X-Git-Url: http://www.git.stargrave.org/?a=blobdiff_plain;f=lib%2FPublicInbox%2FV2Writable.pm;h=2cc87305668256709f773415f750e5f52653503c;hb=017fed7bc4d33ac474a19356994be5bd0bfe68ba;hp=b6532ac5c9476540017f9ee9757cdc7c533cfb46;hpb=b4d127cb83230fe5cee0dcecb573107ad96a7c4c;p=public-inbox.git

diff --git a/lib/PublicInbox/V2Writable.pm b/lib/PublicInbox/V2Writable.pm
index b6532ac5..2cc87305 100644
--- a/lib/PublicInbox/V2Writable.pm
+++ b/lib/PublicInbox/V2Writable.pm
@@ -13,34 +13,31 @@ use PublicInbox::Import;
 use PublicInbox::MID qw(mids);
 use PublicInbox::ContentId qw(content_id content_digest);
 use PublicInbox::Inbox;
-use PublicInbox::OverIdxFork;
+use PublicInbox::OverIdx;
 use PublicInbox::Msgmap;
+use PublicInbox::Spawn qw(spawn);
+use PublicInbox::SearchIdx;
 use IO::Handle;
 
 # an estimate of the post-packed size to the raw uncompressed size
 my $PACKING_FACTOR = 0.4;
 
 # assume 2 cores if GNU nproc(1) is not available
-sub nproc () {
-	int($ENV{NPROC} || `nproc 2>/dev/null` || 2);
+sub nproc_parts () {
+	my $n = int($ENV{NPROC} || `nproc 2>/dev/null` || 2);
+	# subtract for the main process and git-fast-import
+	$n -= 1;
+	$n < 1 ? 1 : $n;
 }
 
-sub new {
-	my ($class, $v2ibx, $creat) = @_;
-	my $dir = $v2ibx->{mainrepo} or die "no mainrepo in inbox\n";
-	unless (-d $dir) {
-		if ($creat) {
-			require File::Path;
-			File::Path::mkpath($dir);
-		} else {
-			die "$dir does not exist\n";
-		}
-	}
-
+sub count_partitions ($) {
+	my ($self) = @_;
 	my $nparts = 0;
-	my $xpfx = "$dir/xap" . PublicInbox::Search::SCHEMA_VERSION;
+	my $xpfx = $self->{xpfx};
 
 	# always load existing partitions in case core count changes:
+	# Also, partition count may change while -watch is running
+	# due to -compact
 	if (-d $xpfx) {
 		foreach my $part (<$xpfx/*>) {
 			-d $part && $part =~ m!/\d+\z! or next;
@@ -50,20 +47,37 @@ sub new {
 			};
 		}
 	}
-	$nparts = nproc() if ($nparts == 0);
+	$nparts;
+}
+
+sub new {
+	my ($class, $v2ibx, $creat) = @_;
+	my $dir = $v2ibx->{mainrepo} or die "no mainrepo in inbox\n";
+	unless (-d $dir) {
+		if ($creat) {
+			require File::Path;
+			File::Path::mkpath($dir);
+		} else {
+			die "$dir does not exist\n";
+		}
+	}
 
 	$v2ibx = PublicInbox::InboxWritable->new($v2ibx);
+
+	my $xpfx = "$dir/xap" . PublicInbox::Search::SCHEMA_VERSION;
 	my $self = {
 		-inbox => $v2ibx,
 		im => undef, #  PublicInbox::Import
-		partitions => $nparts,
 		parallel => 1,
 		transact_bytes => 0,
-		over => PublicInbox::OverIdxFork->new("$xpfx/over.sqlite3"),
+		xpfx => $xpfx,
+		over => PublicInbox::OverIdx->new("$xpfx/over.sqlite3", 1),
 		lock_path => "$dir/inbox.lock",
-		# limit each repo to 1GB or so
+		# limit each git repo (epoch) to 1GB or so
 		rotate_bytes => int((1024 * 1024 * 1024) / $PACKING_FACTOR),
+		last_commit => [], # git repo -> commit
 	};
+	$self->{partitions} = count_partitions($self) || nproc_parts();
 	bless $self, $class;
 }
 
