Make account data sync incremental (#170)

* Clean roomserver consumer

* Make account data sync incremental

* Use a different name for the sync AD table

* Improved error logging

* Created missing topic in tests

* Add client API topic to tests

* Add client API topic to common

* Move data batch retrieval

* Add database index for data retrieval

* Fix typo in table name

* Fix indentation

19 files changed, 500 insertions, 66 deletions

diff --git a/src/github.com/matrix-org/dendrite/clientapi/auth/storage/accounts/account_data_table.go b/src/github.com/matrix-org/dendrite/clientapi/auth/storage/accounts/account_data_table.go
index 63e84a66..0c1fc0ff 100644
--- a/src/github.com/matrix-org/dendrite/clientapi/auth/storage/accounts/account_data_table.go
+++ b/src/github.com/matrix-org/dendrite/clientapi/auth/storage/accounts/account_data_table.go
@@ -44,12 +44,16 @@ const insertAccountDataSQL = `
 const selectAccountDataSQL = "" +
 	"SELECT room_id, type, content FROM account_data WHERE localpart = $1"
 
+const selectAccountDataByTypeSQL = "" +
+	"SELECT content FROM account_data WHERE localpart = $1 AND room_id = $2 AND type = $3"
+
 const deleteAccountDataSQL = "" +
 	"DELETE FROM account_data WHERE localpart = $1 AND room_id = $2 AND type = $3"
 
 type accountDataStatements struct {
-	insertAccountDataStmt *sql.Stmt
-	selectAccountDataStmt *sql.Stmt
+	insertAccountDataStmt       *sql.Stmt
+	selectAccountDataStmt       *sql.Stmt
+	selectAccountDataByTypeStmt *sql.Stmt
 }
 
 func (s *accountDataStatements) prepare(db *sql.DB) (err error) {
@@ -63,6 +67,9 @@ func (s *accountDataStatements) prepare(db *sql.DB) (err error) {
 	if s.selectAccountDataStmt, err = db.Prepare(selectAccountDataSQL); err != nil {
 		return
 	}
+	if s.selectAccountDataByTypeStmt, err = db.Prepare(selectAccountDataByTypeSQL); err != nil {
+		return
+	}
 	return
 }
 
@@ -107,3 +114,31 @@ func (s *accountDataStatements) selectAccountData(localpart string) (
 
 	return
 }
+
+func (s *accountDataStatements) selectAccountDataByType(
+	localpart string, roomID string, dataType string,
+) (data []gomatrixserverlib.ClientEvent, err error) {
+	data = []gomatrixserverlib.ClientEvent{}
+
+	rows, err := s.selectAccountDataByTypeStmt.Query(localpart, roomID, dataType)
+	if err != nil {
+		return
+	}
+
+	for rows.Next() {
+		var content []byte
+
+		if err = rows.Scan(&content); err != nil {
+			return
+		}
+
+		ac := gomatrixserverlib.ClientEvent{
+			Type:    dataType,
+			Content: content,
+		}
+
+		data = append(data, ac)
+	}
+
+	return
+}
diff --git a/src/github.com/matrix-org/dendrite/clientapi/auth/storage/accounts/storage.go b/src/github.com/matrix-org/dendrite/clientapi/auth/storage/accounts/storage.go
index a7b2c786..ca9deac0 100644
--- a/src/github.com/matrix-org/dendrite/clientapi/auth/storage/accounts/storage.go
+++ b/src/github.com/matrix-org/dendrite/clientapi/auth/storage/accounts/storage.go
@@ -224,6 +224,14 @@ func (d *Database) GetAccountData(localpart string) (
 	return d.accountDatas.selectAccountData(localpart)
 }
 
