snapshot of https://github.com/centrifugal/centrifugo.git (master, 2026-09-16; blobs > 131072B omitted)

internal/pubsub/nats.go

@@ -0,0 +1,75 @@
+package pubsub
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/centrifugal/centrifugo/v6/internal/configtypes"
+
+	"github.com/nats-io/nats.go"
+)
+
+// NatsPubSub implements PubSub using NATS.
+type NatsPubSub struct {
+	conn    *nats.Conn
+	subject string
+}
+
+// NewNatsPubSub creates a new NATS-backed PubSub.
+// The subject is constructed as prefix + subjectName.
+func NewNatsPubSub(cfg configtypes.NatsEmptyPrefixed, subjectName string) (*NatsPubSub, error) {
+	url := cfg.URL
+	if url == "" {
+		url = nats.DefaultURL
+	}
+	options := []nats.Option{
+		nats.ReconnectBufSize(-1),
+		nats.MaxReconnects(-1),
+	}
+	if dialTimeout := cfg.DialTimeout.ToDuration(); dialTimeout > 0 {
+		options = append(options, nats.Timeout(dialTimeout))
+	}
+	if writeTimeout := cfg.WriteTimeout.ToDuration(); writeTimeout > 0 {
+		options = append(options, nats.FlusherTimeout(writeTimeout))
+	}
+	if cfg.TLS.Enabled {
+		tlsConfig, err := cfg.TLS.ToGoTLSConfig("nats_pubsub")
+		if err != nil {
+			return nil, fmt.Errorf("error creating NATS TLS config: %w", err)
+		}
+		options = append(options, nats.Secure(tlsConfig))
+	}
+	nc, err := nats.Connect(url, options...)
+	if err != nil {
+		return nil, fmt.Errorf("error connecting to NATS for pubsub: %w", err)
+	}
+	return &NatsPubSub{
+		conn:    nc,
+		subject: cfg.Prefix + subjectName,
+	}, nil
+}
+
+// Publish sends data to the NATS subject.
+func (n *NatsPubSub) Publish(_ context.Context, data []byte) error {
+	return n.conn.Publish(n.subject, data)
+}
+
+// Subscribe listens on the NATS subject and calls handler for each message.
+// Blocks until ctx is cancelled.
+func (n *NatsPubSub) Subscribe(ctx context.Context, handler func(data []byte)) error {
+	sub, err := n.conn.Subscribe(n.subject, func(msg *nats.Msg) {
+		handler(msg.Data)
+	})
+	if err != nil {
+		return fmt.Errorf("error subscribing to NATS subject: %w", err)
+	}
+	defer func() { _ = sub.Unsubscribe() }()
+	<-ctx.Done()
+	return ctx.Err()
+}
+
+// Close closes the NATS connection.
+func (n *NatsPubSub) Close() error {
+	n.conn.Close()
+	return nil
+}