Expose server statistics at /stats

socketserver/internal/server/backend.go

@@ -64,7 +64,7 @@ func getCacheKey(remoteCommand, data string) string {
 // The backend can POST here to publish a message to clients with no caching.
 // The POST arguments are `cmd`, `args`, `channel`, and `scope`.
 // The `scope` argument is required because no attempt is made to infer the scope from the command, unlike /cached_pub.
-func HBackendPublishRequest(w http.ResponseWriter, r *http.Request) {
+func HTTPBackendUncachedPublish(w http.ResponseWriter, r *http.Request) {
 	r.ParseForm()
 	formData, err := UnsealRequest(r.Form)
 	if err != nil {

socketserver/internal/server/handlecore.go

@@ -60,9 +60,11 @@ func SetupServerAndHandle(config *ConfigFile, serveMux *http.ServeMux) {
 	BannerHTML = bannerBytes
 
 	serveMux.HandleFunc("/", HTTPHandleRootURL)
+	serveMux.HandleFunc("/stats", HTTPShowStatistics)
+
 	serveMux.HandleFunc("/drop_backlog", HTTPBackendDropBacklog)
-	serveMux.HandleFunc("/uncached_pub", HBackendPublishRequest)
-	serveMux.HandleFunc("/cached_pub", HBackendUpdateAndPublish)
+	serveMux.HandleFunc("/uncached_pub", HTTPBackendUncachedPublish)
+	serveMux.HandleFunc("/cached_pub", HTTPBackendCachedPublish)
 
 	announceForm, err := SealRequest(url.Values{
 		"startup": []string{"1"},
@@ -118,25 +120,34 @@ func HTTPHandleRootURL(w http.ResponseWriter, r *http.Request) {
 
 // ErrProtocolGeneric is sent in a ErrorCommand Reply.
 var ErrProtocolGeneric error = errors.New("FFZ Socket protocol error.")
+
 // ErrProtocolNegativeMsgID is sent in a ErrorCommand Reply when a negative MessageID is received.
 var ErrProtocolNegativeMsgID error = errors.New("FFZ Socket protocol error: negative or zero message ID.")
+
 // ErrExpectedSingleString is sent in a ErrorCommand Reply when the Arguments are of the wrong type.
 var ErrExpectedSingleString = errors.New("Error: Expected single string as arguments.")
+
 // ErrExpectedSingleInt is sent in a ErrorCommand Reply when the Arguments are of the wrong type.
 var ErrExpectedSingleInt = errors.New("Error: Expected single integer as arguments.")
+
 // ErrExpectedTwoStrings is sent in a ErrorCommand Reply when the Arguments are of the wrong type.
 var ErrExpectedTwoStrings = errors.New("Error: Expected array of string, string as arguments.")
+
 // ErrExpectedStringAndBool is sent in a ErrorCommand Reply when the Arguments are of the wrong type.
 var ErrExpectedStringAndBool = errors.New("Error: Expected array of string, bool as arguments.")
+
 // ErrExpectedStringAndInt is sent in a ErrorCommand Reply when the Arguments are of the wrong type.
 var ErrExpectedStringAndInt = errors.New("Error: Expected array of string, int as arguments.")
+
 // ErrExpectedStringAndIntGotFloat is sent in a ErrorCommand Reply when the Arguments are of the wrong type.
 var ErrExpectedStringAndIntGotFloat = errors.New("Error: Second argument was a float, expected an integer.")
 
 // CloseGotBinaryMessage is the termination reason when the client sends a binary websocket frame.
 var CloseGotBinaryMessage = websocket.CloseError{Code: websocket.CloseUnsupportedData, Text: "got binary packet"}
+
 // CloseTimedOut is the termination reason when the client fails to send or respond to ping frames.
 var CloseTimedOut = websocket.CloseError{Code: websocket.CloseNoStatusReceived, Text: "no ping replies for 5 minutes"}
+
 // CloseFirstMessageNotHello is the termination reason
 var CloseFirstMessageNotHello = websocket.CloseError{
 	Text: "Error - the first message sent must be a 'hello'",
@@ -305,7 +316,7 @@ func getDeadline() time.Time {
 }
 
 func CloseConnection(conn *websocket.Conn, closeMsg *websocket.CloseError) {
-	Statistics.DisconnectCodes[closeMsg.Code]++
+	Statistics.DisconnectCodes[strconv.Itoa(closeMsg.Code)]++
 	Statistics.DisconnectReasons[closeMsg.Text]++
 
 	conn.WriteControl(websocket.CloseMessage, websocket.FormatCloseMessage(closeMsg.Code, closeMsg.Text), getDeadline())

socketserver/internal/server/publisher.go

@@ -351,7 +351,7 @@ func HTTPBackendDropBacklog(w http.ResponseWriter, r *http.Request) {
 // Publish a message to clients, and update the in-server cache for the message.
 // notes:
 // `scope` is implicit in the command
-func HBackendUpdateAndPublish(w http.ResponseWriter, r *http.Request) {
+func HTTPBackendCachedPublish(w http.ResponseWriter, r *http.Request) {
 	r.ParseForm()
 	formData, err := UnsealRequest(r.Form)
 	if err != nil {

socketserver/internal/server/stats.go

@@ -1,26 +1,48 @@
 package server
 
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+)
+
 type StatsData struct {
-	ClientConnectsTotal int64
-	ClientDisconnectsTotal int64
+	ClientConnectsTotal      int64
+	ClientDisconnectsTotal   int64
 	FirstNotHelloDisconnects int64
 
-	DisconnectCodes map[int]int64
+	DisconnectCodes   map[string]int64
 	DisconnectReasons map[string]int64
 
 	CommandsIssuedTotal int64
-	CommandsIssuedMap map[Command]int64
+	CommandsIssuedMap   map[Command]int64
 
 	MessagesSent int64
+
+	Version int
 }
 
+const StatsDataVersion = 1
+
 func newStatsData() *StatsData {
 	return &StatsData{
 		CommandsIssuedMap: make(map[Command]int64),
-		DisconnectCodes: make(map[int]int64),
+		DisconnectCodes:   make(map[string]int64),
 		DisconnectReasons: make(map[string]int64),
+		Version:           StatsDataVersion,
 	}
 }
 
 // Statistics is several variables that get incremented during normal operation of the server.
+// Its structure should be versioned as it is exposed via JSON.
 var Statistics = newStatsData()
+
+func HTTPShowStatistics(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "application/json")
+
+	jsonBytes, _ := json.Marshal(Statistics)
+	outBuf := bytes.NewBuffer(nil)
+	json.Indent(outBuf, jsonBytes, "", "\t")
+
+	outBuf.WriteTo(w)
+}