[collectd] Get collectd data from C++ source code

[Sebastian Harl]

Hi,

On Fri, Aug 03, 2012 at 03:56:20PM +0200, Massimo Canonico wrote:
> I have to get the collectd data (in particular, the idle time of the  
> last 4 measures) and use it in my C++ code.
>
> Is there any example available? Do you have any suggestion concerning  
> which is the best way to do it?

While I have never tested this, this should be fairly simple. You'll
have to make sure that the callback functions and register_module() are
linked according to the C calling conventions, i.e., those functions
have to be declared "extern C". You should then be able to call any C++
code from those functions and compile the whole thing using a C++
compiler.

So, in short, an example should look something like this:

foo.cpp:

  extern "C" {
      #include "collectd.h"
      #include "common.h"
      #include "plugin.h"
  }

  /* further, possibly C++, includes */

  extern "C" {
      static int foo_read(void);
      void module_register(void);
  }

  static int
  foo_read(void) { /* ... */ }

  void
  module_register(void) {
      plugin_register_read("foo", foo_read);
  }

Compile that, again untested, using something like:

  g++ -DHAVE_CONFIG_H -shared -fPIC -o foo.so foo.cpp

In case you manage to get that up and running, it would be nice to get
some feedback / short howto / example / whatever on the list or in the
wiki :-)

HTH,
Sebastian

-- 
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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