Implement ExtraPublicRoomsProvider for p2p demos (#1180)

* Change API and rename to ExtraPublicRoomsProvider

* Make dendritejs work again

* Maybe make libp2p demo work again

* Linting

build/docker/DendriteJS.Dockerfile

@@ -5,7 +5,7 @@
 # $ docker build -t dendritejs -f DendriteJS.Dockerfile .
 # $ docker run --rm -p 8888:80 dendritejs
 # Then visit http://localhost:8888
-FROM golang:1.13.7-alpine3.11 AS gobuild
+FROM golang:1.14-alpine AS gobuild
 
 # Download and build dendrite
 WORKDIR /build

clientapi/api/api.go

@@ -14,9 +14,10 @@
 
 package api
 
-type ExternalPublicRoomsProvider interface {
+import "github.com/matrix-org/gomatrixserverlib"
-	// The list of homeserver domains to query. These servers will receive a request
+
-	// via this API: https://matrix.org/docs/spec/server_server/latest#public-room-directory
+// ExtraPublicRoomsProvider provides a way to inject extra published rooms into /publicRooms requests.
-	// This will be called -on demand- by clients, so cache appropriately!
+type ExtraPublicRoomsProvider interface {
-	Homeservers() []string
+	// Rooms returns the extra rooms. This is called on-demand by clients, so cache appropriately.
+	Rooms() []gomatrixserverlib.PublicRoom
 }

clientapi/clientapi.go

@@ -48,7 +48,7 @@ func AddPublicRoutes(
 	transactionsCache *transactions.Cache,
 	fsAPI federationSenderAPI.FederationSenderInternalAPI,
 	userAPI userapi.UserInternalAPI,
-	extRoomsProvider api.ExternalPublicRoomsProvider,
+	extRoomsProvider api.ExtraPublicRoomsProvider,
 ) {
 	syncProducer := &producers.SyncAPIProducer{
 		Producer: producer,

clientapi/routing/directory_public.go

@@ -22,7 +22,6 @@ import (
 	"strconv"
 	"strings"
 	"sync"
-	"time"
 
 	"github.com/matrix-org/dendrite/clientapi/api"
 	"github.com/matrix-org/dendrite/clientapi/httputil"
@@ -33,6 +32,11 @@ import (
 	"github.com/matrix-org/util"
 )
 
+var (
+	cacheMu          sync.Mutex
+	publicRoomsCache []gomatrixserverlib.PublicRoom
+)
+
 type PublicRoomReq struct {
 	Since  string `json:"since,omitempty"`
 	Limit  int16  `json:"limit,omitempty"`
@@ -46,13 +50,15 @@ type filter struct {
 // GetPostPublicRooms implements GET and POST /publicRooms
 func GetPostPublicRooms(
 	req *http.Request, rsAPI roomserverAPI.RoomserverInternalAPI, stateAPI currentstateAPI.CurrentStateInternalAPI,
+	extRoomsProvider api.ExtraPublicRoomsProvider,
 ) util.JSONResponse {
 	var request PublicRoomReq
 	if fillErr := fillPublicRoomsReq(req, &request); fillErr != nil {
 		return *fillErr
 	}
-	response, err := publicRooms(req.Context(), request, rsAPI, stateAPI)
+	response, err := publicRooms(req.Context(), request, rsAPI, stateAPI, extRoomsProvider)
 	if err != nil {
+		util.GetLogger(req.Context()).WithError(err).Errorf("failed to work out public rooms")
 		return jsonerror.InternalServerError()
 	}
 	return util.JSONResponse{
@@ -61,146 +67,9 @@ func GetPostPublicRooms(
 	}
 }
 
