Add a new component: currentstateserver (#1171)

* Add a new component: currentstateserver - Add a skeleton for it, with databases and a single query method. - Add integration tests for it. - Add listen/address fields in the config (breaking as this will force people to specify this to validate) Not currently hooked up to anything yet. * Unbreak config tests * Add current_state to sample config * comments
2024-11-21 19:21:39 +00:00 · 2020-06-30 10:37:21 +01:00 · 2020-06-30 10:37:21 +01:00 · ca5bbffd8d
commit ca5bbffd8d
parent 3a18b7fc78
19 changed files with 1293 additions and 3 deletions
--- a/currentstateserver/api/api.go
+++ b/currentstateserver/api/api.go
@ -0,0 +1,64 @@
+// 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 api
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"strings"
+
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+type CurrentStateInternalAPI interface {
+	QueryCurrentState(ctx context.Context, req *QueryCurrentStateRequest, res *QueryCurrentStateResponse) error
+}
+
+type QueryCurrentStateRequest struct {
+	RoomID      string
+	StateTuples []gomatrixserverlib.StateKeyTuple
+}
+
+type QueryCurrentStateResponse struct {
+	StateEvents map[gomatrixserverlib.StateKeyTuple]gomatrixserverlib.HeaderedEvent
+}
+
+// MarshalJSON stringifies the StateKeyTuple keys so they can be sent over the wire in HTTP API mode.
+func (r *QueryCurrentStateResponse) MarshalJSON() ([]byte, error) {
+	se := make(map[string]gomatrixserverlib.HeaderedEvent, len(r.StateEvents))
+	for k, v := range r.StateEvents {
+		// use 0x1F (unit separator) as the delimiter between type/state key,
+		se[fmt.Sprintf("%s\x1F%s", k.EventType, k.StateKey)] = v
+	}
+	return json.Marshal(se)
+}
+
+func (r *QueryCurrentStateResponse) UnmarshalJSON(data []byte) error {
+	res := make(map[string]gomatrixserverlib.HeaderedEvent)
+	err := json.Unmarshal(data, &res)
+	if err != nil {
+		return err
+	}
+	r.StateEvents = make(map[gomatrixserverlib.StateKeyTuple]gomatrixserverlib.HeaderedEvent, len(res))
+	for k, v := range res {
+		fields := strings.Split(k, "\x1F")
+		r.StateEvents[gomatrixserverlib.StateKeyTuple{
+			EventType: fields[0],
+			StateKey:  fields[1],
+		}] = v
+	}
+	return nil
+}
--- a/currentstateserver/consumers/roomserver.go
+++ b/currentstateserver/consumers/roomserver.go
@ -0,0 +1,140 @@
+// 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 consumers
+
+import (
+	"context"
+	"encoding/json"
+
+	"github.com/Shopify/sarama"
+	"github.com/matrix-org/dendrite/currentstateserver/storage"
+	"github.com/matrix-org/dendrite/internal"
+	"github.com/matrix-org/dendrite/roomserver/api"
+	"github.com/matrix-org/dendrite/syncapi/types"
+	"github.com/matrix-org/gomatrixserverlib"
+	log "github.com/sirupsen/logrus"
+)
+
+type OutputRoomEventConsumer struct {
+	rsConsumer *internal.ContinualConsumer
+	db         storage.Database
+}
+
+func NewOutputRoomEventConsumer(topicName string, kafkaConsumer sarama.Consumer, store storage.Database) *OutputRoomEventConsumer {
+	consumer := &internal.ContinualConsumer{
+		Topic:          topicName,
+		Consumer:       kafkaConsumer,
+		PartitionStore: store,
+	}
+	s := &OutputRoomEventConsumer{
+		rsConsumer: consumer,
+		db:         store,
+	}
+	consumer.ProcessMessage = s.onMessage
+
+	return s
+}
+
+func (c *OutputRoomEventConsumer) onMessage(msg *sarama.ConsumerMessage) error {
+	// Parse out the event JSON
+	var output api.OutputEvent
+	if err := json.Unmarshal(msg.Value, &output); err != nil {
+		// If the message was invalid, log it and move on to the next message in the stream
+		log.WithError(err).Errorf("roomserver output log: message parse failure")
+		return nil
+	}
+
+	switch output.Type {
+	case api.OutputTypeNewRoomEvent:
+		return c.onNewRoomEvent(context.TODO(), *output.NewRoomEvent)
+	case api.OutputTypeNewInviteEvent:
+	case api.OutputTypeRetireInviteEvent:
+	default:
+		log.WithField("type", output.Type).Debug(
+			"roomserver output log: ignoring unknown output type",
+		)
+	}
+	return nil
+}
+
+func (c *OutputRoomEventConsumer) onNewRoomEvent(
+	ctx context.Context, msg api.OutputNewRoomEvent,
+) error {
+	ev := msg.Event
+
+	addsStateEvents := msg.AddsState()
+
+	ev, err := c.updateStateEvent(ev)
+	if err != nil {
+		return err
+	}
+
+	for i := range addsStateEvents {
+		addsStateEvents[i], err = c.updateStateEvent(addsStateEvents[i])
+		if err != nil {
+			return err
+		}
+	}
+
+	err = c.db.StoreStateEvents(
+		ctx,
+		addsStateEvents,
+		msg.RemovesStateEventIDs,
+	)
+	if err != nil {
+		// panic rather than continue with an inconsistent database
+		log.WithFields(log.Fields{
+			"event":      string(ev.JSON()),
+			log.ErrorKey: err,
+			"add":        msg.AddsStateEventIDs,
+			"del":        msg.RemovesStateEventIDs,
+		}).Panicf("roomserver output log: write event failure")
+	}
+	return nil
+}
+
+// Start consuming from room servers
+func (c *OutputRoomEventConsumer) Start() error {
+	return c.rsConsumer.Start()
+}
+
+func (c *OutputRoomEventConsumer) updateStateEvent(event gomatrixserverlib.HeaderedEvent) (gomatrixserverlib.HeaderedEvent, error) {
+	var stateKey string
+	if event.StateKey() == nil {
+		stateKey = ""
+	} else {
+		stateKey = *event.StateKey()
+	}
+
+	prevEvent, err := c.db.GetStateEvent(
+		context.TODO(), event.RoomID(), event.Type(), stateKey,
+	)
+	if err != nil {
+		return event, err
+	}
+
+	if prevEvent == nil {
+		return event, nil
+	}
+
+	prev := types.PrevEventRef{
+		PrevContent:   prevEvent.Content(),
+		ReplacesState: prevEvent.EventID(),
+		PrevSender:    prevEvent.Sender(),
+	}
+
+	event.Event, err = event.SetUnsigned(prev)
+	return event, err
+}
--- a/currentstateserver/currentstateserver.go
+++ b/currentstateserver/currentstateserver.go
@ -0,0 +1,51 @@
+// 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 currentstateserver
+
+import (
+	"github.com/Shopify/sarama"
+	"github.com/gorilla/mux"
+	"github.com/matrix-org/dendrite/currentstateserver/api"
+	"github.com/matrix-org/dendrite/currentstateserver/consumers"
+	"github.com/matrix-org/dendrite/currentstateserver/internal"
+	"github.com/matrix-org/dendrite/currentstateserver/inthttp"
+	"github.com/matrix-org/dendrite/currentstateserver/storage"
+	"github.com/matrix-org/dendrite/internal/config"
+	"github.com/sirupsen/logrus"
+)
+
+// AddInternalRoutes registers HTTP handlers for the internal API. Invokes functions
+// on the given input API.
