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

util: make chunkbuffer non-quadratic on Windows...

util: make chunkbuffer non-quadratic on Windows The old str-based += collector performed very nicely on Linux, but turns out to be quadratically expensive on Windows, causing chunkbuffer to dominate in profiles. This list-based version has been measured to significantly improve performance with large chunks on Windows, with negligible overall overhead on Linux (though microbenchmarks show it to be about 50% slower). This may increase memory overhead where += didn't behave quadratically. If we want to gather up 1G of data to join, we temporarily have 1G in our list and 1G in our string.

Brodie Rao - - Load All Authors

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      # diffhelpers.py - pure Python implementation of diffhelpers.c

      #

      # Copyright 2009 Matt Mackall <mpm@selenic.com> 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.

      def addlines(fp, hunk, lena, lenb, a, b):

          while True:

              todoa = lena - len(a)

              todob = lenb - len(b)

              num = max(todoa, todob)

              if num == 0:

                  break

              for i in xrange(num):

                  s = fp.readline()

                  c = s[0]

                  if s == "\\ No newline at end of file\n":

                      fix_newline(hunk, a, b)

                      continue

                  if c == "\n":

                      # Some patches may be missing the control char

                      # on empty lines. Supply a leading space.

                      s = " \n"

                  hunk.append(s)

                  if c == "+":

                      b.append(s[1:])

                  elif c == "-":

                      a.append(s)

                  else:

                      b.append(s[1:])

                      a.append(s)

          return 0

      def fix_newline(hunk, a, b):

          l = hunk[-1]

          # tolerate CRLF in last line

          if l.endswith('\r\n'):

              hline = l[:-2]

          else:

              hline = l[:-1]

          c = hline[0]

          if c in " +":

              b[-1] = hline[1:]

          if c in " -":

              a[-1] = hline

          hunk[-1] = hline

          return 0

      def testhunk(a, b, bstart):

          alen = len(a)

          blen = len(b)

          if alen > blen - bstart:

              return -1

          for i in xrange(alen):

              if a[i][1:] != b[i + bstart]:

                  return -1

          return 0

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				# diffhelpers.py - pure Python implementation of diffhelpers.c
				#
				# Copyright 2009 Matt Mackall <mpm@selenic.com> 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.

				def addlines(fp, hunk, lena, lenb, a, b):
				while True:
				todoa = lena - len(a)
				todob = lenb - len(b)
				num = max(todoa, todob)
				if num == 0:
				break
				for i in xrange(num):
				s = fp.readline()
				c = s[0]
				if s == "\\ No newline at end of file\n":
				fix_newline(hunk, a, b)
				continue
				if c == "\n":
				# Some patches may be missing the control char
				# on empty lines. Supply a leading space.
				s = " \n"
				hunk.append(s)
				if c == "+":
				b.append(s[1:])
				elif c == "-":
				a.append(s)
				else:
				b.append(s[1:])
				a.append(s)
				return 0

				def fix_newline(hunk, a, b):
				l = hunk[-1]
				# tolerate CRLF in last line
				if l.endswith('\r\n'):
				hline = l[:-2]
				else:
				hline = l[:-1]
				c = hline[0]

				if c in " +":
				b[-1] = hline[1:]
				if c in " -":
				a[-1] = hline
				hunk[-1] = hline
				return 0


				def testhunk(a, b, bstart):
				alen = len(a)
				blen = len(b)
				if alen > blen - bstart:
				return -1
				for i in xrange(alen):
				if a[i][1:] != b[i + bstart]:
				return -1
				return 0