[e-lang] Surprising message orders

[Mark Miller]

At 05:46 PM 8/23/2004  Monday, David Hopwood wrote:
>However, suppose that Alice and Bob are in the same vat (Carol may be
>in a different vat). In that case, we might suppose that it would be
>possible to queue Alice and Bob's messages in such a way that they
>were guaranteed to arrive at Carol in the same order they were sent.
>Semantically, the effect would be that once any actor in a given vat
>had sent a message M to X, all other X-references *in that vat* would
>be updated to point to "the X that received M".
>
>This is desirable because it allows reasoning about the vat as if it
>were a single actor. It also appears to be efficiently implementable.
>My question is whether E's semantics requires, or should require, this
>stronger version of partial ordering.

It is not a property of the currently stated semantics, but such a stronger 
semantics would be upwards compatible from the current semantics, and this 
stronger semantics happens to already be correctly implemented by the 
current implementation.

As to whether we should make official the stronger semantics you propose, 
it's an interesting question. I could argue it both ways, but first I'd like to
see what others have to say. What do y'all think?


---------------------------

Btw, I am turning into a pumpkin, probably for at least a week or two, so 
don't expect quick reactions from me. Terry and I are moving to Baltimore, 
in order to spend time at Johns Hopkins (home of EROS) from now until May.
Moving a household across the country is rather chaotic, so you may get some 
surprising message orders from me as well. ;)


-- 
Text by me above is hereby placed in the public domain

        Cheers,
        --MarkM