From: Joel Dice Date: Tue, 19 Sep 2006 21:42:20 GMT Subject: Re: Subversion-style incrementing revision numbers Message-ID: In-Reply-To: <20060919211844.GB8259@pasky.or.cz> On Tue, 19 Sep 2006, Petr Baudis wrote: > Dear diary, on Tue, Sep 19, 2006 at 11:07:45PM CEST, I got a letter > where Joel Dice said that... >> Implementation: >> >> A simple, efficient implementation of this feature would be based on a >> single file, $GIT_DIR/history, which would contain a newline-delimited >> list of SHA commit IDs in chronological order, oldest first. The current >> repository IRN would be calculated as the size of that file divided by the >> SHA+newline length, and the commit ID of any IRN could be determined by >> seeking to the correct offset in that file. Every commit would cause a >> new line to be appended to the history file with that commit's ID. >> Finally, a history file could be generated for an existing repository by >> serializing the commit history based on chronological order. > > We already have support for recording something similar, it's called a > revlog. You would just need to modify it to aggregate all the branches > in a single file. Thanks - I'll look at that. > Also, multiple IRNs could refer to a single real commit if you do e.g. > cg-admin-uncommit, since revlog logs revision updates, not new revisions > created. This may or may not be considered a good thing. If you rather > want to just create a new IRN at commit object creation time, also note > that some tools _might_ validly create commit objects and then throw > them away, which would generate non-sensical (and after prune, invalid) > IRNs. I'm not too worried about cg-admin-uncommit or git-reset, since the IRN feature is intended mainly for shared repositories. I would suggest that such commands simply be disallowed for such repositories. The problem of temporary commits certainly needs to be addressed. In this case, may I assume nothing under $GIT_DIR/refs is ever modified? If so, perhaps I could somehow hook into the git-update-ref step. Is that what the revlog code does? - Joel