pmtraversepmns(3) — Linux manual page


PMTRAVERSEPMNS(3)         Library Functions Manual         PMTRAVERSEPMNS(3)

NAME         top

       pmTraversePMNS,  pmTraversePMNS_r  - traverse the performance metrics
       name space

C SYNOPSIS         top

       #include <pcp/pmapi.h>

       int pmTraversePMNS(const char *name, void (*dometric)(const char *));
       int pmTraversePMNS_r(const char *name, void (*dometric_r)(const char *, void *), void *closure);

       cc ... -lpcp

DESCRIPTION         top

       The routine pmTraversePMNS may be used to perform a depth-first
       traversal of the Performance Metrics Name Space (PMNS).

       The traversal starts at the node identified by name - if name is an
       empty string (i.e. ""), the traversal starts at the root of the PMNS.
       Usually name would be the pathname of a non-leaf node in the PMNS.

       For each leaf node (i.e. performance metric) found in the traversal,
       the user-supplied routine dometric is called with the full pathname
       of that metric in the PMNS as the single argument.  This argument is
       null-byte terminated, and is constructed from a buffer that is
       managed internally to pmTraversePMNS.  Consequently the value is only
       valid during the call to dometric - if the pathname needs to be
       retained, it should be copied using strdup(3) before returning from

       The pmTraversePMNS_r routine performs the same function, except the
       callback method func_r has an additional parameter that will be
       closure from the initial call to pmTraversePMNS_r.  The additional
       parameter to pmTraversePMNS_r and the callback method allows the
       caller to pass context through pmTraversePMNS_r and into the callback
       method func_r, making the service more useful for multi-threaded
       applications where thread-private data can be accessed in the
       callback method via the closure argument.

       On success pmTraversePMNS and pmTraversePMNS_r return the number of
       leaf nodes found in the traversal, which will be one (1) if name is
       either a leaf node, or a derived metric or a non-leaf node with one
       child.  If name is a non-leaf node, the returned value will be zero
       or greater (zero is returned in the special case where name is a
       dynamic root node that currently has no children).  In all cases,
       derived metrics present in the PMNS subtree below name are counted as
       leaf-nodes.  If an an error occurs, pmTraversePMNS and
       pmTraversePMNS_r will return a negative error code, as described in
       the DIAGNOSTICS section below.

SEE ALSO         top

       PMAPI(3) and pmGetChildren(3).

DIAGNOSTICS         top

              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
              pmTraversePMNS must be made inside a current context.

              The initial pathname name is not valid in the current PMNS.

              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 ⟨⟩.
       If you have a bug report for this manual page, send it to  This page was obtained from the project's upstream
       Git repository ⟨⟩ on
       2020-08-13.  (At that time, the date of the most recent commit that
       was found in the repository was 2020-08-11.)  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

Performance Co-Pilot                 PCP                   PMTRAVERSEPMNS(3)