Mercurial > hg
comparison 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x 62206adfd571 (34302) obscache: skip updating outdated obscache...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> |
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date | Thu, 06 Jul 2017 14:50:17 +0200 |
parents | b6692ba7d5b0 |
children | dc91580a0a88 |
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34412:83dfbda40e67 | 34413:014d467f9d08 |
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1041 useoperation = repo.ui.configbool('experimental', | 1041 useoperation = repo.ui.configbool('experimental', |
1042 'stabilization.track-operation') | 1042 'stabilization.track-operation') |
1043 if useoperation and operation: | 1043 if useoperation and operation: |
1044 metadata['operation'] = operation | 1044 metadata['operation'] = operation |
1045 | 1045 |
1046 # Effect flag metadata handling | |
1047 saveeffectflag = repo.ui.configbool('experimental', | |
1048 'effect-flags', | |
1049 False) | |
1050 | |
1046 tr = repo.transaction('add-obsolescence-marker') | 1051 tr = repo.transaction('add-obsolescence-marker') |
1047 try: | 1052 try: |
1048 markerargs = [] | 1053 markerargs = [] |
1049 for rel in relations: | 1054 for rel in relations: |
1050 prec = rel[0] | 1055 prec = rel[0] |
1064 npare = tuple(p.node() for p in prec.parents()) | 1069 npare = tuple(p.node() for p in prec.parents()) |
1065 if nprec in nsucs: | 1070 if nprec in nsucs: |
1066 raise error.Abort(_("changeset %s cannot obsolete itself") | 1071 raise error.Abort(_("changeset %s cannot obsolete itself") |
1067 % prec) | 1072 % prec) |
1068 | 1073 |
1074 # Effect flag can be different by relation | |
1075 if saveeffectflag: | |
1076 # The effect flag is saved in a versioned field name for future | |
1077 # evolution | |
1078 effectflag = obsutil.geteffectflag(rel) | |
1079 localmetadata[obsutil.EFFECTFLAGFIELD] = "%d" % effectflag | |
1080 | |
1069 # Creating the marker causes the hidden cache to become invalid, | 1081 # Creating the marker causes the hidden cache to become invalid, |
1070 # which causes recomputation when we ask for prec.parents() above. | 1082 # which causes recomputation when we ask for prec.parents() above. |
1071 # Resulting in n^2 behavior. So let's prepare all of the args | 1083 # Resulting in n^2 behavior. So let's prepare all of the args |
1072 # first, then create the markers. | 1084 # first, then create the markers. |
1073 markerargs.append((nprec, nsucs, npare, localmetadata)) | 1085 markerargs.append((nprec, nsucs, npare, localmetadata)) |