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       pmTraversePMNS, pmRequestTraversePMNS, pmReceiveTraversePMNS - traverse
       the performance metrics name space


       #include <pcp/pmapi.h>

       int pmTraversePMNS(const char *name, void (*dometric)(const char *))
       int pmRequestTraversePMNS(int ctx, const char *name)
       int pmReceiveTraversePMNS(int ctx, void (*dometric)(const char *))

       cc ... -lpcp


       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(3C) before returning from dometric.

       On success pmtraversePMNS returns the number of children of name, which
       may be zero.

       pmRequestTraversePMNS   and   pmReceiveTraversePMNS   are    used    by
       applications  which  must   communicate  with  the PMCD asynchronously.
       These functions take explict context handle ctx which must refer  to  a
       host context (i.e. created by passing PM_CONTEXT_HOST to pmNewContext).
       pmRequestTraversePMNS sends request to PMCD to return sub-tree of  PMNS
       and  returns  without  waiting  for the response, pmReceiveTraversePMNS
       reads reply from PMCD and executes depth-first traversal over  returned
       sub-tree.  It is the responsibility of the application to make sure the
       data are ready before calling pmReceiveTraversePMNS.

       Unlike      its      synchronous      counterpart       pmTraversePMNS,
       pmReceiveTraversePMNS  does  not  perform  any  additional  queries  to
       provide  compatibility  with  older  versions  of  PCP,   it   is   the
       responsibility of an application to implement additional traversals.


       PMAPI(3) and pmGetChildren(3).


              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.

              Context is currently in use by another asynchronous call.