pmUnpackHighResEventRecords - Man Page

#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 pmResult_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 corresponding pmResult/pmResult_v2 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/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 structures 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 pmUnpackEventRecords.

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) pmHighResEventArray/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_AGGREGATE_STATIC.

other values < 0

refer to pmErrStr(3).

PMAPI(3) and pmFreeEventResult(3).

pmFreeHighResEventResult(3).

The man page pmUnpackEventRecords(3) is an alias of pmUnpackHighResEventRecords(3).