+// GetAccountDataByType returns account data matching a given
+// localpart, room ID and type.
+// If no account data could be found, returns an empty array
+// Returns an error if there was an issue with the retrieval
+func (d *Database) GetAccountDataByType(localpart string, roomID string, dataType string) (data []gomatrixserverlib.ClientEvent, err error) {
+	return d.accountDatas.selectAccountDataByType(localpart, roomID, dataType)
+}
+
 func hashPassword(plaintext string) (hash string, err error) {
 	hashBytes, err := bcrypt.GenerateFromPassword([]byte(plaintext), bcrypt.DefaultCost)
 	return string(hashBytes), err
diff --git a/src/github.com/matrix-org/dendrite/clientapi/producers/syncapi.go b/src/github.com/matrix-org/dendrite/clientapi/producers/syncapi.go
new file mode 100644
index 00000000..2597089e
--- /dev/null
+++ b/src/github.com/matrix-org/dendrite/clientapi/producers/syncapi.go
@@ -0,0 +1,65 @@
+// Copyright 2017 Vector Creations Ltd
+//
+// 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 producers
+
+import (
+	"encoding/json"
+
+	"github.com/matrix-org/dendrite/common"
+
+	sarama "gopkg.in/Shopify/sarama.v1"
+)
+
+// SyncAPIProducer produces events for the sync API server to consume
+type SyncAPIProducer struct {
+	Topic    string
+	Producer sarama.SyncProducer
+}
+
+// NewSyncAPIProducer creates a new SyncAPIProducer
+func NewSyncAPIProducer(kafkaURIs []string, topic string) (*SyncAPIProducer, error) {
+	producer, err := sarama.NewSyncProducer(kafkaURIs, nil)
+	if err != nil {
+		return nil, err
+	}
+	return &SyncAPIProducer{
+		Topic:    topic,
+		Producer: producer,
+	}, nil
+}
+
+// SendData sends account data to the sync API server
+func (p *SyncAPIProducer) SendData(userID string, roomID string, dataType string) error {
+	var m sarama.ProducerMessage
+
+	data := common.AccountData{
+		RoomID: roomID,
+		Type:   dataType,
+	}
+	value, err := json.Marshal(data)
+	if err != nil {
+		return err
+	}
+
+	m.Topic = string(p.Topic)
+	m.Key = sarama.StringEncoder(userID)
+	m.Value = sarama.ByteEncoder(value)
+
+	if _, _, err := p.Producer.SendMessage(&m); err != nil {
+		return err
+	}
+
+	return nil
+}
diff --git a/src/github.com/matrix-org/dendrite/clientapi/readers/account_data.go b/src/github.com/matrix-org/dendrite/clientapi/readers/account_data.go
index ca2c2232..d3bb932d 100644
--- a/src/github.com/matrix-org/dendrite/clientapi/readers/account_data.go
+++ b/src/github.com/matrix-org/dendrite/clientapi/readers/account_data.go
@@ -22,6 +22,7 @@ import (
 	"github.com/matrix-org/dendrite/clientapi/auth/storage/accounts"
 	"github.com/matrix-org/dendrite/clientapi/httputil"
 	"github.com/matrix-org/dendrite/clientapi/jsonerror"
+	"github.com/matrix-org/dendrite/clientapi/producers"
 	"github.com/matrix-org/gomatrixserverlib"
 
 	"github.com/matrix-org/util"
@@ -30,7 +31,7 @@ import (
 // SaveAccountData implements PUT /user/{userId}/[rooms/{roomId}/]account_data/{type}
 func SaveAccountData(
 	req *http.Request, accountDB *accounts.Database, device *authtypes.Device,
-	userID string, roomID string, dataType string,
+	userID string, roomID string, dataType string, syncProducer *producers.SyncAPIProducer,
 ) util.JSONResponse {
 	if req.Method != "PUT" {
 		return util.JSONResponse{
@@ -62,6 +63,10 @@ func SaveAccountData(
 		return httputil.LogThenError(req, err)
 	}
 
+	if err := syncProducer.SendData(userID, roomID, dataType); err != nil {
+		return httputil.LogThenError(req, err)
+	}
+
 	return util.JSONResponse{
 		Code: 200,
 		JSON: struct{}{},
diff --git a/src/github.com/matrix-org/dendrite/clientapi/routing/routing.go b/src/github.com/matrix-org/dendrite/clientapi/routing/routing.go
index 5a2935e8..aeb23164 100644
--- a/src/github.com/matrix-org/dendrite/clientapi/routing/routing.go
+++ b/src/github.com/matrix-org/dendrite/clientapi/routing/routing.go
@@ -48,6 +48,7 @@ func Setup(
 	federation *gomatrixserverlib.FederationClient,
 	keyRing gomatrixserverlib.KeyRing,
 	userUpdateProducer *producers.UserUpdateProducer,
+	syncProducer *producers.SyncAPIProducer,
 ) {
 	apiMux := mux.NewRouter()
 
@@ -291,14 +292,14 @@ func Setup(
 	r0mux.Handle("/user/{userID}/account_data/{type}",
 		common.MakeAuthAPI("user_account_data", deviceDB, func(req *http.Request, device *authtypes.Device) util.JSONResponse {
 			vars := mux.Vars(req)
-			return readers.SaveAccountData(req, accountDB, device, vars["userID"], "", vars["type"])
+			return readers.SaveAccountData(req, accountDB, device, vars["userID"], "", vars["type"], syncProducer)
 		}),
 	)
 
 	r0mux.Handle("/user/{userID}/rooms/{roomID}/account_data/{type}",
 		common.MakeAuthAPI("user_account_data", deviceDB, func(req *http.Request, device *authtypes.Device) util.JSONResponse {
 			vars := mux.Vars(req)
-			return readers.SaveAccountData(req, accountDB, device, vars["userID"], vars["roomID"], vars["type"])
+			return readers.SaveAccountData(req, accountDB, device, vars["userID"], vars["roomID"], vars["type"], syncProducer)
 		}),
 	)
 
diff --git a/src/github.com/matrix-org/dendrite/cmd/dendrite-client-api-server/main.go b/src/github.com/matrix-org/dendrite/cmd/dendrite-client-api-server/main.go
index 0f8c035f..6f568b1a 100644
--- a/src/github.com/matrix-org/dendrite/cmd/dendrite-client-api-server/main.go
+++ b/src/github.com/matrix-org/dendrite/cmd/dendrite-client-api-server/main.go
@@ -61,6 +61,12 @@ func main() {
 	if err != nil {
 		log.Panicf("Failed to setup kafka producers(%q): %s", cfg.Kafka.Addresses, err)
 	}
+	syncProducer, err := producers.NewSyncAPIProducer(
+		cfg.Kafka.Addresses, string(cfg.Kafka.Topics.OutputClientData),
+	)
+	if err != nil {
+		log.Panicf("Failed to setup kafka producers(%q): %s", cfg.Kafka.Addresses, err)
+	}
 