-// GetPostPublicRoomsWithExternal is the same as GetPostPublicRooms but also mixes in public rooms from the provider supplied.
-func GetPostPublicRoomsWithExternal(
-	req *http.Request, rsAPI roomserverAPI.RoomserverInternalAPI, stateAPI currentstateAPI.CurrentStateInternalAPI,
-	fedClient *gomatrixserverlib.FederationClient, extRoomsProvider api.ExternalPublicRoomsProvider,
-) util.JSONResponse {
-	var request PublicRoomReq
-	if fillErr := fillPublicRoomsReq(req, &request); fillErr != nil {
-		return *fillErr
-	}
-	response, err := publicRooms(req.Context(), request, rsAPI, stateAPI)
-	if err != nil {
-		return jsonerror.InternalServerError()
-	}
-
-	if request.Since != "" {
-		// TODO: handle pagination tokens sensibly rather than ignoring them.
-		// ignore paginated requests since we don't handle them yet over federation.
-		// Only the initial request will contain federated rooms.
-		return util.JSONResponse{
-			Code: http.StatusOK,
-			JSON: response,
-		}
-	}
-
-	// If we have already hit the limit on the number of rooms, bail.
-	var limit int
-	if request.Limit > 0 {
-		limit = int(request.Limit) - len(response.Chunk)
-		if limit <= 0 {
-			return util.JSONResponse{
-				Code: http.StatusOK,
-				JSON: response,
-			}
-		}
-	}
-
-	// downcasting `limit` is safe as we know it isn't bigger than request.Limit which is int16
-	fedRooms := bulkFetchPublicRoomsFromServers(req.Context(), fedClient, extRoomsProvider.Homeservers(), int16(limit))
-	response.Chunk = append(response.Chunk, fedRooms...)
-
-	// de-duplicate rooms with the same room ID. We can join the room via any of these aliases as we know these servers
-	// are alive and well, so we arbitrarily pick one (purposefully shuffling them to spread the load a bit)
-	var publicRooms []gomatrixserverlib.PublicRoom
-	haveRoomIDs := make(map[string]bool)
-	rand.Shuffle(len(response.Chunk), func(i, j int) {
-		response.Chunk[i], response.Chunk[j] = response.Chunk[j], response.Chunk[i]
-	})
-	for _, r := range response.Chunk {
-		if haveRoomIDs[r.RoomID] {
-			continue
-		}
-		haveRoomIDs[r.RoomID] = true
-		publicRooms = append(publicRooms, r)
-	}
-	// sort by member count
-	sort.SliceStable(publicRooms, func(i, j int) bool {
-		return publicRooms[i].JoinedMembersCount > publicRooms[j].JoinedMembersCount
-	})
-
-	response.Chunk = publicRooms
-
-	return util.JSONResponse{
-		Code: http.StatusOK,
-		JSON: response,
-	}
-}
-
-// bulkFetchPublicRoomsFromServers fetches public rooms from the list of homeservers.
-// Returns a list of public rooms up to the limit specified.
-func bulkFetchPublicRoomsFromServers(
-	ctx context.Context, fedClient *gomatrixserverlib.FederationClient, homeservers []string, limit int16,
-) (publicRooms []gomatrixserverlib.PublicRoom) {
-	// follow pipeline semantics, see https://blog.golang.org/pipelines for more info.
-	// goroutines send rooms to this channel
-	roomCh := make(chan gomatrixserverlib.PublicRoom, int(limit))
-	// signalling channel to tell goroutines to stop sending rooms and quit
-	done := make(chan bool)
-	// signalling to say when we can close the room channel
-	var wg sync.WaitGroup
-	wg.Add(len(homeservers))
-	// concurrently query for public rooms
-	for _, hs := range homeservers {
-		go func(homeserverDomain string) {
-			defer wg.Done()
-			util.GetLogger(ctx).WithField("hs", homeserverDomain).Info("Querying HS for public rooms")
-			fres, err := fedClient.GetPublicRooms(ctx, gomatrixserverlib.ServerName(homeserverDomain), int(limit), "", false, "")
-			if err != nil {
-				util.GetLogger(ctx).WithError(err).WithField("hs", homeserverDomain).Warn(
-					"bulkFetchPublicRoomsFromServers: failed to query hs",
-				)
-				return
-			}
-			for _, room := range fres.Chunk {
-				// atomically send a room or stop
-				select {
-				case roomCh <- room:
-				case <-done:
-					util.GetLogger(ctx).WithError(err).WithField("hs", homeserverDomain).Info("Interrupted whilst sending rooms")
-					return
-				}
-			}
-		}(hs)
-	}
-
-	// Close the room channel when the goroutines have quit so we don't leak, but don't let it stop the in-flight request.
-	// This also allows the request to fail fast if all HSes experience errors as it will cause the room channel to be
-	// closed.
-	go func() {
-		wg.Wait()
-		util.GetLogger(ctx).Info("Cleaning up resources")
-		close(roomCh)
-	}()
-
-	// fan-in results with timeout. We stop when we reach the limit.
-FanIn:
-	for len(publicRooms) < int(limit) || limit == 0 {
-		// add a room or timeout
-		select {
-		case room, ok := <-roomCh:
-			if !ok {
-				util.GetLogger(ctx).Info("All homeservers have been queried, returning results.")
-				break FanIn
-			}
-			publicRooms = append(publicRooms, room)
-		case <-time.After(15 * time.Second): // we've waited long enough, let's tell the client what we got.
-			util.GetLogger(ctx).Info("Waited 15s for federated public rooms, returning early")
-			break FanIn
-		case <-ctx.Done(): // the client hung up on us, let's stop.
-			util.GetLogger(ctx).Info("Client hung up, returning early")
-			break FanIn
-		}
-	}
-	// tell goroutines to stop
-	close(done)
-
-	return publicRooms
-}
-
 func publicRooms(ctx context.Context, request PublicRoomReq, rsAPI roomserverAPI.RoomserverInternalAPI,
-	stateAPI currentstateAPI.CurrentStateInternalAPI) (*gomatrixserverlib.RespPublicRooms, error) {
+	stateAPI currentstateAPI.CurrentStateInternalAPI, extRoomsProvider api.ExtraPublicRoomsProvider,
+) (*gomatrixserverlib.RespPublicRooms, error) {
 