@@ -71,9 +85,9 @@ sub init_inbox {
 	my ($self, $parallel) = @_;
 	$self->{parallel} = $parallel;
 	$self->idx_init;
-	my $max_git = -1;
-	git_dir_latest($self, \$max_git);
-	$self->git_init($max_git >= 0 ? $max_git : 0);
+	my $epoch_max = -1;
+	git_dir_latest($self, \$epoch_max);
+	$self->git_init($epoch_max >= 0 ? $epoch_max : 0);
 	$self->done;
 }
 
@@ -101,8 +115,10 @@ sub add {
 	my $im = $self->importer;
 	my $cmt = $im->add($mime);
 	$cmt = $im->get_mark($cmt);
-	my ($oid, $len, $msgref) = @{$im->{last_object}};
+	$self->{last_commit}->[$self->{epoch_max}] = $cmt;
 
+	my ($oid, $len, $msgref) = @{$im->{last_object}};
+	$self->{over}->add_overview($mime, $len, $num, $oid, $mid0);
 	my $nparts = $self->{partitions};
 	my $part = $num % $nparts;
 	my $idx = $self->idx_part($part);
@@ -112,7 +128,7 @@ sub add {
 		$self->checkpoint;
 	}
 
-	$mime;
+	$cmt;
 }
 
 sub num_for {
@@ -127,7 +143,6 @@ sub num_for {
 		};
 
 		# crap, Message-ID is already known, hope somebody just resent:
-		$self->barrier;
 		foreach my $m (@$mids) {
 			# read-only lookup now safe to do after above barrier
 			my $existing = $self->lookup_content($mime, $m);
@@ -160,19 +175,19 @@ sub num_for_harder {
 
 	my $hdr = $mime->header_obj;
 	my $dig = content_digest($mime);
-	$$mid0 = PublicInbox::Import::digest2mid($dig);
+	$$mid0 = PublicInbox::Import::digest2mid($dig, $hdr);
 	my $num = $self->{mm}->mid_insert($$mid0);
 	unless (defined $num) {
 		# it's hard to spoof the last Received: header
 		my @recvd = $hdr->header_raw('Received');
 		$dig->add("Received: $_") foreach (@recvd);
-		$$mid0 = PublicInbox::Import::digest2mid($dig);
+		$$mid0 = PublicInbox::Import::digest2mid($dig, $hdr);
 		$num = $self->{mm}->mid_insert($$mid0);
 
 		# fall back to a random Message-ID and give up determinism:
 		until (defined($num)) {
 			$dig->add(rand);
-			$$mid0 = PublicInbox::Import::digest2mid($dig);
+			$$mid0 = PublicInbox::Import::digest2mid($dig, $hdr);
 			warn "using random Message-ID <$$mid0> as fallback\n";
 			$num = $self->{mm}->mid_insert($$mid0);
 		}
@@ -197,11 +212,23 @@ sub idx_init {
 	# frequently activated.
 	delete $ibx->{$_} foreach (qw(git mm search));
 
+       if ($self->{parallel}) {
+               pipe(my ($r, $w)) or die "pipe failed: $!";
+               $self->{bnote} = [ $r, $w ];
+               $w->autoflush(1);
+       }
+
 	my $over = $self->{over};
 	$ibx->umask_prepare;
 	$ibx->with_umask(sub {
 		$self->lock_acquire;
-		$over->create($self);
+		$over->create;
+
+		# -compact can change partition count while -watch is idle
+		my $nparts = count_partitions($self);
+		if ($nparts && $nparts != $self->{partitions}) {
+			$self->{partitions} = $nparts;
+		}
 
 		# need to create all parts before initializing msgmap FD
 		my $max = $self->{partitions} - 1;
@@ -225,22 +252,40 @@ sub purge_oids {
 	$self->done;
 	my $pfx = "$self->{-inbox}->{mainrepo}/git";
 	my $purges = [];
-	foreach my $i (0..$self->{max_git}) {
+	foreach my $i (0..$self->{epoch_max}) {
 		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;
 }
 
