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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
	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	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
	159	func 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
	201	func main() {
	202	flag.Parse()
	203	store := start_store()
	204	start_server(store)
	205	}