 	federation := gomatrixserverlib.NewFederationClient(
 		cfg.Matrix.ServerName, cfg.Matrix.KeyID, cfg.Matrix.PrivateKey,
@@ -99,7 +105,7 @@ func main() {
 	routing.Setup(
 		http.DefaultServeMux, http.DefaultClient, *cfg, roomserverProducer,
 		queryAPI, aliasAPI, accountDB, deviceDB, federation, keyRing,
-		userUpdateProducer,
+		userUpdateProducer, syncProducer,
 	)
 	log.Fatal(http.ListenAndServe(string(cfg.Listen.ClientAPI), nil))
 }
diff --git a/src/github.com/matrix-org/dendrite/cmd/dendrite-sync-api-server/main.go b/src/github.com/matrix-org/dendrite/cmd/dendrite-sync-api-server/main.go
index c7870684..77ada412 100644
--- a/src/github.com/matrix-org/dendrite/cmd/dendrite-sync-api-server/main.go
+++ b/src/github.com/matrix-org/dendrite/cmd/dendrite-sync-api-server/main.go
@@ -73,12 +73,19 @@ func main() {
 	if err = n.Load(db); err != nil {
 		log.Panicf("startup: failed to set up notifier: %s", err)
 	}
-	consumer, err := consumers.NewOutputRoomEvent(cfg, n, db)
+	roomConsumer, err := consumers.NewOutputRoomEvent(cfg, n, db)
 	if err != nil {
 		log.Panicf("startup: failed to create room server consumer: %s", err)
 	}
-	if err = consumer.Start(); err != nil {
-		log.Panicf("startup: failed to start room server consumer")
+	if err = roomConsumer.Start(); err != nil {
+		log.Panicf("startup: failed to start room server consumer: %s", err)
+	}
+	clientConsumer, err := consumers.NewOutputClientData(cfg, n, db)
+	if err != nil {
+		log.Panicf("startup: failed to create client API server consumer: %s", err)
+	}
+	if err = clientConsumer.Start(); err != nil {
+		log.Panicf("startup: failed to start client API server consumer: %s", err)
 	}
 
 	log.Info("Starting sync server on ", cfg.Listen.SyncAPI)
diff --git a/src/github.com/matrix-org/dendrite/cmd/syncserver-integration-tests/main.go b/src/github.com/matrix-org/dendrite/cmd/syncserver-integration-tests/main.go
index b0e36c42..e39a8980 100644
--- a/src/github.com/matrix-org/dendrite/cmd/syncserver-integration-tests/main.go
+++ b/src/github.com/matrix-org/dendrite/cmd/syncserver-integration-tests/main.go
@@ -54,6 +54,7 @@ var (
 )
 
 const inputTopic = "syncserverInput"
+const clientTopic = "clientapiserverOutput"
 
 var exe = test.KafkaExecutor{
 	ZookeeperURI:   zookeeperURI,
@@ -134,6 +135,7 @@ func startSyncServer() (*exec.Cmd, chan error) {
 	cfg.Matrix.ServerName = "localhost"
 	cfg.Listen.SyncAPI = config.Address(syncserverAddr)
 	cfg.Kafka.Topics.OutputRoomEvent = config.Topic(inputTopic)
+	cfg.Kafka.Topics.OutputClientData = config.Topic(clientTopic)
 
 	if err := test.WriteConfig(cfg, dir); err != nil {
 		panic(err)
@@ -177,6 +179,10 @@ func prepareKafka() {
 	if err := exe.CreateTopic(inputTopic); err != nil {
 		panic(err)
 	}
+	exe.DeleteTopic(clientTopic)
+	if err := exe.CreateTopic(clientTopic); err != nil {
+		panic(err)
+	}
 }
 
 func testSyncServer(syncServerCmdChan chan error, userID, since, want string) {
diff --git a/src/github.com/matrix-org/dendrite/common/config/config.go b/src/github.com/matrix-org/dendrite/common/config/config.go
index 4b362b5f..324561f6 100644
--- a/src/github.com/matrix-org/dendrite/common/config/config.go
+++ b/src/github.com/matrix-org/dendrite/common/config/config.go
@@ -98,6 +98,8 @@ type Dendrite struct {
 		Topics struct {
 			// Topic for roomserver/api.OutputRoomEvent events.
 			OutputRoomEvent Topic `yaml:"output_room_event"`
+			// Topic for sending account data from client API to sync API
+			OutputClientData Topic `yaml:"output_client_data"`
 			// Topic for user updates (profile, presence)
 			UserUpdates Topic `yaml:"user_updates"`
 		}
@@ -298,6 +300,7 @@ func (config *Dendrite) check() error {
 
