NAME

       pmTraversePMNS, pmTraversePMNS_r - traverse the performance metrics name space

C SYNOPSIS

       #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

       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 addi‐
       tional parameter that will be closure from the initial call to pmTraversePMNS_r.  The additional  parame‐
       ter  to  pmTraversePMNS_r  and  the  callback  method  allows  the  caller to pass context through pmTra‐
       versePMNS_r and into the callback method func_r, making the service more useful for multi-threaded appli‐
       cations 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,  pmTra‐
       versePMNS and pmTraversePMNS_r will return a negative error code, as described in the DIAGNOSTICS section
       below.

DIAGNOSTICS

       PM_ERR_NOPMNS
              Failed  to  access  a PMNS for operation.  Note that if the application hasn't a priori called pm‐
              LoadNameSpace(3) and wants to use the distributed PMNS, then a call to pmTraversePMNS must be made
              inside a current context.

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

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

SEE ALSO

       PMAPI(3) and pmGetChildren(3).

Performance Co-Pilot                                   PCP                                     PMTRAVERSEPMNS(3)