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mem_realtime.go
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mem_realtime.go
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package realtime
import (
"sync"
"github.com/cozy/cozy-stack/pkg/logger"
"github.com/cozy/cozy-stack/pkg/prefixer"
)
var globalPrefixer = prefixer.NewPrefixer(prefixer.GlobalCouchCluster, "", "*")
type memHub struct {
sync.RWMutex
topics map[string]*topic
bySubscribers map[*Subscriber][]string // the list of topic keys by subscriber
}
func newMemHub() *memHub {
return &memHub{
topics: make(map[string]*topic),
bySubscribers: make(map[*Subscriber][]string),
}
}
func (h *memHub) Publish(db prefixer.Prefixer, verb string, doc, oldDoc Doc) {
h.RLock()
defer h.RUnlock()
e := newEvent(db, verb, doc, oldDoc)
key := topicKey(db, doc.DocType())
it := h.topics[key]
if it != nil {
select {
case it.broadcast <- e:
case running := <-it.running:
logger.WithNamespace("realtime").
Warnf("unexpected state: publish with running=%v", running)
if !running {
delete(h.topics, key)
}
}
}
it = h.topics[topicKey(globalPrefixer, "*")]
if it != nil {
it.broadcast <- e
}
}
func (h *memHub) Subscriber(db prefixer.Prefixer) *Subscriber {
return newSubscriber(h, db)
}
func (h *memHub) SubscribeFirehose() *Subscriber {
sub := newSubscriber(h, globalPrefixer)
key := topicKey(sub, "*")
h.subscribe(sub, key)
return sub
}
func (h *memHub) subscribe(sub *Subscriber, key string) {
h.Lock()
go func() {
defer h.Unlock()
h.addTopic(sub, key)
w := &toWatch{sub, ""}
for {
it, exists := h.topics[key]
if !exists {
it = newTopic()
h.topics[key] = it
}
select {
case it.subscribe <- w:
return
case running := <-it.running:
logger.WithNamespace("realtime").
Warnf("unexpected state: subscribe with running=%v", running)
if !running {
delete(h.topics, key)
}
}
}
}()
}
func (h *memHub) unsubscribe(sub *Subscriber, key string) {
h.Lock()
go func() {
defer h.Unlock()
it, exists := h.topics[key]
if !exists {
return
}
h.removeTopic(sub, key)
w := &toWatch{sub, ""}
select {
case it.unsubscribe <- w:
if running := <-it.running; !running {
delete(h.topics, key)
}
case running := <-it.running:
logger.WithNamespace("realtime").
Warnf("unexpected state: unsubscribe with running=%v", running)
if !running {
delete(h.topics, key)
}
}
}()
}
func (h *memHub) watch(sub *Subscriber, key, id string) {
h.Lock()
go func() {
defer h.Unlock()
h.addTopic(sub, key)
w := &toWatch{sub, id}
for {
it, exists := h.topics[key]
if !exists {
it = newTopic()
h.topics[key] = it
}
select {
case it.subscribe <- w:
return
case running := <-it.running:
logger.WithNamespace("realtime").
Warnf("unexpected state: watch with running=%v", running)
if !running {
delete(h.topics, key)
}
}
}
}()
}
func (h *memHub) unwatch(sub *Subscriber, key, id string) {
h.Lock()
go func() {
defer h.Unlock()
it, exists := h.topics[key]
if !exists {
return
}
w := &toWatch{sub, id}
select {
case it.unsubscribe <- w:
if running := <-it.running; !running {
delete(h.topics, key)
}
case running := <-it.running:
logger.WithNamespace("realtime").
Warnf("unexpected state: unwatch with running=%v", running)
if !running {
delete(h.topics, key)
}
}
}()
}
func (h *memHub) close(sub *Subscriber) {
h.RLock()
list := h.bySubscribers[sub]
h.RUnlock()
keys := make([]string, len(list))
copy(keys, list)
for _, key := range keys {
h.unsubscribe(sub, key)
}
}
func (h *memHub) addTopic(sub *Subscriber, key string) {
list := h.bySubscribers[sub]
for _, k := range list {
if k == key {
return
}
}
list = append(list, key)
h.bySubscribers[sub] = list
}
func (h *memHub) removeTopic(sub *Subscriber, key string) {
list := h.bySubscribers[sub]
kept := list[:0]
for _, k := range list {
if k != key {
kept = append(kept, k)
}
}
if len(kept) == 0 {
delete(h.bySubscribers, sub)
} else {
h.bySubscribers[sub] = kept
}
}
func topicKey(db prefixer.Prefixer, doctype string) string {
return db.DBPrefix() + ":" + doctype
}