From 19d330703704a3b667b506c4d14c7e8af98866d4 Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Thu, 29 May 2025 00:20:30 +0000
Subject: [PATCH] xap_helper: mset: ignore non-ultimate exceptions

For requests consisting of multiple queries, ignore Xapian
exceptions for all but the last query.  When sending multiple
queries to the `mset' xap_helper command, we only care about the
result of the first successful query where success is defined as
a non-empty mset response.  Thus an exception is considered an
empty mset and we can try other queries from the same request.
---
 lib/PublicInbox/XapHelper.pm | 15 +++++++++------
 lib/PublicInbox/xh_mset.h    | 23 ++++++++++++++---------
 t/xap_helper.t               | 16 +++++++++++++++-
 3 files changed, 38 insertions(+), 16 deletions(-)

diff --git a/lib/PublicInbox/XapHelper.pm b/lib/PublicInbox/XapHelper.pm
index a36acf469..48203de39 100644
--- a/lib/PublicInbox/XapHelper.pm
+++ b/lib/PublicInbox/XapHelper.pm
@@ -176,12 +176,15 @@ sub cmd_mset { # to be used by WWW + IMAP
 	my @uid_range = @$req{qw(u U)};
 	$opt->{uid_range} = \@uid_range if grep(defined, @uid_range) == 2;
 	$opt->{threadid} = $req->{T} if defined $req->{T};
-	my $mset = $req->{srch}->mset($qry_str, $opt);
-	my $size = $mset->size;
-	while ($size == 0 && @rest) {
-		$mset = $req->{srch}->mset(shift @rest, $opt);
-		$size = $mset->size;
-	}
+	my ($mset, $size);
+	do {
+		eval {
+			$mset = $req->{srch}->mset($qry_str, $opt);
+			$size = $mset->size;
+		};
+		# swallow exceptions for all but the last query
+		die if $@ && !@rest;
+	} while (!$size && (defined($qry_str = shift @rest)));
 	say { $req->{0} } 'mset.size=', $size,
 		' .get_matches_estimated=', $mset->get_matches_estimated;
 	for my $it ($mset->items) {
diff --git a/lib/PublicInbox/xh_mset.h b/lib/PublicInbox/xh_mset.h
index 7d0100932..8591bbf4f 100644
--- a/lib/PublicInbox/xh_mset.h
+++ b/lib/PublicInbox/xh_mset.h
@@ -14,17 +14,22 @@
 static bool cmd_mset(struct req *req)
 {
 	if (optind >= req->argc) ABORT("usage: mset [OPTIONS] WANT QRY_STR");
-	const char *qry_str = req->argv[optind];
 	CLEANUP_FBUF struct fbuf wbuf = {};
-	Xapian::MSet mset = req->code_search ? commit_mset(req, qry_str) :
+	unsigned long long size = 0;
+	Xapian::MSet mset;
+	do {
+		try {
+			const char *qry_str = req->argv[optind++];
+			mset = req->code_search ? commit_mset(req, qry_str) :
 						mail_mset(req, qry_str);
-	unsigned long long size = mset.size();
-	while (size == 0 && ++optind < req->argc) {
-		qry_str = req->argv[optind];
-		mset = req->code_search ? commit_mset(req, qry_str) :
-					mail_mset(req, qry_str);
-		size = mset.size();
-	}
+			size = mset.size();
+		} catch (const Xapian::Error & e) {
+			// swallow exceptions for all but the last query
+			if (optind >= req->argc)
+				throw;
+		}
+	} while (size == 0 && optind < req->argc);
+
 	fbuf_init(&wbuf);
 	fprintf(wbuf.fp, "mset.size=%llu .get_matches_estimated=%llu\n",
 		size, (unsigned long long)mset.get_matches_estimated());
diff --git a/t/xap_helper.t b/t/xap_helper.t
index 41520866f..86b44dd24 100644
--- a/t/xap_helper.t
+++ b/t/xap_helper.t
@@ -249,8 +249,11 @@ for my $n (@NO_CXX) {
 
 	# ensure we can try multiple queries and return the first one
 	# with >0 matches
-	for my $try ([[], []], [['thisbetternotmatchanything'], ['z:0..']]) {
+	for my $try ([[], []], [['thisbetternotmatchanything'], ['z:0..']],
+			[['bogus...range ignored'], []],
+			[['z:0.. dfn:Search.pm'], ['bogus...range never tried']]) {
 		pipe $r, $w;
+		diag explain($try);
 		$xhc->mkreq([$w], qw(mset), @ibx_shard_args, @{$try->[0]},
 					'dfn:lib/PublicInbox/Search.pm',
 					@{$try->[1]});
@@ -286,6 +289,17 @@ for my $n (@NO_CXX) {
 		like $rank, qr/\A\d+\z/, 'rank is a digit';
 		is scalar(@rest), 0, 'no extra rows returned';
 	}
+
+	pipe $r, $w;
+	pipe $err_r, $err_w;
+	$xhc->mkreq([$w, $err_w], qw(mset), @ibx_shard_args, 'bogus...range');
+	close $w;
+	close $err_w;
+	chomp(@res = readline($r));
+	is_deeply \@res, [], 'no output on bogus query';
+	chomp(@res = readline($err_r));
+	ok scalar(@res) && $res[0], 'got error on bogus query';
+
 	my $nr;
 	for my $i (7, 8, 39, 40) {
 		pipe($err_r, $err_w);
-- 
2.47.3