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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
18package main
19
20import "container/list"
21import "encoding/json"
22import "expvar"
23import "flag"
24import "log"
25import "net/http"
26import "strconv"
27import "time"
28
29var port = flag.Int("port", 21059, "Port to listen on")
30
31var frame_count = expvar.NewInt("frame_count")
32var speak_count = expvar.NewInt("speak_count")
33var fetch_count = expvar.NewInt("fetch_count")
34var fetch_wait_count = expvar.NewInt("fetch_wait_count")
35var fetch_wake_count = expvar.NewInt("fetch_wake_count")
36
37type Message struct {
38 Time time.Time
39 ID string
40 Text string
41}
42
43type StoreRequest struct {
44 StartTime time.Time
45 Messages chan<- []Message
46}
47
48type Store struct {
49 Add chan *Message
50 Get chan *StoreRequest
51}
52
53// TODO: Monotonic clock
54
55func manage_store(store Store) {
56 messages := list.New()
57 message_count := 0
58 max_messages := 1000
59 waiting := list.New()
60main:
61 for {
62 select {
63 case new_message, ok := <-store.Add:
64 if !ok {
65 break main
66 }
67 speak_count.Add(1)
68 for waiter := waiting.Front(); waiter != nil; waiter = waiter.Next() {
69 waiter.Value.(*StoreRequest).Messages <- []Message{*new_message}
70 close(waiter.Value.(*StoreRequest).Messages)
71 fetch_wake_count.Add(1)
72 }
73 waiting.Init()
74 messages.PushBack(new_message)
75 if message_count < max_messages {
76 message_count++
77 } else {
78 messages.Remove(messages.Front())
79 }
80 case request, ok := <-store.Get:
81 if !ok {
82 break main
83 }
84 fetch_count.Add(1)
85 if messages.Back() == nil || !request.StartTime.Before(messages.Back().Value.(*Message).Time) {
86 waiting.PushBack(request)
87 fetch_wait_count.Add(1)
88 } else {
89 start := messages.Back()
90 response_size := 1
91 if messages.Front().Value.(*Message).Time.After(request.StartTime) {
92 start = messages.Front()
93 response_size = message_count
94 } else {
95 for start.Prev().Value.(*Message).Time.After(request.StartTime) {
96 start = start.Prev()
97 response_size++
98 }
99 }
100 response_messages := make([]Message, 0, response_size)
101 for m := start; m != nil; m = m.Next() {
102 response_messages = append(response_messages, *m.Value.(*Message))
103 }
104 request.Messages <- response_messages
105 }
106 }
107 }
108}
109
110func start_store() Store {
111 store := Store{make(chan *Message, 20), make(chan *StoreRequest, 20)}
112 go manage_store(store)
113 return store
114}
115
116const frame_html = `<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
117 "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
118
119<html xmlns="http://www.w3.org/1999/xhtml">
120<head>
121 <script type="text/javascript"><!--//--><![CDATA[//><!--
122 var since;
123 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."}]', "*");
124 function go() {
125 var delay = 10000;
126 var xhr = new XMLHttpRequest();
127 xhr.onreadystatechange = function() {
128 if (this.readyState == this.DONE) {
129 if (this.status == 200) {
130 var rtxt = this.responseText;
131 if (rtxt != null) {
132 var r = JSON.parse(rtxt);
133 if (r != null) {
134 window.parent.postMessage(rtxt, "*");
135 delay = 40;
136 if (r.length >= 1 && "Time" in r[r.length-1]) {
137 since = r[r.length-1]["Time"];
138 }
139 }
140 }
141 }
142 window.setTimeout(go, delay);
143 }
144 }
145 var uri = "/fetch";
146 if (since) {
147 uri += '?since="' + since + '"';
148 }
149 xhr.open("GET", uri);
150 xhr.send();
151 }
152 //--><!]]></script>
153</head>
154<body onload="go()">
155</body>
156</html>
157`
158
159func start_server(store Store) {
160 http.HandleFunc("/fetch", func(w http.ResponseWriter, r *http.Request) {
161 var since time.Time
162 url_since := r.FormValue("since")
163 if url_since != "" {
164 err := json.Unmarshal([]byte(url_since), &since)
165 if err != nil {
166 log.Print("fetch: parse since: ", err)
167 w.WriteHeader(http.StatusBadRequest)
168 w.Write([]byte("Could not parse since as date"))
169 return
170 }
171 }
172 messages_from_store := make(chan []Message, 1)
173 store.Get <- &StoreRequest{since, messages_from_store}
174
175 json_encoded, err := json.Marshal(<-messages_from_store)
176 if err != nil {
177 log.Print("json encode: ", err)
178 w.WriteHeader(http.StatusInternalServerError)
179 return
180 }
181 w.Header().Add("Content-Type", "application/json")
182 w.Header().Add("Access-Control-Allow-Origin", "*")
183 w.Write(json_encoded)
184 })
185
186 http.HandleFunc("/speak", func(w http.ResponseWriter, r *http.Request) {
187 store.Add <- &Message{
188 time.Now(),
189 r.FormValue("id"),
190 r.FormValue("text")}
191 })
192
193 http.HandleFunc("/frame", func(w http.ResponseWriter, r *http.Request) {
194 frame_count.Add(1)
195 w.Write([]byte(frame_html));
196 })
197
198 log.Fatal(http.ListenAndServe(":"+strconv.Itoa(*port), nil))
199}
200
201func main() {
202 flag.Parse()
203 store := start_store()
204 start_server(store)
205}