--- /dev/null
+package main
+
+import "container/list"
+import "encoding/json"
+import "log"
+import "net/http"
+import "time"
+
+type Message struct {
+ Time time.Time
+ Text string
+}
+
+type FetchResponse struct {
+ Messages []Message
+ Time time.Time
+}
+
+type StoreRequest struct {
+ StartTime time.Time
+ Messages chan<- []Message
+}
+
+type Store struct {
+ Add chan Message
+ Get chan StoreRequest
+}
+
+// TODO: Monotonic clock
+
+func manage_store(store Store) {
+ messages := list.New()
+ message_count := 0
+ max_messages := 1000
+ waiting := list.New()
+ for {
+ select {
+ case new_message := <-store.Add:
+ messages.PushBack(new_message)
+ for waiter := waiting.Front(); waiter != nil; waiter = waiter.Next() {
+ waiter.Value.(StoreRequest).Messages <- []Message{new_message}
+ close(waiter.Value.(StoreRequest).Messages)
+ }
+ waiting.Init()
+ if message_count < max_messages {
+ message_count++
+ } else {
+ messages.Remove(messages.Front())
+ }
+ case request := <-store.Get:
+ if messages.Back() == nil || request.StartTime.After(messages.Back().Value.(Message).Time) {
+ waiting.PushBack(request)
+ } else {
+ start := messages.Back()
+ response_size := 1
+ if messages.Front().Value.(Message).Time.After(request.StartTime) {
+ start = messages.Front()
+ response_size = message_count
+ } else {
+ for start.Prev().Value.(Message).Time.After(request.StartTime) {
+ start = start.Prev()
+ response_size++
+ }
+ }
+ response_messages := make([]Message, 0, response_size)
+ for m := start; m != nil; m = m.Next() {
+ response_messages = append(response_messages, m.Value.(Message))
+ }
+ request.Messages <- response_messages
+ }
+ }
+ }
+}
+
+func start_store() Store {
+ store := Store{make(chan Message, 20), make(chan StoreRequest, 20)}
+ go manage_store(store)
+ return store
+}
+
+func start_server(store Store) {
+ http.HandleFunc("/fetch", func(w http.ResponseWriter, r *http.Request) {
+ var since time.Time // TODO: Get start time from URL
+ messages_from_store := make(chan []Message, 1)
+ store.Get <- StoreRequest{since, messages_from_store}
+
+ json_encoded, err := json.Marshal(FetchResponse{<-messages_from_store, time.Now()})
+ if err != nil {
+ log.Print("json encode: ", err)
+ w.WriteHeader(http.StatusInternalServerError)
+ return
+ }
+ w.Header().Add("Content-Type", "application/json")
+ w.Write(json_encoded)
+ })
+
+ http.HandleFunc("/speak", func(w http.ResponseWriter, r *http.Request) {
+ text := "woof" // TODO: Get text from URL
+ store.Add <- Message{time.Now(), text}
+ })
+
+ log.Fatal(http.ListenAndServe(":8080", nil))
+}
+
+func main() {
+ store := start_store()
+ start_server(store)
+}