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       __pmLocalPMDA  -  change  the  table  of DSO PMDAs for PM_CONTEXT_LOCAL


       #include <pcp/pmapi.h>
       #include <pcp/impl.h>

       int __pmLocalPMDA(int op, int domain,  const  char  *name,  const  char

       cc ... -lpcp


       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.  On Irix, the per-process  data  was
         only available if $PMDA_LOCAL_PROC is set in the environment.
       * 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.).


       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.


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