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NAME | C++ SYNOPSIS | DESCRIPTION | CONSTRUCTORS & DESTRUCTOR | CONTEXTS | METRICS | TIMEZONES | DEBUGGING | DIAGNOSTICS | SEE ALSO | COLOPHON |
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QMCGROUP(3) Library Functions Manual QMCGROUP(3)
QmcGroup - container representing a single fetch group of metrics
from multiple sources
#include <QmcGroup.h>
c++ ... -lpcp_qmc -lpcp
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 cre‐
ated with QmcGroup::use and QmcGroup::addMetric.
~QmcGroup();
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.
The default context of the group is defined as the first context
created with QmcGroup::use before the first call to QmcGroup::add‐
Metric. 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, PM_CON‐
TEXT_HOST or PM_CONTEXT_ARCHIVE.
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
failed.
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.
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 QmcMet‐
ric::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 in‐
stances (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 automati‐
cally 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.
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 time‐
zone. localTZ, userTZ and groupTZ indicate that the timezone
was set with QmcGroup::useLocalTZ, QmcGroup::useTZ(QString
const&) and QmcGroup::useTZ() respectively. unknownTZ indi‐
cates 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
group.
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.
void dump(ostream &os);
Dump state information about this group to os.
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).
PMAPI(3), QMC(3), QmcContext(3), QmcMetric(3), pmflush(3),
pmprintf(3) and pmSetMode(3).
This page is part of the PCP (Performance Co-Pilot) project. In‐
formation 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
2025-08-11. (At that time, the date of the most recent commit
that was found in the repository was 2025-08-11.) 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 corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a
mail to man-pages@man7.org
Performance Co-Pilot SGI QMCGROUP(3)
Pages that refer to this page: QMC(3), QmcContext(3), QmcMetric(3), QmcSource(3)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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