[collectd] Generalized ignorelist functionality

[Florian Forster]

Hi Lubos,

On Sat, Nov 18, 2006 at 02:48:20PM +0100, Lubo?? Stan??k wrote:
> > - Is the `init' function necessary? If there was polymorphism in C I'd
> >   welcome having a default-argument for the `create' function, but think
> >   think having both, `init' and `create' with basically the same
> >   functionality, is confusing.
> 
> Because you proposed the "ignorelist_t *ignorelist_create (int
> inverse);". The state of the "ignore" is commonly not known to the end
> of the options. Therefore I have created the function not requiring a
> parameter. It can be omitted.

I've removed the function. Plugins need to set a reasonable default
themselves and can change their mind whenever they chose to..

> > - Why did you make the regex-stuff optional? The regex-things are in
> >   POSIX and should therefore exist everywhere. (How well that works can
> >   be seen in `utils_mount.c' *sigh*) Anyway, if someone only writes
> >   `Match foobar' the regex-automaton will essentially do the same as
> >   `strcmp'..
> 
> I do not know much about portability of the POSIX stuff to some
> marginal systems like old HP-UX or Solaris. Therefore the regex is
> selectable to be able to compile collectd without it. If you think it
> is really portable, you can remove the selection.

I've kept the `#if HAVE_REGEX_H' stuff, but removed the argument from
the configure script. The configure script now checks for `regex.h' in
any case.

> >   Also, we would not need the delimiters then, which I don't like that
> >   much.
>
> Do you have another idea how to differentiate strings and regexes?

No. Yes. Well, just _don't_ use string-matching and always use regexes.
If you provide a simple string like `foobar' the regex stuff does the
same without much overhead, but you have the power right there if you
need it. Thoughts and other opinions are welcome :)

Apart from these additional notices: I've merged your code into the
master branch and to have used the interface at least once myself I
implemented some selection stuff for the `df' plugin. You can now
select/ignore partitions depending on (fs-)type, mountpoint and device.
If you want to use the regex-stuff for matching mountpoints, you will
need to use stuff like this:
  Device /^/(media|proc|sys)/
Since the code right now simple removes a leading and a trailing slash,
you don't need to escape internal slashes. That's confusing. Also, the
way to use the string-matching code is like this:
  Device /media/cdrom
This is _not_ parsed as a regular expression, because it's _not_
followed by a slash. That's confusing, too.

Regards,
-octo
-- 
Florian octo Forster
Hacker in training
GnuPG: 0x91523C3D
http://verplant.org/
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