pmatrydeltaindom(3) — Linux manual page


PMATRYDELTAINDOM(3)     Library Functions Manual     PMATRYDELTAINDOM(3)

NAME         top

       pmaTryDeltaInDom - try to translate a physical indom record from
       a ``full indom'' to a ``delta indom''

C SYNOPSIS         top

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

       int pmaTryDeltaInDom(__pmLogCtl *lcp, __int32_t **rbuf,
       __pmLogInDom *lidp);

       cc ... -lpcp_archive -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

       The input instance domain is passed in as either a physical
       metadata record via rbuf or in the ``loaded'' format identified
       by lidp.  As these are alternate formats for the input instance
       domain, pmaTryDeltaInDom demands that exactly one of rbuf and
       lidp must be NULL, else the return value is -2.

       The input instance domain is on the path to being written to the
       archive identified by lcp.

       If possible, the instance domain will be converted to the ``delta
       indom'' format, and the converted instance domain returned via
       rbuf or lidp (whichever is not NULL).  If conversion takes place,
       any storage assocated with the input instance domain will have
       been free'd.

       The ``delta indom'' format is only supported for Version 3
       archives and it is the caller's responsibility to determine if
       calling pmaTryDeltaInDom is appropriate.

       To determine if the ``delta indom'' format is the most efficient
       encoding, pmaTryDeltaInDom maintains a per-instance domain cache
       of the last seen ``full'' instance domain.  To avoid data
       corruption, this means pmaTryDeltaInDom first copies the input
       instance domain.  The copy and the cache are all managed
       privately by pmaTryDeltaInDom so the caller is unaware of this

       The cacheing scheme requires that the caller must call
       pmaTryDeltaInDom for every instance domain record, independent of
       whether the ``delta indom'' format is likely to be appropriate.


       In several places, fatal errors will trigger an error message and
       force the application to exit.

       A return value of -1 indicates that rbuf was not NULL and the
       physical record therein was not a TYPE_INDOM (Version 3 ``full''
       instance domain) record as expected.  A return value of 1 means
       rbuf or lidp has been rewritten, and is now a TYPE_INDOM_DELTA
       record.  Otherwise the return value is 0.

SEE ALSO         top

       pmaDeltaInDom(3), PMAPI(3) and pmaUndeltaInDom(3).

COLOPHON         top

       This page is part of the PCP (Performance Co-Pilot) project.
       Information about the project can be found at 
       ⟨⟩.  If you have a bug report for this manual
       page, send it to  This page was obtained from the
       project's upstream Git repository
       ⟨⟩ on 2022-12-17.
       (At that time, the date of the most recent commit that was found
       in the repository was 2022-12-16.)  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

Performance Co-Pilot               PCP               PMATRYDELTAINDOM(3)