 	checkNotZero("kafka.addresses", int64(len(config.Kafka.Addresses)))
 	checkNotEmpty("kafka.topics.output_room_event", string(config.Kafka.Topics.OutputRoomEvent))
+	checkNotEmpty("kafka.topics.output_client_data", string(config.Kafka.Topics.OutputClientData))
 	checkNotEmpty("database.account", string(config.Database.Account))
 	checkNotEmpty("database.device", string(config.Database.Device))
 	checkNotEmpty("database.server_key", string(config.Database.ServerKey))
diff --git a/src/github.com/matrix-org/dendrite/common/config/config_test.go b/src/github.com/matrix-org/dendrite/common/config/config_test.go
index 7af61968..4275e3d4 100644
--- a/src/github.com/matrix-org/dendrite/common/config/config_test.go
+++ b/src/github.com/matrix-org/dendrite/common/config/config_test.go
@@ -44,6 +44,7 @@ kafka:
   topics:
     input_room_event: input.room
     output_room_event: output.room
+    output_client_data: output.client
 database:
   media_api: "postgresql:///media_api"
   account: "postgresql:///account"
diff --git a/src/github.com/matrix-org/dendrite/common/test/config.go b/src/github.com/matrix-org/dendrite/common/test/config.go
index e429d06b..a28a08d5 100644
--- a/src/github.com/matrix-org/dendrite/common/test/config.go
+++ b/src/github.com/matrix-org/dendrite/common/test/config.go
@@ -82,6 +82,7 @@ func MakeConfig(configDir, kafkaURI, database, host string, startPort int) (*con
 	// TODO: Different servers should be using different topics.
 	// Make this configurable somehow?
 	cfg.Kafka.Topics.OutputRoomEvent = "test.room.output"
+	cfg.Kafka.Topics.OutputClientData = "test.clientapi.output"
 
 	// TODO: Use different databases for the different schemas.
 	// Using the same database for every schema currently works because
diff --git a/src/github.com/matrix-org/dendrite/common/types.go b/src/github.com/matrix-org/dendrite/common/types.go
new file mode 100644
index 00000000..471a2f30
--- /dev/null
+++ b/src/github.com/matrix-org/dendrite/common/types.go
@@ -0,0 +1,22 @@
+// Copyright 2017 Vector Creations Ltd
+//
+// 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 common
+
+// AccountData represents account data sent from the client API server to the
+// sync API server
+type AccountData struct {
+	RoomID string `json:"room_id"`
+	Type   string `json:"type"`
+}
diff --git a/src/github.com/matrix-org/dendrite/syncapi/consumers/clientapi.go b/src/github.com/matrix-org/dendrite/syncapi/consumers/clientapi.go
new file mode 100644
index 00000000..a2a240ff
--- /dev/null
+++ b/src/github.com/matrix-org/dendrite/syncapi/consumers/clientapi.go
@@ -0,0 +1,91 @@
+// Copyright 2017 Vector Creations Ltd
+//
+// 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 (
+	"encoding/json"
+
+	log "github.com/Sirupsen/logrus"
+	"github.com/matrix-org/dendrite/common"
+	"github.com/matrix-org/dendrite/common/config"
+	"github.com/matrix-org/dendrite/syncapi/storage"
+	"github.com/matrix-org/dendrite/syncapi/sync"
+	sarama "gopkg.in/Shopify/sarama.v1"
+)
+
+// OutputClientData consumes events that originated in the client API server.
+type OutputClientData struct {
+	clientAPIConsumer *common.ContinualConsumer
+	db                *storage.SyncServerDatabase
+	notifier          *sync.Notifier
+}
+
+// NewOutputClientData creates a new OutputClientData consumer. Call Start() to begin consuming from room servers.
+func NewOutputClientData(cfg *config.Dendrite, n *sync.Notifier, store *storage.SyncServerDatabase) (*OutputClientData, error) {
+	kafkaConsumer, err := sarama.NewConsumer(cfg.Kafka.Addresses, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	consumer := common.ContinualConsumer{
+		Topic:          string(cfg.Kafka.Topics.OutputClientData),
+		Consumer:       kafkaConsumer,
+		PartitionStore: store,
+	}
+	s := &OutputClientData{
+		clientAPIConsumer: &consumer,
+		db:                store,
+		notifier:          n,
+	}
+	consumer.ProcessMessage = s.onMessage
+
+	return s, nil
+}
+
+// Start consuming from room servers
+func (s *OutputClientData) Start() error {
+	return s.clientAPIConsumer.Start()
+}
+
+// onMessage is called when the sync server receives a new event from the client API server output log.
+// It is not safe for this function to be called from multiple goroutines, or else the
+// sync stream position may race and be incorrectly calculated.
+func (s *OutputClientData) onMessage(msg *sarama.ConsumerMessage) error {
+	// Parse out the event JSON
+	var output common.AccountData
+	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("client API server output log: message parse failure")
+		return nil
+	}
+
+	log.WithFields(log.Fields{
+		"type":    output.Type,
+		"room_id": output.RoomID,
+	}).Info("received data from client API server")
+
+	syncStreamPos, err := s.db.UpsertAccountData(string(msg.Key), output.RoomID, output.Type)
+	if err != nil {
+		log.WithFields(log.Fields{
+			"type":       output.Type,
+			"room_id":    output.RoomID,
+			log.ErrorKey: err,
+		}).Panicf("could not save account data")
+	}
+
+	s.notifier.OnNewEvent(nil, string(msg.Key), syncStreamPos)
+
+	return nil
+}
diff --git a/src/github.com/matrix-org/dendrite/syncapi/consumers/roomserver.go b/src/github.com/matrix-org/dendrite/syncapi/consumers/roomserver.go
index 13159c87..c846705f 100644
--- a/src/github.com/matrix-org/dendrite/syncapi/consumers/roomserver.go
+++ b/src/github.com/matrix-org/dendrite/syncapi/consumers/roomserver.go
@@ -35,12 +35,9 @@ type OutputRoomEvent struct {
 	db                 *storage.SyncServerDatabase
 	notifier           *sync.Notifier
 	query              api.RoomserverQueryAPI
-	serverName         gomatrixserverlib.ServerName
-	keyID              gomatrixserverlib.KeyID
-	privateKey         []byte
 }
 
