[roomserver] Store transaction ID and prevent reprocessing of events (#446)

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

@@ -37,7 +37,7 @@ func NewRoomserverProducer(inputAPI api.RoomserverInputAPI) *RoomserverProducer
 func (c *RoomserverProducer) SendEvents(
 	ctx context.Context, events []gomatrixserverlib.Event, sendAsServer gomatrixserverlib.ServerName,
 	txnID *api.TransactionID,
-) error {
+) (string, error) {
 	ires := make([]api.InputRoomEvent, len(events))
 	for i, event := range events {
 		ires[i] = api.InputRoomEvent{
@@ -83,20 +83,27 @@ func (c *RoomserverProducer) SendEventWithState(
 		StateEventIDs: stateEventIDs,
 	}
 
-	return c.SendInputRoomEvents(ctx, ires)
+	_, err = c.SendInputRoomEvents(ctx, ires)
+	return err
 }
 
 // SendInputRoomEvents writes the given input room events to the roomserver input API.
-func (c *RoomserverProducer) SendInputRoomEvents(ctx context.Context, ires []api.InputRoomEvent) error {
+func (c *RoomserverProducer) SendInputRoomEvents(
+	ctx context.Context, ires []api.InputRoomEvent,
+) (eventID string, err error) {
 	request := api.InputRoomEventsRequest{InputRoomEvents: ires}
 	var response api.InputRoomEventsResponse
-	return c.InputAPI.InputRoomEvents(ctx, &request, &response)
+	err = c.InputAPI.InputRoomEvents(ctx, &request, &response)
+	eventID = response.EventID
+	return
 }
 
 // SendInvite writes the invite event to the roomserver input API.
 // This should only be needed for invite events that occur outside of a known room.
 // If we are in the room then the event should be sent using the SendEvents method.
-func (c *RoomserverProducer) SendInvite(ctx context.Context, inviteEvent gomatrixserverlib.Event) error {
+func (c *RoomserverProducer) SendInvite(
+	ctx context.Context, inviteEvent gomatrixserverlib.Event,
+) error {
 	request := api.InputRoomEventsRequest{
 		InputInviteEvents: []api.InputInviteEvent{{Event: inviteEvent}},
 	}

src/github.com/matrix-org/dendrite/clientapi/routing/createroom.go

@@ -261,7 +261,7 @@ func createRoom(req *http.Request, device *authtypes.Device,
 	}
 
 	// send events to the room server
-	err = producer.SendEvents(req.Context(), builtEvents, cfg.Matrix.ServerName, nil)
+	_, err = producer.SendEvents(req.Context(), builtEvents, cfg.Matrix.ServerName, nil)
 	if err != nil {
 		return httputil.LogThenError(req, err)
 	}

src/github.com/matrix-org/dendrite/clientapi/routing/joinroom.go

@@ -217,7 +217,7 @@ func (r joinRoomReq) joinRoomUsingServers(
 	var queryRes api.QueryLatestEventsAndStateResponse
 	event, err := common.BuildEvent(r.req.Context(), &eb, r.cfg, r.queryAPI, &queryRes)
 	if err == nil {
-		if err = r.producer.SendEvents(r.req.Context(), []gomatrixserverlib.Event{*event}, r.cfg.Matrix.ServerName, nil); err != nil {
+		if _, err = r.producer.SendEvents(r.req.Context(), []gomatrixserverlib.Event{*event}, r.cfg.Matrix.ServerName, nil); err != nil {
 			return httputil.LogThenError(r.req, err)
 		}
 		return util.JSONResponse{

src/github.com/matrix-org/dendrite/clientapi/routing/membership.go

@@ -97,7 +97,7 @@ func SendMembership(
 		return httputil.LogThenError(req, err)
 	}
 