 	var response gomatrixserverlib.RespPublicRooms
 	var limit int16
@@ -216,23 +85,25 @@ func publicRooms(ctx context.Context, request PublicRoomReq, rsAPI roomserverAPI
 		util.GetLogger(ctx).WithError(err).Error("strconv.ParseInt failed")
 		return nil, err
 	}
+	err = nil
 
-	var queryRes roomserverAPI.QueryPublishedRoomsResponse
+	var rooms []gomatrixserverlib.PublicRoom
-	err = rsAPI.QueryPublishedRooms(ctx, &roomserverAPI.QueryPublishedRoomsRequest{}, &queryRes)
+	if request.Since == "" {
-	if err != nil {
+		rooms = refreshPublicRoomCache(ctx, rsAPI, extRoomsProvider, stateAPI)
-		util.GetLogger(ctx).WithError(err).Error("QueryPublishedRooms failed")
+	} else {
-		return nil, err
+		rooms = getPublicRoomsFromCache()
 	}
-	response.TotalRoomCountEstimate = len(queryRes.RoomIDs)
 
-	roomIDs, prev, next := sliceInto(queryRes.RoomIDs, offset, limit)
+	response.TotalRoomCountEstimate = len(rooms)
+
+	chunk, prev, next := sliceInto(rooms, offset, limit)
 	if prev >= 0 {
 		response.PrevBatch = "T" + strconv.Itoa(prev)
 	}
 	if next >= 0 {
 		response.NextBatch = "T" + strconv.Itoa(next)
 	}
-	response.Chunk, err = fillInRooms(ctx, roomIDs, stateAPI)
+	response.Chunk = chunk
 	return &response, err
 }
 
@@ -273,71 +144,6 @@ func fillPublicRoomsReq(httpReq *http.Request, request *PublicRoomReq) *util.JSO
 	return nil
 }
 
-// due to lots of switches
-// nolint:gocyclo
-func fillInRooms(ctx context.Context, roomIDs []string, stateAPI currentstateAPI.CurrentStateInternalAPI) ([]gomatrixserverlib.PublicRoom, error) {
-	avatarTuple := gomatrixserverlib.StateKeyTuple{EventType: "m.room.avatar", StateKey: ""}
-	nameTuple := gomatrixserverlib.StateKeyTuple{EventType: "m.room.name", StateKey: ""}
-	canonicalTuple := gomatrixserverlib.StateKeyTuple{EventType: gomatrixserverlib.MRoomCanonicalAlias, StateKey: ""}
-	topicTuple := gomatrixserverlib.StateKeyTuple{EventType: "m.room.topic", StateKey: ""}
-	guestTuple := gomatrixserverlib.StateKeyTuple{EventType: "m.room.guest_access", StateKey: ""}
-	visibilityTuple := gomatrixserverlib.StateKeyTuple{EventType: gomatrixserverlib.MRoomHistoryVisibility, StateKey: ""}
-	joinRuleTuple := gomatrixserverlib.StateKeyTuple{EventType: gomatrixserverlib.MRoomJoinRules, StateKey: ""}
-
-	var stateRes currentstateAPI.QueryBulkStateContentResponse
-	err := stateAPI.QueryBulkStateContent(ctx, &currentstateAPI.QueryBulkStateContentRequest{
-		RoomIDs:        roomIDs,
-		AllowWildcards: true,
-		StateTuples: []gomatrixserverlib.StateKeyTuple{
-			nameTuple, canonicalTuple, topicTuple, guestTuple, visibilityTuple, joinRuleTuple, avatarTuple,
-			{EventType: gomatrixserverlib.MRoomMember, StateKey: "*"},
-		},
-	}, &stateRes)
-	if err != nil {
-		util.GetLogger(ctx).WithError(err).Error("QueryBulkStateContent failed")
-		return nil, err
-	}
-	chunk := make([]gomatrixserverlib.PublicRoom, len(roomIDs))
-	i := 0
-	for roomID, data := range stateRes.Rooms {
-		pub := gomatrixserverlib.PublicRoom{
-			RoomID: roomID,
-		}
-		joinCount := 0
-		var joinRule, guestAccess string
-		for tuple, contentVal := range data {
-			if tuple.EventType == gomatrixserverlib.MRoomMember && contentVal == "join" {
-				joinCount++
-				continue
-			}
-			switch tuple {
-			case avatarTuple:
-				pub.AvatarURL = contentVal
-			case nameTuple:
-				pub.Name = contentVal
-			case topicTuple:
-				pub.Topic = contentVal
-			case canonicalTuple:
-				pub.CanonicalAlias = contentVal
-			case visibilityTuple:
-				pub.WorldReadable = contentVal == "world_readable"
-			// need both of these to determine whether guests can join
-			case joinRuleTuple:
-				joinRule = contentVal
-			case guestTuple:
-				guestAccess = contentVal
-			}
-		}
-		if joinRule == gomatrixserverlib.Public && guestAccess == "can_join" {
-			pub.GuestCanJoin = true
-		}
-		pub.JoinedMembersCount = joinCount
-		chunk[i] = pub
-		i++
-	}
-	return chunk, nil
-}
-
 // sliceInto returns a subslice of `slice` which honours the since/limit values given.
 //
 //    0  1  2  3  4  5  6   index
@@ -348,7 +154,7 @@ func fillInRooms(ctx context.Context, roomIDs []string, stateAPI currentstateAPI
 //   limit=3&since=6  => G     (prev='3', next='')
 //
 //  A value of '-1' for prev/next indicates no position.
-func sliceInto(slice []string, since int64, limit int16) (subset []string, prev, next int) {
+func sliceInto(slice []gomatrixserverlib.PublicRoom, since int64, limit int16) (subset []gomatrixserverlib.PublicRoom, prev, next int) {
 	prev = -1
 	next = -1
 
