1QMC_METRIC(3)              Library Functions Manual              QMC_METRIC(3)
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NAME

6       QmcMetric - container for a metric and all its values
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C++ SYNOPSIS

9       #include <pcp/pmc/Metric.h>
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11       CC ... -lpcp_pmc -lpcp
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DESCRIPTION

14       A  QmcMetric object is a container for a single metric and all its val‐
15       ues.
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17       The QmcMetricValue structure is used to hold the instance index, values
18       and  errors of each instance.  In the case of a singular metric, a sin‐
19       gle QmcMetricValue object is used.
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21       A QmcMetric object  consists  of  a  list  of  QmcMetricValue  objects,
22       indexes  to the descriptors in the metric's QmcGroup and QmcContext and
23       flags to indicate if the instances are explicit  or  implicit,  and  if
24       only  active  metrics  are  required  after  QmcMetric::updateIndom  is
25       called.
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CONSTRUCTORS

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

33       For metrics with an instance domain it is possible to  add  and  remove
34       any instance, and also update the instance list to reflect changes in a
35       dynamic instance domain.
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37       bool updateIndom();
38           Update the metric to include new instances.  This method will first
39           call  QmcContext::update  to  update  the  instance domain.  If the
40           active flag is set in the QmcGroup::addMetric call, only  instances
41           will  exported  by the metric, otherwise the metric will export all
42           instances listed in the domain.
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44           The ordering of instances may change as  a  result  of  this  call.
45           Instances that already existed will keep their current and previous
46           values and errors, even if they are in a different order.
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48       int addInst(QString const& name);
49           Add the instance name to the metric.   If  the  instance  does  not
50           exist  in  the  instance domain, a PMAPI(3) error will be returned.
51           This method ignores the value of the active flag set in the QmcMet‐
52           ric constructor.
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54       void removeInst(uint_t index);
55           Remove the instance at position index from the metric.
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SEE ALSO

58       PMAPI(3),   QMC(3),   QMC_Context(3),   QMC_Group(3),   pmflush(3)  and
59       pmprintf(3).
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DIAGNOSTICS

62       Error messages are generated using pmprintf(3) but are not flushed.  It
63       is the responsibility of the user to call pmflush(3) to output any mes‐
64       sages.
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66       Additional diagnostics may be activated by adding DBG_TRACE_PMC to  the
67       global pmDebug.
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