[gentoo-portage-dev] /var/db/pkg, package - sizes and formats

[Ned Ludd]

Does anybody know the point of /var/db/pkg/*/*/{[A-Z]*,*.ebuild} when
/var/db/pkg/*/*/env*.bz2 contains all the same info minus the
(CBUILD,CONTENTS,COUNTER,DEBUGBUILD)?

DEBUGBUILD is 0 bytes most of the time. Does it really need to exist in
production environments?

These sparse files add up in size really quickly and I'd like to see
portage shift into a direction where these things are planned out vs
just added. I don't see any reason why portage could not simply extract
the variables portage from the saved environment.bz2 when needed or even
preloading them.

I work on an embedded images and I have the option to dump 100% of
/var/db/ thus having no way of knowing what's installed but I'd like to
keep track of what's installed and not be forced into using a hacked up
methods which post rm stuff from a target ROOT= in order to yield the
desired result of keeping track of data without wasting valuable
resources.

Using patch2 from http://bugs.gentoo.org/show_bug.cgi?id=67190
And a mini subdistro meta ebuild
http://oc12.net/~solar/gensoekris-0.0.1.ebuild
INSTALL_MASK='*.a *.h /usr/include /usr/lib/*.o *.sample' ROOT=/tmp/root
emerge gensoekris -K

du -hs .
12M     .
cd var/db/pkg/
du -hs .
3.8M    .
# About 1/3rd of this file systems entire size is extra pkg data.

# Everything else seems to be in the env so lets kill some of the temp
fluff and do some testing.
find . -name '[A-Z]*' -o -name '*.ebuild' | egrep -v
'CBUILD|CONTENTS|COUNTER' | xargs rm

du -hs .
1.1M    .

# So it seems we could be down from 3.8 to 1.1M and still have all
needed info for portage.

# Now lets take a look at the package and how this could work. I'll use
iptables as an exmaple. When all is said and done we want only an
environment.bz2 left in var/db/pkg/iptables-1.2.11-r2/

ls -l $(portageq envvar PKGDIR)/All/iptables-1.2.11-r2.tbz2
-rw-r--r--  1 root root 179724 Oct 10 00:53
/usr/portage//packages/i386-pc-linux-uclibc//All/iptables-1.2.11-r2.tbz2

# extract the portage made tarball.
mkdir root
tar jxf
/usr/portage//packages/i386-pc-linux-uclibc//All/iptables-1.2.11-r2.tbz2
-C root/
du -hs root
660K    root

# Repack the contents (new pkg format)
cd root
tar jcvf ../iptables-1.2.11-r2.tbz2 ./
cd ../net-firewall/iptables-1.2.11-r2/
bzip2 CONTENTS
bunzip2 environment.bz2
echo CBUILD=$(cat CBUILD) >> environment
echo COUNTER=$(cat COUNTER) >> environment
bzip2 environment
cat CONTENTS.bz2 >> environment.bz2
cd ../../
cat net-firewall/iptables-1.2.11-r2/environment.bz2 >>
iptables-1.2.11-r2.tbz2
ls -l iptables-1.2.11-r2.tbz2
-rw-r--r--  1 root root 174892 Nov  3 19:01 iptables-1.2.11-r2.tbz2

# As we can see the package size has become smaller.
echo $((179724-174892))
4832

# Just for kix take that number and assume say about 100000 users have
about 500 packages installed and see that across the board we could save
the users about
export f=$(($(($((4832*500))*100000))/1024))
dd if=/dev/zero of=$f count=1 bs=$f ; ls -lh $f ; rm $f
-rw-r--r--  1 root root r 226M Nov  3 14:19 235937500
# probably not really realistic as 100k of users don't have buildpkg
enabled.

# Anyway lets test the new package.tbz2.
mkdir root
tar jxf iptables-1.2.11-r2.tbz2  -C root ; echo $?
0
du -hs root
660K    root
# good 660K matches same as portage built tarball that was extracted
into the root/ from before.

# The du -b here could become some other tool which seeks to the second 
BZh9 header in the tarball. But to test that we could still get info out
of the tarballs so portage could use/load it I did.

tail -c $(du  -b net-firewall/iptables-1.2.11-r2/environment.bz2 ) |
bzgrep ^ARCH=

# which returned.
ARCH=x86

# now lets see how big 
rm iptables-1.2.11-r2.tbz2
find . -name '[A-Z]*' | xargs rm
du -hs .
732K    .

# Well sweet we just got a dir that was 3.8M down to 732K and don't
appear to have lost anything.

# New total size
du -hs /tmp/root
8.2M /tmp/root
# which compresses down to about 3.6M nicely (Not bad for 36 pkgs)

# another box which is my desktop is
du -hs /var/db/pkg/ ; du -bhs /var/db/pkg/
83M	/var/db/pkg/
29M	/var/db/pkg/
# I bet most of yours are nearly as large or larger.

# Cost savings here could be alot better for everybody if we moved into
a direction which I just demonstrated. 

In short this all could work if we simply
Compressed the file CONTENTS and appended it to end of environment.bz2
then appended environment.bz2 to the end of the ${P}.tbz2

Anybody see flaws/problems in the basic idea?
Would this structure be suitable as the next gen pkg format?

-- 
Ned Ludd <solar@g.o>
Gentoo (hardened,security,infrastructure,embedded) Developer