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zkClient.go
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zkClient.go
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package ZookeeperServiceDiscovery
import (
"context"
"github.com/go-zookeeper/zk"
"github.com/matoous/go-nanoid/v2"
"google.golang.org/grpc/grpclog"
"strings"
"sync"
"time"
)
type zkClient struct {
sync.RWMutex
conn *zk.Conn
canceler map[string]context.CancelFunc
}
func newZkClient(servers []string, timeout int) (*zkClient, error) {
if timeout == 0 {
timeout = 5
}
conn, _, err := zk.Connect(servers, time.Second*time.Duration(timeout))
if err != nil {
grpclog.Errorf("Could not create ZooKeeper connection: %v", err)
return nil, err
}
grpclog.Infof("Connected to ZooKeeper client")
client := &zkClient{
conn: conn,
canceler: make(map[string]context.CancelFunc),
}
return client, nil
}
func (client *zkClient) CreatePath(path string) (string, error) {
znodes := strings.Split(path, "/")
var curPath string
for _, znode := range znodes {
if len(znode) == 0 {
continue
}
curPath = curPath + "/" + znode
exists, _, _ := client.conn.Exists(curPath)
if exists {
continue
}
_, err := client.conn.Create(curPath, nil, 0, zk.WorldACL(zk.PermAll))
if err != nil {
grpclog.Infof("Failed to create znode: %v", err)
return "", err
}
}
return curPath, nil
}
func (client *zkClient) createNode(path string, ip string) error {
znodes := strings.Split(path, "/")
parentPath := strings.Join(znodes[:len(znodes)-1], "/")
parent, err := client.CreatePath(parentPath)
if err != nil {
return err
}
clientPath := parent + "/" + znodes[len(znodes)-1]
_, err = client.conn.Create(clientPath, []byte(ip), zk.FlagEphemeral, zk.WorldACL(zk.PermAll))
if err != nil {
grpclog.Infof("Failed to register node: %v", err)
return err
}
grpclog.Infof("Registered client on path: %v with IP: %v", clientPath, ip)
return nil
}
func (client *zkClient) RegisterNode(path string, ip string) error {
nodeId, err := gonanoid.New()
if err != nil {
return err
}
path = path + "/" + nodeId
err = client.createNode(path, ip)
if err != nil {
return err
}
ctx, cancel := context.WithCancel(context.Background())
client.Lock()
client.canceler[nodeId] = cancel
client.Unlock()
client.keepalive(ctx, path, ip)
return nil
}
func (client *zkClient) GetRegisteredIps(path string) ([]string, error) {
_, err := client.CreatePath(path)
if err != nil {
grpclog.Errorf("Failed to get nodes: %v", err)
return nil, err
}
children, _, err := client.conn.Children(path)
if err != nil {
grpclog.Errorf("Failed to get nodes: %v", err)
return nil, err
}
var ips []string
for _, node := range children {
val, _, err := client.conn.Get(path + "/" + node)
if err != nil {
grpclog.Errorf("Failed to get node value: %v", err)
return nil, err
}
ips = append(ips, string(val))
}
return ips, nil
}
func (client *zkClient) WatchRegisteredIps(path string) (chan []string, func(), error) {
_, err := client.CreatePath(path)
if err != nil {
grpclog.Errorf("Failed to set watch: %v", err)
return nil, nil, err
}
ips := make(chan []string)
_, _, evChan, err := client.conn.ChildrenW(path)
if err != nil {
grpclog.Errorf("Failed to set watch: %v", err)
return nil, nil, err
}
id, err := gonanoid.New()
if err != nil {
grpclog.Errorf("Failed to set watch: %v", err)
return nil, nil, err
}
watchId := "watch-" + id
ctx, cancel := context.WithCancel(context.Background())
client.Lock()
client.canceler[watchId] = cancel
client.Unlock()
cancelFunc := func() {
client.Lock()
cancel()
delete(client.canceler, watchId)
client.Unlock()
}
go func() {
for {
select {
case <-ctx.Done():
ips <- nil
return
case ev := <-evChan:
if ev.Type != zk.EventNodeChildrenChanged {
_, _, evChan, _ = client.conn.ChildrenW(path)
continue
}
curIps, _ := client.GetRegisteredIps(path)
ips <- curIps
}
}
}()
return ips, cancelFunc, nil
}
func (client *zkClient) keepalive(ctx context.Context, path string, ip string) {
ticker := time.NewTicker(time.Second)
go func() {
for {
select {
case <-ctx.Done():
return
case <-ticker.C:
if client.conn.State() != zk.StateHasSession {
client.createNode(path, ip)
}
}
}
}()
}
func (client *zkClient) Close() {
client.RLock()
for _, cancel := range client.canceler {
cancel()
}
client.RUnlock()
client.conn.Close()
client.conn = nil
}