'\"macro stdmacro
.\"
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.TH PMGETARCHIVEEND 3 "PCP" "Performance Co-Pilot"
.SH NAME
\f3pmGetArchiveEnd\f1 \- locate logical end of file for an archive log
.SH "C SYNOPSIS"
.ft 3
#include <pcp/pmapi.h>
.sp
int pmGetArchiveEnd(struct timeval *\fItvp\fP);
.sp
cc ... \-lpcp
.ft 1
.SH DESCRIPTION
Assuming the current PMAPI context
is associated with an archive log,
.B 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
.IR tvp .
This timestamp may be passed to
.BR pmSetMode (3)
to reliably position the context at the last valid
log record, e.g. in preparation for subsequent reading in
reverse chronological order. 
.PP
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
.BR 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.
.PP
.B 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.
.PP
In the absence of an error, the result returned via
.I tvp
is well-defined.
.PP
.BR pmGetArchiveEnd
preserves the positioning state of the log file prior to
this function call. 
.SH "PCP ENVIRONMENT"
Environment variables with the prefix
.B PCP_
are used to parameterize the file and directory names
used by PCP.
On each installation, the file
.I /etc/pcp.conf
contains the local values for these variables.
The
.B $PCP_CONF
variable may be used to specify an alternative
configuration file,
as described in
.BR pcp.conf (5).
Values for these variables may be obtained programmatically
using the
.BR pmGetConfig (3)
function.
.SH SEE ALSO
.BR PMAPI (3),
.BR pmFetch (3),
.BR pmFetchArchive (3),
.BR pmGetArchiveLabel (3),
.BR pmGetConfig (3),
.BR pmSetMode (3),
.BR pcp.conf (5)
and
.BR pcp.env (5).
.SH DIAGNOSTICS
.IP \f3PM_ERR_NOCONTEXT\f1
the current PMAPI context
is either invalid, or not associated with an archive log
.IP \f3PM_ERR_LOGREC\f1
the archive is sufficiently damaged, that not a single valid
record can be found