upstream/mercurial-mirror Files · mercurial/dirstateguard.py

scmutil: add a simple key-value file helper...

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.

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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()

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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()