Golang Client.Get方法代碼示例

// waitDeletes efficiently waits until all keys matched by Get(key, opts...) are deleted
func waitDeletes(ctx context.Context, client *v3.Client, key string, opts ...v3.OpOption) error {
	getOpts := []v3.OpOption{v3.WithSort(v3.SortByCreatedRev, v3.SortAscend)}
	getOpts = append(getOpts, opts...)
	resp, err := client.Get(ctx, key, getOpts...)
	maxRev := int64(math.MaxInt64)
	getOpts = append(getOpts, v3.WithRev(0))
	for err == nil {
		for len(resp.Kvs) > 0 {
			i := len(resp.Kvs) - 1
			if resp.Kvs[i].CreateRevision <= maxRev {
				break
			}
			resp.Kvs = resp.Kvs[:i]
		}
		if len(resp.Kvs) == 0 {
			break
		}
		lastKV := resp.Kvs[len(resp.Kvs)-1]
		maxRev = lastKV.CreateRevision
		err = waitDelete(ctx, client, string(lastKV.Key), maxRev)
		if err != nil || len(resp.Kvs) == 1 {
			break
		}
		getOpts = append(getOpts, v3.WithLimit(int64(len(resp.Kvs)-1)))
		resp, err = client.Get(ctx, key, getOpts...)
	}
	return err
}

/*
Sync localdir to etcd server state.
WARNING: ALL CONTENT OF localdir WILL BE LOST

Return revision of synced state
*/
func firstSyncEtcDir_v3(prefix string, c *clientv3.Client, localdir string) int64 {
	cleanDir(localdir)

	key, option := prefixToKeyOption(prefix)

	// Get all values
	resp, err := c.Get(context.Background(), key, option, clientv3.WithSort(clientv3.SortByKey, clientv3.SortDescend))
	if err != nil {
		panic(err)
	}

	for _, kv := range resp.Kvs {
		targetPath := keyToLocalPath(strings.TrimPrefix(string(kv.Key), prefix), localdir)
		if targetPath == "" {
			continue
		}
		targetDir := filepath.Dir(targetPath)
		os.MkdirAll(targetDir, DEFAULT_DIRMODE)
		err = ioutil.WriteFile(targetPath, kv.Value, DEFAULT_FILEMODE)
		if err != nil {
			log.Printf("firstSyncEtcDir_v3 error write file '%v': %v\n", targetPath, err)
		}
	}
	return resp.Header.Revision
}

func getKey(ctx context.Context, client *clientv3.Client, key string) (*clientv3.GetResponse, error) {
	for ctx.Err() == nil {
		if gr, err := client.Get(ctx, key); err == nil {
			return gr, nil
		}
	}
	return nil, ctx.Err()
}

func loadEtcdV3Config(client etcdv3.Client, config *server.Config) error {
	configPath := "/" + msg.PathPrefix + "/config"
	resp, err := client.Get(ctx, configPath)
	if err != nil {
		log.Printf("skydns: falling back to default configuration, could not read from etcd: %s", err)
		return nil
	}
	for _, ev := range resp.Kvs {
		if err := json.Unmarshal([]byte(ev.Value), config); err != nil {
			return fmt.Errorf("failed to unmarshal config: %s", err.Error())
		}
	}
	return nil
}

func syncProcess_v3FSEvent(localDir string, serverPrefix string, c3 *clientv3.Client, event fileChangeEvent) {
	etcdPath, err := filepath.Rel(localDir, event.Path)
	if err != nil {
		log.Printf("syncProcess_v3 error get relpath '%v': %v\n", event.Path, err)
		return
	}
	etcdPath = serverPrefix + etcdPath
	etcdPath = strings.Replace(etcdPath, string(os.PathSeparator), "/", -1)

	switch {
	case event.IsRemoved:
		_, err := c3.Delete(context.Background(), etcdPath)
		if err != nil {
			log.Printf("syncProcess_v3 error while delete etcdkey '%v': %v\n", etcdPath, err)
		}
	case event.IsDir:
		files, _ := ioutil.ReadDir(event.Path)
		for _, file := range files {
			path := filepath.Join(event.Path, file.Name())
			content := []byte(nil)
			if !file.IsDir() {
				content, err = ioutil.ReadFile(path)
				if err != nil {
					log.Println(err)
				}
			}
			syncProcess_v3FSEvent(localDir, serverPrefix, c3, fileChangeEvent{
				Path:      path,
				IsDir:     file.IsDir(),
				IsRemoved: false,
				Content:   content,
			})
		}
	case !event.IsDir:
		resp, err := c3.Get(context.Background(), etcdPath)
		if err != nil {
			log.Printf("syncProcess_v3 Can't read key '%v': %v\n", etcdPath, err)
		}
		if len(resp.Kvs) > 0 {
			if bytes.Equal(resp.Kvs[0].Value, event.Content) {
				return
			}
		}
		_, err = c3.Put(context.Background(), etcdPath, string(event.Content))
		if err != nil {
			log.Printf("syncProcess_v3 error while put etcdkey '%v': %v\n", etcdPath, err)
		}
	}
}

