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(5). Values for these variables may be
obtained programmatically using the
pmGetConfig(3) function.
SEE ALSO¶
PMAPI(3),
pmFetch(3),
pmFetchArchive(3),
pmGetArchiveLabel(3),
pmGetConfig(3),
pmSetMode(3),
pcp.conf(5) and
pcp.env(5).
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
