micro/registry/consul_watcher.go

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package registry
import (
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"errors"
"sync"
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"github.com/hashicorp/consul/api"
"github.com/hashicorp/consul/watch"
)
type consulWatcher struct {
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r *consulRegistry
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wp *watch.WatchPlan
watchers map[string]*watch.WatchPlan
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next chan *Result
exit chan bool
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sync.RWMutex
services map[string][]*Service
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}
func newConsulWatcher(cr *consulRegistry) (Watcher, error) {
cw := &consulWatcher{
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r: cr,
exit: make(chan bool),
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next: make(chan *Result, 10),
watchers: make(map[string]*watch.WatchPlan),
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services: make(map[string][]*Service),
}
wp, err := watch.Parse(map[string]interface{}{"type": "services"})
if err != nil {
return nil, err
}
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wp.Handler = cw.handle
go wp.Run(cr.Address)
cw.wp = wp
return cw, nil
}
func (cw *consulWatcher) serviceHandler(idx uint64, data interface{}) {
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entries, ok := data.([]*api.ServiceEntry)
if !ok {
return
}
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serviceMap := map[string]*Service{}
serviceName := ""
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for _, e := range entries {
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serviceName = e.Service.Service
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// version is now a tag
version, found := decodeVersion(e.Service.Tags)
// service ID is now the node id
id := e.Service.ID
// key is always the version
key := version
// address is service address
address := e.Service.Address
// if we can't get the version we bail
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if !found {
continue
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}
svc, ok := serviceMap[key]
if !ok {
svc = &Service{
Endpoints: decodeEndpoints(e.Service.Tags),
Name: e.Service.Service,
Version: version,
}
serviceMap[key] = svc
}
var del bool
for _, check := range e.Checks {
if check.ServiceName != serviceName {
continue
}
if check.ServiceID != id {
continue
}
// delete the node
if check.Status == "critical" {
del = true
break
}
}
// if delete then skip the node
if del {
continue
}
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svc.Nodes = append(svc.Nodes, &Node{
Id: id,
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Address: address,
Port: e.Service.Port,
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Metadata: decodeMetadata(e.Service.Tags),
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})
}
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cw.RLock()
rservices := cw.services
cw.RUnlock()
var newServices []*Service
// serviceMap is the new set of services keyed by name+version
for _, newService := range serviceMap {
// append to the new set of cached services
newServices = append(newServices, newService)
// check if the service exists in the existing cache
oldServices, ok := rservices[serviceName]
if !ok {
// does not exist? then we're creating brand new entries
cw.next <- &Result{Action: "create", Service: newService}
continue
}
// service exists. ok let's figure out what to update and delete version wise
action := "create"
for _, oldService := range oldServices {
// does this version exist?
// no? then default to create
if oldService.Version != newService.Version {
continue
}
// yes? then it's an update
action = "update"
var nodes []*Node
// check the old nodes to see if they've been deleted
for _, oldNode := range oldService.Nodes {
var seen bool
for _, newNode := range newService.Nodes {
if newNode.Id == oldNode.Id {
seen = true
break
}
}
// does the old node exist in the new set of nodes
// no? then delete that shit
if !seen {
nodes = append(nodes, oldNode)
}
}
// it's an update rather than creation
if len(nodes) > 0 {
delService := oldService
delService.Nodes = nodes
cw.next <- &Result{Action: "delete", Service: delService}
}
}
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cw.next <- &Result{Action: action, Service: newService}
}
// Now check old versions that may not be in new services map
for _, old := range rservices[serviceName] {
// old version does not exist in new version map
// kill it with fire!
if _, ok := serviceMap[old.Version]; !ok {
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cw.next <- &Result{Action: "delete", Service: old}
}
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}
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cw.Lock()
cw.services[serviceName] = newServices
cw.Unlock()
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}
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func (cw *consulWatcher) handle(idx uint64, data interface{}) {
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services, ok := data.(map[string][]string)
if !ok {
return
}
// add new watchers
for service, _ := range services {
if _, ok := cw.watchers[service]; ok {
continue
}
wp, err := watch.Parse(map[string]interface{}{
"type": "service",
"service": service,
})
if err == nil {
wp.Handler = cw.serviceHandler
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go wp.Run(cw.r.Address)
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cw.watchers[service] = wp
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cw.next <- &Result{Action: "create", Service: &Service{Name: service}}
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}
}
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cw.RLock()
rservices := cw.services
cw.RUnlock()
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// remove unknown services from registry
for service, _ := range rservices {
if _, ok := services[service]; !ok {
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cw.Lock()
delete(cw.services, service)
cw.Unlock()
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}
}
// remove unknown services from watchers
for service, w := range cw.watchers {
if _, ok := services[service]; !ok {
w.Stop()
delete(cw.watchers, service)
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cw.next <- &Result{Action: "delete", Service: &Service{Name: service}}
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}
}
}
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func (cw *consulWatcher) Next() (*Result, error) {
select {
case <-cw.exit:
return nil, errors.New("result chan closed")
case r, ok := <-cw.next:
if !ok {
return nil, errors.New("result chan closed")
}
return r, nil
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}
return nil, errors.New("result chan closed")
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}
func (cw *consulWatcher) Stop() {
select {
case <-cw.exit:
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return
default:
close(cw.exit)
if cw.wp == nil {
return
}
cw.wp.Stop()
// drain results
for {
select {
case <-cw.next:
default:
return
}
}
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}
}