Poolboy Sample on Phoenix Framework

lib-hello_phoenix-memcached_supervisor.ex

defmodule HelloPhoenix.Memcached.Supervisor do
    use Supervisor

    def start_link do
        Supervisor.start_link(__MODULE__, [])
    end

    def init([]) do
        pool_options = [
            name: {:local, :memcached_pool},
            worker_module: :mcd,
            size: 5,
            max_overflow: 0,
        ]

        arg = ['localhost', 11211]

        children = [
            :poolboy.child_spec(:memcached_pool, pool_options, arg)
        ]

        supervise(children, strategy: :one_for_one)
    end
end

lib-hello_phoenix.ex

defmodule HelloPhoenix do
  use Application

  # See http://elixir-lang.org/docs/stable/elixir/Application.html
  # for more information on OTP Applications
  def start(_type, _args) do
    import Supervisor.Spec, warn: false

    children = [
      # Start the endpoint when the application starts
      supervisor(HelloPhoenix.Endpoint, []),
      # Here you could define other workers and supervisors as children
      # worker(HelloPhoenix.Worker, [arg1, arg2, arg3]),
      supervisor(HelloPhoenix.Memcached.Supervisor, []),
    ]

    # See http://elixir-lang.org/docs/stable/elixir/Supervisor.html
    # for other strategies and supported options
    opts = [strategy: :one_for_one, name: HelloPhoenix.Supervisor]
    Supervisor.start_link(children, opts)
  end

  # Tell Phoenix to update the endpoint configuration
  # whenever the application is updated.
  def config_change(changed, _new, removed) do
    HelloPhoenix.Endpoint.config_change(changed, removed)
    :ok
  end
end

mix.ex

defmodule HelloPhoenix.Mixfile do
  use Mix.Project

  def project do
    [app: :hello_phoenix,
     version: "0.0.1",
     elixir: "~> 1.0",
     elixirc_paths: elixirc_paths(Mix.env),
     compilers: [:phoenix] ++ Mix.compilers,
     build_embedded: Mix.env == :prod,
     start_permanent: Mix.env == :prod,
     deps: deps]
  end

  # Configuration for the OTP application
  #
  # Type `mix help compile.app` for more information
  def application do
    [mod: {HelloPhoenix, []},
     applications: [:phoenix, :phoenix_html, :cowboy, :logger, :poolboy]]
  end

  # Specifies which paths to compile per environment
  defp elixirc_paths(:test), do: ["lib", "web", "test/support"]
  defp elixirc_paths(_),     do: ["lib", "web"]

  # Specifies your project dependencies
  #
  # Type `mix help deps` for examples and options
  defp deps do
    [{:phoenix, "~> 1.0.0"},
     {:phoenix_html, "~> 2.1"},
     {:phoenix_live_reload, "~> 1.0", only: :dev},
     {:poolboy, "~> 1.5.1"},
     {:mcd, github: "EchoTeam/mcd"},
     {:cowboy, "~> 1.0"}]
  end
end

web-controllers-page_controller.ex

defmodule HelloPhoenix.PageController do
  use HelloPhoenix.Web, :controller

  def index(conn, _params) do
    # :poolboy.checkout/2, :poolboy.checkin/2 よりも :poolboy.transaction/2 の方がよさげ?
    val = :poolboy.transaction(:memcached_pool, fn worker ->
        :mcd.set(worker, "key", "Hello Phoenix")
        :mcd.get(worker, "key")
        |> case do
            {:ok, resp} ->
                resp
            _ ->
                "Boom!"
        end
    end)

    json conn, %{val: val}
  end
end