@@ -371,3 +177,61 @@ func sliceInto(slice []string, since int64, limit int16) (subset []string, prev,
 	subset = slice[since:nextIndex]
 	return
 }
+
+func refreshPublicRoomCache(
+	ctx context.Context, rsAPI roomserverAPI.RoomserverInternalAPI, extRoomsProvider api.ExtraPublicRoomsProvider,
+	stateAPI currentstateAPI.CurrentStateInternalAPI,
+) []gomatrixserverlib.PublicRoom {
+	cacheMu.Lock()
+	defer cacheMu.Unlock()
+	var extraRooms []gomatrixserverlib.PublicRoom
+	if extRoomsProvider != nil {
+		extraRooms = extRoomsProvider.Rooms()
+	}
+
+	var queryRes roomserverAPI.QueryPublishedRoomsResponse
+	err := rsAPI.QueryPublishedRooms(ctx, &roomserverAPI.QueryPublishedRoomsRequest{}, &queryRes)
+	if err != nil {
+		util.GetLogger(ctx).WithError(err).Error("QueryPublishedRooms failed")
+		return publicRoomsCache
+	}
+	pubRooms, err := currentstateAPI.PopulatePublicRooms(ctx, queryRes.RoomIDs, stateAPI)
+	if err != nil {
+		util.GetLogger(ctx).WithError(err).Error("PopulatePublicRooms failed")
+		return publicRoomsCache
+	}
+	publicRoomsCache = []gomatrixserverlib.PublicRoom{}
+	publicRoomsCache = append(publicRoomsCache, pubRooms...)
+	publicRoomsCache = append(publicRoomsCache, extraRooms...)
+	publicRoomsCache = dedupeAndShuffle(publicRoomsCache)
+
+	// sort by total joined member count (big to small)
+	sort.SliceStable(publicRoomsCache, func(i, j int) bool {
+		return publicRoomsCache[i].JoinedMembersCount > publicRoomsCache[j].JoinedMembersCount
+	})
+	return publicRoomsCache
+}
+
+func getPublicRoomsFromCache() []gomatrixserverlib.PublicRoom {
+	cacheMu.Lock()
+	defer cacheMu.Unlock()
+	return publicRoomsCache
+}
+
+func dedupeAndShuffle(in []gomatrixserverlib.PublicRoom) []gomatrixserverlib.PublicRoom {
+	// de-duplicate rooms with the same room ID. We can join the room via any of these aliases as we know these servers
+	// are alive and well, so we arbitrarily pick one (purposefully shuffling them to spread the load a bit)
+	var publicRooms []gomatrixserverlib.PublicRoom
+	haveRoomIDs := make(map[string]bool)
+	rand.Shuffle(len(in), func(i, j int) {
+		in[i], in[j] = in[j], in[i]
+	})
+	for _, r := range in {
+		if haveRoomIDs[r.RoomID] {
+			continue
+		}
+		haveRoomIDs[r.RoomID] = true
+		publicRooms = append(publicRooms, r)
+	}
+	return publicRooms
+}

clientapi/routing/directory_public_test.go

@@ -3,16 +3,26 @@ package routing
 import (
 	"reflect"
 	"testing"
+
+	"github.com/matrix-org/gomatrixserverlib"
 )
 
