Mercurial > hg
view mercurial/dirstateguard.py @ 47682:78f7f0d490ee
dirstate-v2: Move fixed-size tree metadata into the docket file
Before this changeset, the dirstate-v2 data file contained not only nodes
and paths that may be reused when appending to an existing file,
but also some fixed-size metadata that applies to the entire tree
and was added at the end of the data file for every append.
This moves that metadata into the docket file, so that repeated "append"
operations without meaningful changes don’t actually need to grow any file.
Differential Revision: https://phab.mercurial-scm.org/D11098
author | Simon Sapin <simon.sapin@octobus.net> |
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date | Thu, 15 Jul 2021 23:02:17 +0200 |
parents | 222a42ac5b2d |
children | 6000f5b25c9b |
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# dirstateguard.py - class to allow restoring dirstate after failure # # Copyright 2005-2007 Olivia Mackall <olivia@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 import os from .i18n import _ from . import ( error, narrowspec, requirements, util, ) class dirstateguard(util.transactional): """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 def getname(prefix): fd, fname = repo.vfs.mkstemp(prefix=prefix) os.close(fd) return fname self._backupname = getname(b'dirstate.backup.%s.' % name) repo.dirstate.savebackup(repo.currenttransaction(), self._backupname) # Don't make this the empty string, things may join it with stuff and # blindly try to unlink it, which could be bad. self._narrowspecbackupname = None if requirements.NARROW_REQUIREMENT in repo.requirements: self._narrowspecbackupname = getname( b'narrowspec.backup.%s.' % name ) narrowspec.savewcbackup(repo, self._narrowspecbackupname) 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 = ( _(b"can't close already inactivated backup: %s") % self._backupname ) raise error.Abort(msg) self._repo.dirstate.clearbackup( self._repo.currenttransaction(), self._backupname ) if self._narrowspecbackupname: narrowspec.clearwcbackup(self._repo, self._narrowspecbackupname) self._active = False self._closed = True def _abort(self): if self._narrowspecbackupname: narrowspec.restorewcbackup(self._repo, self._narrowspecbackupname) self._repo.dirstate.restorebackup( self._repo.currenttransaction(), self._backupname ) self._active = False def release(self): if not self._closed: if not self._active: # already inactivated msg = ( _(b"can't release already inactivated backup: %s") % self._backupname ) raise error.Abort(msg) self._abort()