NAME

       QmcContext - container for a PMAPI context and its metrics

C++ SYNOPSIS

       #include <QmcContext.h>

       CC ... -lqmc -lpcp

DESCRIPTION

       A  QmcContext object is a container for a single PMAPI(3) context.  The object maintains a
       list of all the metric descriptors (QmcDesc),  instance  domains  (QmcIndom)  and  metrics
       (QmcMetric) using the context to minimize the duplication of these objects.

CONSTRUCTORS

       A QmcContext object should be constructed through the QmcGroup::use interface.

DESCRIPTOR LOOKUP

       The  metric  and instance domain descriptors are cached by the QmcContext object to reduce
       duplicate QmcDesc(3) and QmcIndom(3) objects and PMAPI(3) calls required to  create  them.
       Also  the  mapping from metrics names to pmIDs is also maintained to avoid pmLookupName(3)
       calls.

       int lookupDesc(const char *name, pmID& id);
           Search for the metric name in the name list and set id to  the  known  pmID.   If  not
           found, use pmLookupName(3) to get the mapping.  If this call fails, the PMAPI(3) error
           code will be returned.

       int lookupDesc(const char *name, uint_t& desc, uint_t& indom);
           Find the index desc and indom to the QmcDesc object and the QmcIndom  object  for  the
           metric name.  The indexes can then be used with QmcContext::desc and QmcContext::indom
           to obtain references to the real objects.  The methods will return  a  PMAPI(3)  error
           code if the metric descriptor or instance domain could not be obtained.

       int lookupDesc(pmID pmid, uint_t& desc, uint_t& indom);
           Find  the  index  desc and indom to the QmcDesc object and the QmcIndom object for the
           metric pmid.  The indexes can then be used with QmcContext::desc and QmcContext::indom
           to  obtain  references  to the real objects.  The methods will return a PMAPI(3) error
           code if the metric descriptor or instance domain could not be obtained.

SEE ALSO

       PMAPI(3),  QMC(3),  QmcDesc(3),  QmcGroup(3),   QmcIndom(3),   QmcMetric(3),   pmflush(3),
       pmLookupName(3) and pmprintf(3).

DIAGNOSTICS

       Error   messages  are  generated  using  pmprintf(3)  but  are  not  flushed.  It  is  the
       responsibility of the user to call pmflush(3) to output any messages.

       Additional diagnostics may be activated by adding DBG_TRACE_PMC and DBG_TRACE_OPTFETCH  to
       the global pmDebug.