pmlookupname(3) — Linux manual page

NAME | C SYNOPSIS | DESCRIPTION | EXAMPLE | SEE ALSO | DIAGNOSTICS | COLOPHON

PMLOOKUPNAME(3)         Library Functions Manual         PMLOOKUPNAME(3)

NAME         top

       pmLookupName - translate performance metric names into PMIDs

C SYNOPSIS         top

       #include <pcp/pmapi.h>

       int pmLookupName(int numpmid, const char **namelist, pmID *pmidlist);

       cc ... -lpcp

DESCRIPTION         top

       Given a list in namelist containing numpmid full pathnames for
       performance metrics from a Performance Metrics Name Space (PMNS),
       pmLookupName returns the list of associated Performance Metric
       Identifiers (PMIDs) via pmidlist.

       The result from pmLookupName depends on the presence of any
       lookup failures, their severity and the number of metrics being
       looked up.

       1.  If there are no lookup failures, the return value will be
           numpmid.

       2.  If a fatal error is encountered, the return value will be
           less than 0.  For example PM_ERR_TOOSMALL, PM_ERR_NOPMNS or
           PM_ERR_IPC.

       3.  If numpmid is greater than one and non-fatal error(s) are
           encountered, the return value is the number of metric names
           that have successfully been looked up (greater than or equal
           to zero and less than or equal to numpmid).

       4.  If numpmid is one and a non-fatal error is encountered, the
           return value is the error code (less than zero).

       When errors are encountered, any metrics that cannot be looked up
       result in the corresponding element of pmidlist being set to
       PM_ID_NULL.

       The slightly convoluted error protocol allows bulk lookups, then
       probing for more error details in the case of a specific failure,
       as shown in the EXAMPLES section below.

       Note that the error protocol guarantees there is a 1:1
       relationship between the elements of namelist and pmidlist, hence
       both lists contain exactly numpmid elements.  For this reason,
       the caller is expected to have pre-allocated a suitably sized
       array for pmidlist.

EXAMPLE         top

       #include <pcp/pmapi.h>

       #define NUMPMID (sizeof(names)/sizeof(const char *))
       const char *names[] = {
                      "sample.bin",
                      "sample",
                      "sample.bog",
                      "sample.secret.bar",
                      "sample.secret.bar.bad"
                    };
       pmID pmids[NUMPMID];

       int
       main(int argc, char **argv)
       {
           int   sts;
           int   numpmid = NUMPMID;

           pmNewContext(PM_CONTEXT_HOST, "local:");

           sts = pmLookupName(numpmid, names, pmids);

           if (sts < 0) {
            fprintf(stderr, "pmLookupName failed: %s0, pmErrStr(sts));
            exit(1);
           }
           if (sts != numpmid) {
            /*
             * some of the lookups failed ... report the reason(s)
             */
            int  i;

            for (i = 0; i < numpmid; i++) {
                if (pmids[i] != PM_ID_NULL) continue;
                /* this one failed */
                sts = pmLookupName(1, &names[i], &pmids[i]);
                fprintf(stderr, "%s: lookup failed: %s0, names[i], pmErrStr(sts));
            }
            exit(1);
           }

           /* all good ... */
           ...
       }

SEE ALSO         top

       PMAPI(3), pmGetChildren(3), pmGetChildrenStatus(3),
       pmGetConfig(3), pmLoadNameSpace(3), pmNameID(3), pmNewContext(3),
       pcp.conf(5) and pcp.env(5).

DIAGNOSTICS         top

       PM_ERR_TOOSMALL
              numpmid must be at least 1

       PM_ERR_NOPMNS
              Failed to access a PMNS for operation.  Note that if the
              application hasn't a priori called pmLoadNameSpace(3) and
              wants to use the distributed PMNS, then a call to
              pmLookupName must be made after the creation of a context
              (see pmNewContext(3)).

       PM_ERR_NAME
              namelist[0] does not correspond to a valid metric name in
              the PMNS.

       PM_ERR_NONLEAF
              namelist[0] refers to a node in the PMNS but it was not a
              leaf node.

       PM_ERR_*
              Other diagnostics are for protocol failures when accessing
              the distributed PMNS.

COLOPHON         top

       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 2020-12-18.
       (At that time, the date of the most recent commit that was found
       in the repository was 2020-12-18.)  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                   PMLOOKUPNAME(3)

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