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

bdiff: don't check border condition in loop...

bdiff: don't check border condition in loop `plast = a + len - 1`. So, this "for" loop iterates from "a" to "plast", inclusive. So, `p == plast` can only be true on the final iteration of the loop. So checking for it on every loop iteration is wasteful. This patch simply decreases the upper bound of the loop by 1 and adds an explicit check after iteration for the `p == plast` case. We can't simply add 1 to the initial value for "i" because that doesn't do the correct thing on empty input strings. `perfbdiff -m 3041e4d59df2` on the Firefox repo becomes significantly faster: ! wall 0.072763 comb 0.070000 user 0.070000 sys 0.000000 (best of 100) ! wall 0.053221 comb 0.060000 user 0.060000 sys 0.000000 (best of 100) For the curious, this code has its origins in 8b067bde6679, which is the changeset that introduced bdiff.c in 2005. Also, GNU diffutils is able to perform a similar line-based diff in under 20ms. So there's likely more perf wins to be found in this code. One of them is the hashing algorithm. But it looks like mpm spent some time testing hash collisions in d0c48891dd4a. I'd like to do the same before switching away from lyhash, just to be on the safe side.

Gregory Szorc - - Load All Authors

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        Martin Geisler
    
put license and copyright info into comment blocks

              r8226
            
      # node.py - basic nodeid manipulation for mercurial

      #

      # Copyright 2005, 2006 Matt Mackall <mpm@selenic.com>

      #

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

        Matt Mackall
    
Update license to GPLv2+

              r10263
            
      # GNU General Public License version 2 or any later version.

        mpm@selenic.com
    
Break apart hg.py...

              r1089
            
        Gregory Szorc
    
node: use absolute_import

              r25962
            
      from __future__ import absolute_import

        Matt Mackall
    
Replace demandload with new demandimport

              r3877
            
      import binascii

        mpm@selenic.com
    
Break apart hg.py...

              r1089
            
        Siddharth Agarwal
    
node: add 'nullhex', hex-encoded nullid...

              r26980
            
      # This ugly style has a noticeable effect in manifest parsing

      hex = binascii.hexlify

      bin = binascii.unhexlify

        Thomas Arendsen Hein
    
Define and use nullrev (revision of nullid) instead of -1.

              r3578
            
      nullrev = -1

        Gregory Szorc
    
node: use byte literals to construct nullid and wdirid...

              r28585
            
      nullid = b"\0" * 20

        Siddharth Agarwal
    
node: add 'nullhex', hex-encoded nullid...

              r26980
            
      nullhex = hex(nullid)

        mpm@selenic.com
    
Break apart hg.py...

              r1089
            
        Yuya Nishihara
    
node: define experimental identifiers for working directory...

              r25737
            
      # pseudo identifiers for working directory

      # (they are experimental, so don't add too many dependencies on them)

      wdirrev = 0x7fffffff

        Gregory Szorc
    
node: use byte literals to construct nullid and wdirid...

              r28585
            
      wdirid = b"\xff" * 20

        Yuya Nishihara
    
node: define experimental identifiers for working directory...

              r25737
            
        mpm@selenic.com
    
Break apart hg.py...

              r1089
            
      def short(node):

          return hex(node[:6])

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Martin Geisler put license and copyright info into comment blocks	r8226	# node.py - basic nodeid manipulation for mercurial
		#
		# Copyright 2005, 2006 Matt Mackall <mpm@selenic.com>
		#
		# This software may be used and distributed according to the terms of the
Matt Mackall Update license to GPLv2+	r10263	# GNU General Public License version 2 or any later version.
mpm@selenic.com Break apart hg.py...	r1089
Gregory Szorc node: use absolute_import	r25962	from __future__ import absolute_import

Matt Mackall Replace demandload with new demandimport	r3877	import binascii
mpm@selenic.com Break apart hg.py...	r1089
Siddharth Agarwal node: add 'nullhex', hex-encoded nullid...	r26980	# This ugly style has a noticeable effect in manifest parsing
		hex = binascii.hexlify
		bin = binascii.unhexlify

Thomas Arendsen Hein Define and use nullrev (revision of nullid) instead of -1.	r3578	nullrev = -1
Gregory Szorc node: use byte literals to construct nullid and wdirid...	r28585	nullid = b"\0" * 20
Siddharth Agarwal node: add 'nullhex', hex-encoded nullid...	r26980	nullhex = hex(nullid)
mpm@selenic.com Break apart hg.py...	r1089
Yuya Nishihara node: define experimental identifiers for working directory...	r25737	# pseudo identifiers for working directory
		# (they are experimental, so don't add too many dependencies on them)
		wdirrev = 0x7fffffff
Gregory Szorc node: use byte literals to construct nullid and wdirid...	r28585	wdirid = b"\xff" * 20
Yuya Nishihara node: define experimental identifiers for working directory...	r25737
mpm@selenic.com Break apart hg.py...	r1089	def short(node):
		return hex(node[:6])