modules/m_vm_fetch: Split and reorg handler stack; add conf items.

modules/m_vm_fetch.cc

@@ -10,11 +10,15 @@
 
 namespace ircd::m::vm::fetch
 {
-	static void hook_handle_prev(const event &, vm::eval &, const room &);
-	static void auth_chain(const room &, const string_view &remote);
-	static void hook_handle_auth(const event &, vm::eval &, const room &);
-	static void hook_handle(const event &, vm::eval &);
+	static void prev_check(const event &, vm::eval &);
+	static std::forward_list<ctx::future<m::fetch::result>> prev_fetch(const event &, vm::eval &, const room &);
+	static void prev(const event &, vm::eval &, const room &);
+	static void auth_chain_eval(const event &, vm::eval &, const room &, const json::array &);
+	static void auth_chain(const event &, vm::eval &, const room &);
+	static void auth(const event &, vm::eval &, const room &);
+	static void handle(const event &, vm::eval &);
 
+	extern conf::item<size_t> prev_backfill_limit;
 	extern conf::item<seconds> auth_timeout;
 	extern conf::item<bool> enable;
 	extern hookfn<vm::eval &> hook;
@@ -33,6 +37,15 @@ ircd::m::vm::fetch::log
 	"m.vm.fetch"
 };
 
+decltype(ircd::m::vm::fetch::hook)
+ircd::m::vm::fetch::hook
+{
+	handle,
+	{
+		{ "_site",  "vm.fetch" }
+	}
+};
+
 decltype(ircd::m::vm::fetch::enable)
 ircd::m::vm::fetch::enable
 {
@@ -47,13 +60,11 @@ ircd::m::vm::fetch::auth_timeout
 	{ "default",  15L                            },
 };
 
-decltype(ircd::m::vm::fetch::hook)
-ircd::m::vm::fetch::hook
+decltype(ircd::m::vm::fetch::prev_backfill_limit)
+ircd::m::vm::fetch::prev_backfill_limit
 {
-	hook_handle,
-	{
-		{ "_site",  "vm.fetch" }
-	}
+	{ "name",     "ircd.m.vm.fetch.prev.backfill.limit" },
+	{ "default",  128L                                  },
 };
 
 //
@@ -61,13 +72,16 @@ ircd::m::vm::fetch::hook
 //
 
 void
-ircd::m::vm::fetch::hook_handle(const event &event,
-                                vm::eval &eval)
+ircd::m::vm::fetch::handle(const event &event,
+                           vm::eval &eval)
 try
 {
 	assert(eval.opts);
 	assert(eval.opts->fetch);
-	const auto &opts{*eval.opts};
+	const auto &opts
+	{
+		*eval.opts
+	};
 
 	const auto &type
 	{
@@ -94,17 +108,10 @@ try
 	room.event_id = event_id;
 
 	if(opts.fetch_auth)
-		hook_handle_auth(event, eval, room);
+		auth(event, eval, room);
 
 	if(opts.fetch_prev)
-		hook_handle_prev(event, eval, room);
-
-	log::debug
-	{
-		log, "%s in %s complete",
-		loghead(eval),
-		json::get<"room_id"_>(event),
-	};
+		prev(event, eval, room);
 }
 catch(const std::exception &e)
 {
@@ -118,31 +125,40 @@ catch(const std::exception &e)
 	throw;
 }
 
-void
-ircd::m::vm::fetch::hook_handle_auth(const event &event,
-                                     vm::eval &eval,
-                                     const room &room)
+//
+// auth_events handler stack
+//
 
+void
+ircd::m::vm::fetch::auth(const event &event,
+                         vm::eval &eval,
+                         const room &room)
+
+try
 {
 	// Count how many of the auth_events provided exist locally.
 	const auto &opts{*eval.opts};
 	const event::prev prev{event};
+	const size_t auth_count
+	{
+		prev.auth_events_count()
+	};
 
-	size_t exists(0);
-	for(size_t i(0); i < prev.auth_events_count(); ++i)
+	size_t auth_exists{0};
+	for(size_t i(0); i < auth_count; ++i)
 	{
 		const auto &auth_id
 		{
 			prev.auth_event(i)
 		};
 
-		exists += bool(m::exists(auth_id));
+		auth_exists += bool(m::exists(auth_id));
 	}
 
 	// We are satisfied at this point if all auth_events for this event exist,
 	// as those events have themselves been successfully evaluated and so forth.
-	assert(exists <= prev.auth_events_count());
-	if(exists == prev.auth_events_count())
+	assert(auth_exists <= auth_count);
+	if(auth_exists == auth_count)
 		return;
 
