Re: [PATCH 9/9] git-svn: Make fetch ~1.7x faster

Eric Wong wrote:

Adam Roben [off-list ref] wrote:
  

quoted

+package Git::Commands;
    

Can this be a separate file, or a part of Git.pm?  I'm sure other
scripts can eventually use this and I've been meaning to split
git-svn.perl into separate files so it's easier to follow.
  

I had considered doing one of the above, but decided that splitting it 
out could be done if/when it was deemed useful for another script. But 
I'll split it out since you think it's a good idea.

quoted

+use vars qw/$_cat_blob_pid $_cat_blob_in $_cat_blob_out $_cat_blob_ctx $_cat_blob_separator
+	    $_hash_object_pid $_hash_object_in $_hash_object_out $_hash_object_ctx/;
    

I have trouble following long lines, and most of the git code also wraps
at 80-columns.  Dead-tree publishers got this concept right a long
time ago :)
  

Will fix.

quoted

+use strict;
+use warnings;
+use File::Temp qw/tempfile/;
+use Git qw/command_bidi_pipe command_close_bidi_pipe/;
+
+sub _open_cat_blob_if_needed {
+	return if defined($_cat_blob_pid);
+	$_cat_blob_separator = "--------------GITCATFILESEPARATOR-----------";
    

Brian brought this up already, but yes, having pre-defined separators
instead of explicitly-specified sizes makes it all too easy for a
malicious user to commit code that will break things for git-svn users.
  

Yup, will fix this. :-)

quoted

+sub hash_object {
+	my (undef, $fh) = @_;
+
+	my ($tmp_fh, $tmp_filename) = tempfile(UNLINK => 1);
+	while (my $line = <$fh>) {
+		print $tmp_fh $line;
+	}
+	close($tmp_fh);
    

Related to the above.  It's better to sysread()/syswrite() or
read()/print() in a loop with a predefined buffer size rather than to
use a readline() since you could be dealing with files with very long
lines or binaries with no newline characters in them at all.
  

Hm, OK. I'll look for similar code in git-svn and follow that.

quoted

+	_open_hash_object_if_needed();
+	print $_hash_object_out $tmp_filename . "\n";
    

Minor, but

	print $_hash_object_out $tmp_filename, "\n";

avoids creating a new string.
  

Good idea.

Thanks for the feedback! I'll send out some new patches sometime soon.

-Adam