+func AddInternalRoutes(router *mux.Router, intAPI api.CurrentStateInternalAPI) {
+	inthttp.AddRoutes(router, intAPI)
+}
+
+// NewInternalAPI returns a concrete implementation of the internal API. Callers
+// can call functions directly on the returned API or via an HTTP interface using AddInternalRoutes.
+func NewInternalAPI(cfg *config.Dendrite, consumer sarama.Consumer) api.CurrentStateInternalAPI {
+	csDB, err := storage.NewDatabase(string(cfg.Database.CurrentState), cfg.DbProperties())
+	if err != nil {
+		logrus.WithError(err).Panicf("failed to open database")
+	}
+	roomConsumer := consumers.NewOutputRoomEventConsumer(
+		string(cfg.Kafka.Topics.OutputRoomEvent), consumer, csDB,
+	)
+	if err = roomConsumer.Start(); err != nil {
+		logrus.WithError(err).Panicf("failed to start room server consumer")
+	}
+	return &internal.CurrentStateInternalAPI{
+		DB: csDB,
+	}
+}
--- a/currentstateserver/currentstateserver_test.go
+++ b/currentstateserver/currentstateserver_test.go
@ -0,0 +1,180 @@
+// 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 currentstateserver
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"reflect"
+	"testing"
+	"time"
+
+	"github.com/Shopify/sarama"
+	"github.com/gorilla/mux"
+	"github.com/matrix-org/dendrite/currentstateserver/api"
+	"github.com/matrix-org/dendrite/currentstateserver/inthttp"
+	"github.com/matrix-org/dendrite/internal/config"
+	"github.com/matrix-org/dendrite/internal/httputil"
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+	"github.com/matrix-org/dendrite/internal/test"
+	roomserverAPI "github.com/matrix-org/dendrite/roomserver/api"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/naffka"
+)
+
+var (
+	testRoomVersion = gomatrixserverlib.RoomVersionV1
+	testData        = []json.RawMessage{
+		[]byte(`{"auth_events":[],"content":{"creator":"@userid:kaer.morhen"},"depth":0,"event_id":"$0ok8ynDp7kjc95e3:kaer.morhen","hashes":{"sha256":"17kPoH+h0Dk4Omn7Sus0qMb6+oGcf+CZFEgDhv7UKWs"},"origin":"kaer.morhen","origin_server_ts":0,"prev_events":[],"prev_state":[],"room_id":"!roomid:kaer.morhen","sender":"@userid:kaer.morhen","signatures":{"kaer.morhen":{"ed25519:auto":"jP4a04f5/F10Pw95FPpdCyKAO44JOwUQ/MZOOeA/RTU1Dn+AHPMzGSaZnuGjRr/xQuADt+I3ctb5ZQfLKNzHDw"}},"state_key":"","type":"m.room.create"}`),
+		[]byte(`{"auth_events":[["$0ok8ynDp7kjc95e3:kaer.morhen",{"sha256":"sWCi6Ckp9rDimQON+MrUlNRkyfZ2tjbPbWfg2NMB18Q"}]],"content":{"membership":"join"},"depth":1,"event_id":"$LEwEu0kxrtu5fOiS:kaer.morhen","hashes":{"sha256":"B7M88PhXf3vd1LaFtjQutFu4x/w7fHD28XKZ4sAsJTo"},"origin":"kaer.morhen","origin_server_ts":0,"prev_events":[["$0ok8ynDp7kjc95e3:kaer.morhen",{"sha256":"sWCi6Ckp9rDimQON+MrUlNRkyfZ2tjbPbWfg2NMB18Q"}]],"prev_state":[],"room_id":"!roomid:kaer.morhen","sender":"@userid:kaer.morhen","signatures":{"kaer.morhen":{"ed25519:auto":"p2vqmuJn7ZBRImctSaKbXCAxCcBlIjPH9JHte1ouIUGy84gpu4eLipOvSBCLL26hXfC0Zrm4WUto6Hr+ohdrCg"}},"state_key":"@userid:kaer.morhen","type":"m.room.member"}`),
+		[]byte(`{"auth_events":[["$0ok8ynDp7kjc95e3:kaer.morhen",{"sha256":"sWCi6Ckp9rDimQON+MrUlNRkyfZ2tjbPbWfg2NMB18Q"}],["$LEwEu0kxrtu5fOiS:kaer.morhen",{"sha256":"1aKajq6DWHru1R1HJjvdWMEavkJJHGaTmPvfuERUXaA"}]],"content":{"join_rule":"public"},"depth":2,"event_id":"$SMHlqUrNhhBBRLeN:kaer.morhen","hashes":{"sha256":"vIuJQvmMjrGxshAkj1SXe0C4RqvMbv4ZADDw9pFCWqQ"},"origin":"kaer.morhen","origin_server_ts":0,"prev_events":[["$LEwEu0kxrtu5fOiS:kaer.morhen",{"sha256":"1aKajq6DWHru1R1HJjvdWMEavkJJHGaTmPvfuERUXaA"}]],"prev_state":[],"room_id":"!roomid:kaer.morhen","sender":"@userid:kaer.morhen","signatures":{"kaer.morhen":{"ed25519:auto":"hBMsb3Qppo3RaqqAl4JyTgaiWEbW5hlckATky6PrHun+F3YM203TzG7w9clwuQU5F5pZoB1a6nw+to0hN90FAw"}},"state_key":"","type":"m.room.join_rules"}`),
+		[]byte(`{"auth_events":[["$0ok8ynDp7kjc95e3:kaer.morhen",{"sha256":"sWCi6Ckp9rDimQON+MrUlNRkyfZ2tjbPbWfg2NMB18Q"}],["$LEwEu0kxrtu5fOiS:kaer.morhen",{"sha256":"1aKajq6DWHru1R1HJjvdWMEavkJJHGaTmPvfuERUXaA"}]],"content":{"history_visibility":"shared"},"depth":3,"event_id":"$6F1yGIbO0J7TM93h:kaer.morhen","hashes":{"sha256":"Mr23GKSlZW7UCCYLgOWawI2Sg6KIoMjUWO2TDenuOgw"},"origin":"kaer.morhen","origin_server_ts":0,"prev_events":[["$SMHlqUrNhhBBRLeN:kaer.morhen",{"sha256":"SylzE8U02I+6eyEHgL+FlU0L5YdqrVp8OOlxKS9VQW0"}]],"prev_state":[],"room_id":"!roomid:kaer.morhen","sender":"@userid:kaer.morhen","signatures":{"kaer.morhen":{"ed25519:auto":"sHLKrFI3hKGrEJfpMVZSDS3LvLasQsy50CTsOwru9XTVxgRsPo6wozNtRVjxo1J3Rk18RC9JppovmQ5VR5EcDw"}},"state_key":"","type":"m.room.history_visibility"}`),
+		[]byte(`{"auth_events":[["$0ok8ynDp7kjc95e3:kaer.morhen",{"sha256":"sWCi6Ckp9rDimQON+MrUlNRkyfZ2tjbPbWfg2NMB18Q"}],["$LEwEu0kxrtu5fOiS:kaer.morhen",{"sha256":"1aKajq6DWHru1R1HJjvdWMEavkJJHGaTmPvfuERUXaA"}]],"content":{"ban":50,"events":null,"events_default":0,"invite":0,"kick":50,"redact":50,"state_default":50,"users":null,"users_default":0},"depth":4,"event_id":"$UKNe10XzYzG0TeA9:kaer.morhen","hashes":{"sha256":"ngbP3yja9U5dlckKerUs/fSOhtKxZMCVvsfhPURSS28"},"origin":"kaer.morhen","origin_server_ts":0,"prev_events":[["$6F1yGIbO0J7TM93h:kaer.morhen",{"sha256":"A4CucrKSoWX4IaJXhq02mBg1sxIyZEftbC+5p3fZAvk"}]],"prev_state":[],"room_id":"!roomid:kaer.morhen","sender":"@userid:kaer.morhen","signatures":{"kaer.morhen":{"ed25519:auto":"zOmwlP01QL3yFchzuR9WHvogOoBZA3oVtNIF3lM0ZfDnqlSYZB9sns27G/4HVq0k7alaK7ZE3oGoCrVnMkPNCw"}},"state_key":"","type":"m.room.power_levels"}`),
