Add reporting of added/removed subcriptions

socketserver/internal/server/backend.go

@@ -15,6 +15,7 @@ import (
 	"strings"
 	"sync"
 	"time"
+	"github.com/gorilla/websocket"
 )
 
 var backendHttpClient http.Client
@@ -23,6 +24,7 @@ var responseCache *cache.Cache
 
 var getBacklogUrl string
 var postStatisticsUrl string
+var addTopicUrl string
 
 var backendSharedKey [32]byte
 var serverId int
@@ -39,6 +41,7 @@ func SetupBackend(config *ConfigFile) {
 
 	getBacklogUrl = fmt.Sprintf("%s/backlog", backendUrl)
 	postStatisticsUrl = fmt.Sprintf("%s/stats", backendUrl)
+	addTopicUrl = fmt.Sprintf("%s/topics", backendUrl)
 
 	messageBufferPool.New = New4KByteBuffer
 
@@ -203,15 +206,69 @@ func FetchBacklogData(chatSubs []string) ([]ClientMessage, error) {
 		return nil, httpError(resp.StatusCode)
 	}
 	dec := json.NewDecoder(resp.Body)
-	var messages []ClientMessage
+	var messageStrings []string
-	err = dec.Decode(messages)
+	err = dec.Decode(messageStrings)
 	if err != nil {
 		return nil, err
 	}
 
+	var messages = make([]ClientMessage, len(messageStrings))
+	for i, str := range messageStrings {
+		UnmarshalClientMessage([]byte(str), websocket.TextMessage, &messages[i])
+	}
+
 	return messages, nil
 }
 
+type NotOkError struct {
+	Response string
+	Code int
+}
+func (noe NotOkError) Error() string {
+	return fmt.Sprintf("backend returned %d: %s", noe.Code, noe.Response)
+}
+
+func SendNewTopicNotice(topic string) error {
+	return sendTopicNotice(topic, true)
+}
+
+func SendCleanupTopicsNotice(topics []string) error {
+	return sendTopicNotice(strings.Join(topics, ","), false)
+}
+
+func sendTopicNotice(topic string, added bool) error {
+	formData := url.Values{}
+	formData.Set("channels", topic)
+	if added {
+		formData.Set("added", "t")
+	} else {
+		formData.Set("added", "f")
+	}
+
+	sealedForm, err := SealRequest(formData)
+	if err != nil {
+		return err
+	}
+
+	resp, err := backendHttpClient.PostForm(addTopicUrl, sealedForm)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	respBytes, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return err
+	}
+
+	respStr := string(respBytes)
+	if respStr != "ok" {
+		return NotOkError{Code: resp.StatusCode, Response: respStr}
+	}
+
+	return nil
+}
+
 func httpError(statusCode int) error {
 	return fmt.Errorf("backend http error: %d", statusCode)
 }

socketserver/internal/server/publisher.go

@@ -6,6 +6,7 @@ package server
 import (
 	"sync"
 	"time"
+	"log"
 )
 
 type SubscriberList struct {
@@ -82,6 +83,14 @@ func _subscribeWhileRlocked(channelName string, value chan<- ClientMessage) {
 		list.Members = []chan<- ClientMessage{value} // Create it populated, to avoid reaper
 		ChatSubscriptionInfo[channelName] = list
 		ChatSubscriptionLock.Unlock()
+
+		go func(topic string) {
+			err := SendNewTopicNotice(topic)
+			if err != nil {
+				log.Println("error reporting new sub:", err)
+			}
+		}(channelName)
+
 		ChatSubscriptionLock.RLock()
 	} else {
 		list.Lock()
@@ -152,21 +161,28 @@ func UnsubscribeSingleChat(client *ClientInfo, channelName string) {
 	ChatSubscriptionLock.RUnlock()
 }
 
-const ReapingDelay = 120 * time.Minute
+const ReapingDelay = 20 * time.Minute
 
 // Checks ChatSubscriptionInfo for entries with no subscribers every ReapingDelay.
 // Started from SetupServer().
 func deadChannelReaper() {
 	for {
 		time.Sleep(ReapingDelay)
+		var cleanedUp = make([]string, 0, 6)
 		ChatSubscriptionLock.Lock()
 		for key, val := range ChatSubscriptionInfo {
-			if val != nil {
+			if val == nil || len(val.Members) == 0 {
-				if len(val.Members) == 0 {
 				delete(ChatSubscriptionInfo, key)
-				}
+				cleanedUp = append(cleanedUp, key)
 			}
 		}
 		ChatSubscriptionLock.Unlock()
+
+		if len(cleanedUp) != 0 {
+			err := SendCleanupTopicsNotice(cleanedUp)
+			if err != nil {
+				log.Println("error reporting cleaned subs:", err)
+			}
+		}
 	}
 }

socketserver/internal/server/types.go

@@ -34,13 +34,13 @@ type ClientMessage struct {
 	// Message ID. Increments by 1 for each message sent from the client.
 	// When replying to a command, the message ID must be echoed.
 	// When sending a server-initiated message, this is -1.
-	MessageID int
+	MessageID int `json:m`
 	// The command that the client wants from the server.
 	// When sent from the server, the literal string 'True' indicates success.
 	// Before sending, a blank Command will be converted into SuccessCommand.
-	Command Command
+	Command Command `json:c`
 	// Result of json.Unmarshal on the third field send from the client
-	Arguments interface{}
+	Arguments interface{} `json:a`
 
 	origArguments string
 }