 	// At this point we are missing one or more auth_events for this event.
@@ -150,62 +166,80 @@ ircd::m::vm::fetch::hook_handle_auth(const event &event,
 	{
 		log, "%s auth_events:%zu miss:%zu",
 		loghead(eval),
-		prev.auth_events_count(),
-		exists - prev.auth_events_count(),
+		auth_count,
+		auth_exists - auth_count,
 	};
 
-	// We need to figure out where best to sling a request to fetch these
-	// missing auth_events. We prefer the remote client conducting this eval
-	// with their /federation/send/ request which we stored in the opts.
-	const string_view &remote
-	{
-		opts.node_id?
-			opts.node_id:
-		!my_host(json::get<"origin"_>(event))?
-			string_view(json::get<"origin"_>(event)):
-		!my_host(room.room_id.host())?                  //TODO: XXX
-			room.room_id.host():
-			string_view{}
-	};
-
-	// Bail out here if we can't or won't attempt fetching auth_events.
-	if(!opts.fetch_auth || !bool(m::vm::fetch::enable) || !remote)
+	if(!bool(m::vm::fetch::enable))
 		throw vm::error
 		{
-			vm::fault::EVENT, "Failed to fetch auth_events for %s in %s",
-			string_view{event.event_id},
-			json::get<"room_id"_>(event)
+			vm::fault::AUTH, "Fetching auth_events disabled by configuration",
+		};
+
+	if(!opts.fetch_auth)
+		throw vm::error
+		{
+			vm::fault::AUTH, "Not fetching auth_events for this evaluation",
 		};
 
 	// This is a blocking call to recursively fetch and evaluate the auth_chain
 	// for this event. Upon return all of the auth_events for this event will
-	// have themselves been fetched and auth'ed recursively or throws.
-	auth_chain(room, remote);
+	// have themselves been fetched and auth'ed recursively.
+	auth_chain(event, eval, room);
+}
+catch(const std::exception &e)
+{
+	throw vm::error
+	{
+		vm::fault::AUTH, "Failed to fetch all auth_events :%s",
+		string_view{event.event_id},
+		json::get<"room_id"_>(event),
+		e.what()
+	};
 }
 
 void
-ircd::m::vm::fetch::auth_chain(const room &room,
-                               const string_view &remote)
+ircd::m::vm::fetch::auth_chain(const event &event,
+                               vm::eval &eval,
+                               const room &room)
 try
 {
-	log::debug
-	{
-		log, "Fetching auth chain for %s in %s (hint: %s)",
-		string_view{room.event_id},
-		string_view{room.room_id},
-		remote,
-	};
-
+	assert(eval.opts);
 	m::fetch::opts opts;
 	opts.op = m::fetch::op::auth;
 	opts.room_id = room.room_id;
 	opts.event_id = room.event_id;
-	opts.hint = remote;
+
+	// Figure out a remote hint as the primary target to request the missing
+	// auth events from; if provided, m::fetch will ask this remote first. We
+	// try to use the eval.node_id, which is set to a server that is conducting
+	// the eval (i.e in a /send/ or when processing some response data from
+	// them); next we try the origin of the event itself. These remotes are
+	// most likely to provide a satisfying response.
+	opts.hint =
+	{
+		eval.opts->node_id?
+			eval.opts->node_id:
+		!my_host(json::get<"origin"_>(event))?
+			string_view(json::get<"origin"_>(event)):
+			string_view{}
+	};
+
+	log::debug
+	{
+		log, "Fetching auth chain for %s in %s hint:%s",
+		string_view{room.event_id},
+		string_view{room.room_id},
+		opts.hint,
+	};
+
+	// send
 	auto future
 	{
 		m::fetch::start(opts)
 	};
 
+	// recv
 	const auto result
 	{
 		future.get(seconds(auth_timeout))
@@ -216,38 +250,25 @@ try
 		result
 	};
 
+	// parse
 	const json::array &auth_chain
 	{
 		response["auth_chain"]
 	};
 
-	log::debug
-	{
-		log, "Evaluating %zu auth events in chain for %s in %s",
-		auth_chain.size(),
-		string_view{room.event_id},
-		string_view{room.room_id},
-	};
-
-	m::vm::opts vmopts;
-	vmopts.infolog_accept = true;
-	vmopts.fetch_prev = false;
-	vmopts.fetch_state = false;
-	vmopts.warnlog &= ~vm::fault::EXISTS;
-	m::vm::eval
-	{
-		auth_chain, vmopts
-	};
+	auth_chain_eval(event, eval, room, auth_chain);
+}
+catch(const vm::error &e)
+{
+	throw;
 }
 catch(const std::exception &e)
 {
-	thread_local char rembuf[64];
 	log::error
 	{
-		log, "Fetching auth chain for %s in %s from %s :%s",
+		log, "Fetching auth chain for %s in %s :%s",
 		string_view{room.event_id},
 		string_view{room.room_id},
-		string(rembuf, remote),
 		e.what(),
 	};
 