+		// messages
+		[]byte(`{"auth_events":[["$0ok8ynDp7kjc95e3:kaer.morhen",{"sha256":"sWCi6Ckp9rDimQON+MrUlNRkyfZ2tjbPbWfg2NMB18Q"}],["$LEwEu0kxrtu5fOiS:kaer.morhen",{"sha256":"1aKajq6DWHru1R1HJjvdWMEavkJJHGaTmPvfuERUXaA"}]],"content":{"body":"Test Message"},"depth":5,"event_id":"$gl2T9l3qm0kUbiIJ:kaer.morhen","hashes":{"sha256":"Qx3nRMHLDPSL5hBAzuX84FiSSP0K0Kju2iFoBWH4Za8"},"origin":"kaer.morhen","origin_server_ts":0,"prev_events":[["$UKNe10XzYzG0TeA9:kaer.morhen",{"sha256":"KtSRyMjt0ZSjsv2koixTRCxIRCGoOp6QrKscsW97XRo"}]],"room_id":"!roomid:kaer.morhen","sender":"@userid:kaer.morhen","signatures":{"kaer.morhen":{"ed25519:auto":"sqDgv3EG7ml5VREzmT9aZeBpS4gAPNIaIeJOwqjDhY0GPU/BcpX5wY4R7hYLrNe5cChgV+eFy/GWm1Zfg5FfDg"}},"type":"m.room.message"}`),
+		[]byte(`{"auth_events":[["$0ok8ynDp7kjc95e3:kaer.morhen",{"sha256":"sWCi6Ckp9rDimQON+MrUlNRkyfZ2tjbPbWfg2NMB18Q"}],["$LEwEu0kxrtu5fOiS:kaer.morhen",{"sha256":"1aKajq6DWHru1R1HJjvdWMEavkJJHGaTmPvfuERUXaA"}]],"content":{"body":"Test Message"},"depth":6,"event_id":"$MYSbs8m4rEbsCWXD:kaer.morhen","hashes":{"sha256":"kgbYM7v4Ud2YaBsjBTolM4ySg6rHcJNYI6nWhMSdFUA"},"origin":"kaer.morhen","origin_server_ts":0,"prev_events":[["$gl2T9l3qm0kUbiIJ:kaer.morhen",{"sha256":"C/rD04h9wGxRdN2G/IBfrgoE1UovzLZ+uskwaKZ37/Q"}]],"room_id":"!roomid:kaer.morhen","sender":"@userid:kaer.morhen","signatures":{"kaer.morhen":{"ed25519:auto":"x0UoKh968jj/F5l1/R7Ew0T6CTKuew3PLNHASNxqck/bkNe8yYQiDHXRr+kZxObeqPZZTpaF1+EI+bLU9W8GDQ"}},"type":"m.room.message"}`),
+		[]byte(`{"auth_events":[["$0ok8ynDp7kjc95e3:kaer.morhen",{"sha256":"sWCi6Ckp9rDimQON+MrUlNRkyfZ2tjbPbWfg2NMB18Q"}],["$LEwEu0kxrtu5fOiS:kaer.morhen",{"sha256":"1aKajq6DWHru1R1HJjvdWMEavkJJHGaTmPvfuERUXaA"}]],"content":{"body":"Test Message"},"depth":7,"event_id":"$N5x9WJkl9ClPrAEg:kaer.morhen","hashes":{"sha256":"FWM8oz4yquTunRZ67qlW2gzPDzdWfBP6RPHXhK1I/x8"},"origin":"kaer.morhen","origin_server_ts":0,"prev_events":[["$MYSbs8m4rEbsCWXD:kaer.morhen",{"sha256":"fatqgW+SE8mb2wFn3UN+drmluoD4UJ/EcSrL6Ur9q1M"}]],"room_id":"!roomid:kaer.morhen","sender":"@userid:kaer.morhen","signatures":{"kaer.morhen":{"ed25519:auto":"Y+LX/xcyufoXMOIoqQBNOzy6lZfUGB1ffgXIrSugk6obMiyAsiRejHQN/pciZXsHKxMJLYRFAz4zSJoS/LGPAA"}},"type":"m.room.message"}`),
+	}
+	testEvents      = []gomatrixserverlib.HeaderedEvent{}
+	testStateEvents = make(map[gomatrixserverlib.StateKeyTuple]gomatrixserverlib.HeaderedEvent)
+
+	kafkaTopic = "room_events"
+)
+
+func init() {
+	for _, j := range testData {
+		e, err := gomatrixserverlib.NewEventFromTrustedJSON(j, false, testRoomVersion)
+		if err != nil {
+			panic("cannot load test data: " + err.Error())
+		}
+		h := e.Headered(testRoomVersion)
+		testEvents = append(testEvents, h)
+		if e.StateKey() != nil {
+			testStateEvents[gomatrixserverlib.StateKeyTuple{
+				EventType: e.Type(),
+				StateKey:  *e.StateKey(),
+			}] = h
+		}
+	}
+}
+
+func MustWriteOutputEvent(t *testing.T, producer sarama.SyncProducer, out *roomserverAPI.OutputNewRoomEvent) error {
+	value, err := json.Marshal(roomserverAPI.OutputEvent{
+		Type:         roomserverAPI.OutputTypeNewRoomEvent,
+		NewRoomEvent: out,
+	})
+	if err != nil {
+		t.Fatalf("failed to marshal output event: %s", err)
+	}
+	_, _, err = producer.SendMessage(&sarama.ProducerMessage{
+		Topic: kafkaTopic,
+		Key:   sarama.StringEncoder(out.Event.RoomID()),
+		Value: sarama.ByteEncoder(value),
+	})
+	if err != nil {
+		t.Fatalf("failed to send message: %s", err)
+	}
+	return nil
+}
+
+func MustMakeInternalAPI(t *testing.T) (api.CurrentStateInternalAPI, sarama.SyncProducer) {
+	cfg := &config.Dendrite{}
+	cfg.Kafka.Topics.OutputRoomEvent = config.Topic(kafkaTopic)
+	cfg.Database.CurrentState = config.DataSource("file::memory:")
+	db, err := sqlutil.Open(sqlutil.SQLiteDriverName(), "file::memory:", nil)
+	if err != nil {
+		t.Fatalf("Failed to open naffka database: %s", err)
+	}
+	naffkaDB, err := naffka.NewSqliteDatabase(db)
+	if err != nil {
+		t.Fatalf("Failed to setup naffka database: %s", err)
+	}
+	naff, err := naffka.New(naffkaDB)
+	if err != nil {
+		t.Fatalf("Failed to create naffka consumer: %s", err)
+	}
+	return NewInternalAPI(cfg, naff), naff
+}
+
+func TestQueryCurrentState(t *testing.T) {
+	currStateAPI, producer := MustMakeInternalAPI(t)
+	plTuple := gomatrixserverlib.StateKeyTuple{
+		EventType: "m.room.power_levels",
+		StateKey:  "",
+	}
+	plEvent := testEvents[4]
+	MustWriteOutputEvent(t, producer, &roomserverAPI.OutputNewRoomEvent{
+		Event:             plEvent,
+		AddsStateEventIDs: []string{plEvent.EventID()},
+	})
+	// we have no good way to know /when/ the server has consumed the event
+	time.Sleep(100 * time.Millisecond)
+
+	testCases := []struct {
+		req     api.QueryCurrentStateRequest
+		wantRes api.QueryCurrentStateResponse
+		wantErr error
+	}{
+		{
+			req: api.QueryCurrentStateRequest{
+				RoomID: plEvent.RoomID(),
+				StateTuples: []gomatrixserverlib.StateKeyTuple{
+					plTuple,
+				},
+			},
+			wantRes: api.QueryCurrentStateResponse{
+				StateEvents: map[gomatrixserverlib.StateKeyTuple]gomatrixserverlib.HeaderedEvent{
+					plTuple: plEvent,