-	if err := producer.SendEvents(
+	if _, err := producer.SendEvents(
 		req.Context(), []gomatrixserverlib.Event{*event}, cfg.Matrix.ServerName, nil,
 	); err != nil {
 		return httputil.LogThenError(req, err)

src/github.com/matrix-org/dendrite/clientapi/routing/profile.go

@@ -138,7 +138,7 @@ func SetAvatarURL(
 		return httputil.LogThenError(req, err)
 	}
 
-	if err := rsProducer.SendEvents(req.Context(), events, cfg.Matrix.ServerName, nil); err != nil {
+	if _, err := rsProducer.SendEvents(req.Context(), events, cfg.Matrix.ServerName, nil); err != nil {
 		return httputil.LogThenError(req, err)
 	}
 
@@ -230,7 +230,7 @@ func SetDisplayName(
 		return httputil.LogThenError(req, err)
 	}
 
-	if err := rsProducer.SendEvents(req.Context(), events, cfg.Matrix.ServerName, nil); err != nil {
+	if _, err := rsProducer.SendEvents(req.Context(), events, cfg.Matrix.ServerName, nil); err != nil {
 		return httputil.LogThenError(req, err)
 	}
 

src/github.com/matrix-org/dendrite/clientapi/routing/sendevent.go

@@ -107,16 +107,18 @@ func SendEvent(
 		}
 	}
 
-	// pass the new event to the roomserver
-	if err := producer.SendEvents(
+	// pass the new event to the roomserver and receive the correct event ID
+	// event ID in case of duplicate transaction is discarded
+	eventID, err := producer.SendEvents(
 		req.Context(), []gomatrixserverlib.Event{*e}, cfg.Matrix.ServerName, txnAndDeviceID,
-	); err != nil {
+	)
+	if err != nil {
 		return httputil.LogThenError(req, err)
 	}
 
 	res := util.JSONResponse{
 		Code: http.StatusOK,
-		JSON: sendEventResponse{e.EventID()},
+		JSON: sendEventResponse{eventID},
 	}
 	// Add response to transactionsCache
 	if txnID != nil {

src/github.com/matrix-org/dendrite/clientapi/threepid/invites.go

@@ -355,5 +355,6 @@ func emit3PIDInviteEvent(
 		return err
 	}
 
-	return producer.SendEvents(ctx, []gomatrixserverlib.Event{*event}, cfg.Matrix.ServerName, nil)
+	_, err = producer.SendEvents(ctx, []gomatrixserverlib.Event{*event}, cfg.Matrix.ServerName, nil)
+	return err
 }

src/github.com/matrix-org/dendrite/federationapi/routing/join.go

@@ -169,7 +169,7 @@ func SendJoin(
 	// Send the events to the room server.
 	// We are responsible for notifying other servers that the user has joined
 	// the room, so set SendAsServer to cfg.Matrix.ServerName
-	err = producer.SendEvents(ctx, []gomatrixserverlib.Event{event}, cfg.Matrix.ServerName, nil)
+	_, err = producer.SendEvents(ctx, []gomatrixserverlib.Event{event}, cfg.Matrix.ServerName, nil)
 	if err != nil {
 		return httputil.LogThenError(httpReq, err)
 	}

src/github.com/matrix-org/dendrite/federationapi/routing/send.go

@@ -170,7 +170,8 @@ func (t *txnReq) processEvent(e gomatrixserverlib.Event) error {
 	// TODO: Check that the event is allowed by its auth_events.
 
