dirs.addpath: rework algorithm to search forward
This improves performance because it uses strchr rather than a loop.
For LLVM/clang version "Apple LLVM version 6.0 (clang-600.0.56) (based on LLVM
3.5svn)" on OS X, for a repo with over 200,000 files, this improves perfdirs
from 0.248 seconds to 0.230 (7.3%)
For gcc 4.4.6 on Linux, for a test repo with over 500,000 files, this improves
perfdirs from 0.704 seconds to 0.658 (6.5%).
#!/bin/sh
#
# Use this script to generate empty.svndump
#
mkdir temp
cd temp
mkdir project-orig
cd project-orig
mkdir trunk
mkdir branches
mkdir tags
cd ..
svnadmin create svn-repo
svnurl=file://`pwd`/svn-repo
svn import project-orig $svnurl -m "init projA"
svn co $svnurl project
cd project
mkdir trunk/dir
echo a > trunk/dir/a
svn add trunk/dir
svn ci -m adddir
echo b > trunk/b
svn add trunk/b
svn ci -m addb
echo c > c
svn add c
svn ci -m addc
cd ..
# svnsync repo/trunk/dir only so the last two revisions are empty
svnadmin create svn-empty
cat > svn-empty/hooks/pre-revprop-change <<EOF
#!/bin/sh
exit 0
EOF
chmod +x svn-empty/hooks/pre-revprop-change
svnsync init --username svnsync file://`pwd`/svn-empty file://`pwd`/svn-repo/trunk/dir
svnsync sync file://`pwd`/svn-empty
svn log -v file://`pwd`/svn-empty
svnadmin dump svn-empty > ../empty.svndump