ibid mechanism broken

[agoric]

ibid mechanism broken

[warner]

Can you make this into a unit test? I just tried a simple set of arrays (serialize([a1,a2,a3,a3,a2,a1])) and it seems to serialize correctly, but that case isn't introducing any new objects in the post-replacer data, and it sounds like that's the core problem.

The test should probably go into test-marshal.js in "serialize exports". If you can write a test that fails and post it here (or put it on a branch), I'll try to find the fix.

[katelynsills]

Sure, sounds good!

…

On Mon, May 6, 2019, 9:01 AM Brian Warner ***@***.***> wrote: Can you make this into a unit test? I just tried a simple set of arrays ( serialize([a1,a2,a3,a3,a2,a1])) and it seems to serialize correctly, but that case isn't introducing any new objects in the post-replacer data, and it sounds like that's the core problem. The test should probably go into test-marshal.js in "serialize exports". If you can write a test that fails and post it here (or put it on a branch), I'll try to find the fix. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <https://github.com/Agoric/SwingSet/issues/30#issuecomment-489674970>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAST63PEOH2HU7K3YGDWJ6DPUBI4NANCNFSM4HKXWUPQ> .

[katelynsills]

I added a unit test here: Agoric/SwingSet@e6c6350

[warner]

Ah, yeah, this will be tricky. We're saving a lot of code by relying upon the built-in JSON serialization features. But the replacer hook of JSON.stringify is executed on the way into each node during a depth-first traversal, while the reviver hook of JSON.parse is run on the way out of each node. As a result, numbering the nodes by order of appearance to these hooks gets a completely different ordering.

Worst case we'll have to write our own deserializer. It might also be possible to serialize the data, unserialize it (without a reviver), then re-serialize it with a replacer that changes the ibid index for each node to match the other numbering order. Or do the same thing on the receiving side. Neither is particularly appealing.

[erights]

I have some ideas here, to talk about when we're next in at the same time. In the meantime, Agoric/SwingSet@508982d safely turns ibids off in a way that should work well enough in the absence of cycles. However, it will expand pass-by-copy dags into trees.

[warner]

That quick fix sounds good, and our marshalling layer will already combine multiple refs to the same import/export slot into a single index (even without the ibid mechanism). I'll land that now, and then we can defer the full fix until later.

[dckc]

Can you use a path rather than an index, a la cycle?

[erights]

Can you use a path rather than an index, a la cycle?

Perhaps. Opened https://github.com/Agoric/SwingSet/issues/66 to track. Closing this one though, since ibids with indexes are no longer broken.

[warner]

in the old repo. this was SwingSet issue 30