feat: add redis cache and fanout support

server/redis_fanout.go

@@ -0,0 +1,87 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+
+	"github.com/tinode/chat/server/logs"
+	"github.com/tinode/chat/server/store"
+	"github.com/tinode/chat/server/store/types"
+)
+
+func startRedisGroupFanout(ctx context.Context) {
+	if err := store.StartGroupFanoutSubscriber(ctx, currentNodeID(), func(raw []byte) {
+		var msg ServerComMessage
+		if err := json.Unmarshal(raw, &msg); err != nil {
+			logs.Warn.Println("redis group fanout: malformed message", err)
+			return
+		}
+		if !msg.TenantID.IsValid() || msg.RcptTo == "" || types.GetTopicCat(msg.RcptTo) != types.TopicCatGrp {
+			return
+		}
+		msg.sess = nil
+		deliverRedisGroupFanout(&msg)
+	}); err != nil {
+		logs.Warn.Println("redis group fanout: subscriber disabled", err)
+	}
+}
+
+func deliverRedisGroupFanout(msg *ServerComMessage) {
+	key := types.TopicKey{TenantID: msg.TenantID, Topic: msg.RcptTo}
+	if globals.hub.topicGet(key) != nil {
+		select {
+		case globals.hub.routeSrv <- msg:
+		default:
+			logs.Err.Println("redis group fanout: hub routeSrv queue full", msg.RcptTo)
+		}
+		return
+	}
+
+	delivered := 0
+	localMembers := redisGroupFanoutMembers(msg.TenantID, msg.RcptTo)
+	globals.sessionStore.Range(func(_ string, sess *Session) bool {
+		if sess == nil || sess.isCluster() || sess.isProxy() || sess.tenantID != msg.TenantID || sess.sid == msg.SkipSid {
+			return true
+		}
+		_, listedOnline := localMembers[sess.uid.UserId()]
+		if !listedOnline && !sess.hasSub(msg.RcptTo) {
+			return true
+		}
+
+		msgCopy := msg.copy()
+		prepareRedisGroupFanoutMessage(msgCopy, msg.RcptTo)
+		if sess.queueOut(msgCopy) {
+			delivered++
+		} else {
+			logs.Warn.Printf("redis group fanout: session queue full, sid=%s topic=%s", sess.sid, msg.RcptTo)
+		}
+		return true
+	})
+	if delivered == 0 {
+		logs.Info.Println("redis group fanout: no local subscribers for unloaded topic", msg.RcptTo)
+	}
+}
+
+func redisGroupFanoutMembers(tenantID types.TenantID, topic string) map[string]struct{} {
+	uids, err := store.GetTopicNodeOnlineMembers(tenantID, topic, currentNodeID())
+	if err != nil {
+		logs.Warn.Println("redis group fanout: failed to read local online members", topic, err)
+		return nil
+	}
+	members := make(map[string]struct{}, len(uids))
+	for _, uid := range uids {
+		members[uid.UserId()] = struct{}{}
+	}
+	return members
+}
+
+func prepareRedisGroupFanoutMessage(msg *ServerComMessage, topic string) {
+	switch {
+	case msg.Data != nil && msg.Data.Topic == "":
+		msg.Data.Topic = topic
+	case msg.Pres != nil && msg.Pres.Topic == "":
+		msg.Pres.Topic = topic
+	case msg.Info != nil && msg.Info.Topic == "":
+		msg.Info.Topic = topic
+	}
+}