 	// pass the event to the roomserver
-	return t.producer.SendEvents(t.context, []gomatrixserverlib.Event{e}, api.DoNotSendToOtherServers, nil)
+	_, err := t.producer.SendEvents(t.context, []gomatrixserverlib.Event{e}, api.DoNotSendToOtherServers, nil)
+	return err
 }
 
 func checkAllowedByState(e gomatrixserverlib.Event, stateEvents []gomatrixserverlib.Event) error {

src/github.com/matrix-org/dendrite/federationapi/routing/threepid.go

@@ -81,7 +81,7 @@ func CreateInvitesFrom3PIDInvites(
 	}
 
 	// Send all the events
-	if err := producer.SendEvents(req.Context(), evs, cfg.Matrix.ServerName, nil); err != nil {
+	if _, err := producer.SendEvents(req.Context(), evs, cfg.Matrix.ServerName, nil); err != nil {
 		return httputil.LogThenError(req, err)
 	}
 
@@ -153,7 +153,7 @@ func ExchangeThirdPartyInvite(
 	}
 
 	// Send the event to the roomserver
-	if err = producer.SendEvents(
+	if _, err = producer.SendEvents(
 		httpReq.Context(), []gomatrixserverlib.Event{signedEvent.Event}, cfg.Matrix.ServerName, nil,
 	); err != nil {
 		return httputil.LogThenError(httpReq, err)

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

@@ -94,7 +94,9 @@ type InputRoomEventsRequest struct {
 }
 
 // InputRoomEventsResponse is a response to InputRoomEvents
-type InputRoomEventsResponse struct{}
+type InputRoomEventsResponse struct {
+	EventID string `json:"event_id"`
+}
 
 // RoomserverInputAPI is used to write events to the room server.
 type RoomserverInputAPI interface {

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

@@ -32,6 +32,7 @@ type RoomEventDatabase interface {
 	StoreEvent(
 		ctx context.Context,
 		event gomatrixserverlib.Event,
+		txnAndDeviceID *api.TransactionID,
 		authEventNIDs []types.EventNID,
 	) (types.RoomNID, types.StateAtEvent, error)
 	// Look up the state entries for a list of string event IDs
@@ -61,6 +62,13 @@ type RoomEventDatabase interface {
 	MembershipUpdater(
 		ctx context.Context, roomID, targerUserID string,
 	) (types.MembershipUpdater, error)
+	// Look up event ID by transaction's info.
+	// This is used to determine if the room event is processed/processing already.
+	// Returns an empty string if no such event exists.
+	GetTransactionEventID(
+		ctx context.Context, transactionID string,
+		deviceID string, userID string,
+	) (string, error)
 }
 
 // OutputRoomEventWriter has the APIs needed to write an event to the output logs.
@@ -79,32 +87,69 @@ func processRoomEvent(
 	db RoomEventDatabase,
 	ow OutputRoomEventWriter,
 	input api.InputRoomEvent,
-) error {
+) (eventID string, err error) {
 	// Parse and validate the event JSON
 	event := input.Event
 
 	// Check that the event passes authentication checks and work out the numeric IDs for the auth events.
 	authEventNIDs, err := checkAuthEvents(ctx, db, event, input.AuthEventIDs)
 	if err != nil {
-		return err
+		return
+	}
+
+	if input.TransactionID != nil {
+		tdID := input.TransactionID
+		eventID, err = db.GetTransactionEventID(
+			ctx, tdID.TransactionID, tdID.DeviceID, input.Event.Sender(),
+		)
+		// On error OR event with the transaction already processed/processesing
+		if err != nil || eventID != "" {
+			return
+		}
 	}
 
 	// Store the event
-	roomNID, stateAtEvent, err := db.StoreEvent(ctx, event, authEventNIDs)
+	roomNID, stateAtEvent, err := db.StoreEvent(ctx, event, input.TransactionID, authEventNIDs)
 	if err != nil {
-		return err
+		return
 	}
 
 	if input.Kind == api.KindOutlier {
 		// For outliers we can stop after we've stored the event itself as it
 		// doesn't have any associated state to store and we don't need to
 		// notify anyone about it.
-		return nil
+		return event.EventID(), nil
 	}
 
