plucky (3) pmUnpackHighResEventRecords.3.gz

NAME

       pmUnpackEventRecords, pmUnpackHighResEventRecords - unpack event records

C SYNOPSIS

       #include <pcp/pmapi.h>

       int pmUnpackEventRecords(pmValueSet *vsp, int idx, pmResult ***rap);

       int pmUnpackHighResEventRecords(pmValueSet *vsp, int idx, pmHighResResult ***hrap);

       cc ... -lpcp

DESCRIPTION

       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.

RETURN VALUE

       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).

SEE ALSO

       PMAPI(3) and pmFreeEventResult(3).