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 var max_messages = flag.Int("maxmessages", 1000, "Maximum number of messages to retain")
  32
  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         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 robots_txt = `User-agent: *
 117 Disallow: /
 118 `
 119
 120 func start_server(store Store) {
 121         http.HandleFunc("/fetch", func(w http.ResponseWriter, r *http.Request) {
 122                 var since time.Time
 123                 url_since := r.FormValue("since")
 124                 if url_since != "" {
 125                         err := json.Unmarshal([]byte(url_since), &since)
 126                         if err != nil {
 127                                 log.Print("fetch: parse since: ", err)
 128                                 w.WriteHeader(http.StatusBadRequest)
 129                                 w.Write([]byte("Could not parse since as date"))
 130                                 return
 131                         }
 132                 }
 133                 messages_from_store := make(chan []Message, 1)
 134                 store.Get <- &StoreRequest{since, messages_from_store}
 135
 136                 json_encoded, err := json.Marshal(<-messages_from_store)
 137                 if err != nil {
 138                         log.Print("json encode: ", err)
 139                         w.WriteHeader(http.StatusInternalServerError)
 140                         return
 141                 }
 142                 w.Header().Add("Content-Type", "application/json")
 143                 w.Header().Add("Access-Control-Allow-Origin", "*")
 144                 w.Write(json_encoded)
 145         })
 146
 147         http.HandleFunc("/speak", func(w http.ResponseWriter, r *http.Request) {
 148                 store.Add <- &Message{
 149                         time.Now(),
 150                         r.FormValue("id"),
 151                         r.FormValue("text")}
 152         })
 153
 154         http.HandleFunc("/robots.txt", func(w http.ResponseWriter, r *http.Request) {
 155                 w.Write([]byte(robots_txt));
 156         })
 157
 158         log.Fatal(http.ListenAndServe(*localaddress+":"+strconv.Itoa(*port), nil))
 159 }
 160
 161 func main() {
 162         flag.Parse()
 163         store := start_store()
 164         start_server(store)
 165 }