QmcGroup(3) — Linux manual page


QMCGROUP(3)             Library Functions Manual             QMCGROUP(3)

NAME         top

       QmcGroup - container representing a single fetch group of metrics
       from multiple sources

C++ SYNOPSIS         top

       #include <QmcGroup.h>

       c++ ... -lpcp_qmc -lpcp

DESCRIPTION         top

       A QmcGroup object is a container for contexts and metrics that
       should be fetched at the same time.  The class manages the
       QmcContext(3) objects, timezones and bounds for every context
       created with QmcGroup::use and QmcGroup::addMetric.


           Destructor which destroys all metrics and contexts created by
           this group.

       QmcGroup(bool restrictArchives = false);
           Construct a new fetch group.  restrictArchives will restrict
           the creating of multiple archive contexts created from the
           same host.

CONTEXTS         top

       The default context of the group is defined as the first context
       created with QmcGroup::use before the first call to
       QmcGroup::addMetric.  If no context is created before the first
       metric is added, the localhost is used as the default context.
       Therefore, if any metrics specifications contain archive sources,
       an archive source must have been created with QmcGroup::use to
       avoid an error for mixing context types.

       uint_t numContexts() const;
           The number of valid contexts created in this group.

       QmcContext const& context(uint_t index) const
           Return a handle to a context.

       QmcContext& context(uint_t index);
           Return a modifiable handle to a context.

       int mode() const;
           Return the type of context, either PM_CONTEXT_LOCAL,

       QmcContext* which() const;
           Return a handle to the current context of this group. This
           does not call pmUseContext(3) so it may not be the current
           PMAPI(3) context.

       uint_t contextIndex() const
           The index to the current group context.

       int use(int type, char const* source);
           Use the context of type from source.  If a context to this
           source already exists in this group, that context will become
           the current PMAPI(3) context.  Otherwise a new context will
           be created.  The result is the PMAPI(3) context handle for
           the QmcGroup::context or a PMAPI(3) error code if the context

       bool defaultDefined() const;
           Returns true if a default context has been determined.

       int useDefault();
           Use the default context. If a default context has not been
           created, the context to the local host will be attempted.  A
           result less than zero indicates that the method failed with
           the PMAPI(3) error encoded in the result.

       void createLocalContext();
           Create and use a context to the local host.  A result less
           than zero indicates that the method failed with the PMAPI(3)
           error encoded in the result.

METRICS         top

       These addMetric methods should be used to create new metrics as
       the QmcMetric constructors are private. These methods will always
       return a pointer to a QmcMetric object, however the
       QmcMetric::status() field should be checked to ensure the metric
       is valid.

       QmcMetric* addMetric(char const* str, double theScale = 0.0,
           bool active = false);

           Add the metric str to the group, with a scaling factor of
           scale.  If active is set the metric will use only active
           instances (see QmcMetric(3)).

       QmcMetric* addMetric(pmMetricSpec* theMetric, double theScale
           = 0.0, bool active);

           Add the metric theMetric to the group, with a scaling factor
           of scale.  If active is set the metric will use only active
           instances (see QmcMetric(3)).

       int fetch(bool update = true);
           Fetch all the metrics in all the contexts in this group.  If
           update is equal to true, all counter metrics will be
           automatically converted to rates (see QmcMetric(3)).

       int setArchiveMode(int mode, const struct timeval *when,
           int interval);

           Set the mode and time to access all archive contexts in this
           group.  See pmSetMode(3) for more details.

TIMEZONES         top

       These methods assist in the management of multiple timezones and
       help to control the current timezone.

       enum TimeZoneFlag { localTZ, userTZ, groupTZ, unknownTZ };
           Enumeration used to describe the origin of the default
           timezone.  localTZ, userTZ and groupTZ indicate that the
           timezone was set with QmcGroup::useLocalTZ,
           QmcGroup::useTZ(QString const&) and QmcGroup::useTZ()
           respectively.  unknownTZ indicates that a timezone has not
           been set.  userTZ indicates that the timezone was

       int useTZ();
           Use the timezone of the current group context as the default.

       int useTZ(const QString &tz);
           Add and use tz as the default timezone of this group.

       int useLocalTZ();
           Use the timezone of the localhost as the default for this

       void defaultTZ(QString &label, QString &tz);
           Return the label and tz string of the default timezone of
           this group.

       TimeZoneFlag defaultTZ() const
           Return the origin of the default timezone.

       int useDefaultTZ();
           Set the timezone to be the default timezone as defined in a
           previous call to QmcGroup::useTZ or QmcGroup::useLocalTZ.

       struct timeval const& logStart() const;
           Return the earliest starting time of any archives in this
           group.  Assumes that QmcGroup::updateBounds has been called.

       struct timeval const& logEnd() const;
           Return the latest finish time of any archives in this group.
           Assumes that QmcGroup::updateBounds has been called.

       void updateBounds();
           Determine the earliest start and latest finish times of all
           archives in this group.

DEBUGGING         top

       void dump(ostream &os);
           Dump state information about this group to os.

DIAGNOSTICS         top

       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

SEE ALSO         top

       PMAPI(3), QMC(3), QmcContext(3), QmcMetric(3), pmflush(3),
       pmprintf(3) and pmSetMode(3).

COLOPHON         top

       This page is part of the PCP (Performance Co-Pilot) project.
       Information about the project can be found at 
       ⟨http://www.pcp.io/⟩.  If you have a bug report for this manual
       page, send it to pcp@groups.io.  This page was obtained from the
       project's upstream Git repository
       ⟨https://github.com/performancecopilot/pcp.git⟩ on 2024-06-14.
       (At that time, the date of the most recent commit that was found
       in the repository was 2024-06-14.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
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       (which is not part of the original manual page), send a mail to

Performance Co-Pilot               SGI                       QMCGROUP(3)

Pages that refer to this page: QMC(3)QmcContext(3)QmcMetric(3)QmcSource(3)