1 files changed, 93 insertions, 0 deletions
diff --git a/setup/jetstream/nats.go b/setup/jetstream/nats.go
new file mode 100644
index 00000000..eec68d82
--- /dev/null
+++ b/setup/jetstream/nats.go
@@ -0,0 +1,93 @@
+package jetstream
+
+import (
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/Shopify/sarama"
+	"github.com/matrix-org/dendrite/setup/config"
+	"github.com/sirupsen/logrus"
+
+	saramajs "github.com/S7evinK/saramajetstream"
+	natsserver "github.com/nats-io/nats-server/v2/server"
+	"github.com/nats-io/nats.go"
+	natsclient "github.com/nats-io/nats.go"
+)
+
+var natsServer *natsserver.Server
+var natsServerMutex sync.Mutex
+
+func Prepare(cfg *config.JetStream) (nats.JetStreamContext, sarama.Consumer, sarama.SyncProducer) {
+	// check if we need an in-process NATS Server
+	if len(cfg.Addresses) != 0 {
+		return setupNATS(cfg, nil)
+	}
+	natsServerMutex.Lock()
+	if natsServer == nil {
+		var err error
+		natsServer, err = natsserver.NewServer(&natsserver.Options{
+			ServerName:       "monolith",
+			DontListen:       true,
+			JetStream:        true,
+			StoreDir:         string(cfg.StoragePath),
+			NoSystemAccount:  true,
+			AllowNewAccounts: false,
+		})
+		if err != nil {
+			panic(err)
+		}
+		natsServer.ConfigureLogger()
+		go natsServer.Start()
+	}
+	natsServerMutex.Unlock()
+	if !natsServer.ReadyForConnections(time.Second * 10) {
+		logrus.Fatalln("NATS did not start in time")
+	}
+	nc, err := natsclient.Connect("", natsclient.InProcessServer(natsServer))
+	if err != nil {
+		logrus.Fatalln("Failed to create NATS client")
+	}
+	return setupNATS(cfg, nc)
+}
+
+func setupNATS(cfg *config.JetStream, nc *natsclient.Conn) (nats.JetStreamContext, sarama.Consumer, sarama.SyncProducer) {
+	if nc == nil {
+		var err error
+		nc, err = nats.Connect(strings.Join(cfg.Addresses, ","))
+		if err != nil {
+			logrus.WithError(err).Panic("Unable to connect to NATS")
+			return nil, nil, nil
+		}
+	}
+
+	s, err := nc.JetStream()
+	if err != nil {
+		logrus.WithError(err).Panic("Unable to get JetStream context")
+		return nil, nil, nil
+	}
+
+	for _, stream := range streams { // streams are defined in streams.go
+		name := cfg.TopicFor(stream.Name)
+		info, err := s.StreamInfo(name)
+		if err != nil && err != natsclient.ErrStreamNotFound {
+			logrus.WithError(err).Fatal("Unable to get stream info")
+		}
+		if info == nil {
+			stream.Subjects = []string{name}
+			// If we're trying to keep everything in memory (e.g. unit tests)
+			// then overwrite the storage policy.
+			if cfg.InMemory {
+				stream.Storage = nats.MemoryStorage
+			}
+
+			if _, err = s.AddStream(stream); err != nil {
+				logrus.WithError(err).WithField("stream", name).Fatal("Unable to add stream")
+			}
+		}
+	}
+
+	consumer := saramajs.NewJetStreamConsumer(nc, s, "")
+	producer := saramajs.NewJetStreamProducer(nc, s, "")
+	return s, consumer, producer
+}