[PATCH 3/4] v2: support incremental indexing + purge

["Eric Wong (Contractor, The Linux Foundation)" <e@80x24.org>]

This is important for people running mirrors via "git fetch",
as they need to be kept up-to-date.  Purging is also now
supported in mirrors.

The short-lived "--regenerate" option is gone and is now
implicitly enabled as a result.  It's still cheap when
article number regeneration is unnecessary, as we track
the range for each git repository.
---
 MANIFEST                      |   1 +
 lib/PublicInbox/Import.pm     |   3 +-
 lib/PublicInbox/Msgmap.pm     |   5 +
 lib/PublicInbox/V2Writable.pm | 275 ++++++++++++++++++++++++++++++++----------
 script/public-inbox-convert   |   2 +-
 script/public-inbox-index     |  15 +--
 t/v2mirror.t                  | 176 +++++++++++++++++++++++++++
 t/v2reindex.t                 |  10 +-
 8 files changed, 406 insertions(+), 81 deletions(-)
 create mode 100644 t/v2mirror.t

diff --git a/MANIFEST b/MANIFEST
index 2dad988..b17f1be 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -193,6 +193,7 @@ t/time.t
 t/utf8.mbox
 t/v2-add-remove-add.t
 t/v2mda.t
+t/v2mirror.t
 t/v2reindex.t
 t/v2writable.t
 t/view.t
diff --git a/lib/PublicInbox/Import.pm b/lib/PublicInbox/Import.pm
index 73290ee..2529798 100644
--- a/lib/PublicInbox/Import.pm
+++ b/lib/PublicInbox/Import.pm
@@ -192,6 +192,7 @@ sub get_mark {
 	my ($r, $w) = $self->gfi_start;
 	print $w "get-mark $mark\n" or wfail;
 	defined(my $oid = <$r>) or die "get-mark failed, need git 2.6.0+\n";
+	chomp($oid);
 	$oid;
 }
 
@@ -379,7 +380,7 @@ sub add {
 
 	# v2: we need this for Xapian
 	if ($self->{want_object_info}) {
-		chomp(my $oid = $self->get_mark(":$blob"));
+		my $oid = $self->get_mark(":$blob");
 		$self->{last_object} = [ $oid, $n, \$str ];
 	}
 	my $ref = $self->{ref};
diff --git a/lib/PublicInbox/Msgmap.pm b/lib/PublicInbox/Msgmap.pm
index c6a7315..5c37e16 100644
--- a/lib/PublicInbox/Msgmap.pm
+++ b/lib/PublicInbox/Msgmap.pm
@@ -92,6 +92,11 @@ sub last_commit {
 	$self->meta_accessor('last_commit', $commit);
 }
 
+sub last_commit_n {
+	my ($self, $i, $commit) = @_;
+	$self->meta_accessor('last_commit'.$i, $commit);
+}
+
 sub created_at {
 	my ($self, $second) = @_;
 	$self->meta_accessor('created_at', $second);
diff --git a/lib/PublicInbox/V2Writable.pm b/lib/PublicInbox/V2Writable.pm
index b6532ac..5b4d9c0 100644
--- a/lib/PublicInbox/V2Writable.pm
+++ b/lib/PublicInbox/V2Writable.pm
@@ -15,6 +15,7 @@ use PublicInbox::ContentId qw(content_id content_digest);
 use PublicInbox::Inbox;
 use PublicInbox::OverIdxFork;
 use PublicInbox::Msgmap;
+use PublicInbox::Spawn;
 use IO::Handle;
 