+				},
+			},
+		},
+	}
+
+	runCases := func(testAPI api.CurrentStateInternalAPI) {
+		for _, tc := range testCases {
+			var gotRes api.QueryCurrentStateResponse
+			gotErr := testAPI.QueryCurrentState(context.TODO(), &tc.req, &gotRes)
+			if tc.wantErr == nil && gotErr != nil || tc.wantErr != nil && gotErr == nil {
+				t.Errorf("QueryCurrentState error, got %s want %s", gotErr, tc.wantErr)
+				continue
+			}
+			for tuple, wantEvent := range tc.wantRes.StateEvents {
+				gotEvent, ok := gotRes.StateEvents[tuple]
+				if !ok {
+					t.Errorf("QueryCurrentState want tuple %+v but it is missing from the response", tuple)
+					continue
+				}
+				if !reflect.DeepEqual(gotEvent.JSON(), wantEvent.JSON()) {
+					t.Errorf("QueryCurrentState tuple %+v got event JSON %s want %s", tuple, string(gotEvent.JSON()), string(wantEvent.JSON()))
+				}
+			}
+		}
+	}
+	t.Run("HTTP API", func(t *testing.T) {
+		router := mux.NewRouter().PathPrefix(httputil.InternalPathPrefix).Subrouter()
+		AddInternalRoutes(router, currStateAPI)
+		apiURL, cancel := test.ListenAndServe(t, router, false)
+		defer cancel()
+		httpAPI, err := inthttp.NewCurrentStateAPIClient(apiURL, &http.Client{})
+		if err != nil {
+			t.Fatalf("failed to create HTTP client")
+		}
+		runCases(httpAPI)
+	})
+	t.Run("Monolith", func(t *testing.T) {
+		runCases(currStateAPI)
+	})
+}
--- a/currentstateserver/internal/api.go
+++ b/currentstateserver/internal/api.go
@ -0,0 +1,41 @@
+// 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 internal
+
+import (
+	"context"
+
+	"github.com/matrix-org/dendrite/currentstateserver/api"
+	"github.com/matrix-org/dendrite/currentstateserver/storage"
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+type CurrentStateInternalAPI struct {
+	DB storage.Database
+}
+
+func (a *CurrentStateInternalAPI) QueryCurrentState(ctx context.Context, req *api.QueryCurrentStateRequest, res *api.QueryCurrentStateResponse) error {
+	res.StateEvents = make(map[gomatrixserverlib.StateKeyTuple]gomatrixserverlib.HeaderedEvent)
+	for _, tuple := range req.StateTuples {
+		ev, err := a.DB.GetStateEvent(ctx, req.RoomID, tuple.EventType, tuple.StateKey)
+		if err != nil {
+			return err
+		}
+		if ev != nil {
+			res.StateEvents[tuple] = *ev
+		}
+	}
+	return nil
+}
--- a/currentstateserver/inthttp/client.go
+++ b/currentstateserver/inthttp/client.go
@ -0,0 +1,62 @@
+// 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 inthttp
+
+import (
+	"context"
+	"errors"
+	"net/http"
+
+	"github.com/matrix-org/dendrite/currentstateserver/api"
+	"github.com/matrix-org/dendrite/internal/httputil"
+	"github.com/opentracing/opentracing-go"
+)
+
+// HTTP paths for the internal HTTP APIs
+const (
+	QueryCurrentStatePath = "/currentstateserver/queryCurrentState"
+)
+
+// NewCurrentStateAPIClient creates a CurrentStateInternalAPI implemented by talking to a HTTP POST API.
+// If httpClient is nil an error is returned
+func NewCurrentStateAPIClient(
+	apiURL string,
+	httpClient *http.Client,
+) (api.CurrentStateInternalAPI, error) {
+	if httpClient == nil {
+		return nil, errors.New("NewCurrentStateAPIClient: httpClient is <nil>")
+	}
+	return &httpCurrentStateInternalAPI{
+		apiURL:     apiURL,
+		httpClient: httpClient,
+	}, nil
+}
+
+type httpCurrentStateInternalAPI struct {
+	apiURL     string
+	httpClient *http.Client
+}
+
+func (h *httpCurrentStateInternalAPI) QueryCurrentState(
+	ctx context.Context,
+	request *api.QueryCurrentStateRequest,
+	response *api.QueryCurrentStateResponse,
+) error {
+	span, ctx := opentracing.StartSpanFromContext(ctx, "QueryCurrentState")
+	defer span.Finish()
+
+	apiURL := h.apiURL + QueryCurrentStatePath
+	return httputil.PostJSON(ctx, span, h.httpClient, apiURL, request, response)
+}
--- a/currentstateserver/inthttp/server.go
+++ b/currentstateserver/inthttp/server.go
@ -0,0 +1,41 @@
+// 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 inthttp
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"github.com/gorilla/mux"
+	"github.com/matrix-org/dendrite/currentstateserver/api"
+	"github.com/matrix-org/dendrite/internal/httputil"
+	"github.com/matrix-org/util"
+)
+
+func AddRoutes(internalAPIMux *mux.Router, intAPI api.CurrentStateInternalAPI) {
+	internalAPIMux.Handle(QueryCurrentStatePath,
+		httputil.MakeInternalAPI("queryCurrentState", func(req *http.Request) util.JSONResponse {
+			request := api.QueryCurrentStateRequest{}
+			response := api.QueryCurrentStateResponse{}
+			if err := json.NewDecoder(req.Body).Decode(&request); err != nil {
+				return util.MessageResponse(http.StatusBadRequest, err.Error())
+			}
+			if err := intAPI.QueryCurrentState(req.Context(), &request, &response); err != nil {
+				return util.ErrorResponse(err)
+			}
+			return util.JSONResponse{Code: http.StatusOK, JSON: &response}
+		}),
+	)
+}
--- a/currentstateserver/storage/interface.go
+++ b/currentstateserver/storage/interface.go
@ -0,0 +1,32 @@
+// 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 storage
+
+import (
+	"context"
+
+	"github.com/matrix-org/dendrite/internal"
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+type Database interface {
+	internal.PartitionStorer
+	// StoreStateEvents updates the database with new events from the roomserver.
