Merge pull request #60 from matrix-org/kegan/persist-next-batch

Persist next_batch tokens

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

@@ -11,6 +11,31 @@ import (
 	"sync"
 )
 
+type nextBatchStore struct {
+	db *database.ServiceDB
+}
+
+func (s nextBatchStore) Save(userID, nextBatch string) {
+	if err := s.db.UpdateNextBatch(userID, nextBatch); err != nil {
+		log.WithFields(log.Fields{
+			log.ErrorKey: err,
+			"user_id":    userID,
+			"next_batch": nextBatch,
+		}).Error("Failed to persist next_batch token")
+	}
+}
+func (s nextBatchStore) Load(userID string) string {
+	token, err := s.db.LoadNextBatch(userID)
+	if err != nil {
+		log.WithFields(log.Fields{
+			log.ErrorKey: err,
+			"user_id":    userID,
+		}).Error("Failed to load next_batch token")
+		return ""
+	}
+	return token
+}
+
 // A Clients is a collection of clients used for bot services.
 type Clients struct {
 	db       *database.ServiceDB
@@ -141,18 +166,7 @@ func (c *Clients) updateClientInDB(newConfig types.ClientConfig) (new clientEntr
 	return
 }
 
-func (c *Clients) newClient(config types.ClientConfig) (*matrix.Client, error) {
-	homeserverURL, err := url.Parse(config.HomeserverURL)
-	if err != nil {
-		return nil, err
-	}
-
-	client := matrix.NewClient(homeserverURL, config.AccessToken, config.UserID)
-
-	// 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) {
+func (c *Clients) onMessageEvent(client *matrix.Client, event *matrix.Event) {
 	services, err := c.db.LoadServicesForUser(client.UserID)
 	if err != nil {
 		log.WithFields(log.Fields{
@@ -166,9 +180,9 @@ func (c *Clients) newClient(config types.ClientConfig) (*matrix.Client, error) {
 		plugins = append(plugins, service.Plugin(client, event.RoomID))
 	}
 	plugin.OnMessage(plugins, client, event)
-	})
+}
 
-	client.Worker.OnEventType("m.room.bot.options", func(event *matrix.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, "_")
@@ -190,11 +204,10 @@ func (c *Clients) newClient(config types.ClientConfig) (*matrix.Client, error) {
 			"set_by_user_id": event.Sender,
 		}).Error("Failed to persist bot options")
 	}
-	})
+}
 
-	if config.AutoJoinRooms {
-		client.Worker.OnEventType("m.room.member", func(event *matrix.Event) {
-			if event.StateKey != config.UserID {
+func (c *Clients) onRoomMemberEvent(client *matrix.Client, event *matrix.Event) {
+	if event.StateKey != client.UserID {
 		return // not our member event
 	}
 	m := event.Content["membership"]
@@ -205,7 +218,7 @@ func (c *Clients) newClient(config types.ClientConfig) (*matrix.Client, error) {
 	if membership == "invite" {
 		logger := log.WithFields(log.Fields{
 			"room_id":         event.RoomID,
-					"service_user_id": config.UserID,
+			"service_user_id": client.UserID,
 			"inviter":         event.Sender,
 		})
 		logger.Print("Accepting invite from user")
@@ -216,6 +229,31 @@ func (c *Clients) newClient(config types.ClientConfig) (*matrix.Client, error) {
 			logger.Print("Joined room")
 		}
 	}
+}
+
+func (c *Clients) newClient(config types.ClientConfig) (*matrix.Client, error) {
+	homeserverURL, err := url.Parse(config.HomeserverURL)
+	if err != nil {
+		return nil, err
+	}
+
+	client := matrix.NewClient(homeserverURL, config.AccessToken, config.UserID)
+	client.NextBatchStorer = nextBatchStore{c.db}
+
+	// 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) {
+		c.onMessageEvent(client, event)
+	})
+
+	client.Worker.OnEventType("m.room.bot.options", func(event *matrix.Event) {
+		c.onBotOptionsEvent(client, event)
+	})
+
+	if config.AutoJoinRooms {
+		client.Worker.OnEventType("m.room.member", func(event *matrix.Event) {
+			c.onRoomMemberEvent(client, event)
 		})
 	}
 

