get rid of the horribly complex dual-mode
>> code we have now.
> 
> 
> I think that's a good strategy.
> 
>> (Note that we've had lots of frustration with asyncore.  It is
>>    tempting to get rid of that at the same time.  However, we still
>>    need an asynchronous I/O framework.  This would probably requite
>>    a switch to Twisted.  This might be worthwhile, but would almost
>>    certainly entail a lot of risk.  I'm not at all sure the benefit
>>    is worth it unless there were some able volunteers who wanted to
>>    work on it.)
> 
> 
> Last I checked, Twisted could not support a private event loop.  Twisted 
> assumes there is only one event loop for all threads.  I'd like to know 
> if this has changed.  The asyncore module can support a private event 
> loop, although it's ugly--you have to pass the 'map' argument all over 
> the place.

Historical note: asyncore didn't support private event loops either
until I added the extra argument to the constructor.  I'm not sure why
you need to pass the map to anything but the constructor.  Oddly. most,
but not all of the methods that take a map, default to the one set in the
constructor.  I don't really remember the details....

Jim

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