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92d1d6ac SW |
1 | package main |
2 | ||
3 | import "container/list" | |
4 | import "encoding/json" | |
24a546cf | 5 | import "flag" |
92d1d6ac SW |
6 | import "log" |
7 | import "net/http" | |
24a546cf | 8 | import "strconv" |
92d1d6ac SW |
9 | import "time" |
10 | ||
24a546cf SW |
11 | var port = flag.Int("port", 21059, "Port to listen on") |
12 | ||
92d1d6ac SW |
13 | type Message struct { |
14 | Time time.Time | |
15 | Text string | |
16 | } | |
17 | ||
92d1d6ac SW |
18 | type StoreRequest struct { |
19 | StartTime time.Time | |
20 | Messages chan<- []Message | |
21 | } | |
22 | ||
23 | type Store struct { | |
fa5e7c1b SW |
24 | Add chan *Message |
25 | Get chan *StoreRequest | |
92d1d6ac SW |
26 | } |
27 | ||
28 | // TODO: Monotonic clock | |
29 | ||
30 | func manage_store(store Store) { | |
31 | messages := list.New() | |
32 | message_count := 0 | |
33 | max_messages := 1000 | |
34 | waiting := list.New() | |
c282d878 | 35 | main: |
92d1d6ac SW |
36 | for { |
37 | select { | |
c282d878 SW |
38 | case new_message, ok := <-store.Add: |
39 | if !ok { | |
40 | break main | |
41 | } | |
92d1d6ac SW |
42 | messages.PushBack(new_message) |
43 | for waiter := waiting.Front(); waiter != nil; waiter = waiter.Next() { | |
fa5e7c1b SW |
44 | waiter.Value.(*StoreRequest).Messages <- []Message{*new_message} |
45 | close(waiter.Value.(*StoreRequest).Messages) | |
92d1d6ac SW |
46 | } |
47 | waiting.Init() | |
48 | if message_count < max_messages { | |
49 | message_count++ | |
50 | } else { | |
51 | messages.Remove(messages.Front()) | |
52 | } | |
c282d878 SW |
53 | case request, ok := <-store.Get: |
54 | if !ok { | |
55 | break main | |
56 | } | |
fa5e7c1b | 57 | if messages.Back() == nil || !request.StartTime.Before(messages.Back().Value.(*Message).Time) { |
92d1d6ac SW |
58 | waiting.PushBack(request) |
59 | } else { | |
60 | start := messages.Back() | |
61 | response_size := 1 | |
fa5e7c1b | 62 | if messages.Front().Value.(*Message).Time.After(request.StartTime) { |
92d1d6ac SW |
63 | start = messages.Front() |
64 | response_size = message_count | |
65 | } else { | |
fa5e7c1b | 66 | for start.Prev().Value.(*Message).Time.After(request.StartTime) { |
92d1d6ac SW |
67 | start = start.Prev() |
68 | response_size++ | |
69 | } | |
70 | } | |
71 | response_messages := make([]Message, 0, response_size) | |
72 | for m := start; m != nil; m = m.Next() { | |
fa5e7c1b | 73 | response_messages = append(response_messages, *m.Value.(*Message)) |
92d1d6ac SW |
74 | } |
75 | request.Messages <- response_messages | |
76 | } | |
77 | } | |
78 | } | |
79 | } | |
80 | ||
81 | func start_store() Store { | |
fa5e7c1b | 82 | store := Store{make(chan *Message, 20), make(chan *StoreRequest, 20)} |
92d1d6ac SW |
83 | go manage_store(store) |
84 | return store | |
85 | } | |
86 | ||
87 | func start_server(store Store) { | |
88 | http.HandleFunc("/fetch", func(w http.ResponseWriter, r *http.Request) { | |
87ac1d98 SW |
89 | var since time.Time |
90 | url_since := r.FormValue("since") | |
91 | if url_since != "" { | |
92 | err := json.Unmarshal([]byte(url_since), &since) | |
93 | if err != nil { | |
94 | log.Print("fetch: parse since: ", err) | |
95 | w.WriteHeader(http.StatusBadRequest) | |
96 | w.Write([]byte("Could not parse since as date")) | |
97 | return | |
98 | } | |
99 | } | |
92d1d6ac | 100 | messages_from_store := make(chan []Message, 1) |
fa5e7c1b | 101 | store.Get <- &StoreRequest{since, messages_from_store} |
92d1d6ac | 102 | |
9b33d853 | 103 | json_encoded, err := json.Marshal(<-messages_from_store) |
92d1d6ac SW |
104 | if err != nil { |
105 | log.Print("json encode: ", err) | |
106 | w.WriteHeader(http.StatusInternalServerError) | |
107 | return | |
108 | } | |
109 | w.Header().Add("Content-Type", "application/json") | |
110 | w.Write(json_encoded) | |
111 | }) | |
112 | ||
113 | http.HandleFunc("/speak", func(w http.ResponseWriter, r *http.Request) { | |
fa5e7c1b | 114 | store.Add <- &Message{time.Now(), r.FormValue("text")} |
92d1d6ac SW |
115 | }) |
116 | ||
24a546cf | 117 | log.Fatal(http.ListenAndServe(":" + strconv.Itoa(*port), nil)) |
92d1d6ac SW |
118 | } |
119 | ||
120 | func main() { | |
121 | store := start_store() | |
122 | start_server(store) | |
123 | } |