contrib/plan9/9diff

encoding: add fast-path for ASCII uppercase.

This copies the performance hack from encoding.lower (c481761033bd).

The case-folding logic that kicks in on case-insensitive filesystems
hits encoding.upper hard: with a repository with 75k files, the
timings went from

  hg perfstatus
  ! wall 3.156000 comb 3.156250 user 1.625000 sys 1.531250 (best of 3)

to

  hg perfstatus
  ! wall 2.390000 comb 2.390625 user 1.078125 sys 1.312500 (best of 5)

This is a 24% decrease. For comparison, Mercurial 2.0 gives:

  hg perfstatus
  ! wall 2.172000 comb 2.171875 user 0.984375 sys 1.187500 (best of 5)

so we're only 10% slower than before we added the extra case-folding
logic.

The same decrease is seen when executing 'hg status' as normal, where
we go from:

  hg status --time
  time: real 4.322 secs (user 2.219+0.000 sys 2.094+0.000)

to

  hg status --time
  time: real 3.307 secs (user 1.750+0.000 sys 1.547+0.000)

#!/bin/rc
# 9diff - Mercurial extdiff wrapper for diff(1)

rfork e

fn getfiles {
	cd $1 &&
	for(f in `{du -as | awk '{print $2}'})
		test -f $f && echo `{cleanname $f}
}

fn usage {
	echo >[1=2] usage: 9diff [diff options] parent child root
	exit usage
}

opts=()
while(~ $1 -*){
	opts=($opts $1)
	shift
}
if(! ~ $#* 3)
	usage

# extdiff will set the parent and child to a single file if there is
# only one change. If there are multiple changes, directories will be
# set. diff(1) does not cope particularly with directories; instead we
# do the recursion ourselves and diff each file individually.
if(test -f $1)
	diff $opts $1 $2
if not{
	# extdiff will create a snapshot of the working copy to prevent
	# conflicts during the diff. We circumvent this behavior by
	# diffing against the repository root to produce plumbable
	# output. This is antisocial.
	for(f in `{sort -u <{getfiles $1} <{getfiles $2}}){
		file1=$1/$f; test -f $file1 || file1=/dev/null
		file2=$3/$f; test -f $file2 || file2=/dev/null
		diff $opts $file1 $file2
	}
}
exit ''