 	if stateAtEvent.BeforeStateSnapshotNID == 0 {
 		// We haven't calculated a state for this event yet.
 		// Lets calculate one.
+		err = calculateAndSetState(ctx, db, input, roomNID, &stateAtEvent, event)
+		if err != nil {
+			return
+		}
+	}
+
+	if input.Kind == api.KindBackfill {
+		// Backfill is not implemented.
+		panic("Not implemented")
+	}
+
+	// Update the extremities of the event graph for the room
+	return event.EventID(), updateLatestEvents(
+		ctx, db, ow, roomNID, stateAtEvent, event, input.SendAsServer, input.TransactionID,
+	)
+}
+
+func calculateAndSetState(
+	ctx context.Context,
+	db RoomEventDatabase,
+	input api.InputRoomEvent,
+	roomNID types.RoomNID,
+	stateAtEvent *types.StateAtEvent,
+	event gomatrixserverlib.Event,
+) error {
+	var err error
 	if input.HasState {
 		// We've been told what the state at the event is so we don't need to calculate it.
 		// Check that those state events are in the database and store the state.
@@ -122,19 +167,7 @@ func processRoomEvent(
 			return err
 		}
 	}
-		err = db.SetState(ctx, stateAtEvent.EventNID, stateAtEvent.BeforeStateSnapshotNID)
-		if err != nil {
-			return err
-		}
-	}
-
-	if input.Kind == api.KindBackfill {
-		// Backfill is not implemented.
-		panic("Not implemented")
-	}
-
-	// Update the extremities of the event graph for the room
-	return updateLatestEvents(ctx, db, ow, roomNID, stateAtEvent, event, input.SendAsServer, input.TransactionID)
+	return db.SetState(ctx, stateAtEvent.EventNID, stateAtEvent.BeforeStateSnapshotNID)
 }
 
 func processInviteEvent(

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

@@ -60,17 +60,17 @@ func (r *RoomserverInputAPI) InputRoomEvents(
 	ctx context.Context,
 	request *api.InputRoomEventsRequest,
 	response *api.InputRoomEventsResponse,
-) error {
+) (err error) {
 	// We lock as processRoomEvent can only be called once at a time
 	r.mutex.Lock()
 	defer r.mutex.Unlock()
 	for i := range request.InputRoomEvents {
-		if err := processRoomEvent(ctx, r.DB, r, request.InputRoomEvents[i]); err != nil {
+		if response.EventID, err = processRoomEvent(ctx, r.DB, r, request.InputRoomEvents[i]); err != nil {
 			return err
 		}
 	}
 	for i := range request.InputInviteEvents {
-		if err := processInviteEvent(ctx, r.DB, r, request.InputInviteEvents[i]); err != nil {
+		if err = processInviteEvent(ctx, r.DB, r, request.InputInviteEvents[i]); err != nil {
 			return err
 		}
 	}

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

@@ -30,6 +30,7 @@ type statements struct {
 	roomAliasesStatements
 	inviteStatements
 	membershipStatements
+	transactionStatements
 }
 
 func (s *statements) prepare(db *sql.DB) error {
@@ -47,6 +48,7 @@ func (s *statements) prepare(db *sql.DB) error {
 		s.roomAliasesStatements.prepare,
 		s.inviteStatements.prepare,
 		s.membershipStatements.prepare,
+		s.transactionStatements.prepare,
 	} {
 		if err = prepare(db); err != nil {
 			return err

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

@@ -20,6 +20,7 @@ import (
 
 	// Import the postgres database driver.
 	_ "github.com/lib/pq"
+	"github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/dendrite/roomserver/types"
 	"github.com/matrix-org/gomatrixserverlib"
 )
@@ -45,7 +46,8 @@ func Open(dataSourceName string) (*Database, error) {
 
 // StoreEvent implements input.EventDatabase
 func (d *Database) StoreEvent(
-	ctx context.Context, event gomatrixserverlib.Event, authEventNIDs []types.EventNID,
+	ctx context.Context, event gomatrixserverlib.Event,
+	txnAndDeviceID *api.TransactionID, authEventNIDs []types.EventNID,
 ) (types.RoomNID, types.StateAtEvent, error) {
 	var (
 		roomNID          types.RoomNID
@@ -56,6 +58,15 @@ func (d *Database) StoreEvent(
 		err              error
 	)
 