+	StoreStateEvents(ctx context.Context, addStateEvents []gomatrixserverlib.HeaderedEvent, removeStateEventIDs []string) error
+	// GetStateEvent returns the state event of a given type for a given room with a given state key
+	// If no event could be found, returns nil
+	// If there was an issue during the retrieval, returns an error
+	GetStateEvent(ctx context.Context, roomID, evType, stateKey string) (*gomatrixserverlib.HeaderedEvent, error)
+}
--- a/currentstateserver/storage/postgres/current_room_state_table.go
+++ b/currentstateserver/storage/postgres/current_room_state_table.go
@ -0,0 +1,205 @@
+// 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 postgres
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+
+	"github.com/lib/pq"
+	"github.com/matrix-org/dendrite/currentstateserver/storage/tables"
+	"github.com/matrix-org/dendrite/internal"
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+const currentRoomStateSchema = `
+-- Stores the current room state for every room.
+CREATE TABLE IF NOT EXISTS currentstate_current_room_state (
+    -- The 'room_id' key for the state event.
+    room_id TEXT NOT NULL,
+    -- The state event ID
+    event_id TEXT NOT NULL,
+    -- The state event type e.g 'm.room.member'
+    type TEXT NOT NULL,
+    -- The 'sender' property of the event.
+    sender TEXT NOT NULL,
+    -- The state_key value for this state event e.g ''
+    state_key TEXT NOT NULL,
+    -- The JSON for the event. Stored as TEXT because this should be valid UTF-8.
+    headered_event_json TEXT NOT NULL,
+    -- The 'content.membership' value if this event is an m.room.member event. For other
+    -- events, this will be NULL.
+    membership TEXT,
+    -- Clobber based on 3-uple of room_id, type and state_key
+    CONSTRAINT currentstate_current_room_state_unique UNIQUE (room_id, type, state_key)
+);
+-- for event deletion
+CREATE UNIQUE INDEX IF NOT EXISTS currentstate_event_id_idx ON currentstate_current_room_state(event_id, room_id, type, sender);
+-- for querying membership states of users
+CREATE INDEX IF NOT EXISTS currentstate_membership_idx ON currentstate_current_room_state(type, state_key, membership) WHERE membership IS NOT NULL AND membership != 'leave';
+`
+
+const upsertRoomStateSQL = "" +
+	"INSERT INTO currentstate_current_room_state (room_id, event_id, type, sender, state_key, headered_event_json, membership)" +
+	" VALUES ($1, $2, $3, $4, $5, $6, $7)" +
+	" ON CONFLICT ON CONSTRAINT currentstate_room_state_unique" +
+	" DO UPDATE SET event_id = $2, sender=$4, headered_event_json = $6, membership = $7"
+
+const deleteRoomStateByEventIDSQL = "" +
+	"DELETE FROM currentstate_current_room_state WHERE event_id = $1"
+
+const selectRoomIDsWithMembershipSQL = "" +
+	"SELECT room_id FROM currentstate_current_room_state WHERE type = 'm.room.member' AND state_key = $1 AND membership = $2"
+
+const selectStateEventSQL = "" +
+	"SELECT headered_event_json FROM currentstate_current_room_state WHERE room_id = $1 AND type = $2 AND state_key = $3"
+
+const selectEventsWithEventIDsSQL = "" +
+	"SELECT headered_event_json FROM currentstate_current_room_state WHERE event_id = ANY($1)"
+
+type currentRoomStateStatements struct {
+	upsertRoomStateStmt             *sql.Stmt
+	deleteRoomStateByEventIDStmt    *sql.Stmt
+	selectRoomIDsWithMembershipStmt *sql.Stmt
+	selectEventsWithEventIDsStmt    *sql.Stmt
+	selectStateEventStmt            *sql.Stmt
+}
+
+func NewPostgresCurrentRoomStateTable(db *sql.DB) (tables.CurrentRoomState, error) {
+	s := &currentRoomStateStatements{}
+	_, err := db.Exec(currentRoomStateSchema)
+	if err != nil {
+		return nil, err
+	}
+	if s.upsertRoomStateStmt, err = db.Prepare(upsertRoomStateSQL); err != nil {
+		return nil, err
+	}
+	if s.deleteRoomStateByEventIDStmt, err = db.Prepare(deleteRoomStateByEventIDSQL); err != nil {
+		return nil, err
+	}
+	if s.selectRoomIDsWithMembershipStmt, err = db.Prepare(selectRoomIDsWithMembershipSQL); err != nil {
+		return nil, err
+	}
+	if s.selectEventsWithEventIDsStmt, err = db.Prepare(selectEventsWithEventIDsSQL); err != nil {
+		return nil, err
+	}
+	if s.selectStateEventStmt, err = db.Prepare(selectStateEventSQL); err != nil {
+		return nil, err
+	}
+	return s, nil
+}
+
+// SelectRoomIDsWithMembership returns the list of room IDs which have the given user in the given membership state.
