ircd:Ⓜ️:acquire: Add state dispatch component; minor cleanup.

include/ircd/m/acquire.h

@@ -27,6 +27,7 @@ struct ircd::m::acquire
 	const struct opts &opts;
 	vm::opts head_vmopts;
 	vm::opts history_vmopts;
+	vm::opts state_vmopts;
 	std::list<result> fetching;
 
   private:
@@ -44,6 +45,9 @@ struct ircd::m::acquire
 	bool fetch_history(event::idx &);
 	void acquire_history();
 
+	bool fetch_state(const m::event::id &, const string_view &);
+	void acquire_state();
+
   public:
 	acquire(const struct opts &);
 	acquire(const acquire &) = delete;

matrix/acquire.cc

@@ -38,8 +38,19 @@ ircd::m::acquire::acquire::acquire(const struct opts &opts)
 	if(opts.head)
 	{
 		head_vmopts.notify_servers = false;
+		head_vmopts.phase.set(m::vm::phase::NOTIFY, false);
 		head_vmopts.phase.set(m::vm::phase::FETCH_PREV, false);
-		head_vmopts.phase.set(m::vm::phase::FETCH_STATE, opts.state);
+		head_vmopts.phase.set(m::vm::phase::FETCH_STATE, false);
+		head_vmopts.non_conform.set(event::conforms::MISMATCH_HASHES);
+	}
+
+	if(opts.state)
+	{
+		state_vmopts.notify_servers = false;
+		state_vmopts.phase.set(m::vm::phase::FETCH_PREV, false);
+		state_vmopts.phase.set(m::vm::phase::FETCH_STATE, false);
+		state_vmopts.non_conform.set(event::conforms::MISMATCH_HASHES);
+		state_vmopts.wopts.appendix.set(dbs::appendix::ROOM_HEAD, false);
 	}
 
 	if(opts.history)
@@ -48,17 +59,23 @@ ircd::m::acquire::acquire::acquire(const struct opts &opts)
 		history_vmopts.phase.set(m::vm::phase::NOTIFY, false);
 		history_vmopts.phase.set(m::vm::phase::FETCH_PREV, false);
 		history_vmopts.phase.set(m::vm::phase::FETCH_STATE, false);
+		history_vmopts.non_conform.set(event::conforms::MISMATCH_HASHES);
 		history_vmopts.wopts.appendix.set(dbs::appendix::ROOM_HEAD, false);
 	}
 
 	// Branch to acquire head
 	if(opts.head)
-		acquire_head();
+		if(!opts.depth.second)
+			acquire_head();
 
 	// Branch to acquire history
 	if(opts.history)
 		acquire_history();
 
+	// Branch to acquire state
+	if(opts.state)
+		acquire_state();
+
 	// Complete all work before returning, otherwise everything
 	// will be cancelled on unwind.
 	while(!fetching.empty())
@@ -230,6 +247,72 @@ ircd::m::acquire::fetch_history(event::idx &ref_min)
 	return ret;
 }
 
+void
+ircd::m::acquire::acquire_state()
+{
+	m::event::id::buf event_id;
+	if(opts.room.event_id)
+		event_id = opts.room.event_id;
+
+	if(!event_id && opts.viewport_size)
+		event_id = m::event_id(std::nothrow, m::viewport(opts.room).second); //TODO: opts.viewport_size
+
+	if(!event_id && opts.history)
+		event_id = m::event_id(std::nothrow, m::sounding(opts.room).second);
+
+	if(!event_id && opts.head)
+		event_id = m::head(opts.room);
+
+	if(!event_id)
+		return;
+
+	m::room::state::fetch::opts sfopts;
+	sfopts.room.room_id = opts.room.room_id;
+	sfopts.room.event_id = event_id;
+	m::room::state::fetch
+	{
+		sfopts, [this](const m::event::id &event_id, const string_view &remote)
+		{
+			return fetch_state(event_id, remote);
+		}
+	};
+}
+
+bool
+ircd::m::acquire::fetch_state(const m::event::id &event_id,
+                              const string_view &remote)
+{
+	// Bail if interrupted
+	if(ctx::interruption_requested())
+		return false;
+
+	const auto hostpart
+	{
+		event_id.host()
+	};
+
+	const auto hint
+	{
+		hostpart? hostpart: remote
+	};
+
+	const bool submitted
+	{
+		submit(event_id, hint, false, 1, &state_vmopts)
+	};
+
+	if(submitted)
+		log::debug
+		{
+			log, "Fetch %s in state of %s fetching:%zu",
+			string_view{event_id},
+			string_view{opts.room.room_id},
+			fetching.size(),
+		};
+
+	return true;
+}
+
 void
 ircd::m::acquire::acquire_head()
 {
@@ -240,10 +323,6 @@ ircd::m::acquire::acquire_head()
 	{
 		hfopts, [this, &hfopts](const m::event &result)
 		{
-			// Bail if interrupted
-			if(ctx::interruption_requested())
-				return false;
-
 			const auto &[top_id, top_depth, top_idx]
 			{
 				hfopts.top
@@ -258,6 +337,10 @@ bool
 ircd::m::acquire::fetch_head(const m::event &result,
                              const int64_t &top_depth)
 {
+	// Bail if interrupted
+	if(ctx::interruption_requested())
+		return false;
+
 	// Bail if the depth is below the window
 	if(json::get<"depth"_>(result) < opts.depth.first)
 		return false;
@@ -324,6 +407,8 @@ ircd::m::acquire::start(const m::event::id &event_id,
                         const vm::opts *const &vmopts)
 try
 {
+	assert(vmopts);
+
 	fetch::opts fopts;
 	fopts.op = fetch::op::backfill;
 	fopts.room_id = opts.room.room_id;
@@ -438,6 +523,7 @@ try
 		false
 		|| result.vmopts == &this->head_vmopts
 		|| result.vmopts == &this->history_vmopts
+		|| result.vmopts == &this->state_vmopts
 	);
 
 	m::vm::eval