On Thu, Jul 11, 2013 at 6:39 PM, Thomas Gummerer <t.gumme...@gmail.com> wrote: >> Question about the possibility of updating index file directly. If git >> updates a few fields of an entry (but not entrycrc yet) and crashes, >> the entry would become corrupt because its entrycrc does not match the >> content. What do we do? Do we need to save a copy of the entry >> somewhere in the index file (maybe in the conflict data section), so >> that the reader can recover the index? Losing the index because of >> bugs is big deal in my opinion. pre-v5 never faces this because we >> keep the original copy til the end. >> >> Maybe entrycrc should not cover stat fields and statcrc. It would make >> refreshing safer. If the above happens during refresh, only statcrc is >> corrupt and we can just refresh the entry. entrycrc still says the >> other fields are good (and they are). > > The original idea was to change the lock-file for partial writing to > make it work for this case. The exact structure of the file still has > to be defined, but generally it would be done in the following steps: > > 1. Write the changed entry to the lock-file > 2. Change the entry in the index > 3. If we succeed delete the lock-file (commit the transaction) > > If git crashes, and leaves the index corrupted, we can recover the > information from the lock-file and write the new information to the > index file and then delete the lock-file.
Ah makes sense. Still concerned about refreshing though. Updated files are usually few while refreshed files could be a lot more, increasing the cost at #1. -- Duy -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html