@@ -255,9 +276,54 @@ catch(const std::exception &e)
 }
 
 void
-ircd::m::vm::fetch::hook_handle_prev(const event &event,
-                                     vm::eval &eval,
-                                     const room &room)
+ircd::m::vm::fetch::auth_chain_eval(const event &event,
+                                    vm::eval &eval,
+                                    const room &room,
+                                    const json::array &auth_chain)
+try
+{
+	assert(eval.opts);
+	m::vm::opts opts;
+	opts.node_id = eval.opts->node_id;
+	opts.fetch_prev = false;
+	opts.fetch_state = false;
+	opts.infolog_accept = true;
+	opts.warnlog &= ~vm::fault::EXISTS;
+	log::debug
+	{
+		log, "Evaluating auth chain for %s in %s events:%zu",
+		string_view{room.event_id},
+		string_view{room.room_id},
+		auth_chain.size(),
+	};
+
+	// eval
+	m::vm::eval
+	{
+		auth_chain, opts
+	};
+}
+catch(const std::exception &e)
+{
+	log::error
+	{
+		log, "Evaluating auth chain for %s in %s :%s",
+		string_view{room.event_id},
+		string_view{room.room_id},
+		e.what(),
+	};
+
+	throw;
+}
+
+//
+// prev_events handler stack
+//
+
+void
+ircd::m::vm::fetch::prev(const event &event,
+                         vm::eval &eval,
+                         const room &room)
 {
 	const auto &opts{*eval.opts};
 	const event::prev prev{event};
@@ -266,66 +332,36 @@ ircd::m::vm::fetch::hook_handle_prev(const event &event,
 		prev.prev_events_count()
 	};
 
-	size_t prev_exists(0);
-	std::list<ctx::future<m::fetch::result>> futures;
-	for(size_t i(0); i < prev_count; ++i)
+	const size_t prev_exists
 	{
-		const auto &prev_id
-		{
-			prev.prev_event(i)
-		};
+		prev.prev_events_exist()
+	};
 
-		if(m::exists(prev_id))
-		{
-			++prev_exists;
-			continue;
-		}
+	assert(prev_exists <= prev_count);
+	if(prev_count == prev_exists)
+		return;
 
-		if(!opts.fetch_prev || !m::vm::fetch::enable)
-			continue;
-
-		const int64_t room_depth
-		{
-			m::depth(std::nothrow, room)
-		};
-
-		//TODO: XXX
-		const bool recent_event
-		{
-			at<"depth"_>(event) >= room_depth - 20L //TODO: XXX
-		};
-
-		if(!recent_event)
-			continue;
-
-		const ssize_t limit
-		{
-			at<"depth"_>(event) - room_depth
-		};
-
-		m::fetch::opts opts;
-		opts.op = m::fetch::op::backfill;
-		opts.limit = std::min(limit, 32L);
-		opts.room_id = room.room_id;
-		opts.event_id = prev_id;
-		futures.emplace_back(m::fetch::start(opts));
+	if(!opts.fetch_prev || !m::vm::fetch::enable)
+	{
+		prev_check(event, eval);
+		return;
 	}
 
-	// If we have all of the referenced prev_events we are satisfied here.
-	assert(prev_exists < prev_count);
-	if(prev_exists == prev_count)
-		return;
+	auto futures
+	{
+		prev_fetch(event, eval, room)
+	};
 
 	// At this point one or more prev_events are missing; the fetches were
 	// launched asynchronously if the options allowed for it.
 	log::dwarning
 	{
-		log, "%s prev_events:%zu miss:%zu fetching:%zu",
+		log, "%s depth:%ld prev_events:%zu miss:%zu fetching:%zu fetching ...",
 		loghead(eval),
+		at<"depth"_>(event),
 		prev_count,
-		prev_exists,
 		prev_count - prev_exists,
-		futures.size(),
+		std::distance(begin(futures), end(futures)),
 	};
 
 	auto fetching
@@ -333,7 +369,10 @@ ircd::m::vm::fetch::hook_handle_prev(const event &event,
 		ctx::when_all(begin(futures), end(futures))
 	};
 
