Remove intermediary /sync response struct (#102)

The logic required to populate the right bits of `RoomData` tends towards
the complete `/sync` response struct, so just use the actual response struct
and save the hassle of mapping between the two. It may not make much difference
in its current form, but the next PR will make use of this.

This PR has no functional changes.

src/github.com/matrix-org/dendrite/syncapi/storage/syncserver.go

@@ -113,8 +113,7 @@ func (d *SyncServerDatabase) SyncStreamPosition() (types.StreamPosition, error)
 }
 
 // IncrementalSync returns all the data needed in order to create an incremental sync response.
-func (d *SyncServerDatabase) IncrementalSync(userID string, fromPos, toPos types.StreamPosition, numRecentEventsPerRoom int) (data map[string]types.RoomData, returnErr error) {
-	data = make(map[string]types.RoomData)
+func (d *SyncServerDatabase) IncrementalSync(userID string, fromPos, toPos types.StreamPosition, numRecentEventsPerRoom int) (res *types.Response, returnErr error) {
 	returnErr = runTransaction(d.db, func(txn *sql.Tx) error {
 		roomIDs, err := d.roomstate.SelectRoomIDsWithMembership(txn, userID, "join")
 		if err != nil {
@@ -126,6 +125,8 @@ func (d *SyncServerDatabase) IncrementalSync(userID string, fromPos, toPos types
 			return err
 		}
 
+		res = types.NewResponse(toPos)
+
 		// Implement membership change algorithm: https://github.com/matrix-org/synapse/blob/v0.19.3/synapse/handlers/sync.py#L821
 		// - Get membership list changes for this user in this sync response
 		// - For each room which has membership list changes:
@@ -167,35 +168,40 @@ func (d *SyncServerDatabase) IncrementalSync(userID string, fromPos, toPos types
 				return err
 			}
 			state[roomID] = removeDuplicates(state[roomID], recentEvents)
-			roomData := types.RoomData{
-				State:        state[roomID],
-				RecentEvents: recentEvents,
-			}
-			data[roomID] = roomData
+
+			jr := types.NewJoinResponse()
+			jr.Timeline.Events = gomatrixserverlib.ToClientEvents(recentEvents, gomatrixserverlib.FormatSync)
+			jr.Timeline.Limited = false // TODO: if len(events) >= numRecents + 1 and then set limited:true
+			jr.State.Events = gomatrixserverlib.ToClientEvents(state[roomID], gomatrixserverlib.FormatSync)
+			res.Rooms.Join[roomID] = *jr
 		}
 		return nil
 	})
 	return
 }
 
-// CompleteSync returns all the data needed in order to create a complete sync response.
-func (d *SyncServerDatabase) CompleteSync(userID string, numRecentEventsPerRoom int) (pos types.StreamPosition, data map[string]types.RoomData, returnErr error) {
-	data = make(map[string]types.RoomData)
+// CompleteSync a complete /sync API response for the given user.
+func (d *SyncServerDatabase) CompleteSync(userID string, numRecentEventsPerRoom int) (res *types.Response, returnErr error) {
 	// This needs to be all done in a transaction as we need to do multiple SELECTs, and we need to have
 	// a consistent view of the database throughout. This includes extracting the sync stream position.
+	// This does have the unfortunate side-effect that all the matrixy logic resides in this function,
+	// but it's better to not hide the fact that this is being done in a transaction.
 	returnErr = runTransaction(d.db, func(txn *sql.Tx) error {
 		// Get the current stream position which we will base the sync response on.
 		id, err := d.events.MaxID(txn)
 		if err != nil {
 			return err
 		}
-		pos = types.StreamPosition(id)
+		pos := types.StreamPosition(id)
 
