SHA1 lib

I've started working on the last part. Meaning I've started to write a processor for Git pack files. Currently i'm working on implementing v2 of the format. See http://repo.or.cz/w/git.git?a=bl.../technical/pack-format.txt;h=1803e64e465fa4f8f0fe520fc0fd95d0c9def5bd;hb=HEAD for more info.

Damn, broken link ^^

This is the correct one:

http://repo.or.cz/w/git.git?a=bl.../technical/pack-format.txt

Grmbl... http://tinyurl.com/5vvvm5

I'm a little fuzzy on what packs are used for. I understand they're collections of git objects, and I read somewhere they're used as a more efficient mechanism of transferring files between remote repositories. However, I've also read that they can be used as an archiving mechanism. Am I correct at all? Any idea when these events would occur?

I'm assuming that when looking for an object by it's sha1, we interrogate the objects directory, then interrogate any packs if we haven't found our object.

I suppose that would be the flow. Packs are generated when initiating a git fetch or push(for efficient data transfer). But doing git gc in your repo would collect all your git objects into a pack file. Git deletes all the objects from the first_two_chars/rest_of_sha/ dirs. So after git gc only a pack file remains in objects/pack.