[collectd] perl plugin: callback only for one of the thread

Pavel V. pavel2000 at ngs.ru
Tue Feb 28 12:15:40 CET 2017

Hi, Andreas.

> On Mon, Feb 27, 2017 at 10:50 PM Pavel V. <pavel2000 at ngs.ru> wrote:

> How do you implemented read callback registering?

> If you call plugin_register (TYPE_READ, "FooBar", "foobar_read") twice with same
> plugin name, the plugin will be registered only once (with warning at logs)!

> indeed i registered the read callback twice with the same plugin and function
> name. doh. I didn't see any warning in the logs. what should it say?

I assume you use collectd-5.7. It is true?

The reporting function call looks like:

WARNING ("The read function \"%s\" is already registered. "
  "Check for duplicate \"LoadPlugin\" lines "
  "in your configuration!", $pluginname);

> i dont know my hostname before i get called by the config callback (as my hostnames are stored there.)

That is expected and correct.

> so i attempted to register the read callback from within the config callback, which gives me this:

> Feb 28 11:13:54 david collectd[31153]: perl: Execution of callback
> "Collectd::Plugins::OneWireCtlr::my_read_192.168.178.117" failed: unknown
> callback "Collectd::Plugins::OneWireCtlr::my_read_192.168.178.117"

I think that message comes from callback call, not from registration.

Is that function exists in package / added by eval() or you try to use

> I assume registering a callback has to happen earlier?

Just tried:


<Plugin perl>
   IncludeDir "/opt/collectd/share/perl5"
   BaseName "Collectd::Plugins"
   LoadPlugin "FooBar"
   <Plugin FooBar>
       Foo "Bar"


package Collectd::Plugins::FooBar;
use strict;
use warnings;
use Collectd qw( :all );

plugin_register (TYPE_CONFIG, "FooBar", "foobar_config");

sub foobar_config {
  my $config = shift;

  plugin_register (TYPE_READ, "FooBar", "foobar_read");
  plugin_register (TYPE_READ, "FooBar/1", "foobar_read_1");

  return 1;

sub foobar_read { ... };     #Works.
#sub foobar_read_1 { ... };  #Works too.

   ERROR ("AUTOLOAD $AUTOLOAD"); #Called as expected and reports to log:
                                 #AUTOLOAD Collectd::Plugins::FooBar::foobar_read_1

All works as expected. Notice again: I use collectd-5.7, which has new implementation of
perl plugins registration. collectd-5.6 is differ.

 Pavel                          mailto:pavel2000 at ngs.ru

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