On Mon, Jun 2, 2008 at 11:15 AM, Johannes Schindelin <Johannes.Schindelin@xxxxxx> wrote: > Hi, > > On Mon, 2 Jun 2008, Geoffrey Irving wrote: > >> On Mon, Jun 2, 2008 at 9:18 AM, Johannes Schindelin >> <Johannes.Schindelin@xxxxxx> wrote: >> >> > On Mon, 2 Jun 2008, Geoffrey Irving wrote: >> > >> >> On Mon, Jun 2, 2008 at 8:37 AM, Johannes Schindelin >> >> <Johannes.Schindelin@xxxxxx> wrote: >> >> >> >> > Another issue that just hit me: this cache is append-only, so if it >> >> > grows too large, you have no other option than to scratch and >> >> > recreate it. Maybe this needs porcelain support, too? (git gc?) >> >> >> >> If so, the correct operation is to go through the hash and remove >> >> entries that refer to commits that no longer exist. I can add this >> >> if you want. Hopefully somewhere along the way git-gc constructs an >> >> easy to traverse list of extant commits, and this will be >> >> straightforward. >> > >> > I don't know... if you have created a cached patch-id for every commit >> > (by mistake, for example) and do not need it anymore, it might make >> > git-cherry substantially faster to just scrap the cache. >> >> Well, ideally hash maps are O(1), but it could be a difference between a >> "compare 40 bytes" constant and a "read a 4k block into memory" >> constant, so in practice yes. Scrapping it entirely will also make the >> implementation much simpler. >> >> It seems a little sad to wipe all that effort each time, but >> regenerating the cache is likely to be less expensive than a git-gc, so >> it shouldn't change any amortized complexities. > > Well, how about only scrapping the cache if it is older than, say, 2 > weeks, and is larger than, say, 200kB? That should help. That heuristic is insufficient, since it doesn't do anything in the normal case where a new entry appears every few days (e.g., when syncing between two branches with cherry-pick). I don't know what the best alternative is, so I left garbage collection out of the patch I just submitted. We can add it once we decide what to do. I'm not sure it's a serious problem: if you "accidentally" added entries for all commits in the git tree, the file is still under 1M. Geoffrey -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