+sub content_ids ($) {
+	my ($mime) = @_;
+	my @cids = ( content_id($mime) );
+
+	# Email::MIME->as_string doesn't always round-trip, so we may
+	# use a second content_id
+	my $rt = content_id(PublicInbox::MIME->new(\($mime->as_string)));
+	push @cids, $rt if $cids[0] ne $rt;
+	\@cids;
+}
+
+sub content_matches ($$) {
+	my ($cids, $existing) = @_;
+	my $cid = content_id($existing);
+	foreach (@$cids) {
+		return 1 if $_ eq $cid
+	}
+	0
+}
+
 sub remove_internal {
 	my ($self, $mime, $cmt_msg, $purge) = @_;
-	$self->barrier;
 	$self->idx_init;
 	my $im = $self->importer unless $purge;
-	my $ibx = $self->{-inbox};
-	my $srch = $ibx->search;
-	my $cid = content_id($mime);
+	my $over = $self->{over};
+	my $cids = content_ids($mime);
 	my $parts = $self->{idx_parts};
 	my $mm = $self->{mm};
 	my $removed;
@@ -250,41 +295,50 @@ 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 {
-			my ($smsg) = @_;
-			$smsg->load_expand;
-			my $msg = $ibx->msg_by_smsg($smsg);
+		my %gone;
+		my ($id, $prev);
+		while (my $smsg = $over->next_by_mid($mid, \$id, \$prev)) {
+			my $msg = get_blob($self, $smsg);
 			if (!defined($msg)) {
 				warn "broken smsg for $mid\n";
-				return 1; # continue
+				next; # continue
 			}
 			my $orig = $$msg;
 			my $cur = PublicInbox::MIME->new($msg);
-			if (content_id($cur) eq $cid) {
-				$mm->num_delete($smsg->num);
-				# $removed should only be set once assuming
-				# no bugs in our deduplication code:
-				$removed = $smsg;
-				$removed->{mime} = $cur;
-				my $oid = $smsg->{blob};
-				if ($purge) {
-					$purge->{$oid} = 1;
-				} else {
-					$im->remove(\$orig, $cmt_msg);
-				}
-				$orig = undef;
-				$removed->num; # memoize this for callers
-
-				foreach my $idx (@$parts) {
-					$idx->remote_remove($oid, $mid);
-				}
-				$self->{over}->remove_oid($oid, $mid);
+			if (content_matches($cids, $cur)) {
+				$smsg->{mime} = $cur;
+				$gone{$smsg->{num}} = [ $smsg, \$orig ];
 			}
-			1; # continue
-		});
-		$self->barrier;
+		}
+		my $n = scalar keys %gone;
+		next unless $n;
+		if ($n > 1) {
+			warn "BUG: multiple articles linked to <$mid>\n",
+				join(',', sort keys %gone), "\n";
+		}
+		foreach my $num (keys %gone) {
+			my ($smsg, $orig) = @{$gone{$num}};
+			$mm->num_delete($num);
+			# $removed should only be set once assuming
+			# no bugs in our deduplication code:
+			$removed = $smsg;
+			my $oid = $smsg->{blob};
+			if ($purge) {
+				$purge->{$oid} = 1;
+			} else {
+				($mark, undef) = $im->remove($orig, $cmt_msg);
+			}
+			$orig = undef;
+			$self->unindex_oid_remote($oid, $mid);
+		}
+	}
+
+	if (defined $mark) {
+		my $cmt = $im->get_mark($mark);
+		$self->{last_commit}->[$self->{epoch_max}] = $cmt;
 	}
 	if ($purge && scalar keys %$purge) {
 		return purge_oids($self, $purge);
@@ -299,74 +353,119 @@ 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 last_commit_part ($$;$) {
+	my ($self, $i, $cmt) = @_;
+	my $v = PublicInbox::Search::SCHEMA_VERSION();
+	$self->{mm}->last_commit_xap($v, $i, $cmt);
+}
 
