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NAME | C SYNOPSIS | DESCRIPTION | RETURN VALUE | SEE ALSO | COLOPHON |
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PMUNPACKEVENTRECORDS(3) Library Functions Manual PMUNPACKEVENTRECORDS(3)
pmUnpackEventRecords, pmUnpackHighResEventRecords - unpack event
records
#include <pcp/pmapi.h>
int pmUnpackEventRecords(pmValueSet *vsp, int idx, pmResult
***rap);
int pmUnpackHighResEventRecords(pmValueSet *vsp, int idx,
pmHighResResult ***hrap);
cc ... -lpcp
Event records are encoded as a packed array of records within a
pmResult using a container metric with a value of type
PM_TYPE_EVENT , and a pmHighResResult when using a metric of type
PM_TYPE_HIGHRES_EVENT.
pmUnpackEventRecords and pmUnpackHighResEventRecords may be used
to unpack event records from a metric value identified by vsp and
idx. If the metric has a singular value, idx should be 0, else
the ordinal instance value identified by idx will be unpacked,
i.e. vsp->vlist[idx]. The unpacked records are turned into
either pmResult or pmHighResResult structures, one per event
record and one metric per event parameter, and rap is returned as
a pointer to an array (NULL pointer terminated) of pointers to
the result structures.
The only difference between the two result types is the timestamp
scale; the pmHighResResult allows for nanosecond precision,
whereas pmResult allows for microsecond resolution.
Some control information from the packed event records is
unpacked into additional ``anonymous'' metrics as follows:
1. If the event record has a non-zero flags value, then the
corresponding pmResult/pmHighResResult will have the flags
value encoded with the additional metric event.flags that is
inserted ahead of all other event parameters.
2. If the event record flag is set to PM_EVENT_FLAG_MISSED, then
the corresponding pmResult/pmHighResResult will have one
metric event.missed with a value that equals the number of
event records ``missed'' because either the PMDA could not
keep up, or the PMAPI client did not collect the event
records fast enough.
pmUnpackEventRecords returns the number of pmResult structures as
the return value, which is >= 0 for success. Similarly,
pmUnpackHighResEventRecords returns the number of pmHighResResult
structures as the return value, which is >= 0 for success.
rap and the associated pmResult structures may be freed using the
convenience function pmFreeEventResult(3).
Similarly, the hrap and the associated pmHighResResult structures
may be freed using the convenience function
pmFreeHighResEventResult.
The following errors are possible:
PM_ERR_CONV
The values associated with vsp are not encoded using the
format PM_VAL_DPTR or PM_VAL_SPTR, or the flags at the
head of the event record has an unexpected value.
PM_ERR_INST
The value associated with vsp is not singular as expected.
PM_ERR_TYPE
vsp is not a value of type PM_TYPE_EVENT.
PM_ERR_TOOSMALL
The value identified by vsp is not legal because the value
length is less than the minimum size, or the number of
event records encoded in the (value header)
pmEventArray/pmHighResEventArray structure is negative, or
the number of missed event records in the array is
negative.
PM_ERR_TOOBIG
Either vsp indicates more than one value is present (all
the event records are expected to be packed in a single
metric value), or when unpacking the event records, the
processing continues past the end of the enclosing value.
Indicates corruption of the packed event record.
PM_ERR_TYPE
Event parameters must have one of the arithmetic types,
else PM_TYPE_AGGREGATE, PM_TYPE_STRING or
PM_TYPE_AGGREGATE_STATIC.
other values < 0
refer to pmErrStr(3).
PMAPI(3) and pmFreeEventResult(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
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 2024-06-14.
(At that time, the date of the most recent commit that was found
in the repository was 2024-06-14.) 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 PCP PMUNPACKEVENTRECORDS(3)
Pages that refer to this page: pmextractvalue(3), pmfreeeventresult(3)
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HTML rendering created 2024-06-26 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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