GenServe Supervisor study

gistfile1.ex

defmodule Bucket do
    use GenServer

    def start_link(name) do
        GenServer.start_link(__MODULE__, %{}, name: name)
    end

    #callbacks
    def handle_call(request, from, state) do
        case request do
            {:get,key} -> {:reply, Map.get(state,key), state}
            {:put,key,value} -> {:reply,:ok,Map.put(state,key,value)}
            _ -> {:reply,"unsupported method", state}
        end
    end
end

defmodule Bucket.Reg do
    use GenServer
    def start_link do
        GenServer.start_link(__MODULE__, %{}, name: __MODULE__)
    end

    #callbacks
    def handle_call({:create,name},from,state) do
        if(Map.has_key?(state,name)) do
           {:reply,Map.get(state,name),state} 
        else
            {:ok, bucket} = Bucket.Sup.create_bucket(name)
            Process.monitor(bucket)
            {:reply,bucket,Map.put(state,name,bucket)}
        end
    end

    def handle_call({:lookup,name},from,state) do
        {:reply,Map.get(state,name),state}
    end

    def handle_call(_,_,state) do
        {:reply,"Unsupported ops",state}
    end
end

defmodule Bucket.Sup do
    use Supervisor
    def start_link() do
        Supervisor.start_link(__MODULE__,:ok,name: __MODULE__)
    end
    
    def create_bucket(name) do
        #The last parameter must be list, the number of list will match to child start_link function
        Supervisor.start_child(__MODULE__,[name])
    end
    #callbacks
    def init(:ok) do
        children = [
            worker(Bucket,[],restart: :temporary)
        ]
        #simple_one_for_one will not start any child
        supervise(children, strategy: :simple_one_for_one)
    end
end