'\"macro stdmacro
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.TH QMCCONTEXT 3 "SGI" "Performance Co-Pilot"
.SH NAME
\f3QmcContext\f1 \- container for a PMAPI context and its metrics
.SH "C++ SYNOPSIS"
.ft 3
#include <QmcContext.h>
.sp
CC ... \-lqmc \-lpcp
.ft 1
.SH DESCRIPTION
A
.B QmcContext
object is a container for a single
.BR PMAPI (3)
context.  The object maintains a list of all the metric descriptors
.RB ( QmcDesc ),
instance domains
.RB ( QmcIndom )
and
metrics
.RB ( QmcMetric )
using the context to minimize the duplication of these objects.
.SH "CONSTRUCTORS"
A
.B QmcContext
object should be constructed through the
.B QmcGroup::use
interface.
.SH "DESCRIPTOR LOOKUP"
The metric and instance domain descriptors are cached by the
.B QmcContext
object to reduce duplicate
.BR QmcDesc (3)
and
.BR QmcIndom (3)
objects and
.BR PMAPI (3)
calls required to create them.  Also the mapping from metrics names to
.BR pmID s
is also maintained to avoid
.BR pmLookupName (3)
calls.
.TP 4
.B "int lookupDesc(const char *name, pmID& id);"
Search for the metric
.I name
in the name list and set
.B id
to the known
.BR pmID .
If not found, use
.BR pmLookupName (3)
to get the mapping.  If this call fails, the
.BR PMAPI (3)
error code will be returned.
.TP
.B "int lookupDesc(const char *name, uint_t& desc, uint_t& indom);"
Find the index
.I desc
and
.I indom
to the
.B QmcDesc
object and the
.B QmcIndom
object for the metric
.IR name .
The indexes can then be used with
.B QmcContext::desc
and
.B QmcContext::indom
to obtain references to the real objects.
The methods will return a
.BR PMAPI (3)
error code if the metric descriptor or instance domain could not be obtained.
.TP
.B "int lookupDesc(pmID pmid, uint_t& desc, uint_t& indom);"
Find the index
.I desc
and
.I indom
to the
.B QmcDesc
object and the
.B QmcIndom
object for the metric
.IR pmid .
The indexes can then be used with
.B QmcContext::desc
and
.B QmcContext::indom
to obtain references to the real objects.
The methods will return a
.BR PMAPI (3)
error code if the metric descriptor or instance domain could not be obtained.
.SH DIAGNOSTICS
Error messages are generated using
.BR pmprintf (3)
but are not flushed. It is the responsibility of the user to call
.BR pmflush (3)
to output any messages.
.PP
Additional diagnostics may be activated by adding the options
.B pmc
and/or
.B optfetch
to the global debugging specification, as described in
.BR pmSetDebug (3).
.SH SEE ALSO
.BR PMAPI (3),
.BR QMC (3),
.BR QmcDesc (3),
.BR QmcGroup (3),
.BR QmcIndom (3),
.BR QmcMetric (3),
.BR pmflush (3),
.BR pmLookupName (3)
and
.BR pmprintf (3).