__pmconnectlogger(3) — Linux manual page

NAME | C SYNOPSIS | CAVEAT | DESCRIPTION | DIAGNOSTICS | SEE ALSO | COLOPHON

PMCONNECTLOGGER(3)       Library Functions Manual      PMCONNECTLOGGER(3)

NAME         top

       __pmConnectLogger - connect to a performance metrics logger
       control port

C SYNOPSIS         top

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

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

       cc ... -lpcp

CAVEAT         top

       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         top

       Each instance of the Performance Co-Pilot (PCP)  archive  creation
       program  pmlogger(1) supports a control port on which __pmControl‐
       Log(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  connec‐
       tion  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_PRIMARY_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 multiplexed, applica‐
       tions using __pmConnectLogger should use close(2) to terminate the
       connection to pmlogger(1) as soon as they have  finished  communi‐
       cating.

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

DIAGNOSTICS         top

       PM_ERR_PERMISSION
              no permission to connect to the specified pmlogger(1) in‐
              stance

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

       -EADDRINUSE
              the requested control port is already in use

SEE ALSO         top

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

COLOPHON         top

       This page is part of the PCP (Performance Co-Pilot) project.  In‐
       formation about the project can be found at ⟨http://www.pcp.io/⟩.
       If you have a bug report for this manual page, send it to
       pcp@groups.io.  This page was obtained from the project's upstream
       Git repository ⟨https://github.com/performancecopilot/pcp.git⟩ on
       2025-08-11.  (At that time, the date of the most recent commit
       that was found in the repository was 2025-08-11.)  If you discover
       any rendering problems in this HTML version of the page, or you
       believe there is a better or more up-to-date source for the page,
       or you have corrections or improvements to the information in this
       COLOPHON (which is not part of the original manual page), send a
       mail to man-pages@man7.org

Performance Co-Pilot               PCP                 PMCONNECTLOGGER(3)

Pages that refer to this page: __pmcontrollog(3)