pmadeltaindom(3) — Linux manual page

PMADELTAINDOM(3)        Library Functions Manual        PMADELTAINDOM(3)

NAME

       pmaDeltaInDom - generate a ``delta indom'' if two observations of
       an instance domain are different

C SYNOPSIS

       #include <pcp/pmapi.h>
       #include <pcp/libpcp.h>
       #include <pcp/archive.h>

       void pmaDeltaInDom(__pmLogInDom *old, __pmLogInDom *new,
       __pmLogInDom *new_delta);

       cc ... -lpcp_archive -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

       Checks if two observations of the same instance domain are
       identical, and if they are not, tries to generate a ``delta
       indom'' to describe the differences.

       The code assumes (a) old->indom == new->indom and (b) both the
       instance domains are sorted in ascending internal instance
       identifier sequence; see pmaSortInDom(3) to see how to make the
       second condition true.

       The ``delta indom'' format is only supported for Version 3
       archives and it is the caller's responsibility to determine if
       calling pmaDeltaInDom is appropriate, rather than calling
       pmaSameInDom(3) which is the preferred method for V2 archives.

       pmaDeltaInDom returns 0 if the old and new instance domains are
       the same.

       A return value of 1 indicates that the instance domains are
       different and the ``delta indom'' format is not more efficient;
       in this case new_delta is not modified.

       A return value of 2 indicates that the instance domains are
       different and new_delta has been set up to describe the ``delta
       indom'' encoding of the differences;  in this case the caller is
       responsible for freeing new_delta->instlist and
       new_delta->namelist.

       The instance domains are considered different if any of the
       following hold:

       1.  old->numinst != new->numinst

       2.  For some i, old->instlist[i] != new->instlist[i]

       3.  For some i, the strings pointed to by old->namelist[i] and
           new->instlist[i] are not identical

DELTA INDOM FORMAT

       As for a regular instance domain, new_delta->numinst defines the
       number of instance specifications.

       If new_delta->namelist[i] == NULL then the instance identified by
       new_delta->instlist[i] has been deleted from the instance domain.

       If new_delta->namelist[i] != NULL then the instance identified by
       new_delta->instlist[i] has been added to the instance domain.

       Because the ``delta indom'' is only likely to have short-term
       relevance to the caller, the new_delta->namelist[i] entries that
       are not NULL will point back into old->namelist[j] or
       new->namelist[k] and so old and new should not be freed until the
       caller has finished with new_delta.

SEE ALSO

       PMAPI(3), pmaSortInDom(3) and pmaSameInDom(3).

COLOPHON

       This page is part of the PCP (Performance Co-Pilot) project.
       Information 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 2024-06-14.
       (At that time, the date of the most recent commit that was found
       in the repository was 2024-06-14.)  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                  PMADELTAINDOM(3)

Pages that refer to this page: pmasameindom(3), pmatrydeltaindom(3)

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