First cut at minimum-functionality server

diff --git a/server/server.go b/server/server.go
new file mode 100644 (file)
index 0000000..a8b1c53
--- /dev/null
+++ b/server/server.go
@@ -0,0 +1,108 @@
+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)
+}