+func pubRoom(name string) gomatrixserverlib.PublicRoom {
+	return gomatrixserverlib.PublicRoom{
+		Name: name,
+	}
+}
+
 func TestSliceInto(t *testing.T) {
-	slice := []string{"a", "b", "c", "d", "e", "f", "g"}
+	slice := []gomatrixserverlib.PublicRoom{
+		pubRoom("a"), pubRoom("b"), pubRoom("c"), pubRoom("d"), pubRoom("e"), pubRoom("f"), pubRoom("g"),
+	}
 	limit := int16(3)
 	testCases := []struct {
 		since      int64
 		wantPrev   int
 		wantNext   int
-		wantSubset []string
+		wantSubset []gomatrixserverlib.PublicRoom
 	}{
 		{
 			since:      0,

clientapi/routing/routing.go

@@ -61,7 +61,7 @@ func Setup(
 	transactionsCache *transactions.Cache,
 	federationSender federationSenderAPI.FederationSenderInternalAPI,
 	stateAPI currentstateAPI.CurrentStateInternalAPI,
-	extRoomsProvider api.ExternalPublicRoomsProvider,
+	extRoomsProvider api.ExtraPublicRoomsProvider,
 ) {
 
 	publicAPIMux.Handle("/client/versions",
@@ -313,11 +313,7 @@ func Setup(
 	).Methods(http.MethodPut, http.MethodOptions)
 	r0mux.Handle("/publicRooms",
 		httputil.MakeExternalAPI("public_rooms", func(req *http.Request) util.JSONResponse {
-			/* TODO:
+			return GetPostPublicRooms(req, rsAPI, stateAPI, extRoomsProvider)
-			if extRoomsProvider != nil {
-				return GetPostPublicRoomsWithExternal(req, stateAPI, fedClient, extRoomsProvider)
-			} */
-			return GetPostPublicRooms(req, rsAPI, stateAPI)
 		}),
 	).Methods(http.MethodGet, http.MethodPost, http.MethodOptions)
 

cmd/dendrite-demo-libp2p/main.go

@@ -1,6 +1,4 @@
-// Copyright 2017 Vector Creations Ltd
+// Copyright 2020 The Matrix.org Foundation C.I.C.
-// Copyright 2018 New Vector Ltd
-// Copyright 2019-2020 The Matrix.org Foundation C.I.C.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -162,13 +160,12 @@ func main() {
 		&base.Base, federation, rsAPI, keyRing,
 	)
 	rsAPI.SetFederationSenderAPI(fsAPI)
-	/* TODO:
-	publicRoomsDB, err := storage.NewPublicRoomsServerDatabaseWithPubSub(string(base.Base.Cfg.Database.PublicRoomsAPI), base.LibP2PPubsub, cfg.Matrix.ServerName)
-	if err != nil {
-		logrus.WithError(err).Panicf("failed to connect to public rooms db")
-	}
-	*/
 	stateAPI := currentstateserver.NewInternalAPI(base.Base.Cfg, base.Base.KafkaConsumer)
+	provider := newPublicRoomsProvider(base.LibP2PPubsub, rsAPI, stateAPI)
+	err = provider.Start()
+	if err != nil {
+		panic("failed to create new public rooms provider: " + err.Error())
+	}
 
 	monolith := setup.Monolith{
 		Config:        base.Base.Cfg,
@@ -180,13 +177,14 @@ func main() {
 		KafkaConsumer: base.Base.KafkaConsumer,
 		KafkaProducer: base.Base.KafkaProducer,
 
-		AppserviceAPI:       asAPI,
+		AppserviceAPI:          asAPI,
-		EDUInternalAPI:      eduInputAPI,
+		EDUInternalAPI:         eduInputAPI,
-		FederationSenderAPI: fsAPI,
+		FederationSenderAPI:    fsAPI,
-		RoomserverAPI:       rsAPI,
+		RoomserverAPI:          rsAPI,
-		ServerKeyAPI:        serverKeyAPI,
+		ServerKeyAPI:           serverKeyAPI,
-		StateAPI:            stateAPI,
+		StateAPI:               stateAPI,
-		UserAPI:             userAPI,
+		UserAPI:                userAPI,
+		ExtPublicRoomsProvider: provider,
 	}
 	monolith.AddAllPublicRoutes(base.Base.PublicAPIMux)
 

