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 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

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

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

SEE ALSO         top

       PMAPI(3) and pmGetChildren(3).

COLOPHON         top

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Performance Co-Pilot               PCP                 PMTRAVERSEPMNS(3)

Pages that refer to this page: pcp-mpstat(1)pmdachildren(3)pmdainit(3)pmgetderivedcontrol(3)