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transaction: change list of journal entries into a dictionary...

transaction: change list of journal entries into a dictionary The transaction object used to keep a mapping table of path names to journal entries and a list of journal entries consisting of path and file offset to truncate on rollback. The offsets are used in three cases. repair.strip and rollback process all of them in one go, but they care about the order. For them, it is perfectly reasonable to read the journal back from disk as both operations already involve at least one system call per journal entry. The other consumer is the revlog logic for moving from inline to external data storage. It doesn't care about the order of the journal and just needs to original offset stored. Further optimisations are possible here to move the in-memory journal to a set(), but without memoisation of the original revlog size this could turn it into O(n^2) behavior in worst case when many revlogs need to migrated. Differential Revision: https://phab.mercurial-scm.org/D9277

Augie Fackler - - Load All Authors

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      # txnutil.py - transaction related utilities

      #

      #  Copyright FUJIWARA Katsunori <foozy@lares.dti.ne.jp> and others

      #

      # 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 errno

      from . import encoding

      def mayhavepending(root):

          '''return whether 'root' may have pending changes, which are

          visible to this process.

          '''

          return root == encoding.environ.get(b'HG_PENDING')

      def trypending(root, vfs, filename, **kwargs):

          '''Open  file to be read according to HG_PENDING environment variable

          This opens '.pending' of specified 'filename' only when HG_PENDING

          is equal to 'root'.

          This returns '(fp, is_pending_opened)' tuple.

          '''

          if mayhavepending(root):

              try:

                  return (vfs(b'%s.pending' % filename, **kwargs), True)

              except IOError as inst:

                  if inst.errno != errno.ENOENT:

                      raise

          return (vfs(filename, **kwargs), False)

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				# txnutil.py - transaction related utilities
				#
				# Copyright FUJIWARA Katsunori <foozy@lares.dti.ne.jp> and others
				#
				# 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 errno

				from . import encoding


				def mayhavepending(root):
				'''return whether 'root' may have pending changes, which are
				visible to this process.
				'''
				return root == encoding.environ.get(b'HG_PENDING')


				def trypending(root, vfs, filename, **kwargs):
				'''Open file to be read according to HG_PENDING environment variable

				This opens '.pending' of specified 'filename' only when HG_PENDING
				is equal to 'root'.

				This returns '(fp, is_pending_opened)' tuple.
				'''
				if mayhavepending(root):
				try:
				return (vfs(b'%s.pending' % filename, **kwargs), True)
				except IOError as inst:
				if inst.errno != errno.ENOENT:
				raise
				return (vfs(filename, **kwargs), False)