+func (s *currentRoomStateStatements) SelectRoomIDsWithMembership(
+	ctx context.Context,
+	txn *sql.Tx,
+	userID string,
+	membership string,
+) ([]string, error) {
+	stmt := sqlutil.TxStmt(txn, s.selectRoomIDsWithMembershipStmt)
+	rows, err := stmt.QueryContext(ctx, userID, membership)
+	if err != nil {
+		return nil, err
+	}
+	defer internal.CloseAndLogIfError(ctx, rows, "selectRoomIDsWithMembership: rows.close() failed")
+
+	var result []string
+	for rows.Next() {
+		var roomID string
+		if err := rows.Scan(&roomID); err != nil {
+			return nil, err
+		}
+		result = append(result, roomID)
+	}
+	return result, rows.Err()
+}
+
+func (s *currentRoomStateStatements) DeleteRoomStateByEventID(
+	ctx context.Context, txn *sql.Tx, eventID string,
+) error {
+	stmt := sqlutil.TxStmt(txn, s.deleteRoomStateByEventIDStmt)
+	_, err := stmt.ExecContext(ctx, eventID)
+	return err
+}
+
+func (s *currentRoomStateStatements) UpsertRoomState(
+	ctx context.Context, txn *sql.Tx,
+	event gomatrixserverlib.HeaderedEvent, membership *string,
+) error {
+	headeredJSON, err := json.Marshal(event)
+	if err != nil {
+		return err
+	}
+
+	// upsert state event
+	stmt := sqlutil.TxStmt(txn, s.upsertRoomStateStmt)
+	_, err = stmt.ExecContext(
+		ctx,
+		event.RoomID(),
+		event.EventID(),
+		event.Type(),
+		event.Sender(),
+		*event.StateKey(),
+		headeredJSON,
+		membership,
+	)
+	return err
+}
+
+func (s *currentRoomStateStatements) SelectEventsWithEventIDs(
+	ctx context.Context, txn *sql.Tx, eventIDs []string,
+) ([]gomatrixserverlib.HeaderedEvent, error) {
+	stmt := sqlutil.TxStmt(txn, s.selectEventsWithEventIDsStmt)
+	rows, err := stmt.QueryContext(ctx, pq.StringArray(eventIDs))
+	if err != nil {
+		return nil, err
+	}
+	defer internal.CloseAndLogIfError(ctx, rows, "selectEventsWithEventIDs: rows.close() failed")
+	result := []gomatrixserverlib.HeaderedEvent{}
+	for rows.Next() {
+		var eventBytes []byte
+		if err := rows.Scan(&eventBytes); err != nil {
+			return nil, err
+		}
+		// TODO: Handle redacted events
+		var ev gomatrixserverlib.HeaderedEvent
+		if err := json.Unmarshal(eventBytes, &ev); err != nil {
+			return nil, err
+		}
+		result = append(result, ev)
+	}
+	return result, rows.Err()
+}
+
+func (s *currentRoomStateStatements) SelectStateEvent(
+	ctx context.Context, roomID, evType, stateKey string,
+) (*gomatrixserverlib.HeaderedEvent, error) {
+	stmt := s.selectStateEventStmt
+	var res []byte
+	err := stmt.QueryRowContext(ctx, roomID, evType, stateKey).Scan(&res)
+	if err == sql.ErrNoRows {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+	var ev gomatrixserverlib.HeaderedEvent
+	if err = json.Unmarshal(res, &ev); err != nil {
+		return nil, err
+	}
+	return &ev, err
+}
--- a/currentstateserver/storage/postgres/storage.go
+++ b/currentstateserver/storage/postgres/storage.go
@ -0,0 +1,35 @@
+package postgres
+
+import (
+	"database/sql"
+
+	"github.com/matrix-org/dendrite/currentstateserver/storage/shared"
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+)
+
+type Database struct {
+	shared.Database
+	db *sql.DB
+	sqlutil.PartitionOffsetStatements
+}
+
+// NewDatabase creates a new sync server database
+func NewDatabase(dbDataSourceName string, dbProperties sqlutil.DbProperties) (*Database, error) {
+	var d Database
+	var err error
+	if d.db, err = sqlutil.Open("postgres", dbDataSourceName, dbProperties); err != nil {
+		return nil, err
+	}
+	if err = d.PartitionOffsetStatements.Prepare(d.db, "currentstate"); err != nil {
+		return nil, err
+	}
+	currRoomState, err := NewPostgresCurrentRoomStateTable(d.db)
+	if err != nil {
+		return nil, err
+	}
+	d.Database = shared.Database{
+		DB:               d.db,
+		CurrentRoomState: currRoomState,
+	}
+	return &d, nil
+}
--- a/currentstateserver/storage/shared/storage.go
+++ b/currentstateserver/storage/shared/storage.go
@ -0,0 +1,65 @@
+// 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 shared
+
+import (
+	"context"
+	"database/sql"
+
+	"github.com/matrix-org/dendrite/currentstateserver/storage/tables"
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+type Database struct {
+	DB               *sql.DB
+	CurrentRoomState tables.CurrentRoomState
+}
+
+func (d *Database) GetStateEvent(ctx context.Context, roomID, evType, stateKey string) (*gomatrixserverlib.HeaderedEvent, error) {
+	return d.CurrentRoomState.SelectStateEvent(ctx, roomID, evType, stateKey)
+}
+
+func (d *Database) StoreStateEvents(ctx context.Context, addStateEvents []gomatrixserverlib.HeaderedEvent,
+	removeStateEventIDs []string) error {
+	return sqlutil.WithTransaction(d.DB, func(txn *sql.Tx) error {
+		// remove first, then add, as we do not ever delete state, but do replace state which is a remove followed by an add.
+		for _, eventID := range removeStateEventIDs {
+			if err := d.CurrentRoomState.DeleteRoomStateByEventID(ctx, txn, eventID); err != nil {
+				return err
+			}
+		}
+
+		for _, event := range addStateEvents {
+			if event.StateKey() == nil {
+				// ignore non state events
+				continue
+			}
+			var membership *string
+			if event.Type() == "m.room.member" {
+				value, err := event.Membership()
+				if err != nil {
+					return err
+				}
+				membership = &value
+			}
+
+			if err := d.CurrentRoomState.UpsertRoomState(ctx, txn, event, membership); err != nil {
+				return err
+			}
+		}
+		return nil
+	})
+}
--- a/currentstateserver/storage/sqlite3/current_room_state_table.go
+++ b/currentstateserver/storage/sqlite3/current_room_state_table.go
@ -0,0 +1,201 @@
+// 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 sqlite3
+
+import (
+	"context"
+	"database/sql"
+	"encoding/json"
+	"strings"
+
+	"github.com/matrix-org/dendrite/currentstateserver/storage/tables"
+	"github.com/matrix-org/dendrite/internal"
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+const currentRoomStateSchema = `
+-- Stores the current room state for every room.
+CREATE TABLE IF NOT EXISTS currentstate_current_room_state (
+    room_id TEXT NOT NULL,
+    event_id TEXT NOT NULL,
+    type TEXT NOT NULL,
+    sender TEXT NOT NULL,
+    state_key TEXT NOT NULL,
+    headered_event_json TEXT NOT NULL,
+    membership TEXT,
+    UNIQUE (room_id, type, state_key)
+);
+-- for event deletion
+CREATE UNIQUE INDEX IF NOT EXISTS currentstate_event_id_idx ON currentstate_current_room_state(event_id, room_id, type, sender);
+-- for querying membership states of users
+-- CREATE INDEX IF NOT EXISTS currentstate_membership_idx ON currentstate_current_room_state(type, state_key, membership) WHERE membership IS NOT NULL AND membership != 'leave';
+`
+
+const upsertRoomStateSQL = "" +
+	"INSERT INTO currentstate_current_room_state (room_id, event_id, type, sender, state_key, headered_event_json, membership)" +
+	" VALUES ($1, $2, $3, $4, $5, $6, $7)" +
+	" ON CONFLICT (event_id, room_id, type, sender)" +
+	" DO UPDATE SET event_id = $2, sender=$4, headered_event_json = $6, membership = $7"
+
+const deleteRoomStateByEventIDSQL = "" +
+	"DELETE FROM currentstate_current_room_state WHERE event_id = $1"
+
+const selectRoomIDsWithMembershipSQL = "" +
+	"SELECT room_id FROM currentstate_current_room_state WHERE type = 'm.room.member' AND state_key = $1 AND membership = $2"
+
+const selectStateEventSQL = "" +
+	"SELECT headered_event_json FROM currentstate_current_room_state WHERE room_id = $1 AND type = $2 AND state_key = $3"
+
+const selectEventsWithEventIDsSQL = "" +
+	// TODO: The session_id and transaction_id blanks are here because otherwise
+	// the rowsToStreamEvents expects there to be exactly five columns. We need to
+	// figure out if these really need to be in the DB, and if so, we need a
+	// better permanent fix for this. - neilalexander, 2 Jan 2020
+	"SELECT added_at, headered_event_json, 0 AS session_id, false AS exclude_from_sync, '' AS transaction_id" +
+	" FROM currentstate_current_room_state WHERE event_id IN ($1)"
+
+type currentRoomStateStatements struct {
+	upsertRoomStateStmt             *sql.Stmt
+	deleteRoomStateByEventIDStmt    *sql.Stmt
+	selectRoomIDsWithMembershipStmt *sql.Stmt
+	selectStateEventStmt            *sql.Stmt
+}
+
+func NewSqliteCurrentRoomStateTable(db *sql.DB) (tables.CurrentRoomState, error) {
+	s := &currentRoomStateStatements{}
+	_, err := db.Exec(currentRoomStateSchema)
+	if err != nil {
+		return nil, err
+	}
+	if s.upsertRoomStateStmt, err = db.Prepare(upsertRoomStateSQL); err != nil {
+		return nil, err
+	}
+	if s.deleteRoomStateByEventIDStmt, err = db.Prepare(deleteRoomStateByEventIDSQL); err != nil {
+		return nil, err
+	}
+	if s.selectRoomIDsWithMembershipStmt, err = db.Prepare(selectRoomIDsWithMembershipSQL); err != nil {
+		return nil, err
+	}
+	if s.selectStateEventStmt, err = db.Prepare(selectStateEventSQL); err != nil {
+		return nil, err
+	}
+	return s, nil
+}
+
+// SelectRoomIDsWithMembership returns the list of room IDs which have the given user in the given membership state.