-sub done {
+sub set_last_commits ($) {
 	my ($self) = @_;
-	my $im = delete $self->{im};
-	$im->done if $im; # PublicInbox::Import::done
-
-	if (my $mm = delete $self->{mm}) {
-		$mm->{dbh}->commit;
-	}
-
-	# order matters, we can only close {over} after all partitions
-	# are done because the partitions also write to {over}
-	my $parts = delete $self->{idx_parts};
-	if ($parts) {
-		$_->remote_commit for @$parts;
-		$_->remote_close for @$parts;
+	defined(my $epoch_max = $self->{epoch_max}) or return;
+	my $last_commit = $self->{last_commit};
+	foreach my $i (0..$epoch_max) {
+		defined(my $cmt = $last_commit->[$i]) or next;
+		$last_commit->[$i] = undef;
+		last_commit_part($self, $i, $cmt);
 	}
+}
 
-	my $over = $self->{over};
-	$over->remote_commit;
-	$over->remote_close;
-	$self->{transact_bytes} = 0;
-	$self->lock_release if $parts;
+sub barrier_init {
+	my ($self, $n) = @_;
+	$self->{bnote} or return;
+	--$n;
+	my $barrier = { map { $_ => 1 } (0..$n) };
 }
 
-sub checkpoint {
-	my ($self) = @_;
-	my $im = $self->{im};
-	$im->checkpoint if $im; # PublicInbox::Import::checkpoint
-	$self->barrier(1);
+sub barrier_wait {
+	my ($self, $barrier) = @_;
+	my $bnote = $self->{bnote} or return;
+	my $r = $bnote->[0];
+	while (scalar keys %$barrier) {
+		defined(my $l = $r->getline) or die "EOF on barrier_wait: $!";
+		$l =~ /\Abarrier (\d+)/ or die "bad line on barrier_wait: $l";
+		delete $barrier->{$1} or die "bad part[$1] on barrier wait";
+	}
 }
 
-# issue a write barrier to ensure all data is visible to other processes
-# and read-only ops.  Order of data importance is: git > SQLite > Xapian
-sub barrier {
-	my ($self, $fsync) = @_;
+sub checkpoint ($;$) {
+	my ($self, $wait) = @_;
 
 	if (my $im = $self->{im}) {
-		$im->barrier;
+		if ($wait) {
+			$im->barrier;
+		} else {
+			$im->checkpoint;
+		}
 	}
 	my $parts = $self->{idx_parts};
 	if ($parts) {
 		my $dbh = $self->{mm}->{dbh};
-		$dbh->commit; # SQLite msgmap data is second in importance
 
-		my $over = $self->{over};
+		# SQLite msgmap data is second in importance
+		$dbh->commit;
+
+		# SQLite overview is third
+		$self->{over}->commit_lazy;
+
+		# Now deal with Xapian
+		if ($wait) {
+			my $barrier = $self->barrier_init(scalar @$parts);
 
-		# Now deal with Xapian and overview DB
-		$over->barrier_init(scalar(@$parts));
+			# each partition needs to issue a barrier command
+			$_->remote_barrier for @$parts;
 
-		# each partition needs to issue a barrier command to over
-		$_->remote_barrier foreach @$parts;
+			# wait for each Xapian partition
+			$self->barrier_wait($barrier);
+		} else {
+			$_->remote_commit for @$parts;
+		}
 
-		$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;
 }
 
+# issue a write barrier to ensure all data is visible to other processes
+# and read-only ops.  Order of data importance is: git > SQLite > Xapian
+sub barrier { checkpoint($_[0], 1) };
+
+sub done {
+	my ($self) = @_;
+	my $im = delete $self->{im};
+	$im->done if $im; # PublicInbox::Import::done
+	checkpoint($self);
+	my $mm = delete $self->{mm};
+	$mm->{dbh}->commit if $mm;
+	my $parts = delete $self->{idx_parts};
+	if ($parts) {
+		$_->remote_close for @$parts;
+	}
+	$self->{over}->disconnect;
+	delete $self->{bnote};
+	$self->{transact_bytes} = 0;
+	$self->lock_release if $parts;
+}
+
 sub git_init {
-	my ($self, $new) = @_;
+	my ($self, $epoch) = @_;
 	my $pfx = "$self->{-inbox}->{mainrepo}/git";
-	my $git_dir = "$pfx/$new.git";
+	my $git_dir = "$pfx/$epoch.git";
 	my @cmd = (qw(git init --bare -q), $git_dir);
 	PublicInbox::Import::run_die(\@cmd);
 