 # an estimate of the post-packed size to the raw uncompressed size
@@ -63,6 +64,7 @@ sub new {
 		lock_path => "$dir/inbox.lock",
 		# limit each repo to 1GB or so
 		rotate_bytes => int((1024 * 1024 * 1024) / $PACKING_FACTOR),
+		last_commit => [],
 	};
 	bless $self, $class;
 }
@@ -105,6 +107,7 @@ sub add {
 
 	my $nparts = $self->{partitions};
 	my $part = $num % $nparts;
+	$self->{last_commit}->[$self->{max_git}] = $cmt;
 	my $idx = $self->idx_part($part);
 	$idx->index_raw($len, $msgref, $num, $oid, $mid0, $mime);
 	my $n = $self->{transact_bytes} += $len;
@@ -112,7 +115,7 @@ sub add {
 		$self->checkpoint;
 	}
 
-	$mime;
+	$cmt;
 }
 
 sub num_for {
@@ -227,7 +230,7 @@ sub purge_oids {
 	my $purges = [];
 	foreach my $i (0..$self->{max_git}) {
 		my $git = PublicInbox::Git->new("$pfx/$i.git");
-		my $im = $self->import_init($git, 0);
+		my $im = $self->import_init($git, 0, 1);
 		$purges->[$i] = $im->purge_oids($purge);
 	}
 	$purges;
@@ -250,6 +253,7 @@ sub remove_internal {
 	# can be slightly different, so we do not need the user-supplied
 	# message now that we have the mids and content_id
 	$mime = undef;
+	my $mark;
 
 	foreach my $mid (@$mids) {
 		$srch->reopen->each_smsg_by_mid($mid, sub {
@@ -272,7 +276,8 @@ sub remove_internal {
 				if ($purge) {
 					$purge->{$oid} = 1;
 				} else {
-					$im->remove(\$orig, $cmt_msg);
+					($mark, undef) =
+						$im->remove(\$orig, $cmt_msg);
 				}
 				$orig = undef;
 				$removed->num; # memoize this for callers
@@ -286,6 +291,11 @@ sub remove_internal {
 		});
 		$self->barrier;
 	}
+
+	if (defined $mark) {
+		my $cmt = $im->get_mark($mark);
+		$self->{last_commit}->[$self->{max_git}] = $cmt;
+	}
 	if ($purge && scalar keys %$purge) {
 		return purge_oids($self, $purge);
 	}
@@ -299,18 +309,34 @@ sub remove {
 
 sub purge {
 	my ($self, $mime) = @_;
-	remove_internal($self, $mime, undef, {});
+	my $purges = remove_internal($self, $mime, undef, {});
+	$self->idx_init if @$purges; # ->done is called on purges
+	for my $i (0..$#$purges) {
+		defined(my $cmt = $purges->[$i]) or next;
+		$self->{last_commit}->[$i] = $cmt;
+	}
+	$purges;
 }
 
+sub set_last_commits ($) {
+	my ($self) = @_;
+	defined(my $max_git = $self->{max_git}) or return;
+	my $mm = $self->{mm};
+	my $last_commit = $self->{last_commit};
+	foreach my $i (0..$max_git) {
+		defined(my $cmt = $last_commit->[$i]) or next;
+		$last_commit->[$i] = undef;
+		$mm->last_commit_n($i, $cmt);
+	}
+}
 
 sub done {
 	my ($self) = @_;
 	my $im = delete $self->{im};
 	$im->done if $im; # PublicInbox::Import::done
 
-	if (my $mm = delete $self->{mm}) {
-		$mm->{dbh}->commit;
-	}
+	my $mm = $self->{mm};
+	$mm->{dbh}->commit if $mm;
 
 	# order matters, we can only close {over} after all partitions
 	# are done because the partitions also write to {over}
@@ -323,6 +349,14 @@ sub done {
 	my $over = $self->{over};
 	$over->remote_commit;
 	$over->remote_close;
+
+	if ($mm) {
+		$mm->{dbh}->begin_work;
+		set_last_commits($self);
+		$mm->{dbh}->commit;
+		delete $self->{mm};
+	}
+
 	$self->{transact_bytes} = 0;
 	$self->lock_release if $parts;
 }
@@ -358,6 +392,12 @@ sub barrier {
 		$over->barrier_wait; # wait for each Xapian partition
 		$over->commit_fsync if $fsync;
 
