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_CONTEXT_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
                       domain, 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
       pmcd(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-
       suffix 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).