v2writable: support purging messages from git entirely

Purging existing messages is fairly straightforward since we can
take advantage of Xapian and lookup the git object_id with it.

Unfortunately, purging an already "removed" message (which is
no longer in Xapian) is not as easy and we'll need to expose
->purge_oids to purge by the git object_id (currently SHA-1).

Furthermore, we expire reflogs and prune in hopes a dumb HTTP
client won't get the object.

diff --git a/lib/PublicInbox/Import.pm b/lib/PublicInbox/Import.pm
index e07eddab4f245a2a47f368d5dd223d26e2a56770..f00c260b55a96d1ea6e9b2ec55a628e992017379 100644 (file)
--- a/lib/PublicInbox/Import.pm
+++ b/lib/PublicInbox/Import.pm
@@ -430,6 +430,96 @@ sub digest2mid ($) {
        $b64 . '@localhost';
 }
 
+sub clean_purge_buffer {
+       my ($oid, $buf) = @_;
+       my $cmt_msg = "purged $oid\n";
+
+       foreach my $i (0..$#$buf) {
+               my $l = $buf->[$i];
+               if ($l =~ /^author .* (\d+ [\+-]?\d+)$/) {
+                       $buf->[$i] = "author <> $1\n";
+               } elsif ($l =~ /^data (\d+)/) {
+                       $buf->[$i++] = "data " . length($cmt_msg) . "\n";
+                       $buf->[$i] = $cmt_msg;
+                       last;
+               }
+       }
+}
+
+sub purge_oids {
+       my ($self, $purge) = @_;
+       my $tmp = "refs/heads/purge-".((keys %$purge)[0]);
+       my $old = $self->{'ref'};
+       my $git = $self->{git};
+       my @export = (qw(fast-export --no-data --use-done-feature), $old);
+       my ($rd, $pid) = $git->popen(@export);
+       my ($r, $w) = $self->gfi_start;
+       my @buf;
+       my $npurge = 0;
+       while (<$rd>) {
+               if (/^reset (?:.+)/) {
+                       push @buf, "reset $tmp\n";
+               } elsif (/^commit (?:.+)/) {
+                       if (@buf) {
+                               $w->print(@buf) or wfail;
+                               @buf = ();
+                       }
+                       push @buf, "commit $tmp\n";
+               } elsif (/^data (\d+)/) {
+                       # only commit message, so $len is small:
+                       my $len = $1; # + 1 for trailing "\n"
+                       push @buf, $_;
+                       my $n = read($rd, my $buf, $len) or die "read: $!";
+                       $len == $n or die "short read ($n < $len)";
+                       push @buf, $buf;
+               } elsif (/^M 100644 ([a-f0-9]+) /) {
+                       my $oid = $1;
+                       if ($purge->{$oid}) {
+                               my $lf = <$rd>;
+                               if ($lf eq "\n") {
+                                       my $out = join('', @buf);
+                                       $out =~ s/^/# /sgm;
+                                       warn "purge rewriting\n", $out, "\n";
+                                       clean_purge_buffer($oid, \@buf);
+                                       $out = join('', @buf);
+                                       $w->print(@buf, "\n") or wfail;
+                                       @buf = ();
+                                       $npurge++;
+                               } else {
+                                       die "expected LF: $lf\n";
+                               }
+                       } else {
+                               push @buf, $_;
+                       }
+               } else {
+                       push @buf, $_;
+               }
+       }
+       if (@buf) {
+               $w->print(@buf) or wfail;
+       }
+       $w = $r = undef;
+       $self->done;
+       my @git = ('git', "--git-dir=$git->{git_dir}");
+
+       run_die([@git, qw(update-ref), $old, $tmp]) if $npurge;
+
+       run_die([@git, qw(update-ref -d), $tmp]);
+
+       return if $npurge == 0;
+
+       run_die([@git, qw(-c gc.reflogExpire=now gc --prune=all)]);
+       my $err = 0;
+       foreach my $oid (keys %$purge) {
+               my @info = $git->check($oid);
+               if (@info) {
+                       warn "$oid not purged\n";
+                       $err++;
+               }
+       }
+       die "Failed to purge $err object(s)\n" if $err;
+}
+
 1;
 __END__
 =pod

diff --git a/lib/PublicInbox/V2Writable.pm b/lib/PublicInbox/V2Writable.pm
index 9b280c686b547e303dde7245a34d6d9ed93b6a6d..ef9867de35ab225da985cdef5d3052832fcfd422 100644 (file)
--- a/lib/PublicInbox/V2Writable.pm
+++ b/lib/PublicInbox/V2Writable.pm
@@ -209,11 +209,22 @@ sub idx_init {
        $skel->_msgmap_init->{dbh}->begin_work;
 }
 
-sub remove {
-       my ($self, $mime, $cmt_msg) = @_;
+sub purge_oids {
+       my ($self, $purge) = @_; # $purge = { $object_id => 1, ... }
+       $self->done;
+       my $pfx = "$self->{-inbox}->{mainrepo}/git";
+       foreach my $i (0..$self->{max_git}) {
+               my $git = PublicInbox::Git->new("$pfx/$i.git");
+               my $im = $self->import_init($git, 0);
+               $im->purge_oids($purge);
+       }
+}
+
+sub remove_internal {
+       my ($self, $mime, $cmt_msg, $purge) = @_;
        $self->barrier;
        $self->idx_init;
-       my $im = $self->importer;
+       my $im = $self->importer unless $purge;
        my $ibx = $self->{-inbox};
        my $srch = $ibx->search;
        my $cid = content_id($mime);
@@ -245,11 +256,15 @@ sub remove {
                                # no bugs in our deduplication code:
                                $removed = $smsg;
                                $removed->{mime} = $cur;
-                               $im->remove(\$orig, $cmt_msg);
+                               my $oid = $smsg->{blob};
+                               if ($purge) {
+                                       $purge->{$oid} = 1;
+                               } else {
+                                       $im->remove(\$orig, $cmt_msg);
+                               }
                                $orig = undef;
                                $removed->num; # memoize this for callers
 
-                               my $oid = $smsg->{blob};
                                foreach my $idx (@$parts, $skel) {
                                        $idx->remote_remove($oid, $mid);
                                }
@@ -258,9 +273,23 @@ sub remove {
                });
                $self->barrier;
        }
+       if ($purge && scalar keys %$purge) {
+               purge_oids($self, $purge);
+       }
        $removed;
 }
 
+sub remove {
+       my ($self, $mime, $cmt_msg) = @_;
+       remove_internal($self, $mime, $cmt_msg);
+}
+
+sub purge {
+       my ($self, $mime) = @_;
+       remove_internal($self, $mime, undef, {});
+}
+
+
 sub done {
        my ($self) = @_;
        my $locked = defined $self->{idx_parts};

diff --git a/t/v2writable.t b/t/v2writable.t
index c48f060e87978e979fcc72ff64540e42412e104a..0eda432a81bcb0dd59fc7d9bd21a6527ccf4e797 100644 (file)
--- a/t/v2writable.t
+++ b/t/v2writable.t
@@ -231,4 +231,11 @@ EOF
        ok(!$@, '->done is idempotent');
 }
 
+{
+       ok($im->add($mime), 'add message to be purged');
+       local $SIG{__WARN__} = sub {};
+       ok($im->purge($mime), 'purged message');
+       $im->done;
+}
+
 done_testing();