[Monotone-devel] Re: Netsync questions

[graydon hoare]

Nathaniel Smith wrote:

> The case I'd be worried about is possible bugs lurking if you, say,
> have one person syncing against mjw.mt.test1 and someone else syncing
> against mjw.mt at the same time.  This is just a vague fear, though;
> perhaps the wise Graydon has forseen this issue and made it all work
> correctly :-).

huh. this is interesting. there is actually a lurking bug here, but it's 
not the one you think (I think): I just checked, and the merkle trees 
are updated a little too early in the service routine, before the certs 
in question are actually committed to the database. that's bad: an 
aborted sync will think it transferred something when really it did not. 
this will not cause trouble currently because we rebuild merkle trees 
from scratch every time we run a netsync command; but that's a 
"conservative mode" I wish to turn off someday. I've filed a bug.

anyways, that has nothing to do with concurrent writes to multiple 
collections. none of the writes are "really" concurrent in "monotone 
serve" -- it processes each command in a transaction, and in a single 
thread -- so in theory (aside from bugs) there should be nothing wrong 
with writing to multiple collections which overlap. bugs are always a 
concern, of course.

-graydon