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NAME | C SYNOPSIS | DESCRIPTION | CAVEAT | DIAGNOSTICS | SEE ALSO | COLOPHON |
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PMDALABEL(3) Library Functions Manual PMDALABEL(3)
pmdaLabel, pmdaSetLabelCallBack - fill pmLabelSet structures with
metric labels
#include <pcp/pmapi.h>
#include <pcp/pmda.h>
int pmdaLabel(int ident, int type, pmLabelSet **sets, pmdaExt
*pmda);
int pmdaSetLabelCallBack(pmdaInterface *dispatch,
pmdaLabelCallBack callback);
cc ... -lpcp_pmda -lpcp
As part of the Performance Metrics Domain Agent (PMDA) API (see
PMDA(3)), pmdaLabel uses the standard PMDA(3) data structures to
return the labels for performance domain, instance domain, metric
or individual instances in "JSONB" format in the given sets data
structure.
The type argument determines the interpretation of ident and the
requested form of label, as follows:
PM_LABEL_DOMAIN
when ident is a PMDA domain identifier,
PM_LABEL_CLUSTER
when ident is a metric identifier and labels for the cluster
containing that metric are being requested.
PM_LABEL_ITEM
when ident is a metric identifier,
PM_LABEL_INDOM
when ident is an instance domain identifier, or
PM_LABEL_INSTANCES
when ident is a metric identifier and labels for all instances
of that metric are being requested.
The label sets pointer must be initialised to NULL before calling
pmdaLabel and space is only to be allocated when labels are
present and returned. In this case, the return code must indicate
the number of label sets that have been allocated. This will only
ever be greater than one in the PM_LABEL_INSTANCES case.
This is one of the few generic callbacks in libpcp_pmda (see
PMDA(3)) that is incomplete, requiring a further pmdaLabelCallBack
method of its own. The additional callback should be registered
using pmdaSetLabelCallBack and the pmdaLabelCallBack method has
the following prototype:
int func(pmInDom indom, unsigned int inst, pmLabelSet **set)
The purpose of the pmdaLabelCallBack routine is to return the la‐
bel(s) for an individual instance inst of a given instance domain,
indom. Its successful return code differs significantly to pmdaL‐
abel, as described below.
The PMDA must be using PMDA_INTERFACE_7 or later, as specified in
the call to pmdaDSO(3) or pmdaDaemon(3).
On success pmdaLabel returns the number of label sets created.
This is usually zero or one, except in the case of PM_LABEL_IN‐
STANCES where more than one label sets will often be returned, one
for each instance of the requested metric.
By contrast, on success of the pmdaLabelCallBack routine the num‐
ber of labels successfully added to the provided labelset pointer
must be returned (and not the total number of label sets).
If labels for the requested entity could not be obtained due to a
catastrophic failure, such as an out of memory condition, these
routines will return a negative error code.
pminfo(1), malloc(3), PMAPI(3), PMDA(3), pmdaDaemon(3),
pmdaDSO(3), pmdaInit(3) and pmLookupLabels(3).
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
2025-02-02. (At that time, the date of the most recent commit
that was found in the repository was 2025-01-30.) 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 PMDALABEL(3)
Pages that refer to this page: pmdacache(3), pmdainstance(3)
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HTML rendering created 2025-02-02 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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