Re: gc considered dangerous

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Feb 8, 2009, 14:56 UTC
Message-ID: <alpine.DEB.1.00.0902081551290.10279@pacific.mpi-cbg.de>
In-Reply-To: <200902080347.25970.robin.rosenberg.lists@dewire.com>

Hi,

On Sun, 8 Feb 2009, Robin Rosenberg wrote:

> I've seen this. Running git gc on Windows, while having Elipse open can 
> kill your object database.

You had me really scared with the mail subject!

> if gc doesn't find a new optimal pack it tries to rewrite a new pack 
> with the same id. So it rm's the idx file (fine) and the the pack file 
> (not ok) and gives up,

I disagree with your notion that it is fine to kill the existing idx file until the new one has been written successfully.

My preliminary guess is that this code in pack-write.c needs to use the lock file paradigm:

        if (!index_name) {
		[...]
        } else {
                unlink(index_name);
                fd = open(index_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
        }

Ciao, Dscho