On 26/02/2008, Klaus D. Witzel <klaus.witzel at cobss.com> wrote:
> On Tue, 26 Feb 2008 04:51:56 +0100, Igor Stasenko wrote:
>
>  > My head just visited another idea, and i'd like to share it :)
>  >
>  > There was a discussion on how to pass sockets between images safely.
>  > And due to reasons that it's not safe, not easy, and require a lot
>  > changes which may break compatibility, solution was postponed for a
>  > future.
>  >
>  > Now, i think i found the way how to pass the newly created socket to
>  > another image by using a special accept primitive.
>  >
>  > What this primitive should do:
>  >
>  > by taking parameters: interpreter handle, socket handle and channel
>  > name, it should
>  > 1. do validity checks (all handles should be valid e.t.c)
>  > 2. accept new incoming socket connection (socket handle passed to
>  > primitive should be in listen mode)
>
>
> Does your 2. correspond to the line I marked in the following?:
>
>  | localhost serverSocket clientSocket sessionSocket listener |
>   localhost := NetNameResolver localHostAddress.
>   serverSocket := Socket newTCP listenOn: 7680 backlogSize: 1.
>   listener := [serverSocket waitForConnectionFor: 0.5
>         ifTimedOut: [Transcript cr; show: 'timed out ',
>         serverSocket statusString]]
>     forkAt: Processor activeProcess priority.
>   clientSocket := Socket newTCP connectTo: localhost port: 7680.
>   (Delay forMilliseconds: 250) wait.
>  "marked" sessionSocket := serverSocket accept.
>   Transcript cr; show: '[server] ', serverSocket statusString;
>         cr; show: '[session] ', sessionSocket statusString;
>         cr; show: '[client] ', clientSocket statusString;
>         cr; show: 'listener: ', listener browserPrintString; cr.
>   serverSocket destroy.
>   clientSocket destroy.
>   sessionSocket destroy
>
>  You mean, the marked line would be done by the new primitive, the accepted
>  Socket then passed to another HydraVM instance (err, interpreter, via
>  channel)?! That would allow "workers" run on their own CPU :)
>

Yes, approximately.
So, in _another_ image code can look like:

HydraChannel listen: #acceptChannel onData: [:socketHandle |
  | sessionSocket |
   sessionSocket :=  Socket fromHandle: socketHandle.

"we need to check this, because data can come to channel from random source"
   sessionSocket isValid ifTrue: [
         sessionSocket initSemaphores.  "bind new semaphores (read/write/close)"
         [ MyClass startSessionWith: sessionSocket ] fork. " now we
can work with socket"
   ]
]

And at 'dispatcher' side, where you having server socket listening for
connections, it can look like:

interpreter := self selectWorkerWithMinimalLoad.
serverSocket acceptBy: interpreter onChannel: #acceptChannel.

Interesting, that squeakers can implement own
#selectWorkerWithMinimalLoad by any criteria they want, and distribute
threads load by own criteria (assume worker threads passing some
feedback to dispatcher thread). This is unlikely can be achieved using
multiple OS processes setup. In fact, it's nearly impossible :)

-- 
Best regards,
Igor Stasenko AKA sig.