# 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,

    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)

        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)

        self._active = False

        self._closed = True

    def _abort(self):

        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()