Write output events

src/github.com/matrix-org/dendrite/roomserver/api/output.go

@@ -0,0 +1,85 @@
+package api
+
+import (
+	"encoding/json"
+)
+
+// An OutputRoomEvent is written when the roomserver receives a new event.
+type OutputRoomEvent struct {
+	// The JSON bytes of the event.
+	Event []byte
+	// The state event IDs needed to determine who can see this event.
+	// This can be used to tell which users to send the event to.
+	VisibilityEventIDs []string
+	// The latest events in the room after this event.
+	// This can be used to set the prev events for new events in the room.
+	// This also can be used to get the full current state after this event.
+	LatestEventIDs []string
+	// The state event IDs that were added to the state of the room by this event.
+	// Together with RemovesStateEventIDs this allows the receiver to keep an up to date
+	// view of the current state of the room.
+	AddsStateEventIDs []string
+	// The state event IDs that were removed from the state of the room by this event.
+	RemovesStateEventIDs []string
+	// The ID of the event that was output before this event.
+	// Or the empty string if this is the first event output for this room.
+	// This is used by consumers to check if they can safely update their
+	// current state using the delta supplied in AddsStateEventIDs and
+	// RemovesStateEventIDs.
+	// If they the LastSentEventID doesn't match what they were expecting it to
+	// be they can use the LatestEventIDs to request the full current state.
+	LastSentEventID string
+}
+
+// UnmarshalJSON implements json.Unmarshaller
+func (ore *OutputRoomEvent) UnmarshalJSON(data []byte) error {
+	// Create a struct rather than unmarshalling directly into the OutputRoomEvent
+	// so that we can use json.RawMessage.
+	// We use json.RawMessage so that the event JSON is sent as JSON rather than
+	// being base64 encoded which is the default for []byte.
+	var content struct {
+		Event                *json.RawMessage
+		VisibilityEventIDs   []string
+		LatestEventIDs       []string
+		AddsStateEventIDs    []string
+		RemovesStateEventIDs []string
+		LastSentEventID      string
+	}
+	if err := json.Unmarshal(data, &content); err != nil {
+		return err
+	}
+	if content.Event != nil {
+		ore.Event = []byte(*content.Event)
+	}
+	ore.VisibilityEventIDs = content.VisibilityEventIDs
+	ore.LatestEventIDs = content.LatestEventIDs
+	ore.AddsStateEventIDs = content.AddsStateEventIDs
+	ore.RemovesStateEventIDs = content.RemovesStateEventIDs
+	ore.LastSentEventID = content.LastSentEventID
+	return nil
+}
+
+// MarshalJSON implements json.Marshaller
+func (ore OutputRoomEvent) MarshalJSON() ([]byte, error) {
+	// Create a struct rather than marshalling directly from the OutputRoomEvent
+	// so that we can use json.RawMessage.
+	// We use json.RawMessage so that the event JSON is sent as JSON rather than
+	// being base64 encoded which is the default for []byte.
+	event := json.RawMessage(ore.Event)
+	content := struct {
+		Event                *json.RawMessage
+		VisibilityEventIDs   []string
+		LatestEventIDs       []string
+		AddsStateEventIDs    []string
+		RemovesStateEventIDs []string
+		LastSentEventID      string
+	}{
+		Event:                &event,
+		VisibilityEventIDs:   ore.VisibilityEventIDs,
+		LatestEventIDs:       ore.LatestEventIDs,
+		AddsStateEventIDs:    ore.AddsStateEventIDs,
+		RemovesStateEventIDs: ore.RemovesStateEventIDs,
+		LastSentEventID:      ore.LastSentEventID,
+	}
+	return json.Marshal(&content)
+}

src/github.com/matrix-org/dendrite/roomserver/input/consumer.go

@@ -34,15 +34,32 @@ type Consumer struct {
 	// But any equivalent event streaming protocol could be made to implement the same interface.
 	Consumer sarama.Consumer
 	// The database used to store the room events.
-	DB ConsumerDatabase
+	DB       ConsumerDatabase
+	Producer sarama.SyncProducer
 	// The kafkaesque topic to consume room events from.
 	// This is the name used in kafka to identify the stream to consume events from.
-	RoomEventTopic string
+	InputRoomEventTopic string
+	// The kafkaesque topic to output new room events to.
+	// This is the name used in kafka to identify the stream to write events to.
+	OutputRoomEventTopic string
 	// The ErrorLogger for this consumer.
 	// If left as nil then the consumer will panic when it encounters an error
 	ErrorLogger ErrorLogger
 }
 