@@ -384,7 +483,7 @@ sub git_init {
 	PublicInbox::Import::run_die(\@cmd);
 
 	my $alt = "$all/objects/info/alternates";
-	my $new_obj_dir = "../../git/$new.git/objects";
+	my $new_obj_dir = "../../git/$epoch.git/objects";
 	my %alts;
 	if (-e $alt) {
 		open(my $fh, '<', $alt) or die "open < $alt: $!\n";
@@ -423,46 +522,46 @@ sub importer {
 		} else {
 			$self->{im} = undef;
 			$im->done;
-			$self->barrier(1);
 			$im = undef;
-			my $git_dir = $self->git_init(++$self->{max_git});
+			$self->checkpoint;
+			my $git_dir = $self->git_init(++$self->{epoch_max});
 			my $git = PublicInbox::Git->new($git_dir);
 			return $self->import_init($git, 0);
 		}
 	}
-	my $new = 0;
+	my $epoch = 0;
 	my $max;
 	my $latest = git_dir_latest($self, \$max);
 	if (defined $latest) {
 		my $git = PublicInbox::Git->new($latest);
 		my $packed_bytes = $git->packed_bytes;
 		if ($packed_bytes >= $self->{rotate_bytes}) {
-			$new = $max + 1;
+			$epoch = $max + 1;
 		} else {
-			$self->{max_git} = $max;
+			$self->{epoch_max} = $max;
 			return $self->import_init($git, $packed_bytes);
 		}
 	}
-	$self->{max_git} = $new;
-	$latest = $self->git_init($new);
+	$self->{epoch_max} = $epoch;
+	$latest = $self->git_init($epoch);
 	$self->import_init(PublicInbox::Git->new($latest), 0);
 }
 
 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
 sub diff ($$$) {
 	my ($mid, $cur, $new) = @_;
 	use File::Temp qw(tempfile);
-	use PublicInbox::Spawn qw(spawn);
 
 	my ($ah, $an) = tempfile('email-cur-XXXXXXXX', TMPDIR => 1);
 	print $ah $cur->as_string or die "print: $!";
@@ -479,34 +578,39 @@ sub diff ($$$) {
 	unlink($an, $bn);
 }
 
-sub lookup_content {
-	my ($self, $mime, $mid) = @_;
+sub get_blob ($$) {
+	my ($self, $smsg) = @_;
+	if (my $im = $self->{im}) {
+		my $msg = $im->cat_blob($smsg->{blob});
+		return $msg if $msg;
+	}
+	# older message, should be in alternates
 	my $ibx = $self->{-inbox};
+	$ibx->msg_by_smsg($smsg);
+}
 
-	my $srch = $ibx->search->reopen;
-	my $cid = content_id($mime);
-	my $found;
-	$srch->each_smsg_by_mid($mid, sub {
-		my ($smsg) = @_;
-		$smsg->load_expand;
-		my $msg = $ibx->msg_by_smsg($smsg);
+sub lookup_content {
+	my ($self, $mime, $mid) = @_;
+	my $over = $self->{over};
+	my $cids = content_ids($mime);
+	my ($id, $prev);
+	while (my $smsg = $over->next_by_mid($mid, \$id, \$prev)) {
+		my $msg = get_blob($self, $smsg);
 		if (!defined($msg)) {
 			warn "broken smsg for $mid\n";
-			return 1; # continue
+			next;
 		}
 		my $cur = PublicInbox::MIME->new($msg);
-		if (content_id($cur) eq $cid) {
+		if (content_matches($cids, $cur)) {
 			$smsg->{mime} = $cur;
-			$found = $smsg;
-			return 0; # break out of loop
+			return $smsg;
 		}
 
