NAME

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

C SYNOPSIS

       #include <pcp/pmapi.h>

       int pmGetArchiveLabel(pmLogLabel *lp);
       int pmGetHighResArchiveLabel(pmHighResLogLabel *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) and the
       LOGIMPORT(3) programming interface.

       The routines pmGetArchiveLabel and pmGetHighResArchiveLabel 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.

       It  is  recommended  that  new  applications  use  the  high  resolution  API and existing
       applications transition to this interface over time.

       The result returned via the pointer lp is a structure that must be  pre-allocated  by  the
       caller and has one of the following two formats (defined in pmapi.h).

         typedef struct {
           int        magic;       /* PM_LOG_MAGIC | log format version no. */
           pid_t      pid;         /* PID of logger */
           struct timespec start;  /* start of this log */
           char       hostname[PM_MAX_HOSTNAMELEN];   /* collection host full name */
           char       timezone[PM_MAX_TIMEZONELEN];   /* generic, squashed $TZ */
           char       zoneinfo[PM_MAX_ZONEINFOLEN];   /* local platform $TZ */
         } pmHighResLogLabel;

         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;

       Both  forms  can  be  used  with either version 2 or version 3 archive logs.  However, the
       pmHighResLogLabel structure provides the higher resolution start time stored in the  newer
       format,  as  well as the full timezone and extended length host name fields.  For detailed
       information about the log archive on-disk format, refer to LOGARCHIVE(5).

       For an application using pmGetHighResArchiveLabel, the most useful  information  from  the
       archive label is likely to be in the fields start, hostname, timezone, and zoneinfo.

       The  zoneinfo  field contains the most detailed timezone information available, and should
       be used if present (non-zero length string).  It will only not be present in the  case  of
       version  2  archives  -  this  is  a new field added as part of the version 3 format.  The
       timezone field will always be present, however it is the 'squashed' timezone value and  in
       certain situations is not the most accurate timezone.

       For  older  applications  using  pmGetArchiveLabel,  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.

       Both pmGetArchiveLabel and pmGetHighResArchiveLabel return zero for success.

DIAGNOSTICS

       PM_ERR_NOCONTEXT
              the  current  PMAPI  context  is  either  invalid,  or not associated with a set of
              archive logs

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), LOGIMPORT(3),  PMAPI(3),  pmDupContext(3),  pmGetConfig(3),  pmNewContext(3),
       LOGARCHIVE(5), pcp.conf(5) and pcp.env(5).