+func (c *Consumer) WriteOutputRoomEvent(output api.OutputRoomEvent) error {
+	var m sarama.ProducerMessage
+	value, err := json.Marshal(output)
+	if err != nil {
+		return err
+	}
+	m.Topic = c.OutputRoomEventTopic
+	m.Key = sarama.StringEncoder("")
+	m.Value = sarama.ByteEncoder(value)
+	_, _, err = c.Producer.SendMessage(&m)
+	return err
+}
+
 // Start starts the consumer consuming.
 // Starts up a goroutine for each partition in the kafka stream.
 // Returns nil once all the goroutines are started.
@@ -50,7 +67,7 @@ type Consumer struct {
 func (c *Consumer) Start() error {
 	offsets := map[int32]int64{}
 
-	partitions, err := c.Consumer.Partitions(c.RoomEventTopic)
+	partitions, err := c.Consumer.Partitions(c.InputRoomEventTopic)
 	if err != nil {
 		return err
 	}
@@ -59,7 +76,7 @@ func (c *Consumer) Start() error {
 		offsets[partition] = sarama.OffsetOldest
 	}
 
-	storedOffsets, err := c.DB.PartitionOffsets(c.RoomEventTopic)
+	storedOffsets, err := c.DB.PartitionOffsets(c.InputRoomEventTopic)
 	if err != nil {
 		return err
 	}
@@ -70,7 +87,7 @@ func (c *Consumer) Start() error {
 
 	var partitionConsumers []sarama.PartitionConsumer
 	for partition, offset := range offsets {
-		pc, err := c.Consumer.ConsumePartition(c.RoomEventTopic, partition, offset)
+		pc, err := c.Consumer.ConsumePartition(c.InputRoomEventTopic, partition, offset)
 		if err != nil {
 			for _, p := range partitionConsumers {
 				p.Close()
@@ -95,7 +112,7 @@ func (c *Consumer) consumePartition(pc sarama.PartitionConsumer) {
 			// If the message is invalid then log it and move onto the next message in the stream.
 			c.logError(message, err)
 		} else {
-			if err := processRoomEvent(c.DB, input); err != nil {
+			if err := processRoomEvent(c.DB, c, input); err != nil {
 				// If there was an error processing the message then log it and
 				// move onto the next message in the stream.
 				// TODO: If the error was due to a problem talking to the database
@@ -105,7 +122,7 @@ func (c *Consumer) consumePartition(pc sarama.PartitionConsumer) {
 			}
 		}
 		// Advance our position in the stream so that we will start at the right position after a restart.
-		if err := c.DB.SetPartitionOffset(c.RoomEventTopic, message.Partition, message.Offset); err != nil {
+		if err := c.DB.SetPartitionOffset(c.InputRoomEventTopic, message.Partition, message.Offset); err != nil {
 			c.logError(message, err)
 		}
 	}

src/github.com/matrix-org/dendrite/roomserver/input/events.go

@@ -40,7 +40,11 @@ type RoomEventDatabase interface {
 	GetLatestEventsForUpdate(roomNID types.RoomNID) ([]types.StateAtEventAndReference, string, types.RoomRecentEventsUpdater, error)
 }
 
-func processRoomEvent(db RoomEventDatabase, input api.InputRoomEvent) error {
+type OutputRoomEventWriter interface {
+	WriteOutputRoomEvent(output api.OutputRoomEvent) error
+}
+
+func processRoomEvent(db RoomEventDatabase, ow OutputRoomEventWriter, input api.InputRoomEvent) error {
 	// Parse and validate the event JSON
 	event, err := gomatrixserverlib.NewEventFromUntrustedJSON(input.Event)
 	if err != nil {
@@ -95,7 +99,7 @@ func processRoomEvent(db RoomEventDatabase, input api.InputRoomEvent) error {
 	}
 
