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 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.

DIAGNOSTICS

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

CAVEAT

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

SEE ALSO

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