feat(server): extend connection with handle_info and pump

lib/excache/server/connection.ex

@@ -11,7 +11,7 @@ defmodule Excache.Server.Connection do
 
   @impl true
   def init(socket) do
-    base = %{socket: socket, buffer: "", subscriptions: MapSet.new()}
+    base = %{socket: socket, buffer: "", subscriptions: MapSet.new(), blocked: nil}
     {:ok, Map.merge(base, Transaction.initial_state())}
   end
 
@@ -22,16 +22,16 @@ defmodule Excache.Server.Connection do
   end
 
   def handle_info({:tcp, socket, data}, state) do
-    {output, state} = consume(state.buffer <> data, %{state | buffer: ""})
+    state = pump(%{state | buffer: state.buffer <> data})
-
-    unless output == [] do
-      :gen_tcp.send(socket, output)
-    end
-
     :inet.setopts(socket, active: :once)
     {:noreply, state}
   end
 
+  def handle_info({:excacheUnblocked, ref, reply}, %{blocked: ref} = state) do
+    :gen_tcp.send(state.socket, Encoder.encode(reply))
+    {:noreply, pump(%{state | blocked: nil})}
+  end
+
   def handle_info({:tcp_closed, _socket}, state), do: {:stop, :normal, state}
   def handle_info({:tcp_error, _socket, _reason}, state), do: {:stop, :normal, state}
 
@@ -41,6 +41,14 @@ defmodule Excache.Server.Connection do
     {:noreply, state}
   end
 
+  defp pump(%{blocked: nil} = state) do
+    {output, state} = consume(state.buffer, %{state | buffer: ""})
+    unless output == [], do: :gen_tcp.send(state.socket, output)
+    state
+  end
+
+  defp pump(state), do: state
+
   defp consume(buffer, state) do
     case Parser.parse_command(buffer) do
       :incomplete ->
@@ -51,9 +59,16 @@ defmodule Excache.Server.Connection do
 
       {:ok, args, rest} ->
         {replies, state} = Command.execute(args, state)
+        continue(replies, rest, state)
+    end
+  end
+
+  defp continue([{:blocked, ref}], rest, state),
+    do: {[], %{state | buffer: rest, blocked: ref}}
+
+  defp continue(replies, rest, state) do
     encoded = Enum.map(replies, &Encoder.encode/1)
     {more, state} = consume(rest, state)
     {[encoded | more], state}
   end
 end
-end