+		# last_commit is special, don't commit these until
+		# remote partitions are done:
+		$dbh->begin_work;
+		set_last_commits($self);
+		$dbh->commit;
+
 		$dbh->begin_work;
 	}
 	$self->{transact_bytes} = 0;
@@ -449,13 +489,14 @@ sub importer {
 }
 
 sub import_init {
-	my ($self, $git, $packed_bytes) = @_;
+	my ($self, $git, $packed_bytes, $tmp) = @_;
 	my $im = PublicInbox::Import->new($git, undef, undef, $self->{-inbox});
 	$im->{bytes_added} = int($packed_bytes / $PACKING_FACTOR);
 	$im->{want_object_info} = 1;
 	$im->{lock_path} = undef;
 	$im->{path_type} = 'v2';
-	$self->{im} = $im;
+	$self->{im} = $im unless $tmp;
+	$im;
 }
 
 # XXX experimental
@@ -608,63 +649,181 @@ sub reindex_oid {
 	}
 }
 
-sub reindex {
-	my ($self, $regen) = @_;
+# only update last_commit for $i on reindex iff newer than current
+sub update_last_commit {
+	my ($self, $git, $i, $cmt) = @_;
+	my $last = $self->{mm}->last_commit_n($i);
+	if (defined $last && is_ancestor($git, $last, $cmt)) {
+		my @cmd = (qw(rev-list --count), "$last..$cmt");
+		chomp(my $n = $git->qx(@cmd));
+		return if $n ne '' && $n == 0;
+	}
+	$self->{mm}->last_commit_n($i, $cmt);
+}
+
+sub git_dir_n ($$) { "$_[0]->{-inbox}->{mainrepo}/git/$_[1].git" }
+
+sub last_commits {
+	my ($self, $max_git) = @_;
+	my $heads = [];
+	for (my $i = $max_git; $i >= 0; $i--) {
+		$heads->[$i] = $self->{mm}->last_commit_n($i);
+	}
+	$heads;
+}
+
+sub is_ancestor ($$$) {
+	my ($git, $cur, $tip) = @_;
+	return 0 unless $git->check($cur);
+	my $cmd = [ 'git', "--git-dir=$git->{git_dir}",
+		qw(merge-base --is-ancestor), $cur, $tip ];
+	my $pid = spawn($cmd);
+	defined $pid or die "spawning ".join(' ', @$cmd)." failed: $!";
+	waitpid($pid, 0) == $pid or die join(' ', @$cmd) .' did not finish';
+	$? == 0;
+}
+
+sub index_prepare {
+	my ($self, $opts, $max_git, $ranges) = @_;
+	my $regen_max = 0;
+	my $head = $self->{-inbox}->{ref_head} || 'refs/heads/master';
+	for (my $i = $max_git; $i >= 0; $i--) {
+		die "already indexing!\n" if $self->{index_pipe};
+		my $git_dir = git_dir_n($self, $i);
+		-d $git_dir or next; # missing parts are fine
+		my $git = PublicInbox::Git->new($git_dir);
+		chomp(my $tip = $git->qx('rev-parse', $head));
+		my $range;
+		if (defined(my $cur = $ranges->[$i])) {
+			$range = "$cur..$tip";
+			if (is_ancestor($git, $cur, $tip)) { # common case
+				my $n = $git->qx(qw(rev-list --count), $range);
+				chomp($n);
+				if ($n == 0) {
+					$ranges->[$i] = undef;
+					next;
+				}
+			} else {
+				warn <<"";
+discontiguous range: $range
+Rewritten history? (in $git_dir)
+
+				my $base = $git->qx('merge-base', $tip, $cur);
+				chomp $base;
+				if ($base) {
+					$range = "$base..$tip";
+					warn "found merge-base: $base\n"
+				} else {
+					$range = $tip;
+					warn <<"";
+discarding history at $cur
+
+				}
+				warn <<"";
+reindexing $git_dir starting at
+$range
+
+				$self->{"unindex-range.$i"} = "$base..$cur";
+			}
+		} else {
+			$range = $tip; # all of it
+		}
+		$ranges->[$i] = $range;
+
+		# can't use 'rev-list --count' if we use --diff-filter
+		my $fh = $git->popen(qw(log --pretty=tformat:%h
+				--no-notes --no-color --no-renames
+				--diff-filter=AM), $range, '--', 'm');