cmd/dendrite-demo-libp2p/publicrooms.go

@@ -0,0 +1,156 @@
+// Copyright 2020 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	currentstateAPI "github.com/matrix-org/dendrite/currentstateserver/api"
+	roomserverAPI "github.com/matrix-org/dendrite/roomserver/api"
+
+	pubsub "github.com/libp2p/go-libp2p-pubsub"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
+)
+
+const MaintenanceInterval = time.Second * 10
+
+type discoveredRoom struct {
+	time time.Time
+	room gomatrixserverlib.PublicRoom
+}
+
+type publicRoomsProvider struct {
+	pubsub           *pubsub.PubSub
+	topic            *pubsub.Topic
+	subscription     *pubsub.Subscription
+	foundRooms       map[string]discoveredRoom // additional rooms we have learned about from the DHT
+	foundRoomsMutex  sync.RWMutex              // protects foundRooms
+	maintenanceTimer *time.Timer               //
+	roomsAdvertised  atomic.Value              // stores int
+	rsAPI            roomserverAPI.RoomserverInternalAPI
+	stateAPI         currentstateAPI.CurrentStateInternalAPI
+}
+
+func newPublicRoomsProvider(ps *pubsub.PubSub, rsAPI roomserverAPI.RoomserverInternalAPI, stateAPI currentstateAPI.CurrentStateInternalAPI) *publicRoomsProvider {
+	return &publicRoomsProvider{
+		foundRooms: make(map[string]discoveredRoom),
+		pubsub:     ps,
+		rsAPI:      rsAPI,
+		stateAPI:   stateAPI,
+	}
+}
+
+func (p *publicRoomsProvider) Start() error {
+	if topic, err := p.pubsub.Join("/matrix/publicRooms"); err != nil {
+		return err
+	} else if sub, err := topic.Subscribe(); err == nil {
+		p.topic = topic
+		p.subscription = sub
+		go p.MaintenanceTimer()
+		go p.FindRooms()
+		p.roomsAdvertised.Store(0)
+	} else {
+		return err
+	}
+	return nil
+}
+
+func (p *publicRoomsProvider) MaintenanceTimer() {
+	if p.maintenanceTimer != nil && !p.maintenanceTimer.Stop() {
+		<-p.maintenanceTimer.C
+	}
+	p.Interval()
+}
+
+func (p *publicRoomsProvider) Interval() {
+	p.foundRoomsMutex.Lock()
+	for k, v := range p.foundRooms {
+		if time.Since(v.time) > time.Minute {
+			delete(p.foundRooms, k)
+		}
+	}
+	p.foundRoomsMutex.Unlock()
+	if err := p.AdvertiseRooms(); err != nil {
+		fmt.Println("Failed to advertise room in DHT:", err)
+	}
+	p.foundRoomsMutex.RLock()
+	defer p.foundRoomsMutex.RUnlock()
+	fmt.Println("Found", len(p.foundRooms), "room(s), advertised", p.roomsAdvertised.Load(), "room(s)")
+	p.maintenanceTimer = time.AfterFunc(MaintenanceInterval, p.Interval)
+}
+
+func (p *publicRoomsProvider) AdvertiseRooms() error {
+	ctx := context.Background()
+	var queryRes roomserverAPI.QueryPublishedRoomsResponse
+	// Query published rooms on our server. This will not invoke clientapi.ExtraPublicRoomsProvider
+	err := p.rsAPI.QueryPublishedRooms(ctx, &roomserverAPI.QueryPublishedRoomsRequest{}, &queryRes)
+	if err != nil {
+		util.GetLogger(ctx).WithError(err).Error("QueryPublishedRooms failed")
+		return err
+	}
+	ourRooms, err := currentstateAPI.PopulatePublicRooms(ctx, queryRes.RoomIDs, p.stateAPI)
+	if err != nil {
+		util.GetLogger(ctx).WithError(err).Error("PopulatePublicRooms failed")
+		return err
+	}
+	advertised := 0
+	for _, room := range ourRooms {
+		if j, err := json.Marshal(room); err == nil {
+			if err := p.topic.Publish(context.TODO(), j); err != nil {
+				fmt.Println("Failed to publish public room:", err)
+			} else {
+				advertised++
+			}
+		}
+	}
+
+	p.roomsAdvertised.Store(advertised)
+	return nil
+}
+
+func (p *publicRoomsProvider) FindRooms() {
+	for {
+		msg, err := p.subscription.Next(context.Background())
+		if err != nil {
+			continue
+		}
+		received := discoveredRoom{
+			time: time.Now(),
+		}
+		if err := json.Unmarshal(msg.Data, &received.room); err != nil {
+			fmt.Println("Unmarshal error:", err)
+			continue
+		}
+		fmt.Printf("received %+v \n", received)
+		p.foundRoomsMutex.Lock()
+		p.foundRooms[received.room.RoomID] = received
+		p.foundRoomsMutex.Unlock()
+	}
+}
+
+func (p *publicRoomsProvider) Rooms() (rooms []gomatrixserverlib.PublicRoom) {
+	p.foundRoomsMutex.RLock()
+	defer p.foundRoomsMutex.RUnlock()
+	for _, dr := range p.foundRooms {
+		rooms = append(rooms, dr.room)
+	}
+	return
+}

