From 916597595313ecc4a3e0003fbf0f65dd472a28d0 Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Wed, 16 Sep 2020 23:31:19 -0700
Subject: [PATCH] ircd::m::dbs: Supersede index query tool with parallel impl.

---
 include/ircd/m/dbs/dbs.h | 12 ++++++++++++
 matrix/dbs.cc            | 37 ++++++++++++++++++++++++++++++-------
 2 files changed, 42 insertions(+), 7 deletions(-)

diff --git a/include/ircd/m/dbs/dbs.h b/include/ircd/m/dbs/dbs.h
index 5d686bbff..400b1f513 100644
--- a/include/ircd/m/dbs/dbs.h
+++ b/include/ircd/m/dbs/dbs.h
@@ -201,5 +201,17 @@ struct ircd::m::dbs::init
 // Internal utils (here for now)
 namespace ircd::m::dbs
 {
+	size_t find_event_idx(const vector_view<event::idx> &out, const vector_view<const event::id> &in, const write_opts &);
 	event::idx find_event_idx(const event::id &, const write_opts &);
 }
+
+inline ircd::m::event::idx
+ircd::m::dbs::find_event_idx(const event::id &event_id,
+                             const write_opts &wopts)
+{
+	event::idx ret{0};
+	const vector_view<event::idx> out(&ret, 1);
+	const vector_view<const event::id> in(&event_id, 1);
+	find_event_idx(out, in, wopts);
+	return ret;
+}
diff --git a/matrix/dbs.cc b/matrix/dbs.cc
index 7ba91e55c..ac8d330ab 100644
--- a/matrix/dbs.cc
+++ b/matrix/dbs.cc
@@ -390,16 +390,39 @@ ircd::m::dbs::_index_room_redact(db::txn &txn,
 }
 
 // NOTE: QUERY
-ircd::m::event::idx
-ircd::m::dbs::find_event_idx(const event::id &event_id,
+size_t
+ircd::m::dbs::find_event_idx(const vector_view<event::idx> &idx,
+                             const vector_view<const event::id> &event_id,
                              const write_opts &wopts)
 {
-	event::idx ret{0};
-	if(wopts.interpose)
-		ret = wopts.interpose->val(db::op::SET, "_event_idx", event_id, 0UL);
+	const size_t num
+	{
+		std::min(idx.size(), event_id.size())
+	};
 
-	if(wopts.allow_queries && !ret)
-		ret = m::index(std::nothrow, event_id); // query
+	size_t ret(0);
+	if(wopts.interpose)
+		for(size_t i(0); i < num; ++i)
+		{
+			idx[i] = wopts.interpose->val(db::op::SET, "_event_idx", event_id[i], 0UL);
+			ret += idx[i] != 0;
+		}
+
+	// Taken when everything satisfied by interpose
+	if(ret == num || !wopts.allow_queries)
+		return ret;
+
+	// Only do parallel m::index() if there's no results from the prior
+	// queries; they'll get clobbered by the parallel m::index().
+	if(likely(!ret))
+		return m::index(idx, event_id);
+
+	// Fallback to serial queries.
+	for(size_t i(0); i < num; ++i)
+	{
+		idx[i] = m::index(std::nothrow, event_id[i]);
+		ret += idx[i] != 0;
+	}
 
 	return ret;
 }