| | 1 | package main |
| | 2 | |
| | 3 | import "container/list" |
| | 4 | import "encoding/json" |
| | 5 | import "expvar" |
| | 6 | import "flag" |
| | 7 | import "log" |
| | 8 | import "net/http" |
| | 9 | import "strconv" |
| | 10 | import "time" |
| | 11 | |
| | 12 | var port = flag.Int("port", 21059, "Port to listen on") |
| | 13 | |
| | 14 | var speak_count = expvar.NewInt("speak_count") |
| | 15 | var fetch_count = expvar.NewInt("fetch_count") |
| | 16 | var fetch_wait_count = expvar.NewInt("fetch_wait_count") |
| | 17 | var fetch_wake_count = expvar.NewInt("fetch_wake_count") |
| | 18 | |
| | 19 | type Message struct { |
| | 20 | Time time.Time |
| | 21 | ID string |
| | 22 | Text string |
| | 23 | } |
| | 24 | |
| | 25 | type StoreRequest struct { |
| | 26 | StartTime time.Time |
| | 27 | Messages chan<- []Message |
| | 28 | } |
| | 29 | |
| | 30 | type Store struct { |
| | 31 | Add chan *Message |
| | 32 | Get chan *StoreRequest |
| | 33 | } |
| | 34 | |
| | 35 | // TODO: Monotonic clock |
| | 36 | |
| | 37 | func manage_store(store Store) { |
| | 38 | messages := list.New() |
| | 39 | message_count := 0 |
| | 40 | max_messages := 1000 |
| | 41 | waiting := list.New() |
| | 42 | main: |
| | 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 | |
| | 92 | func start_store() Store { |
| | 93 | store := Store{make(chan *Message, 20), make(chan *StoreRequest, 20)} |
| | 94 | go manage_store(store) |
| | 95 | return store |
| | 96 | } |
| | 97 | |
| | 98 | const 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 | |
| | 140 | func 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 | |
| | 180 | func main() { |
| | 181 | store := start_store() |
| | 182 | start_server(store) |
| | 183 | } |
projects / reliable-chat / blame_incremental