+	if txnAndDeviceID != nil {
+		if err = d.statements.insertTransaction(
+			ctx, txnAndDeviceID.TransactionID,
+			txnAndDeviceID.DeviceID, event.Sender(), event.EventID(),
+		); err != nil {
+			return 0, types.StateAtEvent{}, err
+		}
+	}
+
 	if roomNID, err = d.assignRoomNID(ctx, nil, event.RoomID()); err != nil {
 		return 0, types.StateAtEvent{}, err
 	}
@@ -308,6 +319,18 @@ func (d *Database) GetLatestEventsForUpdate(
 	}, nil
 }
 
+// GetTransactionEventID implements input.EventDatabase
+func (d *Database) GetTransactionEventID(
+	ctx context.Context, transactionID string,
+	deviceID string, userID string,
+) (string, error) {
+	eventID, err := d.statements.selectTransactionEventID(ctx, transactionID, deviceID, userID)
+	if err == sql.ErrNoRows {
+		return "", nil
+	}
+	return eventID, err
+}
+
 type roomRecentEventsUpdater struct {
 	transaction
 	d                       *Database

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

@@ -0,0 +1,86 @@
+// 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"
+	"database/sql"
+)
+
+const transactionsSchema = `
+-- The transactions table holds transaction IDs with sender's info and event ID it belongs to.
+-- This table is used by roomserver to prevent reprocessing of events.
+CREATE TABLE IF NOT EXISTS roomserver_transactions (
+	-- The transaction ID of the event.
+	transaction_id TEXT NOT NULL,
+	-- The device ID of the originating transaction.
+	device_id TEXT NOT NULL,
+	-- User ID of the sender who authored the event
+	user_id TEXT NOT NULL,
+	-- Event ID corresponding to the transaction
+	-- Required to return event ID to client on a duplicate request.
+	event_id TEXT NOT NULL,
+	-- A transaction ID is unique for a user and device
+	-- This automatically creates an index.
+	PRIMARY KEY (transaction_id, device_id, user_id)
+);
+`
+const insertTransactionSQL = "" +
+	"INSERT INTO roomserver_transactions (transaction_id, device_id, user_id, event_id)" +
+	" VALUES ($1, $2, $3, $4)"
+
+const selectTransactionEventIDSQL = "" +
+	"SELECT event_id FROM roomserver_transactions" +
+	" WHERE transaction_id = $1 AND device_id = $2 AND user_id = $3"
+
+type transactionStatements struct {
+	insertTransactionStmt        *sql.Stmt
+	selectTransactionEventIDStmt *sql.Stmt
+}
+
+func (s *transactionStatements) prepare(db *sql.DB) (err error) {
+	_, err = db.Exec(transactionsSchema)
+	if err != nil {
+		return
+	}
+
+	return statementList{
+		{&s.insertTransactionStmt, insertTransactionSQL},
+		{&s.selectTransactionEventIDStmt, selectTransactionEventIDSQL},
+	}.prepare(db)
+}
+
+func (s *transactionStatements) insertTransaction(
+	ctx context.Context,
+	transactionID string,
+	deviceID string,
+	userID string,
+	eventID string,
+) (err error) {
+	_, err = s.insertTransactionStmt.ExecContext(
+		ctx, transactionID, deviceID, userID, eventID,
+	)
+	return
+}
+
+func (s *transactionStatements) selectTransactionEventID(
+	ctx context.Context,
+	transactionID string,
+	deviceID string,
+	userID string,
+) (eventID string, err error) {
+	err = s.selectTransactionEventIDStmt.QueryRowContext(
+		ctx, transactionID, deviceID, userID,
+	).Scan(&eventID)
+	return
+}