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NAME | C SYNOPSIS | CAVEAT | DESCRIPTION | DELTA INDOM FORMAT | SEE ALSO | COLOPHON |
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PMADELTAINDOM(3) Library Functions Manual PMADELTAINDOM(3)
pmaDeltaInDom - generate a ``delta indom'' if two observations of
an instance domain are different
#include <pcp/pmapi.h>
#include <pcp/libpcp.h>
#include <pcp/archive.h>
int pmaDeltaInDom(__pmLogInDom *old, __pmLogInDom *new,
__pmLogInDom *new_delta);
cc ... -lpcp_archive -lpcp
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.
Checks if two observations of the same instance domain are identiâ
cal, 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 inâ
stance domains are sorted in ascending internal instance identifiâ
er 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 difâ
ferent 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 difâ
ferent and new_delta has been set up to describe the ``delta inâ
dom'' encoding of the differences; in this case the caller is reâ
sponsible for freeing new_delta->instlist and new_delta->namelist.
The instance domains are considered different if any of the folâ
lowing 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
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 relâ
evance 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 finâ
ished with new_delta.
PMAPI(3), pmaSortInDom(3) and pmaSameInDom(3).
This page is part of the PCP (Performance Co-Pilot) project. Inâ
formation about the project can be found at âĻhttp://www.pcp.io/âĐ.
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 âĻhttps://github.com/performancecopilot/pcp.gitâĐ on
2026-05-24. (At that time, the date of the most recent commit
that was found in the repository was 2026-05-24.) 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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HTML rendering created 2026-05-30 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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