+	// yields context
 	fetching.wait();
+
+	// evaluate results
 	for(auto &future : futures) try
 	{
 		m::fetch::result result
@@ -353,7 +392,7 @@ ircd::m::vm::fetch::hook_handle_prev(const event &event,
 			pdus.size(),
 		};
 
-		m::vm::eval
+		vm::eval
 		{
 			pdus, opts
 		};
@@ -368,19 +407,113 @@ ircd::m::vm::fetch::hook_handle_prev(const event &event,
 		};
 	}
 
-	const bool recount
+	// check if result evals have satisfied this eval now; or throw
+	prev_check(event, eval);
+}
+
+std::forward_list
+<
+	ircd::ctx::future<ircd::m::fetch::result>
+>
+ircd::m::vm::fetch::prev_fetch(const event &event,
+                               vm::eval &eval,
+                               const room &room)
+{
+	const long room_depth
 	{
-		(opts.fetch_prev_any && !prev_exists)
-		|| opts.fetch_prev_all
+		m::depth(std::nothrow, room)
 	};
 
-	if(recount)
+	const long viewport_depth
 	{
-		prev_exists = 0;
-		for(size_t i(0); i < prev_count; ++i)
-			prev_exists += bool(m::exists(prev.prev_event(i)));
+		room_depth - long(room::events::viewport_size)
+	};
+
+	std::forward_list
+	<
+		ctx::future<m::fetch::result>
+	>
+	ret;
+	const event::prev prev{event};
+	for(size_t i(0); i < prev.prev_events_count(); ++i)
+	{
+		const auto &prev_id
+		{
+			prev.prev_event(i)
+		};
+
+		if(m::exists(prev_id))
+			continue;
+
+		const bool recent_event
+		{
+			at<"depth"_>(event) >= viewport_depth
+		};
+
+		if(!recent_event)
+		{
+			log::dwarning
+			{
+				log, "%s no action for missing prev %s; depth:%ld room:%ld viewport:%ld",
+				loghead(eval),
+				string_view{prev_id},
+				at<"depth"_>(event),
+				room_depth,
+				viewport_depth,
+			};
+
+			continue;
+		}
+
+		const long depth_gap
+		{
+			std::max(std::abs(at<"depth"_>(event) - room_depth), 1L)
+		};
+
+		m::fetch::opts opts;
+		opts.op = m::fetch::op::backfill;
+		opts.room_id = room.room_id;
+		opts.event_id = prev_id;
+		opts.limit = size_t(depth_gap);
+		opts.limit = std::min(opts.limit, eval.opts->fetch_prev_limit);
+		opts.limit = std::min(opts.limit, size_t(prev_backfill_limit));
+		log::debug
+		{
+			log, "%s requesting backfill off %s; depth:%ld viewport:%ld room:%ld gap:%ld limit:%zu",
+			loghead(eval),
+			string_view{prev_id},
+			at<"depth"_>(event),
+			viewport_depth,
+			room_depth,
+			depth_gap,
+			opts.limit,
+		};
+
+		ret.emplace_front(m::fetch::start(opts));
 	}
 
+	return ret;
+}
+
+void
+ircd::m::vm::fetch::prev_check(const event &event,
+                               vm::eval &eval)
+{
+	const auto &opts
+	{
+		*eval.opts
+	};
+
+	const event::prev prev
+	{
+		event
+	};
+
+	const size_t prev_exists
+	{
+		prev.prev_events_exist()
+	};
+
 	// Aborts this event if the options want us to guarantee at least one
 	// prev_event was fetched and evaluated for this event. This is generally
 	// used in conjunction with the fetch_prev_wait option to be effective.
@@ -388,19 +521,19 @@ ircd::m::vm::fetch::hook_handle_prev(const event &event,
 		throw vm::error
 		{
 			vm::fault::EVENT, "Failed to fetch any of the %zu prev_events for %s in %s",
-			prev_count,
+			prev.prev_events_count(),
 			string_view{event.event_id},
 			json::get<"room_id"_>(event)
 		};
 
 	// Aborts this event if the options want us to guarantee ALL of the
 	// prev_events were fetched and evaluated for this event.
-	if(opts.fetch_prev_all && prev_exists < prev_count)
+	if(opts.fetch_prev_all && prev_exists < prev.prev_events_count())
 		throw vm::error
 		{
 			vm::fault::EVENT, "Missing %zu of %zu required prev_events for %s in %s",
 			prev_exists,
-			prev_count,
+			prev.prev_events_count(),
 			string_view{event.event_id},
 			json::get<"room_id"_>(event)
 		};