upstream/mercurial-mirror Files · mercurial/pure/base85.py

cmdutil: add class to restore dirstate during unexpected failure...

cmdutil: add class to restore dirstate during unexpected failure Before this patch, after "dirstate.write()" execution, there was no way to restore dirstate to the original status before "dirstate.write()". In some code paths, "dirstate.invalidate()" is used as a kind of "restore .hg/dirstate to the original status", but it just avoids writing changes in memory out, and doesn't actually restore the ".hg/dirstate" file. To fix the issue that the recent (in memory) dirstate isn't visible to external processes (e.g. "precommit" hooks), "dirstate.write()" should be invoked before invocation of external processes. But at the same time, ".hg/dirstate" should be restored to its content before "dirstate.write()" during an unexpected failure in some cases. This patch adds the class "dirstateguard" to easily restore ".hg/dirstate" during unexpected failures. Typical usecase of it is: # (1) build dirstate up .... # (2) write dirstate out, and backup ".hg/dirstate" dsguard = dirstateguard(repo, 'scopename') try: # (3) execute somethig to do: # this may imply making some additional changes on dirstate .... # (4) unlink backed-up dirstate file at the end of dsguard scope dsguard.close() finally: # (5) if execution is aborted before "dsguard.close()", # ".hg/dirstate" is restored from the backup dsguard.release() For this kind of issue, an "extending transaction" approach (in https://titanpad.com/mercurial32-sprint) seems to not be suitable, because: - transaction nesting occurs in some cases (e.g. "shelve => rebase"), and - "dirstate" may be already modified since the beginning of OUTER transaction scope, then - dirstate should be backed up into the file other than "dirstate.journal" at the beginning of INNER transaction scope, but - such alternative backup files are useless for transaction itself, and increases complication of its implementation "transaction" and "dirstateguard" differ from each other also in "what it should do for .hg/dirstate" in cases other than success. ============== ======= ======== ============= type success fail "hg rollback" ============== ======= ======== ============= transaction keep keep restore dirstateguard keep restore (not implied) ============== ======= ======== ============= Some collaboration between transaction and dirstate will probably be introduced in the future. But this layer is needed in all cases.

Patrick Mezard - - Load All Authors

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             base85.py
        
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      # base85.py: pure python base85 codec

      #

      # Copyright (C) 2009 Brendan Cully <brendan@kublai.com>

      #

      # This software may be used and distributed according to the terms of the

      # GNU General Public License version 2 or any later version.

      import struct

      _b85chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ" \

                  "abcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~"

      _b85chars2 = [(a + b) for a in _b85chars for b in _b85chars]

      _b85dec = {}

      def _mkb85dec():

          for i, c in enumerate(_b85chars):

              _b85dec[c] = i

      def b85encode(text, pad=False):

          """encode text in base85 format"""

          l = len(text)

          r = l % 4

          if r:

              text += '\0' * (4 - r)

          longs = len(text) >> 2

          words = struct.unpack('>%dL' % (longs), text)

          out = ''.join(_b85chars[(word // 52200625) % 85] +

                        _b85chars2[(word // 7225) % 7225] +

                        _b85chars2[word % 7225]

                        for word in words)

          if pad:

              return out

          # Trim padding

          olen = l % 4

          if olen:

              olen += 1

          olen += l // 4 * 5

          return out[:olen]

      def b85decode(text):

          """decode base85-encoded text"""

          if not _b85dec:

              _mkb85dec()

          l = len(text)

          out = []

          for i in range(0, len(text), 5):

              chunk = text[i:i + 5]

              acc = 0

              for j, c in enumerate(chunk):

                  try:

                      acc = acc * 85 + _b85dec[c]

                  except KeyError:

                      raise ValueError('bad base85 character at position %d'

                                       % (i + j))

              if acc > 4294967295:

                  raise ValueError('Base85 overflow in hunk starting at byte %d' % i)

              out.append(acc)

          # Pad final chunk if necessary

          cl = l % 5

          if cl:

              acc *= 85 ** (5 - cl)

              if cl > 1:

                  acc += 0xffffff >> (cl - 2) * 8

              out[-1] = acc

          out = struct.pack('>%dL' % (len(out)), *out)

          if cl:

              out = out[:-(5 - cl)]

          return out

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				# base85.py: pure python base85 codec
				#
				# Copyright (C) 2009 Brendan Cully <brendan@kublai.com>
				#
				# This software may be used and distributed according to the terms of the
				# GNU General Public License version 2 or any later version.

				import struct

				_b85chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
				"abcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{\|}~"
				_b85chars2 = [(a + b) for a in _b85chars for b in _b85chars]
				_b85dec = {}

				def _mkb85dec():
				for i, c in enumerate(_b85chars):
				_b85dec[c] = i

				def b85encode(text, pad=False):
				"""encode text in base85 format"""
				l = len(text)
				r = l % 4
				if r:
				text += '\0' * (4 - r)
				longs = len(text) >> 2
				words = struct.unpack('>%dL' % (longs), text)

				out = ''.join(_b85chars[(word // 52200625) % 85] +
				_b85chars2[(word // 7225) % 7225] +
				_b85chars2[word % 7225]
				for word in words)

				if pad:
				return out

				# Trim padding
				olen = l % 4
				if olen:
				olen += 1
				olen += l // 4 * 5
				return out[:olen]

				def b85decode(text):
				"""decode base85-encoded text"""
				if not _b85dec:
				_mkb85dec()

				l = len(text)
				out = []
				for i in range(0, len(text), 5):
				chunk = text[i:i + 5]
				acc = 0
				for j, c in enumerate(chunk):
				try:
				acc = acc * 85 + _b85dec[c]
				except KeyError:
				raise ValueError('bad base85 character at position %d'
				% (i + j))
				if acc > 4294967295:
				raise ValueError('Base85 overflow in hunk starting at byte %d' % i)
				out.append(acc)

				# Pad final chunk if necessary
				cl = l % 5
				if cl:
				acc = 85 * (5 - cl)
				if cl > 1:
				acc += 0xffffff >> (cl - 2) * 8
				out[-1] = acc

				out = struct.pack('>%dL' % (len(out)), *out)
				if cl:
				out = out[:-(5 - cl)]

				return out