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pmLookupName

NAME

pmLookupName, pmRequestNames, pmReceiveNames - translate performance metric names into PMIDs

C SYNOPSIS

#include <pcp/pmapi.h>

 int pmLookupName(int numpmid, char **namelist, pmID *pmidlist)
 int pmRequestNames(int ctx, int numpmid, char **namelist)
 int pmReceiveNames(int ctx, pmID *pmidlist)
 

cc ... -lpcp

DESCRIPTION

Given a list in namelist containing numpmid full pathnames for performance metrics from a Performance Metrics Name Space (PMNS), pmLookupName returns the list of associated Performance Metric Identifiers (PMIDs) via pmidlist.

The result from pmLookupName will be the number of names translated in the absence of errors, else an error code less than zero. When errors are encountered, the corresponding value in pmidlist will be PM_ID_NULL.

Note that the error protocol guarantees there is a 1:1 relationship between the elements of namelist and pmidlist, hence both lists contain exactly numpmid elements. For this reason, the caller is expected to have pre-allocated a suitably sized array for pmidlist.

pmRequestNames and pmReceiveNames 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). pmRequestNames sends request to translate names to PMIDs to PMCD and returns without waiting for the response, pmReceiveNames reads reply from PMCD. It is the responsibility of the application to make sure the data are ready before calling pmReceiveNames to avoid blocking.

SEE ALSO

PMAPI(3), pmGetChildren(3), pmGetChildrenStatus(3), pmGetConfig(3), pmLoadNameSpace(3), pmNameID(3), pmNewContext(3), pcp.conf(4) and pcp.env(4).

DIAGNOSTICS

PM_ERR_TOOSMALL

numpmid must be at least 1

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

PM_ERR_NAME

One or more of the elements of namelist does not correspond to a valid metric name in the PMNS.

PM_ERR_NONLEAF

A name referred to a node in the PMNS but it was not a leaf node.

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.