NAME

       __pmLocalPMDA - change the table of DSO PMDAs for PM_CONTEXT_LOCAL contexts

C SYNOPSIS

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

       int __pmLocalPMDA(int op, int domain, const char *name, const char *init);

       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

       PCP contexts of type PM_CONTEXT_LOCAL are used by clients that wish to fetch metrics directly from one or
       more PMDAs on the local host without involving pmcd(1).  A PMDA that is to be used in this way must  have
       been built as a Dynamic Shared Object (DSO).

       Historically the table of PMDAs available for use with PM_CONTEXT_LOCAL was hardcoded to the following:

       * The PMDA (or PMDAs) that export the operating system performance data and data about process activity.
       * The mmv PMDA.
       * The sample PMDA provided $PCP_LITE_SAMPLE or $PMDA_LOCAL_SAMPLE is set in the environment - used mostly
         for QA and testing.

       The  initial table of PMDAs available for use with PM_CONTEXT_LOCAL is now generated dynamically from all
       those PMDAs that have been installed as DSOs on the local host.  The one exception is the  ``pmcd''  PMDA
       which  only  operates correctly in the address space of a running pmcd(1) process and so is not available
       to an application using a PM_CONTEXT_LOCAL context.

       __pmLocalPMDA provides a number of services to amend the table of PMDAs available for  use  with  PM_CON‐
       TEXT_LOCAL.

       The op argument specifies the what should be done and takes one of the following values and actions:

       PM_LOCAL_ADD    Append  an entry to the table for the PMDA with a Performance Metrics Domain (PMD) of do‐
                       main, the path to the DSO PMDA is given by path and the PMDA's initialization routine  is
                       init.

       PM_LOCAL_DEL    Removes  all entries in the table where the domain matches, or the path matches.  Setting
                       the arguments domain to -1 or path to NULL to force matching on the other argument.   The
                       init argument is ignored.

       PM_LOCAL_CLEAR  Remove all entries from the table.  All the other arguments are ignored in this case.

       The domain, name and init arguments have similar syntax and semantics to the associated fields in the pm‐
       cd(1) configuration file.  The one difference is the path argument which is used by __pmLocalPMDA to find
       a  likely looking DSO by searching in this order: $PCP_PMDAS_DIR/path, path, $PCP_PMDAS_DIR/path.dso-suf‐
       fix and finally path.dso-suffix (dso-suffix is the local platform specific default file name suffix for a
       DSO, e.g.  so for Linux, dylib for Mac OS X, dll for Windows, etc.).

RETURN VALUE

       In most cases, __pmLocalPMDA returns 0 to indicate success.  If op is invalid, then the return  value  is
       PM_ERR_CONV  else if there is no matching table entry found for a PM_LOCAL_DEL operation, PM_ERR_INDOM is
       returned.

SEE ALSO

       pmcd(1), PMAPI(3), pmNewContext(3) and __pmSpecLocalPMDA(3).

Performance Co-Pilot                                                                              PMLOCALPMDA(3)