Re: [pacman-dev] Disk space checking branch "complete"

17 Nov 2010

      On Wed, Nov 17, 2010 at 08:22:14PM +0200, Nezmer wrote:
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On Wed, Nov 17, 2010 at 08:13:08PM +0200, Nezmer wrote:
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On Tue, Nov 16, 2010 at 06:06:32PM -0600, Dan McGee wrote:
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On Tue, Nov 16, 2010 at 5:36 PM, Allan McRae  wrote:
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On 17/11/10 03:25, Nezmer wrote:
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On Tue, Nov 16, 2010 at 09:03:37PM +1000, Allan McRae wrote:
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On 16/11/10 18:02, Bryce Gibson wrote:
>
> Hi Allan,
> I just wanted to ask, it looks like your patches will make a sync fail
> if it
> finds there's not enough space, is that correct?
> Because I'd suggest a warning may be more appropriate, especially for
> use
> cases like compressed filesystems.
> Cheers
> Bryce
> ps. I noticed that space checking can be completely disabled via
> pacman.conf, which may be seen as a suitable solution for people in
> these
> types of situation.
Disabling checking in pacman.conf is what I would recommend in these
sort of cases.  These are the sort of things we will only find out
after we get some widespread usage of the feature.  I would be
interested in what the size calculations actually do on compressed
filesystems.
Allan
On the topic of FS compression(also FS caching and delayed allocation).
The real issue I had was the calculation of install size when building
the package. The calculated size was always *very* small. I addressed
this issue with 2 patches. The 1st one (adding sync before running du)
didn't fix anything. The 2nd patch worked pretty well.
http://gitorious.org/pacman-bsd/pacman-bsd/commit/8b367d4441ba85b5548285d987...
http://gitorious.org/pacman-bsd/pacman-bsd/commit/cf3341fe591293a493bc925e04...
I think that initial "sync" is not needed because du does one anyway. The
second one looks interesting so I have bookmarked it to look at later.
We've putzed around with this a few times, haven't we? This basically
"reverts" this one:
commit 149839c5391e9a93465f86dbb8d095a0150d755d
Author: Xavier Chantry 
Date:   Mon May 26 23:46:01 2008 +0200
du -b is not available on BSD, use du -k instead.
This fixes FS#10459.
There is apparently no portable ways to get the apparent size of a file,
    like du -b does. So the best compromise seems to get the block size in kB,
    and then convert that to byte so that we keep compatibility.
Signed-off-by: Xavier Chantry 
    Signed-off-by: Dan McGee 
There are three or so file sizes that matter:
1) du -s : what we do now, sums up actual taken space so would be more
accurate with many < 4K files.
2) du -sb: what we did before and what is proposed, sums up apparent
size, so does not necessarily best represent installed size (either
sparse files or many <4K files would throw the number off). The 4K
assumption also may not always hold...
3) du --tell-me-how-many-blocks-but-not-compressed : what seems like
perhaps the ideal? I'm not sure, but this would basically
    for file in tree:
        total += ceil(filesize to 4K)
1 is the most portable; 2 we need different flags all over the place;
3 we definitely don't seem to be able to use exiting tools but this
would not be an awful one to write.
-Dan
Is this 3 ?
install_size=0
for f in `find $pkgdir -type f`; do
  (( s=$(${SIZECMD} ${f})/1024 ))
  (( $(${SIZECMD} ${f})%1024 > 0 )) && (( s++ ))
  (( $s < 4 )) && (( s=4 ))
  (( install_size+=${s} ))
done
Unfortunately, this takes around 39 seconds in a 13085 files package.
Correction:
install_size=0
for f in `find $pkgdir -type f`; do
  (( s=$(${SIZECMD} ${f})/1024 ))
  (( $(${SIZECMD} ${f})%1024 )) && (( s++ ))
  (( ${s}%4 )) && (( s+=${s}%4 ))
  (( install_size+=${s} ))
done
Takes around 40 seconds in a 13085 files package.
Fail

As Dan said, This is too slow to be done in bash. I just want to correct
it for reference.

install_size=0
for f in `find $pkgdir -type f`; do
  (( s=$(${SIZECMD} ${f})/1024 ))
  (( $(${SIZECMD} ${f})%1024 )) && (( s++ ))
  (( ${s}%4 )) && (( s+=4-${s}%4 ))
  (( install_size+=${s} ))
done