-type prevMembership struct {
+type prevEventRef struct {
 	PrevContent json.RawMessage `json:"prev_content"`
 	PrevID      string          `json:"replaces_state"`
 	UserID      string          `json:"prev_sender"`
@@ -64,9 +61,6 @@ func NewOutputRoomEvent(cfg *config.Dendrite, n *sync.Notifier, store *storage.S
 		db:                 store,
 		notifier:           n,
 		query:              api.NewRoomserverQueryAPIHTTP(roomServerURL, nil),
-		serverName:         cfg.Matrix.ServerName,
-		keyID:              cfg.Matrix.KeyID,
-		privateKey:         cfg.Matrix.PrivateKey,
 	}
 	consumer.ProcessMessage = s.onMessage
 
@@ -113,13 +107,13 @@ func (s *OutputRoomEvent) onMessage(msg *sarama.ConsumerMessage) error {
 		}).Panicf("roomserver output log: state event lookup failure")
 	}
 
-	ev, err = s.updateStateEvent(ev, s.keyID, s.privateKey)
+	ev, err = s.updateStateEvent(ev)
 	if err != nil {
 		return err
 	}
 
 	for i := range addsStateEvents {
-		addsStateEvents[i], err = s.updateStateEvent(addsStateEvents[i], s.keyID, s.privateKey)
+		addsStateEvents[i], err = s.updateStateEvent(addsStateEvents[i])
 		if err != nil {
 			return err
 		}
@@ -139,7 +133,7 @@ func (s *OutputRoomEvent) onMessage(msg *sarama.ConsumerMessage) error {
 		}).Panicf("roomserver output log: write event failure")
 		return nil
 	}
-	s.notifier.OnNewEvent(&ev, types.StreamPosition(syncStreamPos))
+	s.notifier.OnNewEvent(&ev, "", types.StreamPosition(syncStreamPos))
 
 	return nil
 }
@@ -201,10 +195,7 @@ func (s *OutputRoomEvent) lookupStateEvents(
 	return result, nil
 }
 
-func (s *OutputRoomEvent) updateStateEvent(
-	event gomatrixserverlib.Event, keyID gomatrixserverlib.KeyID,
-	privateKey []byte,
-) (gomatrixserverlib.Event, error) {
+func (s *OutputRoomEvent) updateStateEvent(event gomatrixserverlib.Event) (gomatrixserverlib.Event, error) {
 	var stateKey string
 	if event.StateKey() == nil {
 		stateKey = ""
@@ -221,7 +212,7 @@ func (s *OutputRoomEvent) updateStateEvent(
 		return event, nil
 	}
 
