Mercurial > hg
diff mercurial/obsolete.py @ 34413:014d467f9d08
effectflag: store an empty effect flag for the moment
The idea behind effect flag is to store additional information in obs-markers
about what changed between a changeset and its successor(s). It's a low-level
information that comes without guarantees.
This information can be computed a posteriori, but only if we have all
changesets locally. This is not the case with distributed workflows where you
work with several people or on several computers (eg: laptop + build server).
Storing the effect-flag as a bitfield has several advantages:
- It's compact, we are using one byte per obs-marker at most for the effect-
flag.
- It's compoundable, the obsfate log approach needs to display evolve history
that could spans several obs-markers. Computing the effect-flag between a
changeset and its grand-grand-grand-successor is simple thanks to the
bitfield.
The effect-flag design has also some limitations:
- Evolving a changeset and reverting these changes just after would lead to
two obs-markers with the same effect-flag without information that the first
and third changesets are the same.
The effect-flag current design is a trade-off between compactness and
usefulness.
Storing this information helps commands to display a more complete and
understandable evolve history. For example, obslog (an Evolve command) use it
to improve its output:
x 62206adfd571 (34302) obscache: skip updating outdated obscache...
| rewritten(parent) by Matthieu Laneuville <matthieu.laneuville@octobus...
| rewritten(content) by Boris Feld <boris.feld@octobus.net>
The effect flag is stored in obs-markers metadata while we iterate on the
information we want to store. We plan to extend the existing obsmarkers
bit-field when the effect flag design will be stabilized.
It's different from the CommitCustody concept, effect-flag are not signed and
can be forged. It's also different from the operation metadata as the command
name (for example: amend) could alter a changeset in different ways (changing
the content with hg amend, changing the description with hg amend -e, changing
the user with hg amend -U). Also it's compatible with every custom command
that writes obs-markers without needing to be updated.
The effect-flag is placed behind an experimental flag set to off by default.
Hook the saving of effect flag in create markers, but store only an empty one
for the moment, I will refine the values in effect flag in following patches.
For more information, see:
https://www.mercurial-scm.org/wiki/ChangesetEvolutionDevel#Record_types_of_operation
Differential Revision: https://phab.mercurial-scm.org/D533
author | Boris Feld <boris.feld@octobus.net> |
---|---|
date | Thu, 06 Jul 2017 14:50:17 +0200 |
parents | b6692ba7d5b0 |
children | dc91580a0a88 |
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--- a/mercurial/obsolete.py Fri Jun 30 03:44:00 2017 +0200 +++ b/mercurial/obsolete.py Thu Jul 06 14:50:17 2017 +0200 @@ -1043,6 +1043,11 @@ if useoperation and operation: metadata['operation'] = operation + # Effect flag metadata handling + saveeffectflag = repo.ui.configbool('experimental', + 'effect-flags', + False) + tr = repo.transaction('add-obsolescence-marker') try: markerargs = [] @@ -1066,6 +1071,13 @@ raise error.Abort(_("changeset %s cannot obsolete itself") % prec) + # Effect flag can be different by relation + if saveeffectflag: + # The effect flag is saved in a versioned field name for future + # evolution + effectflag = obsutil.geteffectflag(rel) + localmetadata[obsutil.EFFECTFLAGFIELD] = "%d" % effectflag + # Creating the marker causes the hidden cache to become invalid, # which causes recomputation when we ask for prec.parents() above. # Resulting in n^2 behavior. So let's prepare all of the args