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NAME | C SYNOPSIS | DESCRIPTION | EXAMPLES | BUGS | RETURN VALUE | SEE ALSO | COLOPHON |
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PMPARSEUNITSSTR(3) Library Functions Manual PMPARSEUNITSSTR(3)
pmParseUnitsStr - parse units specification
#include <pcp/pmapi.h>
int pmParseUnitsStr(const char *string, struct pmUnits *out,
double *outMult, char **errMsg);
cc ... -lpcp
pmParseUnitsStr is designed to encapsulate the interpretation of
a units (dimension and scale) specification in command line
switches for use by the PCP client tools.
This function expects to be called with the unit/scale
specification as string. This specification takes the general
form produced by pmUnitsStr(3). Briefly, the format allows
/-separated divisor and dividend, each listing space-separated
dimensions/scales along the space, time, and count axes. There
are also a few extra possibilities:
First, multiple equivalent sets of keywords are accepted for the
time and space dimensions, insensitive to case. For example,
"microseconds", "microsecond", "microsec", "us" are considered
synonymous, as are "kilobytes", "KB", "KiB", "kiloByte", and so
on.
Second, units may be offered in any order, e.g., ms kb count x
10^3 or count x 10^3 kb ms. They may not be repeated within the
denominator or within the numerator. Each scale/unit keyword may
be immediately followed by positive or negative exponents, e.g.,
^-4.
Third, numerical scaling factors may be supplied. These are
factored together with implicit scale conversions into the final
outMult result.
The out and outMult values must both be allocated before calling
pmParseUnitsStr(3). If the conversion is successful,
pmParseUnitsStr returns 0, and fills in out and outMult with the
unit/scales defined by the input parameter. If the argument
strings could not be parsed, it returns a negative status code.
┌──────────────────────────────────┬────────────────┬─────────┐
│ string │ out │ outMult │
├──────────────────────────────────┼────────────────┼─────────┤
│2 count │ {0,1,0,0,0,0} │ 0.5 │
│count / 7.5 nanosecond │ {0,1,-1,0,0,0} │ 7.5 │
│10 kilobytes / 2.5e2 count x 10^3 │ {1,-1,0,1,3,0} │ 25 │
│millisecond / second^2 │ {0,0,-1,0,0,3} │ 1000 │
│mib/s │ {1,0,-1,2,0,3} │ 1 │
└──────────────────────────────────┴────────────────┴─────────┘
For backward compatibility, this interface interprets several
traditional computer science interpretations of space units
incorrectly by the International System of Units (SI) standard.
The accepted unit string - in either singular or plural form -
and the pmParseUnitsStr interpretation for each are:
megabyte(mebibyte), gigabyte(gibibyte), terabyte(tebibyte),
petabyte(pebibyte), exabyte(exbibyte), zettabyte(zebibyte) and
yottabyte(yobibyte).
A zero status indicates success. A negative status indicates an
error, in which case the errMsg pointer will contain a textual
error message, which the caller should later free(3).
PMAPI(3), pmUnitsStr(3), pmConvScale(3), and pmLookupDesc(3).
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
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project's upstream Git repository
⟨https://github.com/performancecopilot/pcp.git⟩ on 2020-12-18.
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Performance Co-Pilot PCP PMPARSEUNITSSTR(3)
Pages that refer to this page: pcp2elasticsearch(1), pcp2graphite(1), pcp2influxdb(1), pcp2json(1), pcp2spark(1), pcp2template(1), pcp2xlsx(1), pcp2xml(1), pcp2zabbix(1), pmdaopenmetrics(1), pmrep(1), pmfetchgroup(3), pmparseunitsstr(3), pmregisterderived(3)
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