Add /all_topics endpoint

Temporarily not protected with sealing, we'll see how the performance is
first.

socketserver/server/handlecore.go

@@ -103,6 +103,7 @@ func SetupServerAndHandle(config *ConfigFile, serveMux *http.ServeMux) {
 	serveMux.HandleFunc("/uncached_pub", HTTPBackendUncachedPublish)
 	serveMux.HandleFunc("/cached_pub", HTTPBackendCachedPublish)
 	serveMux.HandleFunc("/get_sub_count", HTTPGetSubscriberCount)
+	serveMux.HandleFunc("/all_topics", HTTPListAllTopics)
 
 	announceForm, err := Backend.secureForm.Seal(url.Values{
 		"startup": []string{"1"},

socketserver/server/publisher.go

@@ -1,6 +1,7 @@
 package server
 
 import (
+	"encoding/json"
 	"fmt"
 	"net/http"
 	"strconv"
@@ -10,6 +11,7 @@ import (
 
 	"github.com/FrankerFaceZ/FrankerFaceZ/socketserver/server/rate"
 	"github.com/pkg/errors"
+	"golang.org/x/sync/singleflight"
 )
 
 // LastSavedMessage contains a reply to a command along with an expiration time.
@@ -25,6 +27,8 @@ type LastSavedMessage struct {
 var CachedLastMessages = make(map[Command]map[string]LastSavedMessage)
 var CachedLSMLock sync.RWMutex
 
+var singleFlighter singleflight.Group
+
 func cachedMessageJanitor() {
 	for {
 		time.Sleep(1 * time.Hour)
@@ -303,3 +307,19 @@ func HTTPGetSubscriberCount(w http.ResponseWriter, r *http.Request) {
 
 	fmt.Fprint(w, CountSubscriptions(strings.Split(channel, ",")))
 }
+
+func HTTPListAllTopics(w http.ResponseWriter, r *http.Request) {
+	r.ParseForm()
+	_, err := Backend.secureForm.Unseal(r.Form)
+	if err != nil {
+		//w.WriteHeader(403)
+		//fmt.Fprintf(w, "Error: %v", err)
+		//return
+	}
+
+	topicList, _, _ := singleFlighter.Do("/all_topics", func() (interface{}, error) {
+		return GetAllTopics(), nil
+	})
+	w.WriteHeader(200)
+	json.NewEncoder(w).Encode(topicList)
+}

socketserver/server/subscriptions.go

@@ -47,6 +47,20 @@ func CountSubscriptions(channels []string) int {
 	return count
 }
 
+func GetAllTopics() []string {
+	ChatSubscriptionLock.RLock()
+	defer ChatSubscriptionLock.RUnlock()
+
+	count := len(ChatSubscriptionInfo)
+	list := make([]string, count)
+	i := 0
+	for topicName := range ChatSubscriptionInfo {
+		list[i] = topicName
+		i++
+	}
+	return list
+}
+
 func SubscribeChannel(client *ClientInfo, channelName string) {
 	ChatSubscriptionLock.RLock()
 	_subscribeWhileRlocked(channelName, client)