Implement ExtraPublicRoomsProvider for p2p demos (#1180)

* Change API and rename to ExtraPublicRoomsProvider

* Make dendritejs work again

* Maybe make libp2p demo work again

* Linting

5 files changed, 100 insertions, 229 deletions

diff --git a/clientapi/api/api.go b/clientapi/api/api.go
index dae462c0..d96b032f 100644
--- a/clientapi/api/api.go
+++ b/clientapi/api/api.go
@@ -14,9 +14,10 @@
 
 package api
 
-type ExternalPublicRoomsProvider interface {
-	// 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
-	// This will be called -on demand- by clients, so cache appropriately!
-	Homeservers() []string
+import "github.com/matrix-org/gomatrixserverlib"
+
+// ExtraPublicRoomsProvider provides a way to inject extra published rooms into /publicRooms requests.
+type ExtraPublicRoomsProvider interface {
+	// Rooms returns the extra rooms. This is called on-demand by clients, so cache appropriately.
+	Rooms() []gomatrixserverlib.PublicRoom
 }
diff --git a/clientapi/clientapi.go b/clientapi/clientapi.go
index bbce6dcc..029a73da 100644
--- a/clientapi/clientapi.go
+++ b/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,
diff --git a/clientapi/routing/directory_public.go b/clientapi/routing/directory_public.go
index 64600cb4..925c1b8a 100644
--- a/clientapi/routing/directory_public.go
+++ b/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
-	err = rsAPI.QueryPublishedRooms(ctx, &roomserverAPI.QueryPublishedRoomsRequest{}, &queryRes)
-	if err != nil {
-		util.GetLogger(ctx).WithError(err).Error("QueryPublishedRooms failed")
-		return nil, err
+	var rooms []gomatrixserverlib.PublicRoom
+	if request.Since == "" {
+		rooms = refreshPublicRoomCache(ctx, rsAPI, extRoomsProvider, stateAPI)
+	} else {
+		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
+}
diff --git a/clientapi/routing/directory_public_test.go b/clientapi/routing/directory_public_test.go
index f2a1d551..bb3912b8 100644
--- a/clientapi/routing/directory_public_test.go
+++ b/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,
diff --git a/clientapi/routing/routing.go b/clientapi/routing/routing.go
index 85c5c0d9..754fbca8 100644
--- a/clientapi/routing/routing.go
+++ b/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:
-			if extRoomsProvider != nil {
-				return GetPostPublicRoomsWithExternal(req, stateAPI, fedClient, extRoomsProvider)
-			} */
-			return GetPostPublicRooms(req, rsAPI, stateAPI)
+			return GetPostPublicRooms(req, rsAPI, stateAPI, extRoomsProvider)
 		}),
 	).Methods(http.MethodGet, http.MethodPost, http.MethodOptions)