+
 		# XXX DEBUG_DIFF is experimental and may be removed
 		diff($mid, $cur, $mime) if $ENV{DEBUG_DIFF};
-
-		1; # continue
-	});
-	$found;
+	}
+	undef;
 }
 
 sub atfork_child {
@@ -520,6 +624,8 @@ sub atfork_child {
 		$im->atfork_child;
 	}
 	die "unexpected mm" if $self->{mm};
+	close $self->{bnote}->[0] or die "close bnote[0]: $!\n";
+	$self->{bnote}->[1];
 }
 
 sub mark_deleted {
@@ -593,6 +699,7 @@ sub reindex_oid {
 	$mm_tmp->mid_delete($mid0) or
 		die "failed to delete <$mid0> for article #$num\n";
 
+	$self->{over}->add_overview($mime, $len, $num, $oid, $mid0);
 	my $nparts = $self->{partitions};
 	my $part = $num % $nparts;
 	my $idx = $self->idx_part($part);
@@ -608,63 +715,173 @@ sub reindex_oid {
 	}
 }
 
-sub reindex {
-	my ($self, $regen) = @_;
-	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";
+# only update last_commit for $i on reindex iff newer than current
+sub update_last_commit {
+	my ($self, $git, $i, $cmt) = @_;
+	my $last = last_commit_part($self, $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 '' && $n == 0;
+	}
+	last_commit_part($self, $i, $cmt);
+}
+
+sub git_dir_n ($$) { "$_[0]->{-inbox}->{mainrepo}/git/$_[1].git" }
+
+sub last_commits {
+	my ($self, $epoch_max) = @_;
+	my $heads = [];
+	for (my $i = $epoch_max; $i >= 0; $i--) {
+		$heads->[$i] = last_commit_part($self, $i);
+	}
+	$heads;
+}
+
+*is_ancestor = *PublicInbox::SearchIdx::is_ancestor;
+
+sub index_prepare {
+	my ($self, $opts, $epoch_max, $ranges) = @_;
+	my $regen_max = 0;
+	my $head = $self->{-inbox}->{ref_head} || 'refs/heads/master';
+	for (my $i = $epoch_max; $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>;
 	}
-	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>;
+	\$regen_max;
+}
+
+sub unindex_oid_remote {
+	my ($self, $oid, $mid) = @_;
+	$_->remote_remove($oid, $mid) foreach @{$self->{idx_parts}};
+	$self->{over}->remove_oid($oid, $mid);
+}
+
+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;
+	my $over = $self->{over};
+	foreach my $mid (@$mids) {
+		my %gone;
+		my ($id, $prev);
+		while (my $smsg = $over->next_by_mid($mid, \$id, \$prev)) {
+			$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";
 		}
-		die "No messages found in $pfx/*.git, bug?\n" unless $regen_max;
-		$regen = \$regen_max;
+		$self->{unindexed}->{$_}++ foreach keys %gone;
+		$self->unindex_oid_remote($oid, $mid);
 	}
+}
+
+my $x40 = qr/[a-f0-9]{40}/;
+sub unindex {
+	my ($self, $opts, $git, $unindex_range) = @_;
+	my $un = $self->{unindexed} ||= {}; # num => removal count
+	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 $epoch_max;
+	my $latest = git_dir_latest($self, \$epoch_max);
+	return unless defined $latest;
+	$self->idx_init; # acquire lock
+	my $mm_tmp = $self->{mm}->tmp_clone;
+	my $ranges = $opts->{reindex} ? [] : $self->last_commits($epoch_max);
+
+	my ($min, $max) = $mm_tmp->minmax;
+	my $regen = $self->index_prepare($opts, $epoch_max, $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 = $epoch_max; $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 +890,10 @@ 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 +902,7 @@ sub reindex {
 			warn "<$mid>\n";
 		}
 	}
+	$self->done;
 }
 
 1;