|
HTML rendering created 2025-09-06 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. |
|
|
NAME | C SYNOPSIS | DESCRIPTION | RETURN VALUE | SEE ALSO | COLOPHON |
|
|
|
PMUNPACKEVENTRECORDS(3) Library Functions Manual PMUNPACKEVENTRECORDS(3)
pmUnpackHighResEventRecords, pmUnpackEventRecords - unpack event
records
#include <pcp/pmapi.h>
int pmUnpackHighResEventRecords(pmValueSet *vsp, int idx,
pmResult ***hrap);
int pmUnpackEventRecords(pmValueSet *vsp, int idx,
pmResult_v2 ***rap);
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_HIGHRES_EVENT and a pmResult_v2 when using a metric with a
value of type PM_TYPE_EVENT.
pmUnpackHighResEventRecords and pmUnpackEventRecords 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 pmResult_v2 structures, one per event record and one
metric per event parameter, and hrap or 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 pmResult allows for nanosecond precision, whereas pmRe‐
sult_v2 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 cor‐
responding pmResult/pmResult_v2 will have the flags value en‐
coded 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/pmResult_v2 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.
pmUnpackHighResEventRecords returns the number of pmResult struc‐
tures as the return value, which is >= 0 for success. Similarly,
pmUnpackEventRecords returns the number of pmResult_v2 structures
as the return value, which is >= 0 for success.
hrap and the associated pmResult structures may be freed using the
convenience function pmFreeHighResEventResult(3).
Similarly, rap and the associated pmResult_v2 structures may be
freed using the convenience function pmFreeEventResult(3).
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_HIGHRES_EVENT for
pmUnpackHighResEventRecords or PM_TYPE_EVENT for pmUnpack‐
EventRecords.
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) pmHighResEven‐
tArray/pmEventArray 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_AGGRE‐
GATE_STATIC.
other values < 0
refer to pmErrStr(3).
PMAPI(3) and pmFreeEventResult(3).
This page is part of the PCP (Performance Co-Pilot) project. In‐
formation 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
2025-08-11. (At that time, the date of the most recent commit
that was found in the repository was 2025-08-11.) 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)
|
HTML rendering created 2025-09-06 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. |
|