upstream/mercurial-mirror Files · mercurial/cffi/mpatch.py

revlog: efficient implementation of 'descendant'...

revlog: efficient implementation of 'descendant' Iterating over descendants is costly, because there are no "parent -> children" pointers. Walking the other way around is much more efficient, especially on large repositories, where descendant walks can cost seconds. And the other hand, common ancestors code follows links in the right direction and has a compiled implementation. In real life usage, this saved up to 80s during some pull operations, where descendant test happens in extension code.

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      # mpatch.py - CFFI implementation of mpatch.c

      #

      # Copyright 2016 Maciej Fijalkowski <fijall@gmail.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 ..pure.mpatch import *

      from ..pure.mpatch import mpatchError  # silence pyflakes

      from . import _mpatch

      ffi = _mpatch.ffi

      lib = _mpatch.lib

      @ffi.def_extern()

      def cffi_get_next_item(arg, pos):

          all, bins = ffi.from_handle(arg)

          container = ffi.new("struct mpatch_flist*[1]")

          to_pass = ffi.new("char[]", str(bins[pos]))

          all.append(to_pass)

          r = lib.mpatch_decode(to_pass, len(to_pass) - 1, container)

          if r < 0:

              return ffi.NULL

          return container[0]

      def patches(text, bins):

          lgt = len(bins)

          all = []

          if not lgt:

              return text

          arg = (all, bins)

          patch = lib.mpatch_fold(ffi.new_handle(arg),

                                  lib.cffi_get_next_item, 0, lgt)

          if not patch:

              raise mpatchError("cannot decode chunk")

          outlen = lib.mpatch_calcsize(len(text), patch)

          if outlen < 0:

              lib.mpatch_lfree(patch)

              raise mpatchError("inconsistency detected")

          buf = ffi.new("char[]", outlen)

          if lib.mpatch_apply(buf, text, len(text), patch) < 0:

              lib.mpatch_lfree(patch)

              raise mpatchError("error applying patches")

          res = ffi.buffer(buf, outlen)[:]

          lib.mpatch_lfree(patch)

          return res

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				# mpatch.py - CFFI implementation of mpatch.c
				#
				# Copyright 2016 Maciej Fijalkowski <fijall@gmail.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 ..pure.mpatch import *
				from ..pure.mpatch import mpatchError # silence pyflakes
				from . import _mpatch

				ffi = _mpatch.ffi
				lib = _mpatch.lib

				@ffi.def_extern()
				def cffi_get_next_item(arg, pos):
				all, bins = ffi.from_handle(arg)
				container = ffi.new("struct mpatch_flist*[1]")
				to_pass = ffi.new("char[]", str(bins[pos]))
				all.append(to_pass)
				r = lib.mpatch_decode(to_pass, len(to_pass) - 1, container)
				if r < 0:
				return ffi.NULL
				return container[0]

				def patches(text, bins):
				lgt = len(bins)
				all = []
				if not lgt:
				return text
				arg = (all, bins)
				patch = lib.mpatch_fold(ffi.new_handle(arg),
				lib.cffi_get_next_item, 0, lgt)
				if not patch:
				raise mpatchError("cannot decode chunk")
				outlen = lib.mpatch_calcsize(len(text), patch)
				if outlen < 0:
				lib.mpatch_lfree(patch)
				raise mpatchError("inconsistency detected")
				buf = ffi.new("char[]", outlen)
				if lib.mpatch_apply(buf, text, len(text), patch) < 0:
				lib.mpatch_lfree(patch)
				raise mpatchError("error applying patches")
				res = ffi.buffer(buf, outlen)[:]
				lib.mpatch_lfree(patch)
				return res