-	prev := prevMembership{
+	prev := prevEventRef{
 		PrevContent: prevEvent.Content(),
 		PrevID:      prevEvent.EventID(),
 		UserID:      prevEvent.Sender(),
diff --git a/src/github.com/matrix-org/dendrite/syncapi/storage/account_data_table.go b/src/github.com/matrix-org/dendrite/syncapi/storage/account_data_table.go
new file mode 100644
index 00000000..f95e4858
--- /dev/null
+++ b/src/github.com/matrix-org/dendrite/syncapi/storage/account_data_table.go
@@ -0,0 +1,113 @@
+// Copyright 2017 Vector Creations Ltd
+//
+// 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 (
+	"database/sql"
+
+	"github.com/matrix-org/dendrite/syncapi/types"
+)
+
+const accountDataSchema = `
+-- Stores the users account data
+CREATE TABLE IF NOT EXISTS account_data_type (
+    -- The highest numeric ID from the output_room_events at the time of saving the data
+    id BIGINT,
+    -- ID of the user the data belongs to
+    user_id TEXT NOT NULL,
+    -- ID of the room the data is related to (empty string if not related to a specific room)
+    room_id TEXT NOT NULL,
+    -- Type of the data
+    type TEXT NOT NULL,
+
+    PRIMARY KEY(user_id, room_id, type),
+
+    -- We don't want two entries of the same type for the same user
+    CONSTRAINT account_data_unique UNIQUE (user_id, room_id, type)
+);
+
+CREATE UNIQUE INDEX IF NOT EXISTS account_data_id_idx ON account_data_type(id);
+`
+
+const insertAccountDataSQL = "" +
+	"INSERT INTO account_data_type (id, user_id, room_id, type) VALUES ($1, $2, $3, $4)" +
+	" ON CONFLICT ON CONSTRAINT account_data_unique" +
+	" DO UPDATE SET id = EXCLUDED.id"
+
+const selectAccountDataInRangeSQL = "" +
+	"SELECT room_id, type FROM account_data_type" +
+	" WHERE user_id = $1 AND id > $2 AND id <= $3" +
+	" ORDER BY id ASC"
+
+type accountDataStatements struct {
+	insertAccountDataStmt        *sql.Stmt
+	selectAccountDataInRangeStmt *sql.Stmt
+}
+
+func (s *accountDataStatements) prepare(db *sql.DB) (err error) {
+	_, err = db.Exec(accountDataSchema)
+	if err != nil {
+		return
+	}
+	if s.insertAccountDataStmt, err = db.Prepare(insertAccountDataSQL); err != nil {
+		return
+	}
+	if s.selectAccountDataInRangeStmt, err = db.Prepare(selectAccountDataInRangeSQL); err != nil {
+		return
+	}
+	return
+}
+
+func (s *accountDataStatements) insertAccountData(
+	pos types.StreamPosition, userID string, roomID string, dataType string,
+) (err error) {
+	_, err = s.insertAccountDataStmt.Exec(pos, userID, roomID, dataType)
+	return
+}
+
+func (s *accountDataStatements) selectAccountDataInRange(
+	userID string, oldPos types.StreamPosition, newPos types.StreamPosition,
+) (data map[string][]string, err error) {
+	data = make(map[string][]string)
+
+	// If both positions are the same, it means that the data was saved after the
+	// latest room event. In that case, we need to decrement the old position as
+	// it would prevent the SQL request from returning anything.
+	if oldPos == newPos {
+		oldPos--
+	}
+
+	rows, err := s.selectAccountDataInRangeStmt.Query(userID, oldPos, newPos)
+	if err != nil {
+		return
+	}
+
+	for rows.Next() {
+		var dataType string
+		var roomID string
+
+		if err = rows.Scan(&roomID, &dataType); err != nil {
+			return
+		}
+
+		if len(data[roomID]) > 0 {
+			data[roomID] = append(data[roomID], dataType)
+		} else {
+			data[roomID] = []string{dataType}
+		}
+	}
+
+	return
+}
diff --git a/src/github.com/matrix-org/dendrite/syncapi/storage/syncserver.go b/src/github.com/matrix-org/dendrite/syncapi/storage/syncserver.go
index 46231c77..2433b68c 100644
--- a/src/github.com/matrix-org/dendrite/syncapi/storage/syncserver.go
+++ b/src/github.com/matrix-org/dendrite/syncapi/storage/syncserver.go
@@ -41,10 +41,11 @@ type streamEvent struct {
 
 // SyncServerDatabase represents a sync server database
 type SyncServerDatabase struct {
-	db         *sql.DB
-	partitions common.PartitionOffsetStatements
-	events     outputRoomEventsStatements
-	roomstate  currentRoomStateStatements
+	db          *sql.DB
+	partitions  common.PartitionOffsetStatements
+	accountData accountDataStatements
+	events      outputRoomEventsStatements
+	roomstate   currentRoomStateStatements
 }
 
 // NewSyncServerDatabase creates a new sync server database
@@ -58,6 +59,10 @@ func NewSyncServerDatabase(dataSourceName string) (*SyncServerDatabase, error) {
 	if err = partitions.Prepare(db); err != nil {
 		return nil, err
 	}
+	accountData := accountDataStatements{}
+	if err = accountData.prepare(db); err != nil {
+		return nil, err
+	}
 	events := outputRoomEventsStatements{}
 	if err = events.prepare(db); err != nil {
 		return nil, err
@@ -66,7 +71,7 @@ func NewSyncServerDatabase(dataSourceName string) (*SyncServerDatabase, error) {
 	if err := state.prepare(db); err != nil {
 		return nil, err
 	}
-	return &SyncServerDatabase{db, partitions, events, state}, nil
+	return &SyncServerDatabase{db, partitions, accountData, events, state}, nil
 }
 
 // AllJoinedUsersInRooms returns a map of room ID to a list of all joined user IDs.
@@ -274,6 +279,33 @@ func (d *SyncServerDatabase) CompleteSync(userID string, numRecentEventsPerRoom
 	return
 }
 
