Spoon August 2004

spoon@lists.squeakfoundation.org

1 participants
3 discussions

Squat progress 19 August 2004: successful imprintings, call for tests
by Craig Latta 20 Aug '04

20 Aug '04

Hi-- I just experienced an amusing imprinting session. The main application I'm transferring happened to evaluate (HttpAdaptor dataTimeout), which sends Object>>binding. To transfer the latter method, the source system must immediately define and initialize a global variable method literal ("Binding") in the target system. Doing *that* requires defining a couple other classes (BindingsAccessor and DynamicBindings) and initializing them, and defining and signalling a new Exception subclass (BindingsLocator). Well, it all worked. The amusing part is that the target system (basically Dan's 2.2 mini snapshot) had no exception-handling support at the outset; it got imprinted inline as a side effect. :) So, I think this stuff actually works... I plan to make a new release soon, so that others can try to find things that the imprinter can't deal with. In the meantime, I'd appreciate any test suggestions (like the HttpAdaptor one-liner above). thanks, -C -- Craig Latta improvisational musical informaticist craig(a)netjam.org www.netjam.org [|] Proceed for Truth!

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Squat progress 4 August 2004: imprinting at normal speed
by Craig Latta 05 Aug '04

05 Aug '04

Hi-- Just a note to say that I rewrote my imprinting VM changes as proper Slang, so now it runs at normal speed (it only ran under simulation before). This also means one only needs the source and target snapshots (no need for the source-copy or simulator snapshots). It also works with multiple concurrent targets (as in the "behavior broadcasting" example I mentioned previously). -C -- Craig Latta improvisational musical informaticist craig(a)netjam.org www.netjam.org [|] Proceed for Truth!

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Squat progress 2 August 2004: "imprinting"
by Craig Latta 03 Aug '04

03 Aug '04

Hi-- I've implemented the more brute-force means of transferring behavior on demand, as mentioned in my 3 July message. I have successfully transferred, from one snapshot to another, all the methods run in the first million sends of an application, without using the compiler, and without any special consideration for which methods those were. I call this process "imprinting". The main benefit of this approach, as I'm using it now, is making an application smaller by leaving unused behavior behind. (This is useful because I want to minimize the download time of the resulting snapshot.) I can see other interesting uses as well; for example, "behavior broadcasting", in people "tune in" to a running system (e.g., at a demo during a conference), and come away with all the behavior needed to run the demo again for themselves. It's also a good way of transferring unmodularized behavior from one place to another without having to understand its architecture or dependencies. [This reminds me a little of the first Matrix movie, where characters have martial-arts or helicopter-flying skills imprinted onto them. :) But notice they didn't start fighting or flying before the imprinting was finished. That'd be similar to the first on-demand transfer approach I tried, and later shelved (see the Squat mailing list archive). I suppose for reference I'll call the previous approach "active imprinting", and the current one "passive imprinting".] The process works by running the application in a copy of the source snapshot (the "input" snapshot), which reports the ID of each method run to the original source snapshot (via a special virtual machine); the source then ensures that the corresponding methods are installed in the target. The communication between the input and the source, and between the source and the target, is done with remote message-sending (a message-event server in the input sends messages to a message-event client in the source, which then sends messages to a Squat module in the target). In my current sessions, the source is a 3.6 snapshot, and the target is a 2.2 snapshot. This encourages me that the technique will work between snapshots of any likely vintage. -C -- Craig Latta improvisational musical informaticist craig(a)netjam.org www.netjam.org [|] Proceed for Truth!

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Spoon August 2004