+		++$regen_max while <$fh>;
+	}
+	\$regen_max;
+}
+
+sub unindex_oid {
+	my ($self, $git, $oid) = @_;
+	my $msgref = $git->cat_file($oid);
+	my $mime = PublicInbox::MIME->new($msgref);
+	my $mids = mids($mime->header_obj);
+	$mime = $msgref = undef;
+
+	foreach my $mid (@$mids) {
+		my %gone;
+		$self->{-inbox}->search->reopen->each_smsg_by_mid($mid, sub {
+			my ($smsg) = @_;
+			$smsg->load_expand;
+			$gone{$smsg->num} = 1 if $oid eq $smsg->{blob};
+			1; # continue
+		});
+		my $n = scalar keys %gone;
+		next unless $n;
+		if ($n > 1) {
+			warn "BUG: multiple articles linked to $oid\n",
+				join(',',sort keys %gone), "\n";
+		}
+		$self->{unindexed}->{$_}++ foreach keys %gone;
+		$_->remote_remove($oid, $mid) foreach @{$self->{idx_parts}};
+		$self->{over}->remove_oid($oid, $mid);
+		$self->barrier;
+	}
+}
+
+my $x40 = qr/[a-f0-9]{40}/;
+sub unindex {
+	my ($self, $opts, $git, $unindex_range) = @_;
+	my $un = $self->{unindexed} ||= {}; # num => removal count
+	$self->barrier;
+	my $before = scalar keys %$un;
+	my @cmd = qw(log --raw -r
+			--no-notes --no-color --no-abbrev --no-renames);
+	my $fh = $self->{reindex_pipe} = $git->popen(@cmd, $unindex_range);
+	while (<$fh>) {
+		/\A:\d{6} 100644 $x40 ($x40) [AM]\tm$/o or next;
+		$self->unindex_oid($git, $1);
+	}
+	delete $self->{reindex_pipe};
+	$fh = undef;
+
+	return unless $opts->{prune};
+	my $after = scalar keys %$un;
+	return if $before == $after;
+
+	# ensure any blob can not longer be accessed via dumb HTTP
+	PublicInbox::Import::run_die(['git', "--git-dir=$git->{git_dir}",
+		qw(-c gc.reflogExpire=now gc --prune=all)]);
+}
+
+sub index_sync {
+	my ($self, $opts) = @_;
+	$opts ||= {};
 	my $ibx = $self->{-inbox};
-	my $pfx = "$ibx->{mainrepo}/git";
 	my $max_git;
 	my $latest = git_dir_latest($self, \$max_git);
 	return unless defined $latest;
-	my $head = $ibx->{ref_head} || 'refs/heads/master';
 	$self->idx_init; # acquire lock
-	my $x40 = qr/[a-f0-9]{40}/;
 	my $mm_tmp = $self->{mm}->tmp_clone;
-	if (!$regen) {
-		my (undef, $max) = $mm_tmp->minmax;
-		unless (defined $max) {
-			$regen = 1;
-			warn
-"empty msgmap.sqlite3, regenerating article numbers\n";
-		}
-	}
-	my $tip; # latest commit out of all git repos
-	if ($regen) {
-		my $regen_max = 0;
-		for (my $cur = $max_git; $cur >= 0; $cur--) {
-			die "already reindexing!\n" if $self->{reindex_pipe};
-			my $git = PublicInbox::Git->new("$pfx/$cur.git");
-			-d $git->{git_dir} or next; # missing parts are fine
-			chomp($tip = $git->qx('rev-parse', $head)) unless $tip;
-			my $h = $cur == $max_git ? $tip : $head;
-
-			# can't use 'rev-list --count' if we use --diff-filter
-			my $fh = $git->popen(qw(log --pretty=tformat:%h
-					--no-notes --no-color --no-renames
-					--diff-filter=AM), $h, '--', 'm');
-			++$regen_max while <$fh>;
-		}
-		die "No messages found in $pfx/*.git, bug?\n" unless $regen_max;
-		$regen = \$regen_max;
-	}
+	my $ranges = $opts->{reindex} ? [] : $self->last_commits($max_git);
+
+	my ($min, $max) = $mm_tmp->minmax;
+	my $regen = $self->index_prepare($opts, $max_git, $ranges);
+	$$regen += $max if $max;
 	my $D = {};
 	my @cmd = qw(log --raw -r --pretty=tformat:%h
 			--no-notes --no-color --no-abbrev --no-renames);
 