+// GetAccountDataInRange returns all account data for a given user inserted or
+// updated between two given positions
+// Returns a map following the format data[roomID] = []dataTypes
+// If no data is retrieved, returns an empty map
+// If there was an issue with the retrieval, returns an error
+func (d *SyncServerDatabase) GetAccountDataInRange(
+	userID string, oldPos types.StreamPosition, newPos types.StreamPosition,
+) (map[string][]string, error) {
+	return d.accountData.selectAccountDataInRange(userID, oldPos, newPos)
+}
+
+// UpsertAccountData keeps track of new or updated account data, by saving the type
+// of the new/updated data, and the user ID and room ID the data is related to (empty)
+// room ID means the data isn't specific to any room)
+// If no data with the given type, user ID and room ID exists in the database,
+// creates a new row, else update the existing one
+// Returns an error if there was an issue with the upsert
+func (d *SyncServerDatabase) UpsertAccountData(userID string, roomID string, dataType string) (types.StreamPosition, error) {
+	pos, err := d.SyncStreamPosition()
+	if err != nil {
+		return pos, err
+	}
+
+	err = d.accountData.insertAccountData(pos, userID, roomID, dataType)
+	return pos, err
+}
+
 func (d *SyncServerDatabase) addInvitesToResponse(txn *sql.Tx, userID string, res *types.Response) error {
 	// Add invites - TODO: This will break over federation as they won't be in the current state table according to Mark.
 	roomIDs, err := d.roomstate.selectRoomIDsWithMembership(txn, userID, "invite")
diff --git a/src/github.com/matrix-org/dendrite/syncapi/sync/notifier.go b/src/github.com/matrix-org/dendrite/syncapi/sync/notifier.go
index 814660a7..c2fdd8f0 100644
--- a/src/github.com/matrix-org/dendrite/syncapi/sync/notifier.go
+++ b/src/github.com/matrix-org/dendrite/syncapi/sync/notifier.go
@@ -54,39 +54,44 @@ func NewNotifier(pos types.StreamPosition) *Notifier {
 // OnNewEvent is called when a new event is received from the room server. Must only be
 // called from a single goroutine, to avoid races between updates which could set the
 // current position in the stream incorrectly.
-func (n *Notifier) OnNewEvent(ev *gomatrixserverlib.Event, pos types.StreamPosition) {
+// Can be called either with a *gomatrixserverlib.Event, or with an user ID
+func (n *Notifier) OnNewEvent(ev *gomatrixserverlib.Event, userID string, pos types.StreamPosition) {
 	// update the current position then notify relevant /sync streams.
 	// This needs to be done PRIOR to waking up users as they will read this value.
 	n.streamLock.Lock()
 	defer n.streamLock.Unlock()
 	n.currPos = pos
 
-	// Map this event's room_id to a list of joined users, and wake them up.
-	userIDs := n.joinedUsers(ev.RoomID())
-	// If this is an invite, also add in the invitee to this list.
-	if ev.Type() == "m.room.member" && ev.StateKey() != nil {
-		userID := *ev.StateKey()
-		membership, err := ev.Membership()
-		if err != nil {
-			log.WithError(err).WithField("event_id", ev.EventID()).Errorf(
-				"Notifier.OnNewEvent: Failed to unmarshal member event",
-			)
-		} else {
-			// Keep the joined user map up-to-date
-			switch membership {
-			case "invite":
-				userIDs = append(userIDs, userID)
-			case "join":
-				n.addJoinedUser(ev.RoomID(), userID)
-			case "leave":
-				fallthrough
-			case "ban":
-				n.removeJoinedUser(ev.RoomID(), userID)
+	if ev != nil {
+		// Map this event's room_id to a list of joined users, and wake them up.
+		userIDs := n.joinedUsers(ev.RoomID())
+		// If this is an invite, also add in the invitee to this list.
+		if ev.Type() == "m.room.member" && ev.StateKey() != nil {
+			userID := *ev.StateKey()
+			membership, err := ev.Membership()
+			if err != nil {
+				log.WithError(err).WithField("event_id", ev.EventID()).Errorf(
+					"Notifier.OnNewEvent: Failed to unmarshal member event",
+				)
+			} else {
+				// Keep the joined user map up-to-date
+				switch membership {
+				case "invite":
+					userIDs = append(userIDs, userID)
+				case "join":
+					n.addJoinedUser(ev.RoomID(), userID)
+				case "leave":
+					fallthrough
+				case "ban":
+					n.removeJoinedUser(ev.RoomID(), userID)
+				}
 			}
 		}
-	}
 
-	for _, userID := range userIDs {
+		for _, userID := range userIDs {
+			n.wakeupUser(userID, pos)
+		}
+	} else if len(userID) > 0 {
 		n.wakeupUser(userID, pos)
 	}
 }
diff --git a/src/github.com/matrix-org/dendrite/syncapi/sync/notifier_test.go b/src/github.com/matrix-org/dendrite/syncapi/sync/notifier_test.go
index 03e39da0..358243bc 100644
--- a/src/github.com/matrix-org/dendrite/syncapi/sync/notifier_test.go
+++ b/src/github.com/matrix-org/dendrite/syncapi/sync/notifier_test.go
@@ -123,7 +123,7 @@ func TestNewEventAndJoinedToRoom(t *testing.T) {
 	stream := n.fetchUserStream(bob, true)
 	waitForBlocking(stream, 1)
 
-	n.OnNewEvent(&randomMessageEvent, streamPositionAfter)
+	n.OnNewEvent(&randomMessageEvent, "", streamPositionAfter)
 
 	wg.Wait()
 }
@@ -151,7 +151,7 @@ func TestNewInviteEventForUser(t *testing.T) {
 	stream := n.fetchUserStream(bob, true)
 	waitForBlocking(stream, 1)
 
