ircd:Ⓜ️:vm::eval: Improve mfetch_keys related during eval.

include/ircd/m/vm/eval.h

@@ -22,6 +22,7 @@ namespace ircd::m::vm
 	string_view loghead(const mutable_buffer &, const eval &);
 	string_view loghead(const eval &);    // single tls buffer
 
+	size_t fetch_keys(const eval &);
 }
 
 /// Event Evaluation Device
@@ -63,8 +64,6 @@ struct ircd::m::vm::eval
 	vm::phase phase {vm::phase(0)};
 	bool room_internal {false};
 
-	void mfetch_keys() const;
-
   public:
 	operator const event::id::buf &() const
 	{

matrix/vm_eval.cc

@@ -37,6 +37,39 @@ ircd::m::vm::eval::executing;
 decltype(ircd::m::vm::eval::injecting)
 ircd::m::vm::eval::injecting;
 
+size_t
+ircd::m::vm::fetch_keys(const eval &eval)
+{
+	using m::fed::key::server_key;
+
+	assert(eval.opts);
+	const auto &opts
+	{
+		*eval.opts
+	};
+
+	std::set<server_key> miss;
+	for(const auto &event : eval.pdus)
+		for(const auto &[server_name, signatures] : at<"signatures"_>(event))
+			for(const auto &[key_id, signature] : json::object(signatures))
+				if(!m::keys::cache::has(json::get<"origin"_>(event), key_id))
+					miss.emplace(json::get<"origin"_>(event), key_id);
+
+	const std::vector<server_key> queries
+	(
+		begin(miss), end(miss)
+	);
+
+	const size_t fetched
+	{
+		!queries.empty()?
+			m::keys::fetch(queries):
+			0UL
+	};
+
+	return fetched;
+}
+
 ircd::string_view
 ircd::m::vm::loghead(const eval &eval)
 {
@@ -412,68 +445,3 @@ ircd::m::vm::eval::for_each(const std::function<bool (eval &)> &closure)
 
 	return true;
 }
-
-void
-ircd::m::vm::eval::mfetch_keys()
-const
-{
-	using m::fed::key::server_key;
-
-	// Determine federation keys which we don't have.
-	std::set<server_key> miss;
-	for(const auto &event : this->pdus)
-	{
-		assert(opts);
-		const auto &origin
-		{
-			json::get<"origin"_>(event)?
-				string_view{json::get<"origin"_>(event)}:
-				m::user::id{json::get<"sender"_>(event)}.host()
-		};
-
-		// When the node_id is set (eval on behalf of remote) we only parallel
-		// fetch keys from that node for events from that node. This is to
-		// prevent amplification. Note that these will still be evaluated and
-		// key fetching may be attempted, but not here.
-		if(opts->node_id && opts->node_id != origin)
-			continue;
-
-		for(const auto &[server_name, signatures] : at<"signatures"_>(event))
-			for(const auto &[key_id, signature] : json::object(signatures))
-				if(!m::keys::cache::has(origin, key_id))
-					miss.emplace(origin, key_id);
-	}
-
-	if(miss.empty())
-		return;
-
-	log::debug
-	{
-		log, "%s fetching %zu new keys from %zu events...",
-		loghead(*this),
-		miss.size(),
-		this->pdus.size(),
-	};
-
-	const std::vector<server_key> queries
-	(
-		begin(miss), end(miss)
-	);
-
-	const size_t fetched
-	{
-		m::keys::fetch(queries)
-	};
-
-	if(!fetched)
-		return;
-
-	log::info
-	{
-		log, "%s fetched %zu of %zu new keys from %zu events",
-		loghead(*this),
-		fetched,
-		miss.size(),
-		this->pdus.size(),
-	};
-}

matrix/vm_execute.cc

@@ -197,9 +197,29 @@ ircd::m::vm::execute(eval &eval,
 		eval.pdus, events
 	};
 
-	if(likely(opts.phase[phase::VERIFY] && opts.mfetch_keys))
-		if(events.size() > 1)
-			eval.mfetch_keys();
+	const scope_count executing
+	{
+		eval::executing
+	};
+
+	const scope_restore eval_phase
+	{
+		eval.phase, phase::EXECUTE
+	};
+
+	const bool prefetch_keys
+	{
+		opts.phase[phase::VERIFY]
+		&& opts.mfetch_keys
+		&& events.size() > 1
+	};
+
+	const size_t prefetched_keys
+	{
+		prefetch_keys?
+			fetch_keys(eval):
+			0UL
+	};
 
 	size_t accepted(0), existed(0), i, j, k;
 	for(i = 0; i < events.size(); i += j)
@@ -266,17 +286,6 @@ try
 	// danger close; try increasing your stack size.
 	const ctx::stack_usage_assertion sua;
 
-	// m::vm bookkeeping that someone entered this function
-	const scope_count executing
-	{
-		eval::executing
-	};
-
-	const scope_restore eval_phase
-	{
-		eval.phase, phase::EXECUTE
-	};
-
 	const scope_notify notify
 	{
 		vm::dock