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
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:
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.
The value associated with vsp is not singular as expected.
vsp is not a value of type PM_TYPE_EVENT.
The value identified by vbp 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/pmEventHighResArray structure is negative, or
the number of missed event records in the array is
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.
Event parameters must have one of the arithmetic types,
else PM_TYPE_AGGREGATE, PM_TYPE_STRING or
other values < 0
refer to pmErrStr(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
email@example.com. This page was obtained from the project's upstream
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you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
Performance Co-Pilot PCP PMUNPACKEVENTRECORDS(3)