about summary refs log tree commit
diff options
context:
space:
mode:
authorEric Wong <e@yhbt.net>2020-01-26 23:41:02 +0000
committerEric Wong <e@yhbt.net>2020-01-28 03:00:42 +0000
commit8122bd3803b7520ab5421df264406e670e3f902b (patch)
tree79684c51448c7c233dc89cab0a8b9ea7a9a61eca
parent436f9dfcd3e3d3e65cb882fd518634d9f95ac19c (diff)
downloadpublic-inbox-8122bd3803b7520ab5421df264406e670e3f902b.tar.gz
New epochs are the most likely to have loose objects.  git won't
be able to take advantage of pack indices and needs to scan
every alternate for the loose object via open/openat syscalls.
Those syscalls will add up some day when we've got hundreds or
thousands of epochs.
-rw-r--r--lib/PublicInbox/V2Writable.pm42
-rw-r--r--t/v2writable.t24
2 files changed, 55 insertions, 11 deletions
diff --git a/lib/PublicInbox/V2Writable.pm b/lib/PublicInbox/V2Writable.pm
index 9073d9ef..8ad71b54 100644
--- a/lib/PublicInbox/V2Writable.pm
+++ b/lib/PublicInbox/V2Writable.pm
@@ -663,23 +663,43 @@ sub fill_alternates ($$) {
         unless (-d $all) {
                 PublicInbox::Import::init_bare($all);
         }
-        my $alt = "$all/objects/info/alternates";
-        my %alts;
-        my @add;
+        my $info_dir = "$all/objects/info";
+        my $alt = "$info_dir/alternates";
+        my (%alt, $new);
+        my $mode = 0644;
         if (-e $alt) {
                 open(my $fh, '<', $alt) or die "open < $alt: $!\n";
-                %alts = map { chomp; $_ => 1 } (<$fh>);
+                $mode = (stat($fh))[2] & 07777;
+
+                # we assign a sort score to every alternate and favor
+                # the newest (highest numbered) one when we
+                my $score;
+                my $other = 0; # in case admin adds non-epoch repos
+                %alt = map {;
+                        if (m!\A\Q../../\E([0-9]+)\.git/objects\z!) {
+                                $score = $1 + 0;
+                        } else {
+                                $score = --$other;
+                        }
+                        $_ => $score;
+                } split(/\n+/, do { local $/; <$fh> });
         }
+
         foreach my $i (0..$epoch) {
                 my $dir = "../../git/$i.git/objects";
-                push @add, $dir if !$alts{$dir} && -d "$pfx/$i.git";
-        }
-        return unless @add;
-        open my $fh, '>>', $alt or die "open >> $alt: $!\n";
-        foreach my $dir (@add) {
-                print $fh "$dir\n" or die "print >> $alt: $!\n";
+                if (!exists($alt{$dir}) && -d "$pfx/$i.git") {
+                        $alt{$dir} = $i;
+                        $new = 1;
+                }
         }
-        close $fh or die "close $alt: $!\n";
+        return unless $new;
+
+        my ($fh, $tmp) = tempfile('alt-XXXXXXXX', DIR => $info_dir);
+        print $fh join("\n", sort { $alt{$b} <=> $alt{$a} } keys %alt), "\n"
+                or die "print $tmp: $!\n";
+        chmod($mode, $fh) or die "fchmod $tmp: $!\n";
+        close $fh or die "close $tmp $!\n";
+        rename($tmp, $alt) or die "rename $tmp => $alt: $!\n";
 }
 
 sub git_init {
diff --git a/t/v2writable.t b/t/v2writable.t
index 63f27f96..7ceaa6e4 100644
--- a/t/v2writable.t
+++ b/t/v2writable.t
@@ -284,4 +284,28 @@ eval {
 };
 ok($@, 'V2Writable fails on non-existent dir');
 
+{
+        my $v2w = PublicInbox::V2Writable->new($tmp, 1);
+        ok($v2w, 'creat flag works');
+        $v2w->{parallel} = 0;
+        $v2w->init_inbox(0);
+        my $alt = "$tmp->{inboxdir}/all.git/objects/info/alternates";
+        open my $fh, '>>', $alt or die $!;
+        print $fh "$inboxdir/all.git/objects\n" or die $!;
+        chmod(0664, $fh) or die "fchmod: $!";
+        close $fh or die $!;
+        open $fh, '<', $alt or die $!;
+        my $before = do { local $/; <$fh> };
+
+        ok($v2w->git_init(3), 'init a new epoch');
+        open $fh, '<', $alt or die $!;
+        my $after = do { local $/; <$fh> };
+        ok(index($after, $before) > 0,
+                'old contents preserved after adding epoch');
+        like($after, qr!\A[^\n]+?/3\.git/objects\n!s,
+                'first line is newest epoch');
+        my $mode = (stat($alt))[2] & 07777;
+        is($mode, 0664, sprintf('0%03o', $mode).' is 0664');
+}
+
 done_testing();