plucky (3) pmGetHighResArchiveEnd.3.gz

NAME

       pmGetArchiveEnd, pmGetHighResArchiveEnd - locate logical end of file for a set of archives

C SYNOPSIS

       #include <pcp/pmapi.h>

       int pmGetArchiveEnd(struct timeval *tp);
       int pmGetHighResArchiveEnd(struct timespec *tp);

       cc ... -lpcp

DESCRIPTION

       Assuming  the  current  PMAPI  context  is  associated  with  a  set  of  archives,  pmGetArchiveEnd  and
       pmGetHighResArchiveEnd will attempt to find the logical end of file (after the last  complete  record  in
       the  set  of  archives),  and return the last recorded timestamp via tp.  This timestamp may be passed to
       pmSetMode(3) or pmSetModeHighRes(3) to reliably position the context at the last  valid  archive  record,
       e.g. in preparation for subsequent reading in reverse chronological order.

       For  archives  that  are  not concurrently being written, the physical end of file and the logical end of
       file are co-incident.  However if an archive is  being  written  by  pmlogger(1)  at  the  same  time  an
       application is trying to read the archive, the logical end of file may be before the physical end of file
       due to write buffering that is not aligned with the logical record boundaries.

       pmGetArchiveEnd and pmGetHighResArchiveEnd return an error less than  zero  if  the  context  is  neither
       valid,  nor associated with a set of archives, or the set of archives is seriously corrupted.  Otherwise,
       the return value is 0 if there has been no change of state since the last call, or 1 if the  logical  end
       of file has advanced since the last call.

       In the absence of an error, the result returned via tp is well-defined.

       Both  pmGetArchiveEnd and pmGetHighResArchiveEnd preserve the positioning state of the archive file prior
       to this function call.

DIAGNOSTICS

       PM_ERR_NOCONTEXT
              the current PMAPI context is either invalid, or not associated with a set of archives

       PM_ERR_LOGREC
              the set of archives is sufficiently damaged, that not a single valid record can be found

PCP ENVIRONMENT

       Environment variables with the prefix PCP_ are used to parameterize the file and directory names used  by
       PCP.   On  each  installation, the file /etc/pcp.conf contains the local values for these variables.  The
       $PCP_CONF variable may be used to specify an alternative configuration file, as described in pcp.conf(5).
       Values for these variables may be obtained programmatically using the pmGetConfig(3) function.

SEE ALSO

       PMAPI(3),      pmFetch(3),      pmFetchArchive(3),      pmFetchHighRes(3),      pmFetchHighResArchive(3),
       pmGetArchiveLabel(3),  pmGetConfig(3),  pmGetHighResArchiveLabel(3),  pmSetMode(3),  pmSetModeHighRes(3),
       pcp.conf(5) and pcp.env(5).