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 dometric.
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.