NAME
pmTraversePMNS, pmRequestTraversePMNS, pmReceiveTraversePMNS - traverse
the performance metrics name space
C SYNOPSIS
#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
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(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.
SEE ALSO
PMAPI(3) and pmGetChildren(3).
DIAGNOSTICS
PM_ERR_NOPMNS
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.
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.
PM_ERR_CTXBUSY
Context is currently in use by another asynchronous call.