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NAME

       pmStore,  pmRequestStore, pmReceiveStore - modify values of performance
       metrics

C SYNOPSIS

       #include <pcp/pmapi.h>

       int pmStore(const pmResult *result)
       int pmRequestStore(int ctx, const pmResult *result)
       int pmReceiveStore(int ctx)

       cc ... -lpcp

DESCRIPTION

       In some special cases it may be helpful to modify the current values of
       performance  metrics,  e.g.  to reset a counter to zero, or to modify a
       ‘‘metric’’ which is  a  control  variable  for  some  agent  collecting
       performance metrics.

       The routine pmStore is a lightweight inverse of pmFetch(3).

       The  caller  must  build  the  pmResult data structure (of course, this
       could have been returned from an earlier pmFetch(3) call) and then call
       pmStore.

       It  is  an error to pass a request to pmStore in which the numval field
       within any of the pmValueSet structure has a value less than one.

       The  current  Performance  Metrics  Application  Programming  Interface
       (PMAPI)  context  must be one with a host as the source of metrics, and
       the current value of  the  nominated  metrics  will  be  changed,  i.e.
       pmStore  cannot be used to make retrospective changes to information in
       either the archive logs, or in the recent past for real-time sources of
       metrics.

       The return code from pmStore is zero for success.

       pmRequestStore  and  pmReceiveStore are used by applications which must
       communicate with the PMCD asynchronously.  These functions take explict
       context  handle ctx which must refer to a host context (i.e. created by
       passing PM_CONTEXT_HOST to pmNewContext). pmRequestStore sends  request
       to  store data in result in the metrics and returns without waiting for
       the response, pmReceiveStore reads confirmation from PMCD.  It  is  the
       responsibility  of  the  application  to  make  sure the data are ready
       before calling pmReceiveStore to avoid blocking.

SEE ALSO

       PMAPI(3), pmFetch(3) and pmSetMode(3).

DIAGNOSTICS

       PM_ERR_GENERIC
              At least one of the modifications was rejected.  No other status
              is  available from below the PMAPI (this is the lightweight part
              of the functionality!).  In cases where the outcome  of  pmStore
              for  individual metrics is important, the caller should make one
              call to pmStore for each metric.  On  the  other  hand,  a  bulk
              modification  can  be  performed  in  a  single pmStore call for
              situations in which the outcome is not critical.

       PM_ERR_NOTHOST
              The current PMAPI context is an archive rather than a  host,  or
              it  is a host that is not set to the current time, i.e. has been
              ‘‘rewound’’ to the recent past using pmSetMode(3).

       PM_ERR_TOOSMALL
              The number of metrics specified in result is less than one.

       PM_ERR_VALUE
              One or more of the pmValueSets in result has a numval field with
              a value less than one.

       PM_ERR_CTXBUSY
              Context is currently in use by another asynchronous call.