Sync refactor — Part 1 (#1688)

* It's half-alive

* Wakeups largely working

* Other tweaks, typing works

* Fix bugs, add receipt stream

* Delete notifier, other tweaks

* Dedupe a bit, add a template for the invite stream

* Clean up, add templates for other streams

* Don't leak channels

* Bring forward some more PDU logic, clean up other places

* Add some more wakeups

* Use addRoomDeltaToResponse

* Log tweaks, typing fixed?

* Fix timed out syncs

* Don't reset next batch position on timeout

* Add account data stream/position

* End of day

* Fix complete sync for receipt, typing

* Streams package

* Clean up a bit

* Complete sync send-to-device

* Don't drop errors

* More lightweight notifications

* Fix typing positions

* Don't advance position on remove again unless needed

* Device list updates

* Advance account data position

* Use limit for incremental sync

* Limit fixes, amongst other things

* Remove some fmt.Println

* Tweaks

* Re-add notifier

* Fix invite position

* Fixes

* Notify account data without advancing PDU position in notifier

* Apply account data position

* Get initial position for account data

* Fix position update

* Fix complete sync positions

* Review comments @Kegsay

* Room consumer parameters

syncapi/streams/stream_receipt.go

@@ -0,0 +1,91 @@
+package streams
+
+import (
+	"context"
+	"encoding/json"
+
+	eduAPI "github.com/matrix-org/dendrite/eduserver/api"
+	"github.com/matrix-org/dendrite/syncapi/types"
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+type ReceiptStreamProvider struct {
+	StreamProvider
+}
+
+func (p *ReceiptStreamProvider) Setup() {
+	p.StreamProvider.Setup()
+
+	id, err := p.DB.MaxStreamPositionForReceipts(context.Background())
+	if err != nil {
+		panic(err)
+	}
+	p.latest = id
+}
+
+func (p *ReceiptStreamProvider) CompleteSync(
+	ctx context.Context,
+	req *types.SyncRequest,
+) types.StreamPosition {
+	return p.IncrementalSync(ctx, req, 0, p.LatestPosition(ctx))
+}
+
+func (p *ReceiptStreamProvider) IncrementalSync(
+	ctx context.Context,
+	req *types.SyncRequest,
+	from, to types.StreamPosition,
+) types.StreamPosition {
+	var joinedRooms []string
+	for roomID, membership := range req.Rooms {
+		if membership == gomatrixserverlib.Join {
+			joinedRooms = append(joinedRooms, roomID)
+		}
+	}
+
+	lastPos, receipts, err := p.DB.RoomReceiptsAfter(ctx, joinedRooms, from)
+	if err != nil {
+		req.Log.WithError(err).Error("p.DB.RoomReceiptsAfter failed")
+		return from
+	}
+
+	if len(receipts) == 0 || lastPos == 0 {
+		return to
+	}
+
+	// Group receipts by room, so we can create one ClientEvent for every room
+	receiptsByRoom := make(map[string][]eduAPI.OutputReceiptEvent)
+	for _, receipt := range receipts {
+		receiptsByRoom[receipt.RoomID] = append(receiptsByRoom[receipt.RoomID], receipt)
+	}
+
+	for roomID, receipts := range receiptsByRoom {
+		jr := req.Response.Rooms.Join[roomID]
+		var ok bool
+
+		ev := gomatrixserverlib.ClientEvent{
+			Type:   gomatrixserverlib.MReceipt,
+			RoomID: roomID,
+		}
+		content := make(map[string]eduAPI.ReceiptMRead)
+		for _, receipt := range receipts {
+			var read eduAPI.ReceiptMRead
+			if read, ok = content[receipt.EventID]; !ok {
+				read = eduAPI.ReceiptMRead{
+					User: make(map[string]eduAPI.ReceiptTS),
+				}
+			}
+			read.User[receipt.UserID] = eduAPI.ReceiptTS{TS: receipt.Timestamp}
+			content[receipt.EventID] = read
+		}
+		ev.Content, err = json.Marshal(content)
+		if err != nil {
+			req.Log.WithError(err).Error("json.Marshal failed")
+			return from
+		}
+
+		jr.Ephemeral.Events = append(jr.Ephemeral.Events, ev)
+		req.Response.Rooms.Join[roomID] = jr
+	}
+
+	return lastPos
+}