Carlos Eduardo de Paula wrote:

Hi Simon,

Have you looked at the examples project? I made a small example using PB in a producer/consumer demo where the producers and consumers access a shared pool in a server using PB.

You can see it here:

http://code.google.com/p/stacklessexamples/wiki/StacklessTwisted

Oh yeah! This is really great. I'd seen this a while back, but forget it was combining stackless/twisted so nicely! Thanks!

http://stacklessexamples.googlecode.com/svn/trunk/examples/twisted/twistedPr...

http://stacklessexamples.googlecode.com/svn/trunk/examples/twisted/twistedPr...

Regards,

Carlos

On 06/04/2008, at 13:42, Simon Pickles wrote:

...

So I am still fiddling with interesting ways to combine stackless and twisted. Its fun, but I am probably naively hacking! (I always seem to want to use the deprecated code!- probably says a lot about me?)

I'm using Perspective Broker to do remote calls to an app running Twisted-Stackless. PB is positively brilliant, btw.

So say the a remote caller wants to get data from my app. It calls remote_GetData() in my PB app, which uses the actor model(each object has a channel.receive() running in its own tasklet).

remote_GetData() has to send a message thru a stackless.channel() to get the required data, then it must stackless.schedule()

Now it waits for the result to arrive at its own channel.receive(), which then needs to be passed back as the return value of remote_GetData().

Is this possible?

Perhaps like this:

from twisted.spread import pb from twisted.internet import reactor import stackless

dbRx = stackless.channel() pbRx = stackless.channel()

class DataSource: def Listen(self): while 1: msg = dbrx.receive() # a channel will arrive here msg.send(42) stackless.schedule() def __init__(self): stackless.tasklet(self.Listen)()

class pbBroker(pb.Referenceable): def remote_GetData(self): dbRx.send(pbRx) result = pbRx.receive() # return 42 to remote caller thru pb return result

This isn't ideal since I don't want pbBroker to block during the receive. I'd like it to closer resemble the Listen loop of the first class, so other objects can talk to pbBroker while it is waiting. Maybe like this:

class pbBroker(pb.Referenceable): def Listen(self): while 1: msg = self.rx.receive() # do stuff with msg from other local objects stackless.schedule() def __init__(self): self.rx = stackless.channel() stackless.tasklet(self.Listen)() def remote_GetData(self): ch = stackless.channel() dbRx.send(ch) # can block since its a dedicated channel result = ch.receive() # return 42 to remote caller thru pb return result I guess the same problem arise when remote_GetData() has to use a deferred too.

from twisted.enterprise import adbapi dbPool = adbapi.ConnectionPool("MySQLdb", db="db", user="user", passwd="pw")

class pbBroker(pb.Referenceable): def remote_GetDeferredData(self): d = dbPool.runInteraction(DoQuery, "SELECT * FROM users") # DoQuery just wraps a query with try/except d.addCallback(self.GetDeferredData_Success)

def GetDeferredData_Success(self, result): # return to remote caller thru pb return result ## WRONG

How can I return a value for a remote_* call when I only get that value thru another callback?

Sorry its a long and confusing one!

Simon

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