view mercurial/dirstateguard.py @ 39282:828a45233036

debugcommands: introduce debugrevlogindex (BC)

`hg debugindex` was originally invented for displaying revlog index
data and is highly tailored towards that. e.g. it accepts a --format
option to display index data for a particular revlog version and
displays things like offset and length.

As we support non-revlog storage, it makes sense for `hg debugindex`
to display generic index data and for there to exist storage-specific
or storage-aware debug* commands for dumping non-generic index data.

This commit effectively renames `hg debugindex` to
`hg debugrevlogindex` and replaces `hg debugindex` with a version that
is storage agnostic.

Tests using --format have been updated to use `hg debugrevlogindex`.

Output is backwards compatible. The replacement command uses the
formatter, which means output can be templatized.

At some point, we may want to tweak output (e.g. to add the revision
size). But I don't feel like taking a bigger BC break at the moment.

The renamed command/function had to be moved because check-code
enforces alphabetical ordering of commands in this file.

Differential Revision: https://phab.mercurial-scm.org/D4358

# dirstateguard.py - class to allow restoring dirstate after failure
#
# Copyright 2005-2007 Matt Mackall <[e-mail]>
#
# 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,
    narrowspec,
    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
        self._backupname = 'dirstate.backup.%s.%d' % (name, id(self))
        self._narrowspecbackupname = ('narrowspec.backup.%s.%d' %
                                      (name, id(self)))
        repo.dirstate.savebackup(repo.currenttransaction(), self._backupname)
        narrowspec.savebackup(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 = (_("can't close already inactivated backup: %s")
                   % self._backupname)
            raise error.Abort(msg)

        self._repo.dirstate.clearbackup(self._repo.currenttransaction(),
                                         self._backupname)
        narrowspec.clearbackup(self._repo, self._narrowspecbackupname)
        self._active = False
        self._closed = True

    def _abort(self):
        narrowspec.restorebackup(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 = (_("can't release already inactivated backup: %s")
                       % self._backupname)
                raise error.Abort(msg)
            self._abort()