[PATCH 1/3] www: do not bump {over} refcnt on long responses

[Eric Wong <e@80x24.org>]

SQLite files may be replaced or removed by admins while
generating a large threads or mailbox responses.  Ensure we
don't hold onto DBI handles and associated file descriptors
past their cleanup.
---
 lib/PublicInbox/GzipFilter.pm |  6 ++++++
 lib/PublicInbox/Mbox.pm       | 29 ++++++++++++-----------------
 lib/PublicInbox/View.pm       |  6 ++++--
 3 files changed, 22 insertions(+), 19 deletions(-)

diff --git a/lib/PublicInbox/GzipFilter.pm b/lib/PublicInbox/GzipFilter.pm
index c50c26c5..624c2ed3 100644
--- a/lib/PublicInbox/GzipFilter.pm
+++ b/lib/PublicInbox/GzipFilter.pm
@@ -84,6 +84,12 @@ sub gzip_or_die () {
 	$gz;
 }
 
+sub gone { # what: search/over/mm
+	my ($ctx, $what) = @_;
+	warn "W: `$ctx->{ibx}->{name}' $what went away unexpectedly\n";
+	undef;
+}
+
 # for GetlineBody (via Qspawn) when NOT using $env->{'pi-httpd.async'}
 # Also used for ->getline callbacks
 sub translate ($$) {
diff --git a/lib/PublicInbox/Mbox.pm b/lib/PublicInbox/Mbox.pm
index cec76182..dede4825 100644
--- a/lib/PublicInbox/Mbox.pm
+++ b/lib/PublicInbox/Mbox.pm
@@ -124,8 +124,9 @@ sub thread_cb {
 			return $smsg;
 		}
 		# refill result set
-		$ctx->{msgs} = $msgs = $ctx->{over}->get_thread($ctx->{mid},
-								$ctx->{prev});
+		my $over = $ctx->{ibx}->over or return $ctx->gone('over');
+		$ctx->{msgs} = $msgs = $over->get_thread($ctx->{mid},
+							$ctx->{prev});
 		return unless @$msgs;
 		$ctx->{prev} = $msgs->[-1];
 	}
@@ -136,7 +137,6 @@ sub thread_mbox {
 	my $msgs = $ctx->{msgs} = $over->get_thread($ctx->{mid}, {});
 	return [404, [qw(Content-Type text/plain)], []] if !@$msgs;
 	$ctx->{prev} = $msgs->[-1];
-	$ctx->{over} = $over; # bump refcnt
 	require PublicInbox::MboxGz;
 	PublicInbox::MboxGz::mbox_gz($ctx, \&thread_cb, $msgs->[0]->{subject});
 }
@@ -155,22 +155,23 @@ sub emit_range {
 
 sub all_ids_cb {
 	my ($ctx) = @_;
+	my $over = $ctx->{ibx}->over or return $ctx->gone('over');
 	my $ids = $ctx->{ids};
 	do {
 		while ((my $num = shift @$ids)) {
-			my $smsg = $ctx->{over}->get_art($num) or next;
+			my $smsg = $over->get_art($num) or next;
 			return $smsg;
 		}
-		$ctx->{ids} = $ids = $ctx->{over}->ids_after(\($ctx->{prev}));
+		$ctx->{ids} = $ids = $over->ids_after(\($ctx->{prev}));
 	} while (@$ids);
 }
 
 sub mbox_all_ids {
 	my ($ctx) = @_;
 	my $prev = 0;
-	$ctx->{over} = $ctx->{ibx}->over or
+	my $over = $ctx->{ibx}->over or
 		return PublicInbox::WWW::need($ctx, 'Overview');
-	my $ids = $ctx->{over}->ids_after(\$prev) or return
+	my $ids = $over->ids_after(\$prev) or return
 		[404, [qw(Content-Type text/plain)], ["No results found\n"]];
 	$ctx->{ids} = $ids;
 	$ctx->{prev} = $prev;
@@ -179,22 +180,16 @@ sub mbox_all_ids {
 	PublicInbox::MboxGz::mbox_gz($ctx, \&all_ids_cb, 'all');
 }
 
-sub gone ($$) {
-	my ($ctx, $what) = @_;
-	warn "W: `$ctx->{ibx}->{inboxdir}' $what went away unexpectedly\n";
-	undef;
-}
-
 sub results_cb {
 	my ($ctx) = @_;
-	my $over = $ctx->{ibx}->over or return gone($ctx, 'over');
+	my $over = $ctx->{ibx}->over or return $ctx->gone('over');
 	while (1) {
 		while (defined(my $num = shift(@{$ctx->{ids}}))) {
 			my $smsg = $over->get_art($num) or next;
 			return $smsg;
 		}
 		# refill result set, deprioritize since there's many results
-		my $srch = $ctx->{ibx}->isrch or return gone($ctx, 'search');
+		my $srch = $ctx->{ibx}->isrch or return $ctx->gone('search');
 		my $mset = $srch->mset($ctx->{query}, $ctx->{qopts});
 		my $size = $mset->size or return;
 		$ctx->{qopts}->{offset} += $size;
@@ -206,7 +201,7 @@ sub results_cb {
 sub results_thread_cb {
 	my ($ctx) = @_;
 
-	my $over = $ctx->{ibx}->over or return gone($ctx, 'over');
+	my $over = $ctx->{ibx}->over or return $ctx->gone('over');
 	while (1) {
 		while (defined(my $num = shift(@{$ctx->{xids}}))) {
 			my $smsg = $over->get_art($num) or next;
@@ -217,7 +212,7 @@ sub results_thread_cb {
 		next if $over->expand_thread($ctx);
 
 		# refill result set, deprioritize since there's many results
-		my $srch = $ctx->{ibx}->isrch or return gone($ctx, 'search');
+		my $srch = $ctx->{ibx}->isrch or return $ctx->gone('search');
 		my $mset = $srch->mset($ctx->{query}, $ctx->{qopts});
 		my $size = $mset->size or return;
 		$ctx->{qopts}->{offset} += $size;
diff --git a/lib/PublicInbox/View.pm b/lib/PublicInbox/View.pm
index 805e785b..069b9680 100644
--- a/lib/PublicInbox/View.pm
+++ b/lib/PublicInbox/View.pm
@@ -31,7 +31,9 @@ sub msg_page_i {
 	my ($ctx, $eml) = @_;
 	if ($eml) { # called by WwwStream::async_eml or getline
 		my $smsg = $ctx->{smsg};
-		$ctx->{smsg} = $ctx->{over}->next_by_mid(@{$ctx->{next_arg}});
+		my $over = $ctx->{ibx}->over;
+		$ctx->{smsg} = $over ? $over->next_by_mid(@{$ctx->{next_arg}})
+				: $ctx->gone('over');
 		$ctx->{mhref} = ($ctx->{nr} || $ctx->{smsg}) ?
 				"../${\mid_href($smsg->{mid})}/" : '';
 		my $obuf = $ctx->{obuf} = _msg_page_prepare_obuf($eml, $ctx);
@@ -70,7 +72,7 @@ sub msg_page {
 	my ($ctx) = @_;
 	my $ibx = $ctx->{ibx};
 	$ctx->{-obfs_ibx} = $ibx->{obfuscate} ? $ibx : undef;
-	my $over = $ctx->{over} = $ibx->over or return no_over_html($ctx);
+	my $over = $ibx->over or return no_over_html($ctx);
 	my ($id, $prev);
 	my $next_arg = $ctx->{next_arg} = [ $ctx->{mid}, \$id, \$prev ];