NAME

       __pmConnectLogger - connect to a performance metrics logger control port

C SYNOPSIS

       #include "pmapi.h"
       #include "libpcp.h"

       int __pmConnectLogger(const char *hostname, int pid);

       cc ... -lpcp

CAVEAT

       This documentation is intended for internal Performance Co-Pilot (PCP) developer use.

       These  interfaces  are  not part of the PCP APIs that are guaranteed to remain fixed across releases, and
       they may not work, or may provide different semantics at some point in the future.

DESCRIPTION

       Each instance of the Performance Co-Pilot (PCP) archive creation program pmlogger(1) supports  a  control
       port  on  which __pmControlLog(3) requests are received, and responses sent.  Optionally, the pmlogger(1)
       instance may be designated the ``primary'' logger.

       __pmConnectLogger may be used to  establish  a  control  port  connection  to  the  pmlogger(1)  instance
       identified by process id pid on the host hostname.

       One special case is supported; for the reserved pid value of PM_LOG_CONTROL_PORT the requested connection
       is to the control port for the ``primary'' logger, whatever its process id might be.

       On success, __pmConnectLogger returns a non-negative integer, that is a file descriptor that may be  used
       in subsequent communication with the pmlogger(1) instance, e.g. for __pmControlLog(3).

       As  the  control  port to pmlogger(1) is not mulitplexed, applications using __pmConnectLogger should use
       close(2) to terminate the connection to pmlogger(1) as soon as they have finished communicating.

       If the application connects, and the pmlogger(1)  instance  subsequently  terminates,  e.g.  because  the
       associated  pmcd(1)  instance  is  terminated,  the  application  will  have  to  explicitly re-establish
       connection to a re-started pmlogger(1) instance by calling __pmConnectLogger again.

DIAGNOSTICS

       PM_ERR_PERMISSION
              no permission to connect to the specified pmlogger(1) instance

       -ECONNREFUSED
              the designated pmlogger(1) instance does not exist

       -EEADDRINUSE
              the requested control port is already in use

SEE ALSO

       pmcd(1), pmlc(1), pmlogger(1), PMAPI(3) and __pmControlLog(3).