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.