[patch] git svn slowness on win32

[josh robb <josh_robb@fastmail.fm>]

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Hi,

I'm using git svn (1.6.4.msysgit.0) within a WindowsXP VM running
under VMWare fusion on OSX 10.5. For me (and at least one other person
I know) git svn has been unbearably slow.

My profiling shows that almost all of the git-svn runtime is being
spent in DynaLoader (via SVN::Base::import) which I guess is slow in a
virtualized windows environment. For example:

$ time perl /libexec/git-core/git-svn rebase
Current branch master is up to date.

real 2m56.750s
user 0m3.129s
sys 2m39.232s

I've been able to make significant (an order of magnitude)
improvements to it's performance by delaying SVN::Base::import from
running until it's actually needed. After making this change:

$ time perl /libexec/git-core/git-svn rebase
Current branch master is up to date.

real 0m33.407s
user 0m1.409s
sys 0m23.054s

git svn rebase -n goes from 3m7.046s to 0m10.312s.

Would love to get some feedback/thoughts etc...

j.

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--- git-svn.orig	Wed Jul 29 22:55:26 2009
+++ git-svn	Fri Dec  4 13:38:52 2009
@@ -27,11 +27,13 @@
 $| = 1; # unbuffer STDOUT
 
 sub fatal (@) { print STDERR "@_\n"; exit 1 }
-require SVN::Core; # use()-ing this causes segfaults for me... *shrug*
-require SVN::Ra;
-require SVN::Delta;
-if ($SVN::Core::VERSION lt '1.1.0') {
-	fatal "Need SVN::Core 1.1.0 or better (got $SVN::Core::VERSION)";
+sub _req_svn {
+	require SVN::Core; # use()-ing this causes segfaults for me... *shrug*
+	require SVN::Ra;
+	require SVN::Delta;
+	if ($SVN::Core::VERSION lt '1.1.0') {
+		fatal "Need SVN::Core 1.1.0 or better (got $SVN::Core::VERSION)";
+	}
 }
 my $can_compress = eval { require Compress::Zlib; 1};
 push @Git::SVN::Ra::ISA, 'SVN::Ra';
@@ -4379,6 +4381,8 @@
 	my ($class, $url) = @_;
 	$url =~ s!/+$!!;
 	return $RA if ($RA && $RA->{url} eq $url);
+
+	::_req_svn();
 
 	SVN::_Core::svn_config_ensure($config_dir, undef);
 	my ($baton, $callbacks) = SVN::Core::auth_open_helper(_auth_providers);