+func (s *currentRoomStateStatements) SelectRoomIDsWithMembership(
+	ctx context.Context,
+	txn *sql.Tx,
+	userID string,
+	membership string, // nolint: unparam
+) ([]string, error) {
+	stmt := sqlutil.TxStmt(txn, s.selectRoomIDsWithMembershipStmt)
+	rows, err := stmt.QueryContext(ctx, userID, membership)
+	if err != nil {
+		return nil, err
+	}
+	defer internal.CloseAndLogIfError(ctx, rows, "selectRoomIDsWithMembership: rows.close() failed")
+
+	var result []string
+	for rows.Next() {
+		var roomID string
+		if err := rows.Scan(&roomID); err != nil {
+			return nil, err
+		}
+		result = append(result, roomID)
+	}
+	return result, nil
+}
+
+func (s *currentRoomStateStatements) DeleteRoomStateByEventID(
+	ctx context.Context, txn *sql.Tx, eventID string,
+) error {
+	stmt := sqlutil.TxStmt(txn, s.deleteRoomStateByEventIDStmt)
+	_, err := stmt.ExecContext(ctx, eventID)
+	return err
+}
+
+func (s *currentRoomStateStatements) UpsertRoomState(
+	ctx context.Context, txn *sql.Tx,
+	event gomatrixserverlib.HeaderedEvent, membership *string,
+) error {
+	headeredJSON, err := json.Marshal(event)
+	if err != nil {
+		return err
+	}
+
+	// upsert state event
+	stmt := sqlutil.TxStmt(txn, s.upsertRoomStateStmt)
+	_, err = stmt.ExecContext(
+		ctx,
+		event.RoomID(),
+		event.EventID(),
+		event.Type(),
+		event.Sender(),
+		*event.StateKey(),
+		headeredJSON,
+		membership,
+	)
+	return err
+}
+
+func (s *currentRoomStateStatements) SelectEventsWithEventIDs(
+	ctx context.Context, txn *sql.Tx, eventIDs []string,
+) ([]gomatrixserverlib.HeaderedEvent, error) {
+	iEventIDs := make([]interface{}, len(eventIDs))
+	for k, v := range eventIDs {
+		iEventIDs[k] = v
+	}
+	query := strings.Replace(selectEventsWithEventIDsSQL, "($1)", sqlutil.QueryVariadic(len(iEventIDs)), 1)
+	rows, err := txn.QueryContext(ctx, query, iEventIDs...)
+	if err != nil {
+		return nil, err
+	}
+	defer internal.CloseAndLogIfError(ctx, rows, "selectEventsWithEventIDs: rows.close() failed")
+	result := []gomatrixserverlib.HeaderedEvent{}
+	for rows.Next() {
+		var eventBytes []byte
+		if err := rows.Scan(&eventBytes); err != nil {
+			return nil, err
+		}
+		// TODO: Handle redacted events
+		var ev gomatrixserverlib.HeaderedEvent
+		if err := json.Unmarshal(eventBytes, &ev); err != nil {
+			return nil, err
+		}
+		result = append(result, ev)
+	}
+	return result, nil
+}
+
+func (s *currentRoomStateStatements) SelectStateEvent(
+	ctx context.Context, roomID, evType, stateKey string,
+) (*gomatrixserverlib.HeaderedEvent, error) {
+	stmt := s.selectStateEventStmt
+	var res []byte
+	err := stmt.QueryRowContext(ctx, roomID, evType, stateKey).Scan(&res)
+	if err == sql.ErrNoRows {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+	var ev gomatrixserverlib.HeaderedEvent
+	if err = json.Unmarshal(res, &ev); err != nil {
+		return nil, err
+	}
+	return &ev, err
+}
--- a/currentstateserver/storage/sqlite3/storage.go
+++ b/currentstateserver/storage/sqlite3/storage.go
@ -0,0 +1,39 @@
+package sqlite3
+
+import (
+	"database/sql"
+
+	"github.com/matrix-org/dendrite/currentstateserver/storage/shared"
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+)
+
+type Database struct {
+	shared.Database
+	db *sql.DB
+	sqlutil.PartitionOffsetStatements
+}
+
+// NewDatabase creates a new sync server database
+// nolint: gocyclo
+func NewDatabase(dataSourceName string) (*Database, error) {
+	var d Database
+	cs, err := sqlutil.ParseFileURI(dataSourceName)
+	if err != nil {
+		return nil, err
+	}
+	if d.db, err = sqlutil.Open(sqlutil.SQLiteDriverName(), cs, nil); err != nil {
+		return nil, err
+	}
+	if err = d.PartitionOffsetStatements.Prepare(d.db, "currentstate"); err != nil {
+		return nil, err
+	}
+	currRoomState, err := NewSqliteCurrentRoomStateTable(d.db)
+	if err != nil {
+		return nil, err
+	}
+	d.Database = shared.Database{
+		DB:               d.db,
+		CurrentRoomState: currRoomState,
+	}
+	return &d, nil
+}
--- a/currentstateserver/storage/storage.go
+++ b/currentstateserver/storage/storage.go
@ -0,0 +1,41 @@
+// 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.
+
+// +build !wasm
+
+package storage
+
+import (
+	"net/url"
+
+	"github.com/matrix-org/dendrite/currentstateserver/storage/postgres"
+	"github.com/matrix-org/dendrite/currentstateserver/storage/sqlite3"
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+)
+
+// NewDatabase opens a database connection.
+func NewDatabase(dataSourceName string, dbProperties sqlutil.DbProperties) (Database, error) {
+	uri, err := url.Parse(dataSourceName)
+	if err != nil {
+		return postgres.NewDatabase(dataSourceName, dbProperties)
+	}
+	switch uri.Scheme {
+	case "postgres":
+		return postgres.NewDatabase(dataSourceName, dbProperties)
+	case "file":
+		return sqlite3.NewDatabase(dataSourceName)
+	default:
+		return postgres.NewDatabase(dataSourceName, dbProperties)
+	}
+}
--- a/currentstateserver/storage/storage_wasm.go
+++ b/currentstateserver/storage/storage_wasm.go
@ -0,0 +1,42 @@
+// 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 storage
+
+import (
+	"fmt"
+	"net/url"
+
+	"github.com/matrix-org/dendrite/currentstateserver/storage/sqlite3"
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+)
+
+// NewDatabase opens a database connection.
