Mercurial > hg
view contrib/memory.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x 62206adfd571 (34302) obscache: skip updating outdated obscache...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 | de5c9d0e02ea |
children | 2372284d9457 |
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# memory.py - track memory usage # # Copyright 2009 Matt Mackall <mpm@selenic.com> and others # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. '''helper extension to measure memory usage Reads current and peak memory usage from ``/proc/self/status`` and prints it to ``stderr`` on exit. ''' from __future__ import absolute_import def memusage(ui): """Report memory usage of the current process.""" result = {'peak': 0, 'rss': 0} with open('/proc/self/status', 'r') as status: # This will only work on systems with a /proc file system # (like Linux). for line in status: parts = line.split() key = parts[0][2:-1].lower() if key in result: result[key] = int(parts[1]) ui.write_err(", ".join(["%s: %.1f MiB" % (k, v / 1024.0) for k, v in result.iteritems()]) + "\n") def extsetup(ui): ui.atexit(memusage, ui)