Re: [Gnu-arch-users] Re: Why we might use subversion instead of arch.

[Aaron Bentley]

Charles Duffy wrote:

> (Re _why_ revlibs are still useful in cases like yours, I'll leave that
> to someone like Tom who's more qualified to answer).
>  
Well, I'm not like Tom, but...
There's one case where we can be *absolutely* certain that two files are 
identical from the file info alone-- the case where the files are 
hard-links of one another. 

If your working directory is hard-linked to a revision library, this 
means that we can determine which files are unchanged without even 
looking at the inode signatures.

(That's in the 1.2 release.)

One non-linked revision takes up about the same space as a pristine.  A 
hard-linked revision takes much less (just the cost of unlinkables like 
directories).  Additional revisions have a similar cost.

Plus, revlibs aren't in your tree, so they don't confuse find, grep, and 
other standard unix tools.

A lot of work has been done already to let revlibs work everywhere that 
pristines do.  Now Tom's talking about replacing pristines with "sliding 
revlibs", which would be like the LRU pruning Miles mentioned.

(In the meantime, James Blackwell has a pruning script in tlacontrib.)

Aaron