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.
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
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
email@example.com. This page was obtained from the project's upstream
Git repository ⟨https://github.com/performancecopilot/pcp.git⟩ 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
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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)