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

@@ -77,6 +77,23 @@ 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
+}
+
+// LoadNextBatch loads the next_batch token for the given user.
+func (d *ServiceDB) LoadNextBatch(userID string) (nextBatch string, err error) {
+	err = runTransaction(d.db, func(txn *sql.Tx) error {
+		nextBatch, err = selectNextBatchTxn(txn, userID)
+		return err
+	})
+	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 +129,28 @@ 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 selectNextBatchSQL = `
+SELECT next_batch FROM matrix_clients WHERE user_id = $1
+`
+
+func selectNextBatchTxn(txn *sql.Tx, userID string) (string, error) {
+	var nextBatch string
+	row := txn.QueryRow(selectNextBatchSQL, userID)
+	if err := row.Scan(&nextBatch); err != nil {
+		return "", err
+	}
+	return nextBatch, nil
+}
+
 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

@@ -28,9 +28,23 @@ import (
 )
 
 var (
-	filterJSON = json.RawMessage(`{"room":{"timeline":{"limit":0}}}`)
+	filterJSON = json.RawMessage(`{"room":{"timeline":{"limit":50}}}`)
 )
 
+// NextBatchStorer controls loading/saving of next_batch tokens for users
+type NextBatchStorer interface {
+	// Save a next_batch token for a given user. Best effort.
+	Save(userID, nextBatch string)
+	// Load a next_batch token for a given user. Return an empty string if no token exists.
+	Load(userID string) string
+}
+
+// noopNextBatchStore does not load or save next_batch tokens.
+type noopNextBatchStore struct{}
+
+func (s noopNextBatchStore) Save(userID, nextBatch string) {}
+func (s noopNextBatchStore) Load(userID string) string     { return "" }
+
 // Client represents a Matrix client.
 type Client struct {
 	HomeserverURL   *url.URL
@@ -43,6 +57,7 @@ type Client struct {
 	syncingID       uint32 // Identifies the current Sync. Only one Sync can be active at any given time.
 	httpClient      *http.Client
 	filterID        string
+	NextBatchStorer NextBatchStorer
 }
 
 func (cli *Client) buildURL(urlPath ...string) string {
@@ -191,7 +206,7 @@ func (cli *Client) Sync() {
 		"user_id": cli.UserID,
 	})
 
-	// TODO: Store the filter ID and sync token in the database
+	// TODO: Store the filter ID in the database
 	filterID, err := cli.createFilter()
 	if err != nil {
 		logger.WithError(err).Fatal("Failed to create filter")
@@ -199,9 +214,9 @@ func (cli *Client) Sync() {
 	}
 	cli.filterID = filterID
 	logger.WithField("filter", filterID).Print("Got filter ID")
-	nextToken := ""
+	nextToken := cli.NextBatchStorer.Load(cli.UserID)
 
-	logger.Print("Starting sync")
+	logger.WithField("next_batch", nextToken).Print("Starting sync")
 
 	channel := make(chan syncHTTPResponse, 5)
 
@@ -232,18 +247,26 @@ func (cli *Client) Sync() {
 		//  Check that the syncing state hasn't changed
 		// Either because we've stopped syncing or another sync has been started.
 		// We discard the response from our sync.
-		// TODO: Store the next_batch token so that the next sync can resume
-		// from where this sync left off.
 		if cli.getSyncingID() != syncingID {
 			logger.Print("Stopping sync")
 			return
 		}
 
+		isFirstSync := nextToken == ""
+
 		// Update client state
 		nextToken = syncResponse.NextBatch
 		logger.WithField("next_batch", nextToken).Print("Received sync response")
+
+		// 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.
+		cli.NextBatchStorer.Save(cli.UserID, nextToken)
+
+		if !isFirstSync {
 			channel <- syncResponse
 		}
+	}
 }
 
 func (cli *Client) incrementSyncingID() uint32 {
@@ -344,6 +367,7 @@ 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 {
@@ -366,6 +390,10 @@ func NewClient(homeserverURL *url.URL, accessToken string, userID string) *Clien
 		Prefix:        "/_matrix/client/r0",
 	}
 	cli.Worker = newWorker(&cli)
+	// By default, use a no-op next_batch storer which will never save tokens and always
+	// "load" the empty string as a token. The client will work with this storer: it just won't
+	// remember the token across restarts. In practice, a database backend should be used.
+	cli.NextBatchStorer = noopNextBatchStore{}
 	cli.Rooms = make(map[string]*Room)
 	cli.httpClient = &http.Client{}