[rrd-developers] librrd4 dependancies

[Sebastian Harl]

Hi David,

On Sat, Jun 27, 2009 at 11:36:03PM -0700, david at lang.hm wrote:
> I can see how rrdtool would have depenancies on various graphics  
> libraries (since in most environments it creates graphs), but librrd4 
> only populates the rrd datastores, it doesn't create the graphs so why
> does it depend on libcairo and libpango?

Unfortunately, this assertion is wrong. librrd bundles _all_ function-
ality found in RRDtool - including graph creation. In fact, the rrdtool
binary is only a small wrapper around the library, basically parsing the
first command line option and then dispatching stuff to the right
function.

> this is the list of packages that get added on my systems when I add  
> librrd4
>
> defoma fontconfig fontconfig-config libcairo2 libdatrie0 
> libdirectfb-1.0-0 libfontconfig1 libfreetype6 libnewt0.52 libpango1.0-0 
> libpango1.0-common libpixman-1-0 libpng12-0 librrd4 libthai-data libthai0 
> libts-0.0-0 libx11-6 libx11-data libxau6 libxcb-render-util0 
> libxcb-render0 libxcb-xlib0 libxcb1 libxdmcp6 libxft2 libxrender1 
> ttf-dejavu ttf-dejavu-core ttf-dejavu-extra whiptail
>
> for a desktop this may not matter, but for embeded things or systems  
> with small flash disks (i.e. OLPC and netbooks) these packages do add up
[...]

I fully agree that splitting the graphing part and other database
handling would be _very_ nice to have. However, this is an issue that
has to be discussed and implemented upstream - it's not a "side-effect"
of the Debian packaging. I've thus Cc'ed the upstream developers mailing
list, hoping for comments and suggestions.

Imho, the best thing to do would be to separate graphing into it's own
library, say librrd-graph. Just doing so should require adapting the
build system only. However, this introduced backward-incompatible
changes to the API and ABI of librrd, so it would require a major soname
version bump, so Tobi has to decide about that. I do not expect that
lots of C programs use rrd_graph*(), so only few other projects should
be affected by that change and require code (and build system) changes
[1].

Cheers,
Sebastian

[1] The following packages seem to be affected in Debian: lm-sensors-3,
    ntop, xymon. I was using the following shell snippet to do a quick
    check (in Debian unstable):

      pkgs=$( ( build-rdeps librrd-dev; build-rdeps librrd2-dev ) \
          | egrep -v '^(Reverse|Found|-)' | sort -u )
      for pkg in $pkgs; do
          apt-get source $pkg; ( cd $pkg-*; egrep -r '\<rrd_graph' . )
      done

-- 
Sebastian "tokkee" Harl +++ GnuPG-ID: 0x8501C7FC +++ http://tokkee.org/

Those who would give up Essential Liberty to purchase a little Temporary
Safety, deserve neither Liberty nor Safety.         -- Benjamin Franklin

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