cmd/dendritejs/main.go

@@ -211,7 +211,7 @@ func main() {
 	)
 	fedSenderAPI := federationsender.NewInternalAPI(base, federation, rsAPI, &keyRing)
 	rsAPI.SetFederationSenderAPI(fedSenderAPI)
-	p2pPublicRoomProvider := NewLibP2PPublicRoomsProvider(node, fedSenderAPI)
+	p2pPublicRoomProvider := NewLibP2PPublicRoomsProvider(node, fedSenderAPI, federation)
 
 	stateAPI := currentstateserver.NewInternalAPI(base.Cfg, base.KafkaConsumer)
 

cmd/dendritejs/publicrooms.go

@@ -18,22 +18,29 @@ package main
 
 import (
 	"context"
+	"sync"
+	"time"
 
 	"github.com/matrix-org/dendrite/federationsender/api"
 	go_http_js_libp2p "github.com/matrix-org/go-http-js-libp2p"
 	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
 )
 
 type libp2pPublicRoomsProvider struct {
 	node      *go_http_js_libp2p.P2pLocalNode
 	providers []go_http_js_libp2p.PeerInfo
 	fedSender api.FederationSenderInternalAPI
+	fedClient *gomatrixserverlib.FederationClient
 }
 
-func NewLibP2PPublicRoomsProvider(node *go_http_js_libp2p.P2pLocalNode, fedSender api.FederationSenderInternalAPI) *libp2pPublicRoomsProvider {
+func NewLibP2PPublicRoomsProvider(
+	node *go_http_js_libp2p.P2pLocalNode, fedSender api.FederationSenderInternalAPI, fedClient *gomatrixserverlib.FederationClient,
+) *libp2pPublicRoomsProvider {
 	p := &libp2pPublicRoomsProvider{
 		node:      node,
 		fedSender: fedSender,
+		fedClient: fedClient,
 	}
 	node.RegisterFoundProviders(p.foundProviders)
 	return p
@@ -62,10 +69,86 @@ func (p *libp2pPublicRoomsProvider) foundProviders(peerInfos []go_http_js_libp2p
 	p.providers = peerInfos
 }
 
-func (p *libp2pPublicRoomsProvider) Homeservers() []string {
+func (p *libp2pPublicRoomsProvider) Rooms() []gomatrixserverlib.PublicRoom {
+	return bulkFetchPublicRoomsFromServers(context.Background(), p.fedClient, p.homeservers())
+}
+
+func (p *libp2pPublicRoomsProvider) homeservers() []string {
 	result := make([]string, len(p.providers))
 	for i := range p.providers {
 		result[i] = p.providers[i].Id
 	}
 	return result
 }
+
+// bulkFetchPublicRoomsFromServers fetches public rooms from the list of homeservers.
+// Returns a list of public rooms.
+func bulkFetchPublicRoomsFromServers(
+	ctx context.Context, fedClient *gomatrixserverlib.FederationClient, homeservers []string,
+) (publicRooms []gomatrixserverlib.PublicRoom) {
+	limit := 200
+	// follow pipeline semantics, see https://blog.golang.org/pipelines for more info.
+	// goroutines send rooms to this channel
+	roomCh := make(chan gomatrixserverlib.PublicRoom, int(limit))
+	// signalling channel to tell goroutines to stop sending rooms and quit
+	done := make(chan bool)
+	// signalling to say when we can close the room channel
+	var wg sync.WaitGroup
+	wg.Add(len(homeservers))
+	// concurrently query for public rooms
+	for _, hs := range homeservers {
+		go func(homeserverDomain string) {
+			defer wg.Done()
+			util.GetLogger(ctx).WithField("hs", homeserverDomain).Info("Querying HS for public rooms")
+			fres, err := fedClient.GetPublicRooms(ctx, gomatrixserverlib.ServerName(homeserverDomain), int(limit), "", false, "")
+			if err != nil {
+				util.GetLogger(ctx).WithError(err).WithField("hs", homeserverDomain).Warn(
+					"bulkFetchPublicRoomsFromServers: failed to query hs",
+				)
+				return
+			}
+			for _, room := range fres.Chunk {
+				// atomically send a room or stop
+				select {
+				case roomCh <- room:
+				case <-done:
+					util.GetLogger(ctx).WithError(err).WithField("hs", homeserverDomain).Info("Interrupted whilst sending rooms")
+					return
+				}
+			}
+		}(hs)
+	}
+
+	// Close the room channel when the goroutines have quit so we don't leak, but don't let it stop the in-flight request.
+	// This also allows the request to fail fast if all HSes experience errors as it will cause the room channel to be
+	// closed.
+	go func() {
+		wg.Wait()
+		util.GetLogger(ctx).Info("Cleaning up resources")
+		close(roomCh)
+	}()
+
+	// fan-in results with timeout. We stop when we reach the limit.
+FanIn:
+	for len(publicRooms) < int(limit) || limit == 0 {
+		// add a room or timeout
+		select {
+		case room, ok := <-roomCh:
+			if !ok {
+				util.GetLogger(ctx).Info("All homeservers have been queried, returning results.")
+				break FanIn
+			}
+			publicRooms = append(publicRooms, room)
+		case <-time.After(15 * time.Second): // we've waited long enough, let's tell the client what we got.
+			util.GetLogger(ctx).Info("Waited 15s for federated public rooms, returning early")
+			break FanIn
+		case <-ctx.Done(): // the client hung up on us, let's stop.
+			util.GetLogger(ctx).Info("Client hung up, returning early")
+			break FanIn
+		}
+	}
+	// tell goroutines to stop
+	close(done)
+
+	return publicRooms
+}

