ircd:Ⓜ️ Add central interface for room state prefetch; add console cmd; apply to client sync.

include/ircd/m/room.h

@@ -298,6 +298,10 @@ struct ircd::m::room::state
 	event::id::buf get(std::nothrow_t, const string_view &type, const string_view &state_key = "") const;
 	event::id::buf get(const string_view &type, const string_view &state_key = "") const;
 
+	// Initiate a database prefetch on the state to cache for future access.
+	size_t prefetch(const string_view &type, const event::idx &start = 0, const event::idx &stop = 0) const;
+	size_t prefetch(const event::idx &start = 0, const event::idx &stop = 0) const;
+
 	state(const m::room &room, const event::fetch::opts *const & = nullptr);
 	state() = default;
 	state(const state &) = delete;

ircd/m/m.cc

@@ -2466,6 +2466,30 @@ const
 // m/room.h
 //
 
+size_t
+ircd::m::room::state::prefetch(const event::idx &start,
+                               const event::idx &stop)
+const
+{
+	return prefetch(string_view{}, start, stop);
+}
+
+size_t
+ircd::m::room::state::prefetch(const string_view &type,
+                               const event::idx &start,
+                               const event::idx &stop)
+const
+{
+	using prototype = size_t (const state &, const string_view &, const std::pair<event::idx, event::idx> &);
+
+	static mods::import<prototype> function
+	{
+		"m_room", "state__prefetch"
+	};
+
+	return function(*this, type, std::pair<event::idx, event::idx>{start, stop});
+}
+
 ircd::m::room
 ircd::m::create(const id::room &room_id,
                 const id::user &creator,

modules/client/sync.cc

@@ -995,16 +995,7 @@ ircd::m::sync::polylog::room_state(shortpoll &sp,
 	};
 
 	if(bool(prefetch_state))
-	{
-		state.for_each([&]
-		(const m::event::idx &event_idx)
-		{
-			if(event_idx < sp.since || event_idx >= sp.current)
-				return;
-
-			m::prefetch(event_idx, fopts);
-		});
-	}
+		state.prefetch(sp.since, sp.current);
 
 	state.for_each([&]
 	(const m::event &event)

modules/console.cc

@@ -6090,6 +6090,62 @@ console_cmd__room__state__rebuild__history(opt &out, const string_view &line)
 	return true;
 }
 
+bool
+console_cmd__room__state__prefetch(opt &out, const string_view &line)
+{
+	const params param{line, " ",
+	{
+		"room_id", "[event_id_or_type]", "[type]"
+	}};
+
+	const auto &room_id
+	{
+		m::room_id(param.at("room_id"))
+	};
+
+	const auto &event_id_or_type
+	{
+		param.at("[event_id_or_type]", string_view{})
+	};
+
+	const auto is_event_id
+	{
+		m::has_sigil(event_id_or_type) && valid(m::id::EVENT, event_id_or_type)
+	};
+
+	const string_view &event_id
+	{
+		is_event_id?
+			event_id_or_type:
+			string_view{}
+	};
+
+	const auto &type
+	{
+		is_event_id?
+			param.at("[type]", string_view{}):
+			event_id_or_type
+	};
+
+	const m::room room
+	{
+		room_id, event_id
+	};
+
+	const m::room::state state
+	{
+		room
+	};
+
+	const size_t prefetched
+	{
+		state.prefetch(type)
+	};
+
+	out << "prefetched " << prefetched << std::endl;
+	return true;
+}
+
 bool
 console_cmd__room__count(opt &out, const string_view &line)
 {

modules/m_room.cc

@@ -467,6 +467,35 @@ state__rebuild_history(const m::room &room)
 	return ret;
 }
 
+extern "C" size_t
+state__prefetch(const m::room::state &state,
+                const string_view &type,
+                const std::pair<m::event::idx, m::event::idx> &range)
+{
+	const m::event::fetch::opts &fopts
+	{
+		state.fopts?
+			*state.fopts:
+			m::event::fetch::default_opts
+	};
+
+	size_t ret{0};
+	state.for_each(type, m::event::closure_idx{[&ret, &fopts, &range]
+	(const m::event::idx &event_idx)
+	{
+		if(event_idx < range.first)
+			return;
+
+		if(range.second && event_idx > range.second)
+			return;
+
+		m::prefetch(event_idx, fopts);
+		++ret;
+	}});
+
+	return ret;
+}
+
 extern "C" size_t
 head__rebuild(const m::room &room)
 {