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pmgetarchivelabel(3)

NAME

   pmGetArchiveLabel  -  fetch  the label record from a set of performance
   metrics archive logs

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  a  set  of  archive  logs  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 a set of archive logs



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