-	# if we are regenerating, we must not use a newer tip commit than what
-	# the regeneration counter used:
-	$tip ||= $head;
-
 	# work backwards through history
-	for (my $cur = $max_git; $cur >= 0; $cur--) {
+	my $last_commit = [];
+	for (my $i = $max_git; $i >= 0; $i--) {
+		my $git_dir = git_dir_n($self, $i);
 		die "already reindexing!\n" if delete $self->{reindex_pipe};
-		my $cmt;
-		my $git_dir = "$pfx/$cur.git";
 		-d $git_dir or next; # missing parts are fine
 		my $git = PublicInbox::Git->new($git_dir);
-		my $h = $cur == $max_git ? $tip : $head;
-		my $fh = $self->{reindex_pipe} = $git->popen(@cmd, $h);
+		my $unindex = delete $self->{"unindex-range.$i"};
+		$self->unindex($opts, $git, $unindex) if $unindex;
+		defined(my $range = $ranges->[$i]) or next;
+		my $fh = $self->{reindex_pipe} = $git->popen(@cmd, $range);
+		my $cmt;
 		while (<$fh>) {
-			if (/\A$x40$/o) {
+			if (/\A$x40$/o && !defined($cmt)) {
 				chomp($cmt = $_);
 			} elsif (/\A:\d{6} 100644 $x40 ($x40) [AM]\tm$/o) {
 				$self->reindex_oid($mm_tmp, $D, $git, $1,
@@ -673,19 +832,10 @@ sub reindex {
 				$self->mark_deleted($D, $git, $1);
 			}
 		}
+		$fh = undef;
 		delete $self->{reindex_pipe};
+		$self->update_last_commit($git, $i, $cmt) if defined $cmt;
 	}
-	my $gaps;
-	if ($regen && $$regen != 0) {
-		warn "W: leftover article number ($$regen)\n";
-		$gaps = 1;
-	}
-	my ($min, $max) = $mm_tmp->minmax;
-	if (defined $max) {
-		warn "W: leftover article numbers at $min..$max\n";
-		$gaps = 1;
-	}
-	warn "W: were old git partitions deleted?\n" if $gaps;
 	my @d = sort keys %$D;
 	if (@d) {
 		warn "BUG: ", scalar(@d)," unseen deleted messages marked\n";
@@ -694,6 +844,7 @@ sub reindex {
 			warn "<$mid>\n";
 		}
 	}
+	$self->done;
 }
 
