From 5b0af2f5090155f0f632b9971da2af2d056660f1 Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Tue, 13 Nov 2018 17:33:18 -0800
Subject: [PATCH] modules/m_room: Add utility to clear the state root entries
 for all room events.

---
 modules/console.cc | 33 +++++++++++++++++++++++++++++++
 modules/m_room.cc  | 49 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+)

diff --git a/modules/console.cc b/modules/console.cc
index f39cecea2..7edc540dc 100644
--- a/modules/console.cc
+++ b/modules/console.cc
@@ -6419,6 +6419,39 @@ console_cmd__room__state__rebuild__history(opt &out, const string_view &line)
 	return true;
 }
 
+bool
+console_cmd__room__state__history__clear(opt &out, const string_view &line)
+{
+	const params param{line, " ",
+	{
+		"room_id"
+	}};
+
+	const auto &room_id
+	{
+		m::room_id(param.at(0))
+	};
+
+	const m::room room
+	{
+		room_id
+	};
+
+	using prototype = size_t (const m::room &);
+	static mods::import<prototype> state__clear_history
+	{
+		"m_room", "state__clear_history"
+	};
+
+	const size_t count
+	{
+		state__clear_history(room)
+	};
+
+	out << "done " << count << std::endl;
+	return true;
+}
+
 bool
 console_cmd__room__state__prefetch(opt &out, const string_view &line)
 {
diff --git a/modules/m_room.cc b/modules/m_room.cc
index 114d6c697..f8c6200dc 100644
--- a/modules/m_room.cc
+++ b/modules/m_room.cc
@@ -467,6 +467,55 @@ state__rebuild_history(const m::room &room)
 	return ret;
 }
 
+//TODO: state btree.
+extern "C" size_t
+state__clear_history(const m::room &room)
+{
+	static const db::gopts gopts
+	{
+		db::get::NO_CACHE
+	};
+
+	db::txn txn
+	{
+		*m::dbs::events
+	};
+
+	auto it
+	{
+		m::dbs::room_events.begin(room.room_id, gopts)
+	};
+
+	size_t ret{0};
+	for(; it; ++it, ret++)
+	{
+		const auto pair
+		{
+			m::dbs::room_events_key(it->first)
+		};
+
+		const auto &depth{std::get<0>(pair)};
+		const auto &event_idx{std::get<1>(pair)};
+		thread_local char buf[m::dbs::ROOM_EVENTS_KEY_MAX_SIZE];
+		const string_view key
+		{
+			m::dbs::room_events_key(buf, room.room_id, depth, event_idx)
+		};
+
+		db::txn::append
+		{
+			txn, m::dbs::room_events,
+			{
+				db::op::SET,
+				key
+			}
+		};
+	}
+
+	txn();
+	return ret;
+}
+
 conf::item<ulong>
 state__prefetch__yield_modulus
 {