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