Re: kernel.bkbits.net off the air

[Andrea Arcangeli]

On Mon, Nov 10, 2003 at 10:27:33AM -0800, Davide Libenzi wrote:
> On Mon, 10 Nov 2003, H. Peter Anvin wrote:
> 
> > >>The best way to fix this isn't to add locking to rsync, but to add two
> > >>files inside or outside the tree, each one is a sequence number, so you
> > >>fetch file1 first, then you rsync and you fetch file2, then you compare
> > >>them. If they're the same, your rsync copy is coherent. It's the same
> > >>locking we introduced with vgettimeofday.
> > >>
> > >>Ideally rsync could learn to check the sequence numbers by itself but I
> > >>don't mind a bit of scripting outside of rsync.
> > > 
> > > Wouldn't a simpler  "stop-rsync -> update-root -> start-rsync" work? If 
> > > you'll hit an update you will get a error from your local rsync, that will 
> > > let you know to retry the operation.
> > 
> > Part of the problem is that there are multiple steps in the rsync chain, 
> > some of which can't be stopped in this way.
> > 
> > The sequence number idea looks sensible to me.  Larry, would it be too 
> > much work to have the cvs repository generator generate these files?
> 
> So the update of the rsync repo should do something like:
> 
> update file1
> update repo
> update file2
> 
> Isn't it? I do not understand how this guarantee coherency:
> 
> Kernel.org             Me
>                        get file1 (old value)
> update file1           get repo-file1 (old value)
> update repo-file1
> ...
> update repo-fileJ
> ...                    get repo-fileJ (new value)
> update repo-fileN      get file2 (old value)
> update file2

you must pick file2 before file1:

	you:

	do
		get file2
		get repo-file1-j
		get file1
	while file2 != file1 && sleep 10
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