NAME¶
pmGetArchiveLabel - fetch the label record from a performance metrics
archive log
C SYNOPSIS¶
#include <pcp/pmapi.h>
int pmGetArchiveLabel(pmLogLabel *
lp);
cc ... -lpcp
DESCRIPTION¶
Within the framework of the Performance Co-Pilot (PCP), archive logs of
performance metrics values may be accumulated and saved using the program
pmlogger(1).
The routine
pmGetArchiveLabel may be used to fetch the label record from
an archive log that has already been opened using
pmNewContext(3), or
pmDupContext(3), and thereby associated with the current Performance
Metrics Application Programming Interface (PMAPI) context.
The result returned via the pointer
lp is a structure that must be
pre-allocated by the caller and has the following format (defined in
pmapi.h).
/*
* Label Record at the start of every log file
*/
typedef struct {
int ll_magic; /* PM_LOG_MAGIC | log format version no. */
pid_t ll_pid; /* PID of logger */
struct timeval ll_start;/* start of this log */
char ll_hostname[PM_LOG_MAXHOSTLEN]; /* name of collection host */
char ll_tz[40]; /* $TZ at collection host */
} pmLogLabel;
For an application, the most useful information from the archive label is likely
to be in the fields
ll_start,
ll_hostname or
ll_tz.
Note that the size of the
ll_hostname field is
PM_LOG_MAXHOSTLEN
(64 bytes) which is less than
MAXHOSTNAMELEN (see
gethostbyname(3)) on some platforms. These semantics are necessary to
retain backwards compatibility with the PCP archive file format.
pmGetArchiveLabel returns zero for success.
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¶
pmlogger(1),
PMAPI(3),
pmDupContext(3),
pmGetConfig(3),
pmNewContext(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