ircd:Ⓜ️:room::aliases::cache: Add remote fetching; improve interface.

include/ircd/m/room/aliases.h

@@ -46,8 +46,11 @@ struct ircd::m::room::aliases::cache
 	static bool for_each(const string_view &server, const closure_bool &);
 	static bool for_each(const closure_bool &);
 	static bool has(const alias &);
+	static void fetch(const alias &, const net::hostport &remote);
+	static bool fetch(std::nothrow_t, const alias &, const net::hostport &remote);
 	static bool get(std::nothrow_t, const alias &, const id::closure &);
 	static void get(const alias &, const id::closure &);
+	static id::buf get(std::nothrow_t, const alias &);
 	static id::buf get(const alias &);
 	static bool set(const alias &, const id &);
 	static bool del(const alias &);

ircd/m_room.cc

@@ -2469,11 +2469,63 @@ ircd::m::room::aliases::cache::set(const alias &a,
 	return call(a, i);
 }
 
+bool
+ircd::m::room::aliases::cache::fetch(std::nothrow_t,
+                                     const alias &a,
+                                     const net::hostport &hp)
+try
+{
+	fetch(a, hp);
+	return true;
+}
+catch(const std::exception &e)
+{
+	thread_local char buf[384];
+	log::error
+	{
+		log, "Failed to fetch room_id for %s from %s :%s",
+		string_view{a},
+		string(buf, hp),
+		e.what(),
+	};
+
+	return false;
+}
+
+void
+ircd::m::room::aliases::cache::fetch(const alias &a,
+                                     const net::hostport &hp)
+{
+	using prototype = void (const alias &, const net::hostport &);
+
+	static mods::import<prototype> call
+	{
+		"m_room_aliases", "ircd::m::room::aliases::cache::fetch"
+	};
+
+	return call(a, hp);
+}
+
 ircd::m::room::id::buf
 ircd::m::room::aliases::cache::get(const alias &a)
 {
 	id::buf ret;
-	get(a, [&ret](const id &room_id)
+	get(a, [&ret]
+	(const id &room_id)
+	{
+		ret = room_id;
+	});
+
+	return ret;
+}
+
+ircd::m::room::id::buf
+ircd::m::room::aliases::cache::get(std::nothrow_t,
+                                   const alias &a)
+{
+	id::buf ret;
+	get(std::nothrow, a, [&ret]
+	(const id &room_id)
 	{
 		ret = room_id;
 	});

modules/m_room_aliases.cc

@@ -35,6 +35,13 @@ alias_cache_ttl
 	{ "default", 604800L                         },
 };
 
+conf::item<seconds>
+alias_fetch_timeout
+{
+	{ "name",    "ircd.m.room.aliases.fetch.timeout" },
+	{ "default", 10L                                 },
+};
+
 //
 // m::room::aliases
 //
@@ -98,7 +105,7 @@ ircd::m::room::aliases::cache::del(const alias &alias)
 
 	const auto &event_idx
 	{
-		alias_room.get("ircd.room.alias", key)
+		alias_room.get(std::nothrow, "ircd.room.alias", key)
 	};
 
 	if(!event_idx)
@@ -106,7 +113,7 @@ ircd::m::room::aliases::cache::del(const alias &alias)
 
 	const auto event_id
 	{
-		m::event_id(event_idx)
+		m::event_id(event_idx, std::nothrow)
 	};
 
 	if(!event_id)
@@ -154,22 +161,35 @@ ircd::m::room::aliases::cache::get(std::nothrow_t,
 		alias.swap(swapbuf)
 	};
 
-	const auto &event_idx
+	m::event::idx event_idx
 	{
-		alias_room.get("ircd.room.alias", key)
+		alias_room.get(std::nothrow, "ircd.room.alias", key)
 	};
 
-	bool ret{false};
 	if(!event_idx)
-		return ret;
+	{
+		if(!fetch(std::nothrow, alias, alias.host()))
+			return false;
+
+		event_idx = alias_room.get(std::nothrow, "ircd.room.alias", key);
+	}
 
 	time_t ts;
 	if(!m::get(event_idx, "origin_server_ts", ts))
-		return ret;
+		return false;
 
 	if(ircd::time() - ts > seconds(alias_cache_ttl).count())
-		return ret;
+	{
+		if(!fetch(std::nothrow, alias, alias.host()))
+			return false;
 
+		event_idx = alias_room.get(std::nothrow, "ircd.room.alias", key);
+	}
+
+	if(!event_idx)
+		return false;
+
+	bool ret{false};
 	m::get(std::nothrow, event_idx, "content", [&closure, &ret]
 	(const json::object &content)
 	{
@@ -271,7 +291,7 @@ ircd::m::room::aliases::cache::has(const alias &alias)
 
 	const auto &event_idx
 	{
-		alias_room.get("ircd.room.alias", key)
+		alias_room.get(std::nothrow, "ircd.room.alias", key)
 	};
 
 	if(!event_idx)