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monitor.go
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monitor.go
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package main
import (
"code.google.com/p/go.net/websocket"
"encoding/json"
"io"
"log"
"net/http"
"os"
"runtime"
"strconv"
"time"
)
type wsConnection struct {
// The websocket connection.
ws *websocket.Conn
// Buffered channel of outbound messages.
send chan string
}
type monitorHub struct {
connections map[*wsConnection]bool
broadcast chan string
register chan *wsConnection
unregister chan *wsConnection
}
var hub = monitorHub{
broadcast: make(chan string),
register: make(chan *wsConnection, 10),
unregister: make(chan *wsConnection, 10),
connections: make(map[*wsConnection]bool),
}
func (h *monitorHub) run() {
for {
select {
case c := <-h.register:
h.connections[c] = true
log.Println("Queuing initial status")
c.send <- initialStatus()
case c := <-h.unregister:
log.Println("Unregistering connection")
delete(h.connections, c)
case m := <-h.broadcast:
for c := range h.connections {
if len(c.send)+5 > cap(c.send) {
log.Println("WS connection too close to cap")
c.send <- `{"error": "too slow"}`
close(c.send)
go c.ws.Close()
h.unregister <- c
continue
}
select {
case c.send <- m:
default:
close(c.send)
delete(h.connections, c)
log.Println("Closing channel when sending")
go c.ws.Close()
}
}
}
}
}
func (c *wsConnection) reader() {
for {
var message string
err := websocket.Message.Receive(c.ws, &message)
if err != nil {
log.Println("WS read error:", err)
break
}
log.Println("WS message", message)
// TODO(ask) take configuration options etc
//h.broadcast <- message
}
c.ws.Close()
}
func (c *wsConnection) writer() {
for message := range c.send {
err := websocket.Message.Send(c.ws, message)
if err != nil {
log.Println("WS write error:", err)
break
}
}
c.ws.Close()
}
func wsHandler(ws *websocket.Conn) {
log.Println("Starting new WS connection")
c := &wsConnection{send: make(chan string, 180), ws: ws}
hub.register <- c
defer func() {
log.Println("sending unregister message")
hub.unregister <- c
}()
go c.writer()
c.reader()
}
func initialStatus() string {
status := map[string]string{"v": VERSION, "id": serverId}
hostname, err := os.Hostname()
if err == nil {
status["h"] = hostname
}
message, err := json.Marshal(status)
return string(message)
}
func logStatus() {
log.Println(initialStatus())
lastQueryCount := qCounter
for {
newQueries := qCounter - lastQueryCount
lastQueryCount = qCounter
log.Println("goroutines", runtime.NumGoroutine(), "queries", newQueries)
time.Sleep(60 * time.Second)
}
}
func monitor() {
go logStatus()
if len(*flaghttp) == 0 {
return
}
go hub.run()
go httpHandler()
lastQueryCount := qCounter
for {
newQueries := qCounter - lastQueryCount
lastQueryCount = qCounter
status := map[string]string{}
status["up"] = strconv.Itoa(int(time.Since(timeStarted).Seconds()))
status["qs"] = strconv.FormatUint(qCounter, 10)
status["qps"] = strconv.FormatUint(newQueries, 10)
message, err := json.Marshal(status)
if err == nil {
hub.broadcast <- string(message)
}
time.Sleep(1 * time.Second)
}
}
func MainServer(w http.ResponseWriter, req *http.Request) {
if req.RequestURI != "/version" {
http.NotFound(w, req)
return
}
io.WriteString(w, `<html><head><title>GeoDNS `+
VERSION+`</title><body>`+
initialStatus()+
`</body></html>`)
}
func httpHandler() {
http.Handle("/monitor", websocket.Handler(wsHandler))
http.HandleFunc("/", MainServer)
log.Fatal(http.ListenAndServe(*flaghttp, nil))
}