NAME
pmGetArchiveEnd - locate logical end of file for an archive log
C SYNOPSIS
#include <pcp/pmapi.h>
int pmGetArchiveEnd(struct timeval *tvp);
cc ... -lpcp
DESCRIPTION
Assuming the current PMAPI context is associated with an archive log,
pmGetArchiveEnd will attempt to find the logical end of file (after the
last complete record in the archive), and return the last recorded
timestamp via tvp. This timestamp may be passed to pmSetMode(3) to
reliably position the context at the last valid log record, e.g. in
preparation for subsequent reading in reverse chronological order.
For archive logs that are not concurrently being written, the physical
end of file and the logical end of file are co-incident. However if an
archive log 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 returns an error less than zero if the context is
neither valid, nor associated with an archive, or the archive 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 tvp is well-
defined.
pmGetArchiveEnd preserves the positioning state of the log file prior
to this function call.
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(4). Values for these variables may be
obtained programatically using the pmGetConfig(3) function.
SEE ALSO
PMAPI(3), pmFetch(3), pmFetchArchive(3), pmGetArchiveLabel(3),
pmGetConfig(3), pmSetMode(3), pcp.conf(4) and pcp.env(4).
DIAGNOSTICS
PM_ERR_NOCONTEXT
the current PMAPI context is either invalid, or not associated
with an archive log
PM_ERR_LOGREC
the archive is sufficiently damaged, that not a single valid
record can be found