C SYNOPSIS

#include <pcp/pmapi.h>

int pmNameAll(pmID pmid, char ***nameset)
int pmRequestNameAll(int ctx, pmID pmid)
int pmReceiveNameAll(int ctx, char ***nameset)

cc ... -lpcp

DESCRIPTION

Given a Performance Metric ID (PMID) via pmid, pmNameAll will determine all the corresponding metric names, if any, in the Performance Metrics Name Space (PMNS), and return these via nameset.

The resulting list of pointers nameset and the values (the relative names) that the pointers reference will have been allocated by pmNameAll with a single call to malloc(3C), and it is the responsibility of the pmNameAll caller to free(nameset) to release the space when it is no longer required.

In the absence of errors, pmNameAll returns the number of names in nameset.

For many examples of a PMNS, there will be a 1:1 mapping between a name and a PMID, and under these circumstances, pmNameID(3) provides a slightly simpler interface in the absence of duplicate names for a particular PMID.

pmRequestNameAll and pmReceiveNameAll 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). pmRequestNameAll sends request to PMCD to return names of all metrics matching a PMID and returns without waiting for the response, pmReceiveNameAll reads reply from PMCD. It is the responsibility of the application to make sure the data are ready before calling pmReceiveNameAll to avoid blocking.

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 pmNameAll must be made after the creation of a context (see pmNewContext(3)).

PM_ERR_PMID

pmid does not correspond to a defined PMID in the 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.