/
zookeeper_client.go
249 lines (211 loc) · 6.53 KB
/
zookeeper_client.go
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package base
import (
"errors"
"fmt"
"github.com/golang/glog"
"github.com/samuel/go-zookeeper/zk"
"path"
"strconv"
"strings"
"time"
)
const (
Root = "/descartes"
ElectionRoot = Root + "/election"
HeartbeatRoot = Root + "/heartbeat"
LongRunTaskRoot = Root + "/long_run_tasks"
)
type ZooKeeperClient struct {
conn *zk.Conn
config BaseConfig
}
func NewZooKeeperClient(serverConfig BaseConfig) *ZooKeeperClient {
if servers, ok := serverConfig[ZooKeeperServers]; !ok || servers == "" {
glog.Errorf("Missing ZooKeeper server configuration")
return nil
}
if serverConfig[ZooKeeperRoot] == "" {
serverConfig[ZooKeeperRoot] = Root
}
if serverConfig[ZooKeeperElectionRoot] == "" {
serverConfig[ZooKeeperElectionRoot] = ElectionRoot
}
if serverConfig[ZooKeeperHeartbeatRoot] == "" {
serverConfig[ZooKeeperHeartbeatRoot] = HeartbeatRoot
}
if serverConfig[ZooKeeperLongRunTask] == "" {
serverConfig[ZooKeeperLongRunTask] = LongRunTaskRoot
}
servers := strings.Split(serverConfig[ZooKeeperServers], ";")
conn, _, err := zk.Connect(servers, 10*time.Second)
if err != nil {
glog.Errorf("Failed to create ZooKeeper Connection, error=%s", err)
return nil
}
client := &ZooKeeperClient{
conn: conn,
config: serverConfig,
}
go func() {
if err != nil {
conn.Close()
}
}()
err = client.mkdirRecursive(ElectionRoot)
if err != nil {
return nil
}
err = client.mkdirRecursive(HeartbeatRoot)
if err != nil {
return nil
}
return client
}
// Return GUID strings of the participant in the format of node_%010d
// For e.g, /descartes/election/_c_11f6c4b023b29f33e17d4340ac6815f2-node_0000000010
func (client *ZooKeeperClient) JoinElection(node string) (string, error) {
fullPath := fmt.Sprintf("%s/%s_", client.config[ZooKeeperElectionRoot], node)
res, err := client.conn.CreateProtectedEphemeralSequential(fullPath, nil, zk.WorldACL(zk.PermAll))
if err != nil {
glog.Errorf("Failed to join client node=%s, error=%s", node, err)
return "", err
}
glog.Infof("%s joined the leader election.", node)
return res, nil
}
// nodeGUID is the result returned in JoinElection
// Compare all children in the election node, select the one which has min
// sequential number
func (client *ZooKeeperClient) IsLeader(nodeGUID string) (bool, error) {
participants, err := client.Children(client.config[ZooKeeperElectionRoot])
if err != nil {
return false, err
}
seqNum, err := strconv.ParseInt(nodeGUID[len(nodeGUID)-10:], 10, 32)
if err != nil {
glog.Errorf("Failed to parse %s to int", nodeGUID[len(nodeGUID)-10:])
return false, err
}
var otherParticipants []int32
for _, participant := range participants {
num, err := strconv.ParseInt(participant[len(participant)-10:], 10, 32)
if err != nil {
glog.Errorf("Failed to parse %s to int", participant[len(participant)-10:])
return false, err
}
otherParticipants = append(otherParticipants, int32(num))
}
// FIXME overfollow and rejoin
for _, num := range otherParticipants {
if num < int32(seqNum) {
return false, nil
}
}
return true, nil
}
func (client *ZooKeeperClient) ElectionParticipants() ([]string, error) {
return client.Children(client.config[ZooKeeperElectionRoot])
}
func (client *ZooKeeperClient) WatchElectionParticipants() (<-chan zk.Event, error) {
return client.ChildrenW(client.config[ZooKeeperElectionRoot])
}
func (client *ZooKeeperClient) Children(parentNode string) ([]string, error) {
children, _, err := client.conn.Children(parentNode)
if err != nil {
return nil, err
}
return children, nil
}
// ChildrenW returns a channel which can receive events when something happened
// to the children
func (client *ZooKeeperClient) ChildrenW(parentNode string) (<-chan zk.Event, error) {
_, _, eventChan, err := client.conn.ChildrenW(parentNode)
return eventChan, err
}
func (client *ZooKeeperClient) Close() {
client.conn.Close()
}
// DeleteNode deletes the latest version data on the node
func (client *ZooKeeperClient) DeleteNode(node string, ignoreNotExists bool) error {
_, stat, err := client.conn.Get(node)
if err != nil {
if err == zk.ErrNoNode && ignoreNotExists {
return nil
}
glog.Errorf("Failed to get node=%s", node)
return err
}
return client.conn.Delete(node, stat.Version)
}
// Create stores a new value at node.
func (client *ZooKeeperClient) CreateNode(node string, value []byte, ephemeral, ignoreExists bool) error {
if !strings.HasPrefix(node, "/") {
glog.Errorf("Invalid node=%s, should begin with /", node)
return errors.New("Invalid node")
}
if err := client.mkdirRecursive(path.Dir(node)); err != nil {
glog.Errorf("Failed to create node=%s", path.Dir(node))
return err
}
flags := int32(0)
if ephemeral {
flags = zk.FlagEphemeral
}
_, err := client.conn.Create(node, value, flags, zk.WorldACL(zk.PermAll))
if err == nil || (err == zk.ErrNodeExists && ignoreExists) {
return nil
}
glog.Errorf("Failed to create node=%s, error=%s", node, err)
return err
}
// GetNode returns the attached payload of the latest version on the node
func (client *ZooKeeperClient) GetNode(node string, ignoreNotExists bool) ([]byte, error) {
data, _, err := client.conn.Get(node)
if err == nil || (err == zk.ErrNoNode && ignoreNotExists) {
return data, nil
}
glog.Errorf("Failed to get node=%s, error=%s", node, err)
return nil, err
}
// SetNode sets the payload on the node
func (client *ZooKeeperClient) SetNode(node string, value []byte) error {
_, stat, err := client.conn.Get(node)
if err != nil {
glog.Errorf("Failed to get node=%s, error=%s", node, err)
return err
}
stat, err = client.conn.Set(node, value, stat.Version)
if err != nil {
glog.Errorf("Failed to set node=%s, error=%s", node, err)
}
return err
}
// NodeExists check if the node already exists
func (client *ZooKeeperClient) NodeExists(node string) (bool, error) {
res, _, err := client.conn.Exists(node)
return res, err
}
// MkdirAll creates a directory recursively
func (client *ZooKeeperClient) mkdirRecursive(node string) error {
parent := path.Dir(node)
if parent != "/" {
if err := client.mkdirRecursive(parent); err != nil {
glog.Errorf("Failed to create node=%s", parent)
return err
}
}
_, err := client.conn.Create(node, nil, 0, zk.WorldACL(zk.PermAll))
if err == zk.ErrNodeExists {
return nil
}
return err
}
func (client *ZooKeeperClient) IsDisconnected() bool {
return client.conn.State() == zk.StateDisconnected
}
func (client *ZooKeeperClient) IsConnected() bool {
return client.conn.State() == zk.StateConnected
}
func (client *ZooKeeperClient) IsExpired() bool {
return client.conn.State() == zk.StateExpired
}