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git-svn: Reduce temp file usage when dealing with non-links
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Currently, in sub 'close_file', git-svn creates a temporary file and
copies the contents of the blob to be written into it. This is useful
for symlinks because svn stores symlinks in the form:

link $FILE_PATH

Git creates a blob only out of '$FILE_PATH' and uses file mode to
indicate that the blob should be interpreted as a symlink.

As git-hash-object is invoked with --stdin-paths, a duplicate of the
link from svn must be created that leaves off the first five bytes,
i.e. 'link '. However, this is wholly unnecessary for normal blobs,
though, as we already have a temp file with their contents. Copying
the entire file gains nothing, and effectively requires a file to be
written twice before making it into the object db.

This patch corrects that issue, holding onto the substr-like
duplication for symlinks, but skipping it altogether for normal blobs
by reusing the existing temp file.

Signed-off-by: Marcus Griep <marcus@griep.us>
Acked-by: Eric Wong <normalperson@yhbt.net>
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Marcus Griep authored and Eric Wong committed Aug 13, 2008
1 parent 0b19138 commit 510b094
Showing 1 changed file with 22 additions and 24 deletions.
46 changes: 22 additions & 24 deletions git-svn.perl
Original file line number Diff line number Diff line change
@@ -3268,38 +3268,36 @@ sub close_file {
"expected: $exp\n got: $got\n";
}
}
sysseek($fh, 0, 0) or croak $!;
if ($fb->{mode_b} == 120000) {
eval {
sysread($fh, my $buf, 5) == 5 or croak $!;
$buf eq 'link ' or die "$path has mode 120000",
" but is not a link";
};
if ($@) {
warn "$@\n";
sysseek($fh, 0, 0) or croak $!;
}
}

my $tmp_fh = Git::temp_acquire('svn_hash');
my $result;
while ($result = sysread($fh, my $string, 1024)) {
my $wrote = syswrite($tmp_fh, $string, $result);
defined($wrote) && $wrote == $result
or croak("write ",
$tmp_fh->filename, ": $!\n");
}
defined $result or croak $!;
sysseek($fh, 0, 0) or croak $!;
sysread($fh, my $buf, 5) == 5 or croak $!;

unless ($buf eq 'link ') {
warn "$path has mode 120000",
" but is not a link\n";
} else {
my $tmp_fh = Git::temp_acquire('svn_hash');
my $res;
while ($res = sysread($fh, my $str, 1024)) {
my $out = syswrite($tmp_fh, $str, $res);
defined($out) && $out == $res
or croak("write ",
$tmp_fh->filename,
": $!\n");
}
defined $res or croak $!;

Git::temp_release($fh, 1);
($fh, $tmp_fh) = ($tmp_fh, $fh);
Git::temp_release($tmp_fh, 1);
}
}

$hash = $::_repository->hash_and_insert_object(
$tmp_fh->filename);
$fh->filename);
$hash =~ /^[a-f\d]{40}$/ or die "not a sha1: $hash\n";

Git::temp_release($fb->{base}, 1);
Git::temp_release($tmp_fh, 1);
Git::temp_release($fh, 1);
} else {
$hash = $fb->{blob} or die "no blob information\n";
}

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