-	n.OnNewEvent(&aliceInviteBobEvent, streamPositionAfter)
+	n.OnNewEvent(&aliceInviteBobEvent, "", streamPositionAfter)
 
 	wg.Wait()
 }
@@ -182,7 +182,7 @@ func TestMultipleRequestWakeup(t *testing.T) {
 	stream := n.fetchUserStream(bob, true)
 	waitForBlocking(stream, 3)
 
-	n.OnNewEvent(&randomMessageEvent, streamPositionAfter)
+	n.OnNewEvent(&randomMessageEvent, "", streamPositionAfter)
 
 	wg.Wait()
 
@@ -217,7 +217,7 @@ func TestNewEventAndWasPreviouslyJoinedToRoom(t *testing.T) {
 	}()
 	bobStream := n.fetchUserStream(bob, true)
 	waitForBlocking(bobStream, 1)
-	n.OnNewEvent(&bobLeaveEvent, streamPositionAfter)
+	n.OnNewEvent(&bobLeaveEvent, "", streamPositionAfter)
 	leaveWG.Wait()
 
 	// send an event into the room. Make sure alice gets it. Bob should not.
@@ -246,7 +246,7 @@ func TestNewEventAndWasPreviouslyJoinedToRoom(t *testing.T) {
 	waitForBlocking(aliceStream, 1)
 	waitForBlocking(bobStream, 1)
 
-	n.OnNewEvent(&randomMessageEvent, streamPositionAfter2)
+	n.OnNewEvent(&randomMessageEvent, "", streamPositionAfter2)
 	aliceWG.Wait()
 
 	// it's possible that at this point alice has been informed and bob is about to be informed, so wait
diff --git a/src/github.com/matrix-org/dendrite/syncapi/sync/requestpool.go b/src/github.com/matrix-org/dendrite/syncapi/sync/requestpool.go
index 953e5f4f..a207b815 100644
--- a/src/github.com/matrix-org/dendrite/syncapi/sync/requestpool.go
+++ b/src/github.com/matrix-org/dendrite/syncapi/sync/requestpool.go
@@ -80,7 +80,7 @@ func (rp *RequestPool) OnIncomingSyncRequest(req *http.Request, device *authtype
 		if err != nil {
 			res = httputil.LogThenError(req, err)
 		} else {
-			syncData, err = rp.appendAccountData(syncData, device.UserID)
+			syncData, err = rp.appendAccountData(syncData, device.UserID, *syncReq, currentPos)
 			if err != nil {
 				res = httputil.LogThenError(req, err)
 			} else {
@@ -113,7 +113,9 @@ func (rp *RequestPool) currentSyncForUser(req syncRequest, currentPos types.Stre
 	return rp.db.IncrementalSync(req.userID, req.since, currentPos, req.limit)
 }
 
-func (rp *RequestPool) appendAccountData(data *types.Response, userID string) (*types.Response, error) {
+func (rp *RequestPool) appendAccountData(
+	data *types.Response, userID string, req syncRequest, currentPos types.StreamPosition,
+) (*types.Response, error) {
 	// TODO: We currently send all account data on every sync response, we should instead send data
 	// that has changed on incremental sync responses
 	localpart, _, err := gomatrixserverlib.SplitID('@', userID)
@@ -121,16 +123,56 @@ func (rp *RequestPool) appendAccountData(data *types.Response, userID string) (*
 		return nil, err
 	}
 
-	global, rooms, err := rp.accountDB.GetAccountData(localpart)
+	if req.since == types.StreamPosition(0) {
+		// If this is the initial sync, we don't need to check if a data has
+		// already been sent. Instead, we send the whole batch.
+		var global []gomatrixserverlib.ClientEvent
+		var rooms map[string][]gomatrixserverlib.ClientEvent
+		global, rooms, err = rp.accountDB.GetAccountData(localpart)
+		if err != nil {
+			return nil, err
+		}
+		data.AccountData.Events = global
+
+		for r, j := range data.Rooms.Join {
+			if len(rooms[r]) > 0 {
+				j.AccountData.Events = rooms[r]
+				data.Rooms.Join[r] = j
+			}
+		}
+
+		return data, nil
+	}
+
+	// Sync is not initial, get all account data since the latest sync
+	dataTypes, err := rp.db.GetAccountDataInRange(userID, req.since, currentPos)
 	if err != nil {
 		return nil, err
 	}
-	data.AccountData.Events = global
 
-	for r, j := range data.Rooms.Join {
-		if len(rooms[r]) > 0 {
-			j.AccountData.Events = rooms[r]
-			data.Rooms.Join[r] = j
+	if len(dataTypes) == 0 {
+		return data, nil
+	}
+
+	// Iterate over the rooms
+	for roomID, dataTypes := range dataTypes {
+		events := []gomatrixserverlib.ClientEvent{}
+		// Request the missing data from the database
+		for _, dataType := range dataTypes {
+			evs, err := rp.accountDB.GetAccountDataByType(localpart, roomID, dataType)
+			if err != nil {
+				return nil, err
+			}
+			events = append(events, evs...)
+		}
+
+		// Append the data to the response
+		if len(roomID) > 0 {
+			jr := data.Rooms.Join[roomID]
+			jr.AccountData.Events = events
+			data.Rooms.Join[roomID] = jr
+		} else {
+			data.AccountData.Events = events
 		}
 	}