/
watcher.go
250 lines (219 loc) · 4.78 KB
/
watcher.go
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package zookeeper
import (
"errors"
"path"
"github.com/micro/go-micro/v2/registry"
"github.com/samuel/go-zookeeper/zk"
)
type zookeeperWatcher struct {
wo registry.WatchOptions
client *zk.Conn
stop chan bool
results chan result
respChan chan watchResponse
}
type watchResponse struct {
event zk.Event
service *registry.Service
err error
}
type result struct {
res *registry.Result
err error
}
func newZookeeperWatcher(r *zookeeperRegistry, opts ...registry.WatchOption) (registry.Watcher, error) {
var wo registry.WatchOptions
for _, o := range opts {
o(&wo)
}
zw := &zookeeperWatcher{
wo: wo,
client: r.client,
stop: make(chan bool),
results: make(chan result),
respChan: make(chan watchResponse),
}
go zw.watch()
return zw, nil
}
func (zw *zookeeperWatcher) writeRespChan(resp *watchResponse) {
if resp == nil {
return
}
select {
case <-zw.stop:
default:
zw.respChan <- *resp
}
}
func (zw *zookeeperWatcher) writeResult(r *result) {
if r == nil {
return
}
select {
case <-zw.stop:
default:
zw.results <- *r
}
}
func (zw *zookeeperWatcher) watchDir(key string) {
for {
// get current children for a key
children, _, childEventCh, err := zw.client.ChildrenW(key)
if err != nil {
zw.writeRespChan(&watchResponse{zk.Event{}, nil, err})
return
}
select {
case e := <-childEventCh:
if e.Type != zk.EventNodeChildrenChanged {
continue
}
newChildren, _, err := zw.client.Children(e.Path)
if err != nil {
zw.writeRespChan(&watchResponse{e, nil, err})
return
}
// a node was added -- watch the new node
for _, i := range newChildren {
if contains(children, i) {
continue
}
newNode := path.Join(e.Path, i)
if key == prefix {
// a new service was created under prefix
go zw.watchDir(newNode)
nodes, _, _ := zw.client.Children(newNode)
for _, node := range nodes {
n := path.Join(newNode, node)
go zw.watchKey(n)
s, _, err := zw.client.Get(n)
if err != nil {
continue
}
e.Type = zk.EventNodeCreated
srv, err := decode(s)
if err != nil {
continue
}
zw.writeRespChan(&watchResponse{e, srv, err})
}
} else {
go zw.watchKey(newNode)
s, _, err := zw.client.Get(newNode)
if err != nil {
continue
}
e.Type = zk.EventNodeCreated
srv, err := decode(s)
if err != nil {
continue
}
zw.writeRespChan(&watchResponse{e, srv, err})
}
}
case <-zw.stop:
// There is no way to stop GetW/ChildrenW so just quit
return
}
}
}
func (zw *zookeeperWatcher) watchKey(key string) {
for {
s, _, keyEventCh, err := zw.client.GetW(key)
if err != nil {
zw.writeRespChan(&watchResponse{zk.Event{}, nil, err})
return
}
select {
case e := <-keyEventCh:
switch e.Type {
case zk.EventNodeDataChanged, zk.EventNodeCreated, zk.EventNodeDeleted:
if e.Type != zk.EventNodeDeleted {
// get the updated service
s, _, err = zw.client.Get(e.Path)
if err != nil {
continue
}
}
srv, err := decode(s)
if err != nil {
continue
}
zw.writeRespChan(&watchResponse{e, srv, err})
}
if e.Type == zk.EventNodeDeleted {
//The Node was deleted - stop watching
return
}
case <-zw.stop:
// There is no way to stop GetW/ChildrenW so just quit
return
}
}
}
func (zw *zookeeperWatcher) watch() {
services := func() []string {
if len(zw.wo.Service) > 0 {
return []string{zw.wo.Service}
}
allServices, _, err := zw.client.Children(prefix)
if err != nil {
zw.writeResult(&result{nil, err})
}
return allServices
}
//watch every service
for _, service := range services() {
sPath := childPath(prefix, service)
go zw.watchDir(sPath)
children, _, err := zw.client.Children(sPath)
if err != nil {
zw.writeResult(&result{nil, err})
}
for _, c := range children {
go zw.watchKey(path.Join(sPath, c))
}
}
var service *registry.Service
var action string
for {
select {
case <-zw.stop:
return
case rsp := <-zw.respChan:
if rsp.err != nil {
zw.writeResult(&result{nil, rsp.err})
continue
}
switch rsp.event.Type {
case zk.EventNodeDataChanged:
action = "update"
service = rsp.service
case zk.EventNodeDeleted:
action = "delete"
service = rsp.service
case zk.EventNodeCreated:
action = "create"
service = rsp.service
}
}
zw.writeResult(&result{®istry.Result{Action: action, Service: service}, nil})
}
}
func (zw *zookeeperWatcher) Stop() {
select {
case <-zw.stop:
return
default:
close(zw.stop)
}
}
func (zw *zookeeperWatcher) Next() (*registry.Result, error) {
select {
case <-zw.stop:
return nil, errors.New("watcher stopped")
case r := <-zw.results:
return r.res, r.err
}
}