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_typing.go

@@ -0,0 +1,57 @@
+package streams
+
+import (
+	"context"
+	"encoding/json"
+
+	"github.com/matrix-org/dendrite/eduserver/cache"
+	"github.com/matrix-org/dendrite/syncapi/types"
+	"github.com/matrix-org/gomatrixserverlib"
+)
+
+type TypingStreamProvider struct {
+	StreamProvider
+	EDUCache *cache.EDUCache
+}
+
+func (p *TypingStreamProvider) CompleteSync(
+	ctx context.Context,
+	req *types.SyncRequest,
+) types.StreamPosition {
+	return p.IncrementalSync(ctx, req, 0, p.LatestPosition(ctx))
+}
+
+func (p *TypingStreamProvider) IncrementalSync(
+	ctx context.Context,
+	req *types.SyncRequest,
+	from, to types.StreamPosition,
+) types.StreamPosition {
+	var err error
+	for roomID, membership := range req.Rooms {
+		if membership != gomatrixserverlib.Join {
+			continue
+		}
+
+		jr := req.Response.Rooms.Join[roomID]
+
+		if users, updated := p.EDUCache.GetTypingUsersIfUpdatedAfter(
+			roomID, int64(from),
+		); updated {
+			ev := gomatrixserverlib.ClientEvent{
+				Type: gomatrixserverlib.MTyping,
+			}
+			ev.Content, err = json.Marshal(map[string]interface{}{
+				"user_ids": users,
+			})
+			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 to
+}