NAME

       pmdaChildren - translate a PMID to a set of dynamic performance metric names

C SYNOPSIS

       #include <pcp/pmapi.h>
       #include <pcp/pmda.h>

       int pmdaChildren(char *name, int traverse, char ***offspring, int **status,
               pmdaExt *pmda);

       cc ... -lpcp_pmda -lpcp

DESCRIPTION

       As part of the Performance Metrics Domain Agent (PMDA) API (see PMDA(3)), pmdaChildren  is
       the  generic  callback  for  returning  dynamic  metric  names (and their status) that are
       descendants of name.

       Because implementing dynamic performance metrics requires specific PMDA support,  and  the
       facility is an optional component of a PMDA (most PMDAs do not support dynamic performance
       metrics), pmdaChildren is a skeleton implementation that returns PM_ERR_NAME.

       A PMDA that supports dynamic performance metrics will  provide  a  private  callback  that
       replaces  pmdaChildren  (by  assignment  to  version.four.children  of  the  pmdaInterface
       structure) and takes the initial metric name and returns names  via  offspring[]  and  the
       leaf or non-leaf status of each via status[].

       If  traverse is 0, then the behaviour is akin to pmGetChildren(3) and offspring[] contains
       the relative name component for the immediate descendants of name.

       If traverse is 1, then the behaviour is akin to pmTraversePMNS(3) and offspring[] contains
       the absolute names of all dynamic metrics that are decedents of name.

       The  resulting  list  of  pointers  offspring  and  the string values (the names) that the
       pointers reference will have  been  allocated  by  pmdaChildren  with  a  single  call  to
       malloc(3),  and  the caller of pmdaChildren will call free(offspring) to release the space
       when it is no longer required.  The same holds true  for  the  status  array,  namely  the
       caller  of  pmdaChildren  will call free(status) to release the space when it is no longer
       required.

CAVEAT

       The PMDA must be using PMDA_PROTOCOL_4 or later, as specified in the call to pmdaDSO(3) or
       pmdaDaemon(3).

DIAGNOSTICS

       pmdaChildren  returns  PM_ERR_NAME  if the name is not recognized or cannot be translated,
       otherwise the number of descendent metric names found.

SEE ALSO

       PMAPI(3),  PMDA(3),   pmdaDaemon(3),   pmdaDSO(3),   pmdaMain(3),   pmGetChildren(3)   and
       pmTraversePMNS(3).