Mercurial > hg
view mercurial/dirstateguard.py @ 31553:56acc4250900
scmutil: add a simple key-value file helper
The purpose of the added class is to serve purposes like save files of shelve
or state files of shelve, rebase and histedit. Keys of these files can be
alphanumeric and start with letters, while values must not contain newlines.
In light of Mercurial's reluctancy to use Python's json module, this tries
to provide a reasonable alternative for a non-nested named data.
Comparing to current approach of storing state in plain text files, where
semantic meaning of lines of text is only determined by their oreder,
simple key-value file allows for reordering lines and thus helps handle
optional values.
Initial use-case I see for this is obs-shelve's shelve files. Later we
can possibly migrate state files to this approach.
The test is in a new file beause I did not figure out where to put it
within existing test suite. If you give me a better idea, I will gladly
follow it.
author | Kostia Balytskyi <ikostia@fb.com> |
---|---|
date | Fri, 10 Mar 2017 14:33:42 -0800 |
parents | 751639bf6fc4 |
children | ec306bc6915b |
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# dirstateguard.py - class to allow restoring dirstate after failure # # Copyright 2005-2007 Matt Mackall <mpm@selenic.com> # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. from __future__ import absolute_import from .i18n import _ from . import ( error, ) class dirstateguard(object): '''Restore dirstate at unexpected failure. At the construction, this class does: - write current ``repo.dirstate`` out, and - save ``.hg/dirstate`` into the backup file This restores ``.hg/dirstate`` from backup file, if ``release()`` is invoked before ``close()``. This just removes the backup file at ``close()`` before ``release()``. ''' def __init__(self, repo, name): self._repo = repo self._active = False self._closed = False self._suffix = '.backup.%s.%d' % (name, id(self)) repo.dirstate.savebackup(repo.currenttransaction(), self._suffix) self._active = True def __del__(self): if self._active: # still active # this may occur, even if this class is used correctly: # for example, releasing other resources like transaction # may raise exception before ``dirstateguard.release`` in # ``release(tr, ....)``. self._abort() def close(self): if not self._active: # already inactivated msg = (_("can't close already inactivated backup: dirstate%s") % self._suffix) raise error.Abort(msg) self._repo.dirstate.clearbackup(self._repo.currenttransaction(), self._suffix) self._active = False self._closed = True def _abort(self): self._repo.dirstate.restorebackup(self._repo.currenttransaction(), self._suffix) self._active = False def release(self): if not self._closed: if not self._active: # already inactivated msg = (_("can't release already inactivated backup:" " dirstate%s") % self._suffix) raise error.Abort(msg) self._abort()