currentstateserver/api/wrapper.go

@@ -0,0 +1,75 @@
+package api
+
+import (
+	"context"
+
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
+)
+
+// PopulatePublicRooms extracts PublicRoom information for all the provided room IDs. The IDs are not checked to see if they are visible in the
+// published room directory.
+// due to lots of switches
+// nolint:gocyclo
+func PopulatePublicRooms(ctx context.Context, roomIDs []string, stateAPI CurrentStateInternalAPI) ([]gomatrixserverlib.PublicRoom, error) {
+	avatarTuple := gomatrixserverlib.StateKeyTuple{EventType: "m.room.avatar", StateKey: ""}
+	nameTuple := gomatrixserverlib.StateKeyTuple{EventType: "m.room.name", StateKey: ""}
+	canonicalTuple := gomatrixserverlib.StateKeyTuple{EventType: gomatrixserverlib.MRoomCanonicalAlias, StateKey: ""}
+	topicTuple := gomatrixserverlib.StateKeyTuple{EventType: "m.room.topic", StateKey: ""}
+	guestTuple := gomatrixserverlib.StateKeyTuple{EventType: "m.room.guest_access", StateKey: ""}
+	visibilityTuple := gomatrixserverlib.StateKeyTuple{EventType: gomatrixserverlib.MRoomHistoryVisibility, StateKey: ""}
+	joinRuleTuple := gomatrixserverlib.StateKeyTuple{EventType: gomatrixserverlib.MRoomJoinRules, StateKey: ""}
+
+	var stateRes QueryBulkStateContentResponse
+	err := stateAPI.QueryBulkStateContent(ctx, &QueryBulkStateContentRequest{
+		RoomIDs:        roomIDs,
+		AllowWildcards: true,
+		StateTuples: []gomatrixserverlib.StateKeyTuple{
+			nameTuple, canonicalTuple, topicTuple, guestTuple, visibilityTuple, joinRuleTuple, avatarTuple,
+			{EventType: gomatrixserverlib.MRoomMember, StateKey: "*"},
+		},
+	}, &stateRes)
+	if err != nil {
+		util.GetLogger(ctx).WithError(err).Error("QueryBulkStateContent failed")
+		return nil, err
+	}
+	chunk := make([]gomatrixserverlib.PublicRoom, len(roomIDs))
+	i := 0
+	for roomID, data := range stateRes.Rooms {
+		pub := gomatrixserverlib.PublicRoom{
+			RoomID: roomID,
+		}
+		joinCount := 0
+		var joinRule, guestAccess string
+		for tuple, contentVal := range data {
+			if tuple.EventType == gomatrixserverlib.MRoomMember && contentVal == "join" {
+				joinCount++
+				continue
+			}
+			switch tuple {
+			case avatarTuple:
+				pub.AvatarURL = contentVal
+			case nameTuple:
+				pub.Name = contentVal
+			case topicTuple:
+				pub.Topic = contentVal
+			case canonicalTuple:
+				pub.CanonicalAlias = contentVal
+			case visibilityTuple:
+				pub.WorldReadable = contentVal == "world_readable"
+			// need both of these to determine whether guests can join
+			case joinRuleTuple:
+				joinRule = contentVal
+			case guestTuple:
+				guestAccess = contentVal
+			}
+		}
+		if joinRule == gomatrixserverlib.Public && guestAccess == "can_join" {
+			pub.GuestCanJoin = true
+		}
+		pub.JoinedMembersCount = joinCount
+		chunk[i] = pub
+		i++
+	}
+	return chunk, nil
+}

internal/setup/monolith.go

@@ -58,7 +58,7 @@ type Monolith struct {
 	StateAPI            currentstateAPI.CurrentStateInternalAPI
 
 	// Optional
-	ExtPublicRoomsProvider api.ExternalPublicRoomsProvider
+	ExtPublicRoomsProvider api.ExtraPublicRoomsProvider
 }
 
 // AddAllPublicRoutes attaches all public paths to the given router