 	// Update the extremities of the event graph for the room
-	if err := updateLatestEvents(db, roomNID, stateAtEvent, event); err != nil {
+	if err := updateLatestEvents(db, ow, roomNID, stateAtEvent, event); err != nil {
 		return err
 	}
 

src/github.com/matrix-org/dendrite/roomserver/input/latest_events.go

@@ -2,6 +2,7 @@ package input
 
 import (
 	"bytes"
+	"github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/dendrite/roomserver/types"
 	"github.com/matrix-org/gomatrixserverlib"
 )
@@ -22,7 +23,7 @@ import (
 //      7 <----- latest
 //
 func updateLatestEvents(
-	db RoomEventDatabase, roomNID types.RoomNID, stateAtEvent types.StateAtEvent, event gomatrixserverlib.Event,
+	db RoomEventDatabase, ow OutputRoomEventWriter, roomNID types.RoomNID, stateAtEvent types.StateAtEvent, event gomatrixserverlib.Event,
 ) (err error) {
 	oldLatest, lastEventIDSent, updater, err := db.GetLatestEventsForUpdate(roomNID)
 	if err != nil {
@@ -42,12 +43,12 @@ func updateLatestEvents(
 		}
 	}()
 
-	err = doUpdateLatestEvents(updater, oldLatest, lastEventIDSent, roomNID, stateAtEvent, event)
+	err = doUpdateLatestEvents(updater, ow, oldLatest, lastEventIDSent, roomNID, stateAtEvent, event)
 	return
 }
 
 func doUpdateLatestEvents(
-	updater types.RoomRecentEventsUpdater, oldLatest []types.StateAtEventAndReference, lastEventIDSent string, roomNID types.RoomNID, stateAtEvent types.StateAtEvent, event gomatrixserverlib.Event,
+	updater types.RoomRecentEventsUpdater, ow OutputRoomEventWriter, oldLatest []types.StateAtEventAndReference, lastEventIDSent string, roomNID types.RoomNID, stateAtEvent types.StateAtEvent, event gomatrixserverlib.Event,
 ) error {
 	var err error
 	var prevEvents []gomatrixserverlib.EventReference
@@ -76,7 +77,11 @@ func doUpdateLatestEvents(
 		StateAtEvent:   stateAtEvent,
 	})
 
-	// TODO: Send the event to the output logs.
+	// Send the event to the output logs.
+	// We do this inside the database transaction to ensure that we only mark an event as sent if we sent it.
+	if err = writeEvent(ow, lastEventIDSent, event, newLatest); err != nil {
+		return err
+	}
 
 	if err = updater.SetLatestEvents(roomNID, newLatest, stateAtEvent.EventNID); err != nil {
 		return err
@@ -121,3 +126,17 @@ func calculateLatest(oldLatest []types.StateAtEventAndReference, alreadyReferenc
 
 	return newLatest
 }
+
+func writeEvent(ow OutputRoomEventWriter, lastEventIDSent string, event gomatrixserverlib.Event, latest []types.StateAtEventAndReference) error {
+
+	latestEventIDs := make([]string, len(latest))
+	for i := range latest {
+		latestEventIDs[i] = latest[i].EventID
+	}
+
+	return ow.WriteOutputRoomEvent(api.OutputRoomEvent{
+		Event:           event.JSON(),
+		LastSentEventID: lastEventIDSent,
+		LatestEventIDs:  latestEventIDs,
+	})
+}

src/github.com/matrix-org/dendrite/roomserver/roomserver/roomserver.go

@@ -10,9 +10,10 @@ import (
 )
 
 var (
-	database       = os.Getenv("DATABASE")
-	kafkaURIs      = strings.Split(os.Getenv("KAFKA_URIS"), ",")
-	roomEventTopic = os.Getenv("TOPIC_ROOM_EVENT")
+	database             = os.Getenv("DATABASE")
+	kafkaURIs            = strings.Split(os.Getenv("KAFKA_URIS"), ",")
+	inputRoomEventTopic  = os.Getenv("TOPIC_INPUT_ROOM_EVENT")
+	outputRoomEventTopic = os.Getenv("TOPIC_OUTPUT_ROOM_EVENT")
 )
 
 func main() {
@@ -26,10 +27,17 @@ func main() {
 		panic(err)
 	}
 
+	kafkaProducer, err := sarama.NewSyncProducer(kafkaURIs, nil)
+	if err != nil {
+		panic(err)
+	}
+
 	consumer := input.Consumer{
-		Consumer:       kafkaConsumer,
-		DB:             db,
-		RoomEventTopic: roomEventTopic,
+		Consumer:             kafkaConsumer,
+		DB:                   db,
+		Producer:             kafkaProducer,
+		InputRoomEventTopic:  inputRoomEventTopic,
+		OutputRoomEventTopic: outputRoomEventTopic,
 	}
 
 	if err = consumer.Start(); err != nil {