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[reliable-chat] / 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
31 var frame_count = expvar.NewInt("frame_count")
32 var speak_count = expvar.NewInt("speak_count")
33 var fetch_count = expvar.NewInt("fetch_count")
34 var fetch_wait_count = expvar.NewInt("fetch_wait_count")
35 var fetch_wake_count = expvar.NewInt("fetch_wake_count")
36
37 type Message struct {
38 Time time.Time
39 ID string
40 Text string
41 }
42
43 type StoreRequest struct {
44 StartTime time.Time
45 Messages chan<- []Message
46 }
47
48 type Store struct {
49 Add chan *Message
50 Get chan *StoreRequest
51 }
52
53 // TODO: Monotonic clock
54
55 func manage_store(store Store) {
56 messages := list.New()
57 message_count := 0
58 max_messages := 1000
59 waiting := list.New()
60 main:
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
110 func start_store() Store {
111 store := Store{make(chan *Message, 20), make(chan *StoreRequest, 20)}
112 go manage_store(store)
113 return store
114 }
115
116 const 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 function go() {
124 var delay = 10000;
125 var xhr = new XMLHttpRequest();
126 xhr.onreadystatechange = function() {
127 if (this.readyState == this.DONE) {
128 if (this.status == 200) {
129 var rtxt = this.responseText;
130 if (rtxt != null) {
131 var r = JSON.parse(rtxt);
132 if (r != null) {
133 window.parent.postMessage(rtxt, "*");
134 delay = 40;
135 if (r.length >= 1 && "Time" in r[r.length-1]) {
136 since = r[r.length-1]["Time"];
137 }
138 }
139 }
140 }
141 window.setTimeout(go, delay);
142 }
143 }
144 var uri = "/fetch";
145 if (since) {
146 uri += '?since="' + since + '"';
147 }
148 xhr.open("GET", uri);
149 xhr.send();
150 }
151 //--><!]]></script>
152 </head>
153 <body onload="go()">
154 </body>
155 </html>
156 `
157
158 func start_server(store Store) {
159 http.HandleFunc("/fetch", func(w http.ResponseWriter, r *http.Request) {
160 var since time.Time
161 url_since := r.FormValue("since")
162 if url_since != "" {
163 err := json.Unmarshal([]byte(url_since), &since)
164 if err != nil {
165 log.Print("fetch: parse since: ", err)
166 w.WriteHeader(http.StatusBadRequest)
167 w.Write([]byte("Could not parse since as date"))
168 return
169 }
170 }
171 messages_from_store := make(chan []Message, 1)
172 store.Get <- &StoreRequest{since, messages_from_store}
173
174 json_encoded, err := json.Marshal(<-messages_from_store)
175 if err != nil {
176 log.Print("json encode: ", err)
177 w.WriteHeader(http.StatusInternalServerError)
178 return
179 }
180 w.Header().Add("Content-Type", "application/json")
181 w.Header().Add("Access-Control-Allow-Origin", "*")
182 w.Write(json_encoded)
183 })
184
185 http.HandleFunc("/speak", func(w http.ResponseWriter, r *http.Request) {
186 store.Add <- &Message{
187 time.Now(),
188 r.FormValue("id"),
189 r.FormValue("text")}
190 })
191
192 http.HandleFunc("/frame", func(w http.ResponseWriter, r *http.Request) {
193 frame_count.Add(1)
194 w.Write([]byte(frame_html));
195 })
196
197 log.Fatal(http.ListenAndServe(":"+strconv.Itoa(*port), nil))
198 }
199
200 func main() {
201 flag.Parse()
202 store := start_store()
203 start_server(store)
204 }