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PMDACHILDREN(3)         Library Functions Manual         PMDACHILDREN(3)

НАЗВАНИЕ

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

C СИНТАКСИС

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

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

       cc ... -lpcp_pmda -lpcp

ОПИСАНИЕ

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

       Because implementing dynamic performance metrics requires specif‐
       ic PMDA support, and the facility is an optional component  of  a
       PMDA (most PMDAs do not support dynamic performance metrics), pm‐
       daChildren 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 im‐
       mediate descendants of name.

       If traverse is 1, then the behaviour is akin to pmTraversePMNS(3)
       and offspring[] contains the absolute names of all  dynamic  met‐
       rics 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 sta‐
       tus array, namely the caller of pmdaChildren will call  free(sta‐
       tus) to release the space when it is no longer required.

ПРЕДУПРЕЖДЕНИЕ

       The PMDA must be using PMDA_INTERFACE_4 or later, as specified in
       the call to pmdaDSO(3) or pmdaDaemon(3).

ДИАГНОСТИКА

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

СМОТРИТЕ ТАКЖЕ

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

КОЛОФОН

       This page is part of the PCP (Performance Co-Pilot) project.  In‐
       formation about the project can be found at ⟨http://www.pcp.io/⟩.
       If  you  have  a  bug  report  for  this  manual page, send it to
       pcp@groups.io.   This  page  was  obtained  from  the   project's
       upstream                      Git                      repository
       ⟨https://github.com/performancecopilot/pcp.git⟩  on   2024-06-14.
       (At  that time, the date of the most recent commit that was found
       in the repository was 2024-06-14.)  If you discover any rendering
       problems in this HTML version of the page, or you  believe  there
       is  a  better or more up-to-date source for the page, or you have
       corrections or improvements to the information in  this  COLOPHON
       (which  is  not part of the original manual page), send a mail to
       man-pages@man7.org

Performance Co-Pilot               PCP                   PMDACHILDREN(3)

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