+func NewDatabase(
+	dataSourceName string,
+	dbProperties sqlutil.DbProperties, // nolint:unparam
+) (Database, error) {
+	uri, err := url.Parse(dataSourceName)
+	if err != nil {
+		return nil, fmt.Errorf("Cannot use postgres implementation")
+	}
+	switch uri.Scheme {
+	case "postgres":
+		return nil, fmt.Errorf("Cannot use postgres implementation")
+	case "file":
+		return sqlite3.NewDatabase(dataSourceName)
+	default:
+		return nil, fmt.Errorf("Cannot use postgres implementation")
+	}
+}
--- a/currentstateserver/storage/tables/interface.go
+++ b/currentstateserver/storage/tables/interface.go
@ -0,0 +1,31 @@
+// 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 tables
+
+import (
+	"context"
+	"database/sql"
+
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+type CurrentRoomState interface {
+	SelectStateEvent(ctx context.Context, roomID, evType, stateKey string) (*gomatrixserverlib.HeaderedEvent, error)
+	SelectEventsWithEventIDs(ctx context.Context, txn *sql.Tx, eventIDs []string) ([]gomatrixserverlib.HeaderedEvent, error)
+	UpsertRoomState(ctx context.Context, txn *sql.Tx, event gomatrixserverlib.HeaderedEvent, membership *string) error
+	DeleteRoomStateByEventID(ctx context.Context, txn *sql.Tx, eventID string) error
+	// SelectRoomIDsWithMembership returns the list of room IDs which have the given user in the given membership state.
+	SelectRoomIDsWithMembership(ctx context.Context, txn *sql.Tx, userID string, membership string) ([]string, error)
+}
--- a/dendrite-config.yaml
+++ b/dendrite-config.yaml
@ -121,6 +121,7 @@ database:
    federation_sender: "postgres://dendrite:itsasecret@localhost/dendrite_federationsender?sslmode=disable"
    appservice: "postgres://dendrite:itsasecret@localhost/dendrite_appservice?sslmode=disable"
    public_rooms_api: "postgres://dendrite:itsasecret@localhost/dendrite_publicroomsapi?sslmode=disable"
+    current_state: "postgres://dendrite:itsasecret@localhost/dendrite_currentstate?sslmode=disable"
    max_open_conns: 100
    max_idle_conns: 2
    conn_max_lifetime: -1
@ -143,6 +144,7 @@ listen:
    key_server: "localhost:7779"
    server_key_api: "localhost:7780"
    user_api: "localhost:7781"
+    current_state_server: "localhost:7782"

 # The configuration for tracing the dendrite components.
 tracing:
--- a/internal/config/config.go
+++ b/internal/config/config.go
@ -160,10 +160,13 @@ type Dendrite struct {
 	// Postgres Config
 	Database struct {
 		// The Account database stores the login details and account information
-		// for local users. It is accessed by the ClientAPI.
+		// for local users. It is accessed by the UserAPI.
 		Account DataSource `yaml:"account"`
+		// The CurrentState database stores the current state of all rooms.
+		// It is accessed by the CurrentStateServer.
+		CurrentState DataSource `yaml:"current_state"`
 		// The Device database stores session information for the devices of logged
-		// in local users. It is accessed by the ClientAPI, the MediaAPI and the SyncAPI.
+		// in local users. It is accessed by the UserAPI.
 		Device DataSource `yaml:"device"`
 		// The MediaAPI database stores information about files uploaded and downloaded
 		// by local users. It is only accessed by the MediaAPI.
@ -222,6 +225,7 @@ type Dendrite struct {
 	Bind struct {
 		MediaAPI         Address `yaml:"media_api"`
 		ClientAPI        Address `yaml:"client_api"`
+		CurrentState     Address `yaml:"current_state_server"`
 		FederationAPI    Address `yaml:"federation_api"`
 		ServerKeyAPI     Address `yaml:"server_key_api"`
 		AppServiceAPI    Address `yaml:"appservice_api"`
@ -238,6 +242,7 @@ type Dendrite struct {
 	Listen struct {
 		MediaAPI         Address `yaml:"media_api"`
 		ClientAPI        Address `yaml:"client_api"`
+		CurrentState     Address `yaml:"current_state_server"`
 		FederationAPI    Address `yaml:"federation_api"`
 		ServerKeyAPI     Address `yaml:"server_key_api"`
 		AppServiceAPI    Address `yaml:"appservice_api"`
@ -601,6 +606,7 @@ func (config *Dendrite) checkDatabase(configErrs *configErrors) {
 	checkNotEmpty(configErrs, "database.media_api", string(config.Database.MediaAPI))
 	checkNotEmpty(configErrs, "database.sync_api", string(config.Database.SyncAPI))
 	checkNotEmpty(configErrs, "database.room_server", string(config.Database.RoomServer))
+	checkNotEmpty(configErrs, "database.current_state", string(config.Database.CurrentState))
 }

 // checkListen verifies the parameters listen.* are valid.
@ -613,6 +619,7 @@ func (config *Dendrite) checkListen(configErrs *configErrors) {
 	checkNotEmpty(configErrs, "listen.edu_server", string(config.Listen.EDUServer))
 	checkNotEmpty(configErrs, "listen.server_key_api", string(config.Listen.EDUServer))
 	checkNotEmpty(configErrs, "listen.user_api", string(config.Listen.UserAPI))
+	checkNotEmpty(configErrs, "listen.current_state_server", string(config.Listen.CurrentState))
 }

 // checkLogging verifies the parameters logging.* are valid.
@ -735,6 +742,15 @@ func (config *Dendrite) UserAPIURL() string {
 	return "http://" + string(config.Listen.UserAPI)
 }

+// CurrentStateAPIURL returns an HTTP URL for where the currentstateserver is listening.
+func (config *Dendrite) CurrentStateAPIURL() string {
+	// Hard code the currentstateserver to talk HTTP for now.
+	// If we support HTTPS we need to think of a practical way to do certificate validation.
+	// People setting up servers shouldn't need to get a certificate valid for the public
+	// internet for an internal API.
+	return "http://" + string(config.Listen.CurrentState)
+}
+
 // EDUServerURL returns an HTTP URL for where the EDU server is listening.
 func (config *Dendrite) EDUServerURL() string {
 	// Hard code the EDU server to talk HTTP for now.
@ -753,7 +769,7 @@ func (config *Dendrite) FederationSenderURL() string {
 	return "http://" + string(config.Listen.FederationSender)
 }

-// FederationSenderURL returns an HTTP URL for where the federation sender is listening.
+// ServerKeyAPIURL returns an HTTP URL for where the federation sender is listening.
 func (config *Dendrite) ServerKeyAPIURL() string {
 	// Hard code the server key API server to talk HTTP for now.
 	// If we support HTTPS we need to think of a practical way to do certificate validation.
--- a/internal/config/config_test.go
+++ b/internal/config/config_test.go
@ -55,6 +55,7 @@ database:
  sync_api: "postgresql:///syn_api"
  room_server: "postgresql:///room_server"
  appservice: "postgresql:///appservice"
+  current_state: "postgresql:///current_state"
 listen:
  room_server: "localhost:7770"
  client_api: "localhost:7771"
@ -64,6 +65,7 @@ listen:
  appservice_api: "localhost:7777"
  edu_server: "localhost:7778"
  user_api: "localhost:7779"
+  current_state_server: "localhost:7775"
 logging:
  - type: "file"
    level: "info"