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NAME | C SYNOPSIS | DESCRIPTION | CAVEAT | DIAGNOSTICS | SEE ALSO | COLOPHON |
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PMDACHILDREN(3) Library Functions Manual PMDACHILDREN(3)
pmdaChildren - translate a PMID to a set of dynamic performance
metric names
#include <pcp/pmapi.h>
#include <pcp/pmda.h>
int pmdaChildren(char *name, int traverse, char ***offspring,
int **status, pmdaExt *pmda);
cc ... -lpcp_pmda -lpcp
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.
The PMDA must be using PMDA_PROTOCOL_4 or later, as specified in
the call to pmdaDSO(3) or pmdaDaemon(3).
pmdaChildren returns PM_ERR_NAME if the name is not recognized or
cannot be translated, otherwise the number of descendent metric
names found.
PMAPI(3), PMDA(3), pmdaDaemon(3), pmdaDSO(3), pmdaMain(3),
pmGetChildren(3) and pmTraversePMNS(3).
This page is part of the PCP (Performance Co-Pilot) project.
Information 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 2022-12-17.
(At that time, the date of the most recent commit that was found
in the repository was 2022-12-16.) 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)
Pages that refer to this page: pmdamain(3)
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