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Implement nicknames
[reliable-chat] / server / server.go
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1package main
2
3import "container/list"
4import "encoding/json"
5import "expvar"
6import "flag"
7import "log"
8import "net/http"
9import "strconv"
10import "time"
11
12var port = flag.Int("port", 21059, "Port to listen on")
13
14var speak_count = expvar.NewInt("speak_count")
15var fetch_count = expvar.NewInt("fetch_count")
16var fetch_wait_count = expvar.NewInt("fetch_wait_count")
17var fetch_wake_count = expvar.NewInt("fetch_wake_count")
18
19type Message struct {
20 Time time.Time
21 ID string
22 Text string
23}
24
25type StoreRequest struct {
26 StartTime time.Time
27 Messages chan<- []Message
28}
29
30type Store struct {
31 Add chan *Message
32 Get chan *StoreRequest
33}
34
35// TODO: Monotonic clock
36
37func manage_store(store Store) {
38 messages := list.New()
39 message_count := 0
40 max_messages := 1000
41 waiting := list.New()
42main:
43 for {
44 select {
45 case new_message, ok := <-store.Add:
46 if !ok {
47 break main
48 }
49 speak_count.Add(1)
50 for waiter := waiting.Front(); waiter != nil; waiter = waiter.Next() {
51 waiter.Value.(*StoreRequest).Messages <- []Message{*new_message}
52 close(waiter.Value.(*StoreRequest).Messages)
53 fetch_wake_count.Add(1)
54 }
55 waiting.Init()
56 messages.PushBack(new_message)
57 if message_count < max_messages {
58 message_count++
59 } else {
60 messages.Remove(messages.Front())
61 }
62 case request, ok := <-store.Get:
63 if !ok {
64 break main
65 }
66 fetch_count.Add(1)
67 if messages.Back() == nil || !request.StartTime.Before(messages.Back().Value.(*Message).Time) {
68 waiting.PushBack(request)
69 fetch_wait_count.Add(1)
70 } else {
71 start := messages.Back()
72 response_size := 1
73 if messages.Front().Value.(*Message).Time.After(request.StartTime) {
74 start = messages.Front()
75 response_size = message_count
76 } else {
77 for start.Prev().Value.(*Message).Time.After(request.StartTime) {
78 start = start.Prev()
79 response_size++
80 }
81 }
82 response_messages := make([]Message, 0, response_size)
83 for m := start; m != nil; m = m.Next() {
84 response_messages = append(response_messages, *m.Value.(*Message))
85 }
86 request.Messages <- response_messages
87 }
88 }
89 }
90}
91
92func start_store() Store {
93 store := Store{make(chan *Message, 20), make(chan *StoreRequest, 20)}
94 go manage_store(store)
95 return store
96}
97
98const frame_html = `<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
99 "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
100
101<html xmlns="http://www.w3.org/1999/xhtml">
102<head>
103 <script type="text/javascript"><!--//--><![CDATA[//><!--
104 var since;
105 function go() {
106 var delay = 10000;
107 var xhr = new XMLHttpRequest();
108 xhr.onreadystatechange = function() {
109 if (this.readyState == this.DONE) {
110 if (this.status == 200) {
111 var rtxt = this.responseText;
112 if (rtxt != null) {
113 var r = JSON.parse(rtxt);
114 if (r != null) {
115 window.parent.postMessage(rtxt, "*");
116 delay = 40;
117 if (r.length >= 1 && "Time" in r[r.length-1]) {
118 since = r[r.length-1]["Time"];
119 }
120 }
121 }
122 }
123 window.setTimeout(go, delay);
124 }
125 }
126 var uri = "/fetch";
127 if (since) {
128 uri += '?since="' + since + '"';
129 }
130 xhr.open("GET", uri);
131 xhr.send();
132 }
133 //--><!]]></script>
134</head>
135<body onload="go()">
136</body>
137</html>
138`
139
140func start_server(store Store) {
141 http.HandleFunc("/fetch", func(w http.ResponseWriter, r *http.Request) {
142 var since time.Time
143 url_since := r.FormValue("since")
144 if url_since != "" {
145 err := json.Unmarshal([]byte(url_since), &since)
146 if err != nil {
147 log.Print("fetch: parse since: ", err)
148 w.WriteHeader(http.StatusBadRequest)
149 w.Write([]byte("Could not parse since as date"))
150 return
151 }
152 }
153 messages_from_store := make(chan []Message, 1)
154 store.Get <- &StoreRequest{since, messages_from_store}
155
156 json_encoded, err := json.Marshal(<-messages_from_store)
157 if err != nil {
158 log.Print("json encode: ", err)
159 w.WriteHeader(http.StatusInternalServerError)
160 return
161 }
162 w.Header().Add("Content-Type", "application/json")
163 w.Write(json_encoded)
164 })
165
166 http.HandleFunc("/speak", func(w http.ResponseWriter, r *http.Request) {
167 store.Add <- &Message{
168 time.Now(),
169 r.FormValue("id"),
170 r.FormValue("text")}
171 })
172
173 http.HandleFunc("/frame", func(w http.ResponseWriter, r *http.Request) {
174 w.Write([]byte(frame_html));
175 })
176
177 log.Fatal(http.ListenAndServe(":"+strconv.Itoa(*port), nil))
178}
179
180func main() {
181 store := start_store()
182 start_server(store)
183}