Re: [Monotone-devel] cvs import

[Markus Schiltknecht]

Hi,

Michael Haggerty wrote:
> Markus Schiltknecht wrote:
> > With such an algorithm, you won't rely on the timestamps, but only on
> > the dependencies. Thus, what other advantages would the blob method have?
>
> Step 2 is essentially the creation of a blob, isn't it?

Sure. Except that you won't have inter-blob dependencies to resolve.

> And steps 2 and 3 could be an infinite loop, because of
>
>    1   2
>    |   |
>    A   B
>    |   |
>    B   A

True, but you could easily check for that. Just remember what you've 
already tried and don't try again. To me the question is: what to do 
then? Split A into two commits around B:

A1 - B - A2 - C

Or (for monotone or git): try to seperate into individual commits (not 
always possible) and create two heads, which then merge later on. I.e.:

    .- A --.
   /        \
--x          x-- C
   \        /
    '- B --'

Or even merge A and B into one single revision (since you can't 
determine exactly what belongs to A and what to B), thus:

AB - C

> This can arise if two (nonatomic, remember) CVS commits are going on at
> the same time, even without clock errors.  Of course more complicated
> loops can also arise.

Yes, but the problem stays the same for Nathaniel's continuous algorithm 
and for your blob-method.

> Yes, but branches and especially tags are very slippery.  They don't
> even have to be created (chronologically) before a succeeding commit on
> the same file.  So you'll have branch/tag events rising to the top of
> the frontier and you need some way to decide when to process them.

If you apply the exactly same algorithm for 'commit', 'tag' and 'branch' 
events, I don't see no problem there.

Except the 'loop' resolution will work differently if your loop consists 
of not only commits.

> Not that this part is much easier in the blob scheme, except that from
> early on you have a global picture of the topology of branches/tags so I
> think it should be easier to design the heuristics that will be needed.

Ah, that's a difference. What do we gain with the 'global picture'?

Regards

Markus