feat: registry.

registry/eureka/eureka.go

@@ -0,0 +1,137 @@
+package eureka
+
+import (
+	"context"
+	"strings"
+	"sync"
+	"time"
+)
+
+type subscriber struct {
+	appID    string
+	callBack func()
+}
+
+type API struct {
+	cli             *Client
+	allInstances    map[string][]Instance
+	subscribers     map[string]*subscriber
+	refreshInterval time.Duration
+	lock            sync.Mutex
+}
+
+func NewAPI(ctx context.Context, client *Client, refreshInterval time.Duration) *API {
+	e := &API{
+		cli:             client,
+		allInstances:    make(map[string][]Instance),
+		subscribers:     make(map[string]*subscriber),
+		refreshInterval: refreshInterval,
+	}
+
+	// it is required to broadcast for the first time
+	go e.broadcast()
+
+	go e.refresh(ctx)
+
+	return e
+}
+
+func (e *API) refresh(ctx context.Context) {
+	ticker := time.NewTicker(e.refreshInterval)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-ticker.C:
+			e.broadcast()
+		}
+	}
+}
+
+func (e *API) broadcast() {
+	instances := e.cacheAllInstances()
+	if instances == nil {
+		return
+	}
+
+	for _, subscriber := range e.subscribers {
+		go subscriber.callBack()
+	}
+	defer e.lock.Unlock()
+	e.lock.Lock()
+	e.allInstances = instances
+}
+
+func (e *API) cacheAllInstances() map[string][]Instance {
+	items := make(map[string][]Instance)
+	instances := e.cli.FetchAllUpInstances(context.Background())
+	for _, instance := range instances {
+		items[e.ToAppID(instance.App)] = append(items[instance.App], instance)
+	}
+
+	return items
+}
+
+func (e *API) Register(ctx context.Context, serviceName string, endpoints ...Endpoint) error {
+	appID := e.ToAppID(serviceName)
+	upInstances := make(map[string]struct{})
+
+	for _, ins := range e.GetService(ctx, appID) {
+		upInstances[ins.InstanceID] = struct{}{}
+	}
+
+	for _, ep := range endpoints {
+		if _, ok := upInstances[ep.InstanceID]; !ok {
+			if err := e.cli.Register(ctx, ep); err != nil {
+				return err
+			}
+			go e.cli.Heartbeat(ep)
+		}
+	}
+
+	return nil
+}
+
+// Deregister ctx is the same as register ctx
+func (e *API) Deregister(ctx context.Context, endpoints []Endpoint) error {
+	for _, ep := range endpoints {
+		if err := e.cli.Deregister(ctx, ep.AppID, ep.InstanceID); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (e *API) Subscribe(serverName string, fn func()) error {
+	e.lock.Lock()
+	defer e.lock.Unlock()
+	appID := e.ToAppID(serverName)
+	e.subscribers[appID] = &subscriber{
+		appID:    appID,
+		callBack: fn,
+	}
+	go e.broadcast()
+	return nil
+}
+
+func (e *API) GetService(ctx context.Context, serverName string) []Instance {
+	appID := e.ToAppID(serverName)
+	if ins, ok := e.allInstances[appID]; ok {
+		return ins
+	}
+
+	// if not in allInstances of API, you can try to obtain it separately again
+	return e.cli.FetchAppUpInstances(ctx, appID)
+}
+
+func (e *API) Unsubscribe(serverName string) {
+	e.lock.Lock()
+	defer e.lock.Unlock()
+	delete(e.subscribers, e.ToAppID(serverName))
+}
+
+func (e *API) ToAppID(serverName string) string {
+	return strings.ToUpper(serverName)
+}