 1;
diff --git a/script/public-inbox-convert b/script/public-inbox-convert
index 56ac44f..9aa2781 100755
--- a/script/public-inbox-convert
+++ b/script/public-inbox-convert
@@ -125,6 +125,6 @@ my $mm = $old->mm;
 $mm->{dbh}->sqlite_backup_to_file("$new_dir/msgmap.sqlite3") if $mm;
 $v2w->done;
 if ($index) {
-	$v2w->reindex;
+	$v2w->index_sync;
 	$v2w->done;
 }
diff --git a/script/public-inbox-index b/script/public-inbox-index
index 52d6ba7..73f88ac 100755
--- a/script/public-inbox-index
+++ b/script/public-inbox-index
@@ -23,12 +23,12 @@ if ($@) {
 }
 
 my $reindex;
-my $regen;
+my $prune;
 my $jobs = undef;
 my %opts = (
 	'--reindex' => \$reindex,
-	'--regenerate' => \$regen,
 	'--jobs|j=i' => \$jobs,
+	'--prune' => \$prune,
 );
 GetOptions(%opts) or die "bad command-line args\n$usage";
 die "--jobs must be positive\n" if defined $jobs && $jobs <= 0;
@@ -115,16 +115,7 @@ sub index_dir {
 				}
 			}
 		}
-		my $mm = $repo->mm;
-		my (undef, $max) = $mm->minmax if $mm;
-		if (defined($max) && !$reindex && !$regen) {
-			die
-"v2 inboxes may only use --reindex and/or --regenerate once\n".
-"msgmap.sqlite3 is initialized\n";
-		}
-
-		$v2w->reindex($regen);
-		$v2w->done;
+		$v2w->index_sync({ reindex => $reindex, prune => $prune });
 	} else {
 		my $s = PublicInbox::SearchIdx->new($repo, 1);
 		$s->index_sync({ reindex => $reindex });
diff --git a/t/v2mirror.t b/t/v2mirror.t
new file mode 100644
index 0000000..0c66aef
--- /dev/null
+++ b/t/v2mirror.t
@@ -0,0 +1,176 @@
+# Copyright (C) 2018 all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+use strict;
+use warnings;
+use Test::More;
+
+# Integration tests for HTTP cloning + mirroring
+foreach my $mod (qw(Plack::Util Plack::Builder Danga::Socket
+			HTTP::Date HTTP::Status Search::Xapian DBD::SQLite)) {
+	eval "require $mod";
+	plan skip_all => "$mod missing for v2mirror.t" if $@;
+}
+use File::Temp qw/tempdir/;
+use IO::Socket;
+use POSIX qw(dup2);
+use PublicInbox::V2Writable;
+use PublicInbox::MIME;
+use PublicInbox::Config;
+use Fcntl qw(FD_CLOEXEC F_SETFD F_GETFD);
+# FIXME: too much setup
+my $tmpdir = tempdir('pi-v2mirror-XXXXXX', TMPDIR => 1, CLEANUP => 1);
+my $script = 'blib/script/public-inbox';
+my $pi_config = "$tmpdir/config";
+{
+	open my $fh, '>', $pi_config or die "open($pi_config): $!";
+	print $fh <<"" or die "print $pi_config: $!";
+[publicinbox "v2"]
+	mainrepo = $tmpdir/in
+	address = test\@example.com
+
+	close $fh or die "close($pi_config): $!";
+}
+local $ENV{PI_CONFIG} = $pi_config;
+
+my $cfg = PublicInbox::Config->new($pi_config);
+my $ibx = $cfg->lookup('test@example.com');
+ok($ibx, 'inbox found');
+$ibx->{version} = 2;
+my $v2w = PublicInbox::V2Writable->new($ibx, 1);
+ok $v2w, 'v2w loaded';
+$v2w->{parallel} = 0;
+my $mime = PublicInbox::MIME->new(<<'');
+From: Me <me@example.com>
+To: You <you@example.com>
+Subject: a
+Date: Thu, 01 Jan 1970 00:00:00 +0000
+
+for my $i (1..9) {
+	$mime->header_set('Message-ID', "<$i\@example.com>");
+	$mime->header_set('Subject', "subject = $i");
+	ok($v2w->add($mime), "add msg $i OK");
+}
+$v2w->barrier;
+
+my %opts = (
+	LocalAddr => '127.0.0.1',
+	ReuseAddr => 1,
+	Proto => 'tcp',
+	Listen => 1024,
+);
+my ($sock, $pid);
+END { kill 'TERM', $pid if defined $pid };
+
+$! = 0;
+$sock = IO::Socket::INET->new(%opts);
+ok($sock, 'sock created');
+my $fl = fcntl($sock, F_GETFD, 0);
+$pid = fork;
+if ($pid == 0) {
+	# pretend to be systemd
+	fcntl($sock, F_SETFD, $fl &= ~FD_CLOEXEC);
+	dup2(fileno($sock), 3) or die "dup2 failed: $!\n";
+	$ENV{LISTEN_PID} = $$;
+	$ENV{LISTEN_FDS} = 1;
+	exec "$script-httpd", "--stdout=$tmpdir/out", "--stderr=$tmpdir/err";
+	die "FAIL: $!\n";
+}
+ok(defined $pid, 'forked httpd process successfully');
