Persist next_batch tokens

Indirect this through a `NextBatchStore` type to get around circular dependencies
which are formed if you try to inline it in the `Sync()` while loop.

Fork out event handlers to separate functions in `Clients` to make gocyclo happy.

Add `UPDATE` query for `next_batch`.

src/github.com/matrix-org/go-neb/clients/clients.go

@@ -141,6 +141,71 @@ func (c *Clients) updateClientInDB(newConfig types.ClientConfig) (new clientEntr
 	return
 }
 
+func (c *Clients) onMessageEvent(client *matrix.Client, event *matrix.Event) {
+	services, err := c.db.LoadServicesForUser(client.UserID)
+	if err != nil {
+		log.WithFields(log.Fields{
+			log.ErrorKey:      err,
+			"room_id":         event.RoomID,
+			"service_user_id": client.UserID,
+		}).Warn("Error loading services")
+	}
+	var plugins []plugin.Plugin
+	for _, service := range services {
+		plugins = append(plugins, service.Plugin(client, event.RoomID))
+	}
+	plugin.OnMessage(plugins, client, event)
+}
+
+func (c *Clients) onBotOptionsEvent(client *matrix.Client, event *matrix.Event) {
+	// see if these options are for us. The state key is the user ID with a leading _
+	// to get around restrictions in the HS about having user IDs as state keys.
+	targetUserID := strings.TrimPrefix(event.StateKey, "_")
+	if targetUserID != client.UserID {
+		return
+	}
+	// these options fully clobber what was there previously.
+	opts := types.BotOptions{
+		UserID:      client.UserID,
+		RoomID:      event.RoomID,
+		SetByUserID: event.Sender,
+		Options:     event.Content,
+	}
+	if _, err := c.db.StoreBotOptions(opts); err != nil {
+		log.WithFields(log.Fields{
+			log.ErrorKey:     err,
+			"room_id":        event.RoomID,
+			"bot_user_id":    client.UserID,
+			"set_by_user_id": event.Sender,
+		}).Error("Failed to persist bot options")
+	}
+}
+
+func (c *Clients) onRoomMemberEvent(client *matrix.Client, event *matrix.Event) {
+	if event.StateKey != client.UserID {
+		return // not our member event
+	}
+	m := event.Content["membership"]
+	membership, ok := m.(string)
+	if !ok {
+		return
+	}
+	if membership == "invite" {
+		logger := log.WithFields(log.Fields{
+			"room_id":         event.RoomID,
+			"service_user_id": client.UserID,
+			"inviter":         event.Sender,
+		})
+		logger.Print("Accepting invite from user")
+
+		if _, err := client.JoinRoom(event.RoomID, "", event.Sender); err != nil {
+			logger.WithError(err).Print("Failed to join room")
+		} else {
+			logger.Print("Joined room")
+		}
+	}
+}
+
 func (c *Clients) newClient(config types.ClientConfig) (*matrix.Client, error) {
 	homeserverURL, err := url.Parse(config.HomeserverURL)
 	if err != nil {
@@ -149,73 +214,29 @@ func (c *Clients) newClient(config types.ClientConfig) (*matrix.Client, error) {
 
 	client := matrix.NewClient(homeserverURL, config.AccessToken, config.UserID)
 
+	client.OnSaveNextBatch(func(nextBatch string) {
+		if err := c.db.UpdateNextBatch(client.UserID, nextBatch); err != nil {
+			log.WithFields(log.Fields{
+				log.ErrorKey: err,
+				"next_batch": nextBatch,
+			}).Error("Failed to persist next_batch token")
+		}
+	})
+
 	// TODO: Check that the access token is valid for the userID by peforming
 	// a request against the server.
 
 	client.Worker.OnEventType("m.room.message", func(event *matrix.Event) {
-		services, err := c.db.LoadServicesForUser(client.UserID)
-		if err != nil {
-			log.WithFields(log.Fields{
-				log.ErrorKey:      err,
-				"room_id":         event.RoomID,
-				"service_user_id": client.UserID,
-			}).Warn("Error loading services")
-		}
-		var plugins []plugin.Plugin
-		for _, service := range services {
-			plugins = append(plugins, service.Plugin(client, event.RoomID))
-		}
-		plugin.OnMessage(plugins, client, event)
+		c.onMessageEvent(client, event)
 	})
 
 	client.Worker.OnEventType("m.room.bot.options", func(event *matrix.Event) {
-		// see if these options are for us. The state key is the user ID with a leading _
-		// to get around restrictions in the HS about having user IDs as state keys.
-		targetUserID := strings.TrimPrefix(event.StateKey, "_")
-		if targetUserID != client.UserID {
-			return
-		}
-		// these options fully clobber what was there previously.
-		opts := types.BotOptions{
-			UserID:      client.UserID,
-			RoomID:      event.RoomID,
-			SetByUserID: event.Sender,
-			Options:     event.Content,
-		}
-		if _, err := c.db.StoreBotOptions(opts); err != nil {
-			log.WithFields(log.Fields{
-				log.ErrorKey:     err,
-				"room_id":        event.RoomID,
-				"bot_user_id":    client.UserID,
-				"set_by_user_id": event.Sender,
-			}).Error("Failed to persist bot options")
-		}
+		c.onBotOptionsEvent(client, event)
 	})
 