// compact compacts etcd store and returns current rev.
// If it couldn't get current revision, the old rev will be returned.
func compact(ctx context.Context, client *clientv3.Client, oldRev int64) (int64, error) {
	resp, err := client.Get(ctx, "/")
	if err != nil {
		return oldRev, err
	}
	curRev := resp.Header.Revision
	if oldRev == 0 {
		return curRev, nil
	}
	err = client.Compact(ctx, oldRev)
	if err != nil {
		return curRev, err
	}
	return curRev, nil
}

func doSerializedGet(ctx context.Context, client *v3.Client, results chan result) {
	for {
		st := time.Now()
		_, err := client.Get(ctx, "abc", v3.WithSerializable())
		if ctx.Err() != nil {
			break
		}
		var errStr string
		if err != nil {
			errStr = err.Error()
		}
		res := result{errStr: errStr, duration: time.Since(st), happened: time.Now()}
		results <- res
	}
	close(results)
}

// compact compacts etcd store and returns current rev.
// If it couldn't get current revision, the old rev will be returned.
func compact(ctx context.Context, client *clientv3.Client, oldRev int64) (int64, error) {
	resp, err := client.Get(ctx, "/")
	if err != nil {
		return oldRev, err
	}
	curRev := resp.Header.Revision
	if oldRev == 0 {
		return curRev, nil
	}
	err = client.Compact(ctx, oldRev)
	if err != nil {
		return curRev, err
	}
	glog.Infof("etcd: Compacted rev %d, endpoints %v", oldRev, client.Endpoints())
	return curRev, nil
}

func lockUntilSignal(c *clientv3.Client, lockname string) error {
	s, err := concurrency.NewSession(c)
	if err != nil {
		return err
	}

	m := concurrency.NewMutex(s, lockname)
	ctx, cancel := context.WithCancel(context.TODO())

	// unlock in case of ordinary shutdown
	donec := make(chan struct{})
	sigc := make(chan os.Signal, 1)
	signal.Notify(sigc, os.Interrupt, os.Kill)
	go func() {
		<-sigc
		cancel()
		close(donec)
	}()

	s, serr := concurrency.NewSession(c)
	if serr != nil {
		return serr
	}

	if err := m.Lock(ctx); err != nil {
		return err
	}

	k, kerr := c.Get(ctx, m.Key())
	if kerr != nil {
		return kerr
	}
	if len(k.Kvs) == 0 {
		return errors.New("lock lost on init")
	}

	display.Get(*k)

	select {
	case <-donec:
		return m.Unlock(context.TODO())
	case <-s.Done():
	}

	return errors.New("session expired")
}

func prepareObjs(ctx context.Context, e *event, client *clientv3.Client, codec runtime.Codec, versioner storage.Versioner) (curObj runtime.Object, oldObj runtime.Object, err error) {
	if !e.isDeleted {
		curObj, err = decodeObj(codec, versioner, e.value, e.rev)
		if err != nil {
			return nil, nil, err
		}
	}
	if e.isDeleted || !e.isCreated {
		getResp, err := client.Get(ctx, e.key, clientv3.WithRev(e.rev-1))
		if err != nil {
			return nil, nil, err
		}
		oldObj, err = decodeObj(codec, versioner, getResp.Kvs[0].Value, getResp.Kvs[0].ModRevision)
		if err != nil {
			return nil, nil, err
		}
	}
	return curObj, oldObj, nil
}

func campaign(c *clientv3.Client, election string, prop string) error {
	s, err := concurrency.NewSession(c)
	if err != nil {
		return err
	}
	e := concurrency.NewElection(s, election)
	ctx, cancel := context.WithCancel(context.TODO())

	donec := make(chan struct{})
	sigc := make(chan os.Signal, 1)
	signal.Notify(sigc, os.Interrupt, os.Kill)
	go func() {
		<-sigc
		cancel()
		close(donec)
	}()

	s, serr := concurrency.NewSession(c)
	if serr != nil {
		return serr
	}

	if err = e.Campaign(ctx, prop); err != nil {
		return err
	}

	// print key since elected
	resp, err := c.Get(ctx, e.Key())
	if err != nil {
		return err
	}
	display.Get(*resp)

	select {
	case <-donec:
	case <-s.Done():
		return errors.New("elect: session expired")
	}

	return e.Resign(context.TODO())
}

func prepareObjs(ctx context.Context, e *event, client *clientv3.Client, codec runtime.Codec, versioner storage.Versioner) (curObj runtime.Object, oldObj runtime.Object, err error) {
	if !e.isDeleted {
		curObj, err = decodeObj(codec, versioner, e.value, e.rev)
		if err != nil {
			return nil, nil, err
		}
	}
	if e.isDeleted || !e.isCreated {
		getResp, err := client.Get(ctx, e.key, clientv3.WithRev(e.rev-1))
		if err != nil {
			return nil, nil, err
		}
		// Note that this sends the *old* object with the etcd revision for the time at
		// which it gets deleted.
		// We assume old object is returned only in Deleted event. Users (e.g. cacher) need
		// to have larger than previous rev to tell the ordering.
		oldObj, err = decodeObj(codec, versioner, getResp.Kvs[0].Value, e.rev)
		if err != nil {
			return nil, nil, err
		}
	}
	return curObj, oldObj, nil
}