git.scottworley.com Git - reliable-chat/blob - server/server.go

   1 /*  reliable-chat - multipath chat
   2  *  Copyright (C) 2012  Scott Worley <sworley@chkno.net>
   3  *
   4  *  This program is free software: you can redistribute it and/or modify
   5  *  it under the terms of the GNU Affero General Public License as
   6  *  published by the Free Software Foundation, either version 3 of the
   7  *  License, or (at your option) any later version.
   8  *
   9  *  This program is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *  GNU Affero General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU Affero General Public License
  15  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 package main
  19
  20 import "container/list"
  21 import "encoding/json"
  22 import "expvar"
  23 import "flag"
  24 import "log"
  25 import "net/http"
  26 import "strconv"
  27 import "time"
  28
  29 var port = flag.Int("port", 21059, "Port to listen on")
  30 var localaddress = flag.String("localaddress", "", "Local address to bind to")
  31
  32 var frame_count = expvar.NewInt("frame_count")
  33 var speak_count = expvar.NewInt("speak_count")
  34 var fetch_count = expvar.NewInt("fetch_count")
  35 var fetch_wait_count = expvar.NewInt("fetch_wait_count")
  36 var fetch_wake_count = expvar.NewInt("fetch_wake_count")
  37
  38 type Message struct {
  39         Time time.Time
  40         ID   string
  41         Text string
  42 }
  43
  44 type StoreRequest struct {
  45         StartTime time.Time
  46         Messages  chan<- []Message
  47 }
  48
  49 type Store struct {
  50         Add chan *Message
  51         Get chan *StoreRequest
  52 }
  53
  54 // TODO: Monotonic clock
  55
  56 func manage_store(store Store) {
  57         messages := list.New()
  58         message_count := 0
  59         max_messages := 1000
  60         waiting := list.New()
  61 main:
  62         for {
  63                 select {
  64                 case new_message, ok := <-store.Add:
  65                         if !ok {
  66                                 break main
  67                         }
  68                         speak_count.Add(1)
  69                         for waiter := waiting.Front(); waiter != nil; waiter = waiter.Next() {
  70                                 waiter.Value.(*StoreRequest).Messages <- []Message{*new_message}
  71                                 close(waiter.Value.(*StoreRequest).Messages)
  72                                 fetch_wake_count.Add(1)
  73                         }
  74                         waiting.Init()
  75                         messages.PushBack(new_message)
  76                         if message_count < max_messages {
  77                                 message_count++
  78                         } else {
  79                                 messages.Remove(messages.Front())
  80                         }
  81                 case request, ok := <-store.Get:
  82                         if !ok {
  83                                 break main
  84                         }
  85                         fetch_count.Add(1)
  86                         if messages.Back() == nil || !request.StartTime.Before(messages.Back().Value.(*Message).Time) {
  87                                 waiting.PushBack(request)
  88                                 fetch_wait_count.Add(1)
  89                         } else {
  90                                 start := messages.Back()
  91                                 response_size := 1
  92                                 if messages.Front().Value.(*Message).Time.After(request.StartTime) {
  93                                         start = messages.Front()
  94                                         response_size = message_count
  95                                 } else {
  96                                         for start.Prev().Value.(*Message).Time.After(request.StartTime) {
  97                                                 start = start.Prev()
  98                                                 response_size++
  99                                         }
 100                                 }
 101                                 response_messages := make([]Message, 0, response_size)
 102                                 for m := start; m != nil; m = m.Next() {
 103                                         response_messages = append(response_messages, *m.Value.(*Message))
 104                                 }
 105                                 request.Messages <- response_messages
 106                         }
 107                 }
 108         }
 109 }
 110
 111 func start_store() Store {
 112         store := Store{make(chan *Message, 20), make(chan *StoreRequest, 20)}
 113         go manage_store(store)
 114         return store
 115 }
 116
 117 const frame_html = `<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
 118   "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
 119
 120 <html xmlns="http://www.w3.org/1999/xhtml">
 121 <head>
 122  <script type="text/javascript"><!--//--><![CDATA[//><!--
 123   var since;
 124   window.parent.postMessage('[{"Time":"2000-01-01T00:00:00.000000-00:00","ID":"/frame deprecation warning","Text":"*** You are using an old version of the client.  Please upgrade."}]', "*");
 125   function go() {
 126    var delay = 10000;
 127    var xhr = new XMLHttpRequest();
 128    xhr.onreadystatechange = function() {
 129     if (this.readyState == this.DONE) {
 130      if (this.status == 200) {
 131       var rtxt = this.responseText;
 132       if (rtxt != null) {
 133        var r = JSON.parse(rtxt);
 134        if (r != null) {
 135         window.parent.postMessage(rtxt, "*");
 136         delay = 40;
 137         if (r.length >= 1 && "Time" in r[r.length-1]) {
 138          since = r[r.length-1]["Time"];
 139         }
 140        }
 141       }
 142      }
 143      window.setTimeout(go, delay);
 144     }
 145    }
 146    var uri = "/fetch";
 147    if (since) {
 148     uri += '?since="' + since + '"';
 149    }
 150    xhr.open("GET", uri);
 151    xhr.send();
 152   }
 153   //--><!]]></script>
 154 </head>
 155 <body onload="go()">
 156 </body>
 157 </html>
 158 `
 159
 160 const robots_txt = `User-agent: *
 161 Disallow: /
 162 `
 163
 164 func start_server(store Store) {
 165         http.HandleFunc("/fetch", func(w http.ResponseWriter, r *http.Request) {
 166                 var since time.Time
 167                 url_since := r.FormValue("since")
 168                 if url_since != "" {
 169                         err := json.Unmarshal([]byte(url_since), &since)
 170                         if err != nil {
 171                                 log.Print("fetch: parse since: ", err)
 172                                 w.WriteHeader(http.StatusBadRequest)
 173                                 w.Write([]byte("Could not parse since as date"))
 174                                 return
 175                         }
 176                 }
 177                 messages_from_store := make(chan []Message, 1)
 178                 store.Get <- &StoreRequest{since, messages_from_store}
 179
 180                 json_encoded, err := json.Marshal(<-messages_from_store)
 181                 if err != nil {
 182                         log.Print("json encode: ", err)
 183                         w.WriteHeader(http.StatusInternalServerError)
 184                         return
 185                 }
 186                 w.Header().Add("Content-Type", "application/json")
 187                 w.Header().Add("Access-Control-Allow-Origin", "*")
 188                 w.Write(json_encoded)
 189         })
 190
 191         http.HandleFunc("/speak", func(w http.ResponseWriter, r *http.Request) {
 192                 store.Add <- &Message{
 193                         time.Now(),
 194                         r.FormValue("id"),
 195                         r.FormValue("text")}
 196         })
 197
 198         http.HandleFunc("/frame", func(w http.ResponseWriter, r *http.Request) {
 199                 frame_count.Add(1)
 200                 w.Write([]byte(frame_html));
 201         })
 202
 203         http.HandleFunc("/robots.txt", func(w http.ResponseWriter, r *http.Request) {
 204                 w.Write([]byte(robots_txt));
 205         })
 206
 207         log.Fatal(http.ListenAndServe(*localaddress+":"+strconv.Itoa(*port), nil))
 208 }
 209
 210 func main() {
 211         flag.Parse()
 212         store := start_store()
 213         start_server(store)
 214 }