'\"macro stdmacro
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.TH PMGETARCHIVEEND 3 "PCP" "Performance Co-Pilot"
.SH NAME
\f3pmGetArchiveEnd\f1,
\f3pmGetHighResArchiveEnd\f1 \- locate logical end of file for a set of archives
.SH "C SYNOPSIS"
.ft 3
#include <pcp/pmapi.h>
.sp
.nf
int pmGetArchiveEnd(struct timeval *\fItp\fP);
.br
int pmGetHighResArchiveEnd(struct timespec *\fItp\fP);
.fi
.sp
cc ... \-lpcp
.ft 1
.SH DESCRIPTION
Assuming the current PMAPI context
is associated with a set of archives,
.B pmGetArchiveEnd
and
.B 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
.IR tp .
This timestamp may be passed to
.BR pmSetMode (3)
or
.BR pmSetHighResMode (3)
to reliably position the context at the last valid
archive record, e.g. in preparation for subsequent reading in
reverse chronological order.
.PP
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
.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
and
.B 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.
.PP
In the absence of an error, the result returned via
.I tp
is well-defined.
.PP
Both
.BR pmGetArchiveEnd
and
.BR pmGetHighResArchiveEnd
preserve the positioning state of the archive file prior to
this function call.
.SH DIAGNOSTICS
.IP \f3PM_ERR_NOCONTEXT\f1
the current PMAPI context
is either invalid, or not associated with a set of archives
.IP \f3PM_ERR_LOGREC\f1
the set of archives is sufficiently damaged, that not a single valid
record can be found
.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 pmGetHighResArchiveLabel (3),
.BR pmFetchHighRes (3),
.BR pmFetchHighResArchive (3),
.BR pmSetModeHighRes (3),
.BR pmSetMode (3),
.BR pcp.conf (5)
and
.BR pcp.env (5).