+my ($host, $port) = ($sock->sockhost, $sock->sockport);
+$sock = undef;
+
+my @cmd = (qw(git clone --mirror -q), "http://$host:$port/v2/0",
+	"$tmpdir/m/git/0.git");
+
+is(system(@cmd), 0, 'cloned OK');
+ok(-d "$tmpdir/m/git/0.git", 'mirror OK');;
+
+@cmd = ("$script-init", '-V2', 'm', "$tmpdir/m", 'http://example.com/m',
+	'alt@example.com');
+is(system(@cmd), 0, 'initialized public-inbox -V2');
+is(system("$script-index", "$tmpdir/m"), 0, 'indexed');
+
+my $mibx = { mainrepo => "$tmpdir/m", address => 'alt@example.com' };
+$mibx = PublicInbox::Inbox->new($mibx);
+is_deeply([$mibx->mm->minmax], [$ibx->mm->minmax], 'index synched minmax');
+
+for my $i (10..15) {
+	$mime->header_set('Message-ID', "<$i\@example.com>");
+	$mime->header_set('Subject', "subject = $i");
+	ok($v2w->add($mime), "add msg $i OK");
+}
+$v2w->barrier;
+is(system('git', "--git-dir=$tmpdir/m/git/0.git", 'fetch', '-q'), 0,
+	'fetch successful');
+
+my $mset = $mibx->search->reopen->query('m:15@example.com', {mset => 1});
+is(scalar($mset->items), 0, 'new message not found in mirror, yet');
+is(system("$script-index", "$tmpdir/m"), 0, 'index updated');
+is_deeply([$mibx->mm->minmax], [$ibx->mm->minmax], 'index synched minmax');
+$mset = $mibx->search->reopen->query('m:15@example.com', {mset => 1});
+is(scalar($mset->items), 1, 'found message in mirror');
+
+# purge:
+$mime->header_set('Message-ID', '<10@example.com>');
+$mime->header_set('Subject', 'subject = 10');
+{
+	my @warn;
+	local $SIG{__WARN__} = sub { push @warn, @_ };
+	ok($v2w->purge($mime), 'purge a message');
+	my $warn = join('', @warn);
+	like($warn, qr/purge rewriting/);
+	my @subj = ($warn =~ m/^# subject .*$/mg);
+	is_deeply(\@subj, ["# subject = 10"], "only rewrote one");
+}
+
+$v2w->barrier;
+
+my $msgs = $mibx->search->{over_ro}->get_thread('10@example.com');
+my $to_purge = $msgs->[0]->{blob};
+like($to_purge, qr/\A[a-f0-9]{40,}\z/, 'read blob to be purged');
+$mset = $ibx->search->reopen->query('m:10@example.com', {mset => 1});
+is(scalar($mset->items), 0, 'purged message gone from origin');
+
+is(system('git', "--git-dir=$tmpdir/m/git/0.git", 'fetch', '-q'), 0,
+	'fetch successful');
+{
+	open my $err, '+>', "$tmpdir/index-err" or die "open: $!";
+	my $ipid = fork;
+	if ($ipid == 0) {
+		dup2(fileno($err), 2) or die "dup2 failed: $!";
+		exec("$script-index", '--prune', "$tmpdir/m");
+		die "exec fail: $!";
+	}
+	ok($ipid, 'running index..');
+	is(waitpid($ipid, 0), $ipid, 'index --prune done');
+	is($?, 0, 'no error from index');
+	ok(seek($err, 0, 0), 'rewound stderr');
+	$err = eval { local $/; <$err> };
+	like($err, qr/discontiguous range/, 'warned about discontiguous range');
+	unlike($err, qr/fatal/, 'no scary fatal error shown');
+}
+
+$mset = $mibx->search->reopen->query('m:10@example.com', {mset => 1});
+is(scalar($mset->items), 0, 'purged message not found in mirror');
+is_deeply([$mibx->mm->minmax], [$ibx->mm->minmax], 'minmax still synced');
+for my $i ((1..9),(11..15)) {
+	$mset = $mibx->search->query("m:$i\@example.com", {mset => 1});
+	is(scalar($mset->items), 1, "$i\@example.com remains visible");
+}
+is($mibx->git->check($to_purge), undef, 'unindex+prune successful in mirror');
+
+{
+	my @warn;
+	local $SIG{__WARN__} = sub { push @warn, @_ };
+	$v2w->index_sync;
+	is_deeply(\@warn, [], 'no warnings from index_sync after purge');
+}
+
+$v2w->done;
+ok(kill('TERM', $pid), 'killed httpd');
+$pid = undef;
+waitpid(-1, 0);
+
+done_testing();
+
+1;
diff --git a/t/v2reindex.t b/t/v2reindex.t
index bf44fa0..9bc271f 100644
--- a/t/v2reindex.t
+++ b/t/v2reindex.t
@@ -49,14 +49,14 @@ $im->done;
 my $minmax = [ $ibx->mm->minmax ];
 ok(defined $minmax->[0] && defined $minmax->[1], 'minmax defined');
 
