erez-rabih

get “/users/:id”, 
    private: %{validate: %{id: &validate_integer/1, active: &validate_boolean/1}} do
  # Controller logic goes here
end

erez-rabih

iex> Dispatcher.run d, "a", fn -> 1/0 end
:ok
iex> 
17:41:39.336 [error] Process #PID<0.97.0> raised an exception
** (ArithmeticError) bad argument in arithmetic expression
    :erlang./(1, 0)
    lib/dispatcher.ex:27: anonymous fn/3 in Dispatcher.handle_cast/2
iex> Dispatcher.result d, "a"            
{:error,
 {:badarith,

erez-rabih

defmodule Dispatcher do
  use GenServer

  @timeout 10000

  def start() do
    GenServer.start(__MODULE__, [])
  end

  def result(s, task_id), do: GenServer.call(s, {:result, task_id})

erez-rabih

iex> Dispatcher.run(d, "a", fn -> 1/0 end)                         
:ok
iex> 
17:38:19.429 [error] Process #PID<0.152.0> raised an exception
** (ArithmeticError) bad argument in arithmetic expression
    :erlang./(1, 0)
    lib/dispatcher.ex:27: anonymous fn/3 in Dispatcher.handle_cast/2
iex> Dispatcher.result(d, "a")            
:pending
iex> Dispatcher.result(d, "a")

erez-rabih

iex> Dispatcher.run(d, "a", fn -> :timer.sleep(12000);  "done" end)
:ok
iex> Dispatcher.result(d, "a")                                     
:pending
iex> Dispatcher.result(d, "a")
:pending
iex> Dispatcher.result(d, "a")
:timeout
iex> Dispatcher.result(d, "a")
nil

erez-rabih

defmodule Dispatcher do
  use GenServer

  @timeout 10000
  
  # .
  # .
  # .
  # Same stuff as before

erez-rabih

iex> Dispatcher.run(d, "a", fn -> :timer.sleep(8000); "done" end)
:ok
iex> Dispatcher.result(d, "a")
:pending
iex> Dispatcher.result(d, "a")
:pending
iex> Dispatcher.result(d, "a")
"done"
iex> Dispatcher.result(d, "a")
nil

erez-rabih

defmodule Dispatcher do
  .
  .
  .
  # Everything until handle_call stays the same

  def handle_call({:result, task_id}, _from, results) do
    case Map.fetch(results, task_id) do
      {:ok, :pending} -> {:reply, :pending, results}
      {:ok, result} -> {:reply, result, Map.delete(results, task_id)}

erez-rabih

iex> Dispatcher.run(d, “c”, fn -> :timer.sleep(8000); “finished” end) 
:ok
iex> Dispatcher.result d, “c”
** (exit) exited in: GenServer.call(#PID<0.96.0>, {:result, “c”}, 5000)
 ** (EXIT) time out
 (elixir) lib/gen_server.ex:831: GenServer.call/3

erez-rabih

iex> {:ok, d} = Dispatcher.start()
{:ok, #PID<0.96.0>}
iex> Dispatcher.run(d, "a", fn -> 1 + 1 end)
:ok
iex> Dispatcher.run(d, "b", fn -> 2 + 2 end)          
:ok
iex> Dispatcher.result(d, "a")                           
2
iex> Dispatcher.result(d, "b")
4