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Extract Git::SVN::Migration from git-svn.
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Straight cut & paste.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
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Michael G. Schwern authored and Eric Wong committed Jul 27, 2012
1 parent b0e7525 commit b772cb9
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258 changes: 1 addition & 257 deletions git-svn.perl
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use Git::SVN;
use Git::SVN::Log;
use Git::SVN::Migration;
use Git::SVN::Utils qw(fatal can_compress);

use Git qw(
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}


package Git::SVN::Migration;
# these version numbers do NOT correspond to actual version numbers
# of git nor git-svn. They are just relative.
#
# v0 layout: .git/$id/info/url, refs/heads/$id-HEAD
#
# v1 layout: .git/$id/info/url, refs/remotes/$id
#
# v2 layout: .git/svn/$id/info/url, refs/remotes/$id
#
# v3 layout: .git/svn/$id, refs/remotes/$id
# - info/url may remain for backwards compatibility
# - this is what we migrate up to this layout automatically,
# - this will be used by git svn init on single branches
# v3.1 layout (auto migrated):
# - .rev_db => .rev_db.$UUID, .rev_db will remain as a symlink
# for backwards compatibility
#
# v4 layout: .git/svn/$repo_id/$id, refs/remotes/$repo_id/$id
# - this is only created for newly multi-init-ed
# repositories. Similar in spirit to the
# --use-separate-remotes option in git-clone (now default)
# - we do not automatically migrate to this (following
# the example set by core git)
#
# v5 layout: .rev_db.$UUID => .rev_map.$UUID
# - newer, more-efficient format that uses 24-bytes per record
# with no filler space.
# - use xxd -c24 < .rev_map.$UUID to view and debug
# - This is a one-way migration, repositories updated to the
# new format will not be able to use old git-svn without
# rebuilding the .rev_db. Rebuilding the rev_db is not
# possible if noMetadata or useSvmProps are set; but should
# be no problem for users that use the (sensible) defaults.
use strict;
use warnings;
use Carp qw/croak/;
use File::Path qw/mkpath/;
use File::Basename qw/dirname basename/;

our $_minimize;
use Git qw(
command
command_noisy
command_output_pipe
command_close_pipe
);

sub migrate_from_v0 {
my $git_dir = $ENV{GIT_DIR};
return undef unless -d $git_dir;
my ($fh, $ctx) = command_output_pipe(qw/rev-parse --symbolic --all/);
my $migrated = 0;
while (<$fh>) {
chomp;
my ($id, $orig_ref) = ($_, $_);
next unless $id =~ s#^refs/heads/(.+)-HEAD$#$1#;
next unless -f "$git_dir/$id/info/url";
my $new_ref = "refs/remotes/$id";
if (::verify_ref("$new_ref^0")) {
print STDERR "W: $orig_ref is probably an old ",
"branch used by an ancient version of ",
"git-svn.\n",
"However, $new_ref also exists.\n",
"We will not be able ",
"to use this branch until this ",
"ambiguity is resolved.\n";
next;
}
print STDERR "Migrating from v0 layout...\n" if !$migrated;
print STDERR "Renaming ref: $orig_ref => $new_ref\n";
command_noisy('update-ref', $new_ref, $orig_ref);
command_noisy('update-ref', '-d', $orig_ref, $orig_ref);
$migrated++;
}
command_close_pipe($fh, $ctx);
print STDERR "Done migrating from v0 layout...\n" if $migrated;
$migrated;
}

sub migrate_from_v1 {
my $git_dir = $ENV{GIT_DIR};
my $migrated = 0;
return $migrated unless -d $git_dir;
my $svn_dir = "$git_dir/svn";

# just in case somebody used 'svn' as their $id at some point...
return $migrated if -d $svn_dir && ! -f "$svn_dir/info/url";

print STDERR "Migrating from a git-svn v1 layout...\n";
mkpath([$svn_dir]);
print STDERR "Data from a previous version of git-svn exists, but\n\t",
"$svn_dir\n\t(required for this version ",
"($::VERSION) of git-svn) does not exist.\n";
my ($fh, $ctx) = command_output_pipe(qw/rev-parse --symbolic --all/);
while (<$fh>) {
my $x = $_;
next unless $x =~ s#^refs/remotes/##;
chomp $x;
next unless -f "$git_dir/$x/info/url";
my $u = eval { ::file_to_s("$git_dir/$x/info/url") };
next unless $u;
my $dn = dirname("$git_dir/svn/$x");
mkpath([$dn]) unless -d $dn;
if ($x eq 'svn') { # they used 'svn' as GIT_SVN_ID:
mkpath(["$git_dir/svn/svn"]);
print STDERR " - $git_dir/$x/info => ",
"$git_dir/svn/$x/info\n";
rename "$git_dir/$x/info", "$git_dir/svn/$x/info" or
croak "$!: $x";
# don't worry too much about these, they probably
# don't exist with repos this old (save for index,
# and we can easily regenerate that)
foreach my $f (qw/unhandled.log index .rev_db/) {
rename "$git_dir/$x/$f", "$git_dir/svn/$x/$f";
}
} else {
print STDERR " - $git_dir/$x => $git_dir/svn/$x\n";
rename "$git_dir/$x", "$git_dir/svn/$x" or
croak "$!: $x";
}
$migrated++;
}
command_close_pipe($fh, $ctx);
print STDERR "Done migrating from a git-svn v1 layout\n";
$migrated;
}