 	if config.AutoJoinRooms {
 		client.Worker.OnEventType("m.room.member", func(event *matrix.Event) {
-			if event.StateKey != config.UserID {
-				return // not our member event
-			}
-			m := event.Content["membership"]
-			membership, ok := m.(string)
-			if !ok {
-				return
-			}
-			if membership == "invite" {
-				logger := log.WithFields(log.Fields{
-					"room_id":         event.RoomID,
-					"service_user_id": config.UserID,
-					"inviter":         event.Sender,
-				})
-				logger.Print("Accepting invite from user")
-
-				if _, err := client.JoinRoom(event.RoomID, "", event.Sender); err != nil {
-					logger.WithError(err).Print("Failed to join room")
-				} else {
-					logger.Print("Joined room")
-				}
-			}
+			c.onRoomMemberEvent(client, event)
 		})
 	}
 

src/github.com/matrix-org/go-neb/database/db.go

@@ -77,6 +77,14 @@ func (d *ServiceDB) LoadMatrixClientConfig(userID string) (config types.ClientCo
 	return
 }
 
+// UpdateNextBatch updates the next_batch token for the given user.
+func (d *ServiceDB) UpdateNextBatch(userID, nextBatch string) (err error) {
+	err = runTransaction(d.db, func(txn *sql.Tx) error {
+		return updateNextBatchTxn(txn, userID, nextBatch)
+	})
+	return
+}
+
 // LoadService loads a service from the database.
 // Returns sql.ErrNoRows if the service isn't in the database.
 func (d *ServiceDB) LoadService(serviceID string) (service types.Service, err error) {

src/github.com/matrix-org/go-neb/database/schema.go

@@ -129,6 +129,15 @@ func updateMatrixClientConfigTxn(txn *sql.Tx, now time.Time, config types.Client
 	return err
 }
 
+const updateNextBatchSQL = `
+UPDATE matrix_clients SET next_batch = $1 WHERE user_id = $2
+`
+
+func updateNextBatchTxn(txn *sql.Tx, userID, nextBatch string) error {
+	_, err := txn.Exec(updateNextBatchSQL, nextBatch, userID)
+	return err
+}
+
 const selectServiceSQL = `
 SELECT service_type, service_user_id, service_json FROM services
 	WHERE service_id = $1

src/github.com/matrix-org/go-neb/matrix/matrix.go

@@ -28,21 +28,22 @@ import (
 )
 
 var (
-	filterJSON = json.RawMessage(`{"room":{"timeline":{"limit":0}}}`)
+	filterJSON = json.RawMessage(`{"room":{"timeline":{"limit":50}}}`)
 )
 
 // Client represents a Matrix client.
 type Client struct {
-	HomeserverURL *url.URL
-	Prefix        string
-	UserID        string
-	AccessToken   string
-	Rooms         map[string]*Room
-	Worker        *Worker
-	syncingMutex  sync.Mutex
-	syncingID     uint32 // Identifies the current Sync. Only one Sync can be active at any given time.
-	httpClient    *http.Client
-	filterID      string
+	HomeserverURL  *url.URL
+	Prefix         string
+	UserID         string
+	AccessToken    string
+	Rooms          map[string]*Room
+	Worker         *Worker
+	syncingMutex   sync.Mutex
+	syncingID      uint32 // Identifies the current Sync. Only one Sync can be active at any given time.
+	httpClient     *http.Client
+	filterID       string
+	nextBatchSaver func(string)
 }
 
 func (cli *Client) buildURL(urlPath ...string) string {
@@ -239,13 +240,30 @@ func (cli *Client) Sync() {
 			return
 		}
 
+		isFirstSync := nextToken == ""
+
 		// Update client state
 		nextToken = syncResponse.NextBatch
 		logger.WithField("next_batch", nextToken).Print("Received sync response")
-		channel <- syncResponse
+
+		// Save the token now *before* passing it through to the worker. This means it's possible
+		// to not process some events, but it means that we won't get constantly stuck processing
+		// a malformed/buggy event which keeps making us panic.
+		if cli.nextBatchSaver != nil {
+			cli.nextBatchSaver(nextToken)
+		}
+
+		if !isFirstSync {
+			channel <- syncResponse
+		}
 	}
 }
 
+// OnSaveNextBatch is a function which can save the next_batch token passed to it
+func (cli *Client) OnSaveNextBatch(fn func(string)) {
+	cli.nextBatchSaver = fn
+}
+
 func (cli *Client) incrementSyncingID() uint32 {
 	cli.syncingMutex.Lock()
 	defer cli.syncingMutex.Unlock()
@@ -344,6 +362,7 @@ func (cli *Client) doSync(timeout int, since string) ([]byte, error) {
 	log.WithFields(log.Fields{
 		"since":   since,
 		"timeout": timeout,
+		"user_id": cli.UserID,
 	}).Print("Syncing")
 	res, err := http.Get(urlPath)
 	if err != nil {