make tail with param ?l= (HTTP only)

cmd/circologd/http.go

@@ -38,6 +38,7 @@ func parseParameterL(r *http.Request) (int, error) {
 
 func parseParameters(w http.ResponseWriter, r *http.Request) (circolog.ClientOptions, error) {
 	var opts circolog.ClientOptions
+	opts.BacklogLength = 10 // default
 	err := r.ParseForm()
 	if err != nil {
 		log.Println("error parsing http request", err)
@@ -86,7 +87,9 @@ func getWSHandler(hub circolog.Hub) http.HandlerFunc {
 		if err != nil {
 			return
 		}
-		client := circolog.Client{Messages: make(chan format.LogParts, 20)}
+		client := circolog.Client{Messages: make(chan format.LogParts, 20),
+			Options: circolog.ClientOptions{BacklogLength: -1},
+		}
 		hub.Register <- client
 
 		// Allow collection of memory referenced by the caller by doing all work in

hub.go

@@ -49,21 +49,26 @@ func (h *Hub) register(cl Client) {
 			h.clients[cl] = true
 		}
 
-		circbufDoExit := false
-		h.circbuf.Do(func(x interface{}) {
-			if circbufDoExit {
-				return
-			}
-			if x != nil {
+		howmany := cl.Options.BacklogLength
+		if howmany > h.circbuf.Len() || howmany == -1 {
+			howmany = h.circbuf.Len()
+		}
+		buf := h.circbuf.Move(-howmany)
+		for i := 0; i < howmany; i++ {
+			item := buf.Value
+			if item != nil {
 				select { // send with short timeout
-				case cl.Messages <- x.(format.LogParts):
+				case cl.Messages <- item.(format.LogParts):
 					break
 				case <-time.After(500 * time.Millisecond):
-					circbufDoExit = true
-					break
+					close(cl.Messages)
+					return
 				}
 			}
-		})
+
+			buf = buf.Next()
+		}
+
 		if cl.Options.Nofollow {
 			close(cl.Messages)
 		}