feat: registry.

registry/eureka/watcher.go

@@ -0,0 +1,60 @@
+package eureka
+
+import (
+	"context"
+
+	"github.com/go-kratos/kratos/v2/registry"
+)
+
+var _ registry.Watcher = (*watcher)(nil)
+
+type watcher struct {
+	ctx        context.Context
+	cancel     context.CancelFunc
+	cli        *API
+	watchChan  chan struct{}
+	serverName string
+}
+
+func newWatch(ctx context.Context, cli *API, serverName string) (*watcher, error) {
+	w := &watcher{
+		ctx:        ctx,
+		cli:        cli,
+		serverName: serverName,
+		watchChan:  make(chan struct{}, 1),
+	}
+	w.ctx, w.cancel = context.WithCancel(ctx)
+	e := w.cli.Subscribe(
+		serverName,
+		func() {
+			w.watchChan <- struct{}{}
+		},
+	)
+	return w, e
+}
+
+func (w *watcher) Next() (services []*registry.ServiceInstance, err error) {
+	select {
+	case <-w.ctx.Done():
+		return nil, w.ctx.Err()
+	case <-w.watchChan:
+		instances := w.cli.GetService(w.ctx, w.serverName)
+		services = make([]*registry.ServiceInstance, 0, len(instances))
+		for _, instance := range instances {
+			services = append(services, &registry.ServiceInstance{
+				ID:        instance.Metadata["ID"],
+				Name:      instance.Metadata["Name"],
+				Version:   instance.Metadata["Version"],
+				Endpoints: []string{instance.Metadata["Endpoints"]},
+				Metadata:  instance.Metadata,
+			})
+		}
+		return
+	}
+}
+
+func (w *watcher) Stop() error {
+	w.cancel()
+	w.cli.Unsubscribe(w.serverName)
+	return nil
+}