sub read_old_urls {
my ($l_map, $pfx, $path) = @_;
my @dir;
foreach (<$path/*>) {
if (-r "$_/info/url") {
$pfx .= '/' if $pfx && $pfx !~ m!/$!;
my $ref_id = $pfx . basename $_;
my $url = ::file_to_s("$_/info/url");
$l_map->{$ref_id} = $url;
} elsif (-d $_) {
push @dir, $_;
}
}
foreach (@dir) {
my $x = $_;
$x =~ s!^\Q$ENV{GIT_DIR}\E/svn/!!o;
read_old_urls($l_map, $x, $_);
}
}

sub migrate_from_v2 {
my @cfg = command(qw/config -l/);
return if grep /^svn-remote\..+\.url=/, @cfg;
my %l_map;
read_old_urls(\%l_map, '', "$ENV{GIT_DIR}/svn");
my $migrated = 0;

require Git::SVN;
foreach my $ref_id (sort keys %l_map) {
eval { Git::SVN->init($l_map{$ref_id}, '', undef, $ref_id) };
if ($@) {
Git::SVN->init($l_map{$ref_id}, '', $ref_id, $ref_id);
}
$migrated++;
}
$migrated;
}

sub minimize_connections {
require Git::SVN;
require Git::SVN::Ra;

my $r = Git::SVN::read_all_remotes();
my $new_urls = {};
my $root_repos = {};
foreach my $repo_id (keys %$r) {
my $url = $r->{$repo_id}->{url} or next;
my $fetch = $r->{$repo_id}->{fetch} or next;
my $ra = Git::SVN::Ra->new($url);

# skip existing cases where we already connect to the root
if (($ra->{url} eq $ra->{repos_root}) ||
($ra->{repos_root} eq $repo_id)) {
$root_repos->{$ra->{url}} = $repo_id;
next;
}

my $root_ra = Git::SVN::Ra->new($ra->{repos_root});
my $root_path = $ra->{url};
$root_path =~ s#^\Q$ra->{repos_root}\E(/|$)##;
foreach my $path (keys %$fetch) {
my $ref_id = $fetch->{$path};
my $gs = Git::SVN->new($ref_id, $repo_id, $path);

# make sure we can read when connecting to
# a higher level of a repository
my ($last_rev, undef) = $gs->last_rev_commit;
if (!defined $last_rev) {
$last_rev = eval {
$root_ra->get_latest_revnum;
};
next if $@;
}
my $new = $root_path;
$new .= length $path ? "/$path" : '';
eval {
$root_ra->get_log([$new], $last_rev, $last_rev,
0, 0, 1, sub { });
};
next if $@;
$new_urls->{$ra->{repos_root}}->{$new} =
{ ref_id => $ref_id,
old_repo_id => $repo_id,
old_path => $path };
}
}

my @emptied;
foreach my $url (keys %$new_urls) {
# see if we can re-use an existing [svn-remote "repo_id"]
# instead of creating a(n ugly) new section:
my $repo_id = $root_repos->{$url} || $url;

my $fetch = $new_urls->{$url};
foreach my $path (keys %$fetch) {
my $x = $fetch->{$path};
Git::SVN->init($url, $path, $repo_id, $x->{ref_id});
my $pfx = "svn-remote.$x->{old_repo_id}";

my $old_fetch = quotemeta("$x->{old_path}:".
"$x->{ref_id}");
command_noisy(qw/config --unset/,
"$pfx.fetch", '^'. $old_fetch . '$');
delete $r->{$x->{old_repo_id}}->
{fetch}->{$x->{old_path}};
if (!keys %{$r->{$x->{old_repo_id}}->{fetch}}) {
command_noisy(qw/config --unset/,
"$pfx.url");
push @emptied, $x->{old_repo_id}
}
}
}
if (@emptied) {
my $file = $ENV{GIT_CONFIG} || "$ENV{GIT_DIR}/config";
print STDERR <<EOF;
The following [svn-remote] sections in your config file ($file) are empty
and can be safely removed:
EOF
print STDERR "[svn-remote \"$_\"]\n" foreach @emptied;
}
}

sub migration_check {
migrate_from_v0();
migrate_from_v1();
migrate_from_v2();
minimize_connections() if $_minimize;
}

package Git::IndexInfo;
use strict;
use warnings;
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