NAME

       QmcMetric - container for a metric and all its values

C++ SYNOPSIS

       #include <pcp/pmc/Metric.h>

       c++ ... -lpcp_qmc -lpcp

DESCRIPTION

       A QmcMetric object is a container for a single metric and all its values.

       The  QmcMetricValue structure is used to hold the instance index, values and errors of each instance.  In
       the case of a singular metric, a single QmcMetricValue object is used.

       A QmcMetric object consists of a list of QmcMetricValue  objects,  indexes  to  the  descriptors  in  the
       metric's  QmcGroup and QmcContext and flags to indicate if the instances are explicit or implicit, and if
       only active metrics are required after QmcMetric::updateIndom is called.

CONSTRUCTORS

       Metrics should be constructed through the QmcGroup::addMetric  methods  as  this  will  ensure  that  the
       references to the metric's context, descriptor and instance domain are correctly initialized.

INSTANCES

       For  metrics  with  an instance domain it is possible to add and remove any instance, and also update the
       instance list to reflect changes in a dynamic instance domain.

       bool updateIndom();
           Update the metric to include new instances.  This method will first call QmcContext::update to update
           the instance domain.  If the active flag is set in the QmcGroup::addMetric call, only instances  will
           exported by the metric, otherwise the metric will export all instances listed in the domain.

           The  ordering  of instances may change as a result of this call.  Instances that already existed will
           keep their current and previous values and errors, even if they are in a different order.

       int addInst(QString const& name);
           Add the instance name to the metric.  If the instance does  not  exist  in  the  instance  domain,  a
           PMAPI(3)  error  will  be  returned.   This  method  ignores  the value of the active flag set in the
           QmcMetric constructor.

       void removeInst(uint_t index);
           Remove the instance at position index from the metric.

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 the option pmc to the global debugging specification,
       as described in pmSetDebug(3).

SEE ALSO

       PMAPI(3), QMC(3), QmcContext(3), QmcGroup(3), pmflush(3) and pmprintf(3).

Performance Co-Pilot                                   SGI                                          QMCMETRIC(3)