'\"macro stdmacro
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.TH PMUNITSSTR 3 "PCP" "Performance Co-Pilot"
.SH NAME
\f3pmUnitsStr\f1,
\f3pmUnitsStr_r \- convert a performance metric's units into a string
.SH "C SYNOPSIS"
.ft 3
#include <pcp/pmapi.h>
.sp
const char *pmUnitsStr(const pmUnits *\fIpu\fP);
.br
char *pmUnitsStr_r(const pmUnits *\fIpu\fP, char *\fIbuf\fP, int \fIbuflen\fP);
.sp
cc ... \-lpcp
.ft 1
.SH DESCRIPTION
.de CW
.ie t \f(CW\\$1\f1\\$2
.el \fI\\$1\f1\\$2
..
The encoding of a performance metric's dimensionality and scale uses
a
.CW pmUnits
structure; see
.BR pmLookupDesc (3).
.PP
As an aid to labeling graphs and tables, or for error messages,
.B pmUnitsStr
will take a dimension and scale specification as per
.IR pu ,
and return the
corresponding text string.
The
.B pmUnitsStr_r
function does the same, but stores the result in a user-supplied buffer
.I buf
of length
.IR buflen ,
which should have room for at least 60 bytes.
.PP
For example
.CW "{1, -2, 0, PM_SPACE_MBYTE, PM_TIME_SEC, 0}" , 
as the value of
.I *pu
gives the result string
.CW "Mbyte / sec^2" .
.PP
The string value result from
.B pmUnitsStr
is held in a single static buffer, so the returned value is
only valid until the next call to
.BR pmUnitsStr .
.PP
If the ``count'' dimension is non-zero, and the ``count'' scale is not
zero, then the text string will
include a decimal scaling factor, eg.
.CW "count x 10^6" .
.PP
As a special case, if all components of the dimension are zero, then the
``count'' scale is used to produce the text.  If this scale is zero the
result is an empty string, otherwise the result is of the form
.CW "x1 0^2" .
.SH NOTES
.B pmUnitsStr
returns a pointer to a static buffer and hence is not thread-safe.
Multi-threaded applications should use
.B pmUnitsStr_r
instead.
.SH SEE ALSO
.BR PMAPI (3),
.BR pmAtomStr (3),
.BR pmConvScale (3),
.BR pmExtractValue (3),
.BR pmLookupDesc (3),
.BR pmPrintValue (3)
and
.BR pmTypeStr (3).