-eval { $im->reindex };
+eval { $im->index_sync({reindex => 1}) };
 is($@, '', 'no error from reindexing');
 $im->done;
 
 my $xap = "$mainrepo/xap".PublicInbox::Search::SCHEMA_VERSION();
 remove_tree($xap);
 ok(!-d $xap, 'Xapian directories removed');
-eval { $im->reindex };
+eval { $im->index_sync({reindex => 1}) };
 is($@, '', 'no error from reindexing');
 $im->done;
 ok(-d $xap, 'Xapian directories recreated');
@@ -70,9 +70,9 @@ ok(!-d $xap, 'Xapian directories removed again');
 {
 	my @warn;
 	local $SIG{__WARN__} = sub { push @warn, @_ };
-	eval { $im->reindex };
+	eval { $im->index_sync({reindex => 1}) };
 	is($@, '', 'no error from reindexing without msgmap');
-	like(join(' ', @warn), qr/regenerat/, 'warned about regenerating');
+	is(scalar(@warn), 0, 'no warnings from reindexing');
 	$im->done;
 	ok(-d $xap, 'Xapian directories recreated');
 	delete $ibx->{mm};
@@ -85,7 +85,7 @@ ok(!-d $xap, 'Xapian directories removed again');
 {
 	my @warn;
 	local $SIG{__WARN__} = sub { push @warn, @_ };
-	eval { $im->reindex(my $regen = 1) };
+	eval { $im->index_sync({reindex => 1}) };
 	is($@, '', 'no error from reindexing without msgmap');
 	is_deeply(\@warn, [], 'no warnings');
 	$im->done;
-- 
EW