 		// Extract room state and recent events for all rooms the user is joined to.
 		roomIDs, err := d.roomstate.SelectRoomIDsWithMembership(txn, userID, "join")
 		if err != nil {
 			return err
 		}
+
+		// Build up a /sync response
+		res = types.NewResponse(pos)
 		for _, roomID := range roomIDs {
 			stateEvents, err := d.roomstate.CurrentState(txn, roomID)
 			if err != nil {
@@ -209,12 +215,13 @@ func (d *SyncServerDatabase) CompleteSync(userID string, numRecentEventsPerRoom
 			}
 
 			stateEvents = removeDuplicates(stateEvents, recentEvents)
-
-			data[roomID] = types.RoomData{
-				State:        stateEvents,
-				RecentEvents: recentEvents,
-			}
+			jr := types.NewJoinResponse()
+			jr.Timeline.Events = gomatrixserverlib.ToClientEvents(recentEvents, gomatrixserverlib.FormatSync)
+			jr.Timeline.Limited = true
+			jr.State.Events = gomatrixserverlib.ToClientEvents(stateEvents, gomatrixserverlib.FormatSync)
+			res.Rooms.Join[roomID] = *jr
 		}
+		// TODO: Add invites!
 		return nil
 	})
 	return

src/github.com/matrix-org/dendrite/syncapi/sync/requestpool.go

@@ -24,7 +24,6 @@ import (
 	"github.com/matrix-org/dendrite/clientapi/jsonerror"
 	"github.com/matrix-org/dendrite/syncapi/storage"
 	"github.com/matrix-org/dendrite/syncapi/types"
-	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/matrix-org/util"
 )
 
@@ -102,36 +101,9 @@ func (rp *RequestPool) OnIncomingSyncRequest(req *http.Request) util.JSONRespons
 }
 
 func (rp *RequestPool) currentSyncForUser(req syncRequest, currentPos types.StreamPosition) (*types.Response, error) {
-	if req.since == types.StreamPosition(0) {
-		pos, data, err := rp.db.CompleteSync(req.userID, req.limit)
-		if err != nil {
-			return nil, err
-		}
-		res := types.NewResponse(pos)
-		for roomID, d := range data {
-			jr := types.NewJoinResponse()
-			jr.Timeline.Events = gomatrixserverlib.ToClientEvents(d.RecentEvents, gomatrixserverlib.FormatSync)
-			jr.Timeline.Limited = true
-			jr.State.Events = gomatrixserverlib.ToClientEvents(d.State, gomatrixserverlib.FormatSync)
-			res.Rooms.Join[roomID] = *jr
-		}
-		return res, nil
-	}
-
 	// TODO: handle ignored users
-
-	data, err := rp.db.IncrementalSync(req.userID, req.since, currentPos, req.limit)
-	if err != nil {
-		return nil, err
-	}
-
-	res := types.NewResponse(currentPos)
-	for roomID, d := range data {
-		jr := types.NewJoinResponse()
-		jr.Timeline.Events = gomatrixserverlib.ToClientEvents(d.RecentEvents, gomatrixserverlib.FormatSync)
-		jr.Timeline.Limited = false // TODO: if len(events) >= numRecents + 1 and then set limited:true
-		jr.State.Events = gomatrixserverlib.ToClientEvents(d.State, gomatrixserverlib.FormatSync)
-		res.Rooms.Join[roomID] = *jr
+	if req.since == types.StreamPosition(0) {
+		return rp.db.CompleteSync(req.userID, req.limit)
 	}
-	return res, nil
+	return rp.db.IncrementalSync(req.userID, req.since, currentPos, req.limit)
 }

src/github.com/matrix-org/dendrite/syncapi/types/types.go

@@ -28,12 +28,6 @@ func (sp StreamPosition) String() string {
 	return strconv.FormatInt(int64(sp), 10)
 }
 
-// RoomData represents the data for a room suitable for building a sync response from.
-type RoomData struct {
-	State        []gomatrixserverlib.Event
-	RecentEvents []gomatrixserverlib.Event
-}
-
 // Response represents a /sync API response. See https://matrix.org/docs/spec/client_server/r0.2.0.html#get-matrix-client-r0-sync
 type Response struct {
 	NextBatch   string `json:"next_batch"`