From: Eric Wong <e@80x24.org>
Date: Sun, 23 Feb 2025 13:13:35 +0000 (+0000)
Subject: xh_thread_fp: optimize OR query generation
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=da87e953fa92de4ecb91e318477e1ee84ed4fe81;p=thirdparty%2Fpublic-inbox.git

xh_thread_fp: optimize OR query generation

For Xapian >= 1.4.10 users, using `|=' will reduce allocations.
`|=' still works for Xapian 1.3.2 .. 1.4.9 users, and I'm not
sure if Xapian 1.2.x is relevant anymore, especially for our
new C++-only features.

While operator overloading is often confusing and frustrating to
me when reading someone else's code, the optimization seems worth
it since (AFAIK) there's no other way to get the allocation
reduction.

cf. Olly in xapian-discuss <20250222043050.GA17282@survex.com>
---

diff --git a/lib/PublicInbox/xh_thread_fp.h b/lib/PublicInbox/xh_thread_fp.h
index 27b5cfcb5..8f0385f14 100644
--- a/lib/PublicInbox/xh_thread_fp.h
+++ b/lib/PublicInbox/xh_thread_fp.h
@@ -17,10 +17,10 @@ static enum exc_iter xpand_col_iter(Xapian::Query *xqry,
 	try {
 		Xapian::Document doc = i->get_document();
 		std::string val = doc.get_value(column);
-		*xqry = Xapian::Query(Xapian::Query::OP_OR, *xqry,
-				Xapian::Query(
-					Xapian::Query::OP_VALUE_RANGE,
-					column, val, val));
+		// n.b. Xapian 1.4.10+ optimizes `|=' to reduce allocation.
+		// operator overloading is confusing, yes :<
+		*xqry |= Xapian::Query(Xapian::Query::OP_VALUE_RANGE,
+					column, val, val);
 	} catch (const Xapian::DatabaseModifiedError &e) {
 		cur_srch->db->reopen();
 		return ITER_RETRY;