Elixir游戏服设计三

Posted 2020-07-14 damnit

玩家进程用gen_server来建模，我不直接使用 use GenServer, 而是使用exactor，该库可以去掉反锁的接口定义。

我们新建一个 player_server_manager app吧, 使用 mix new player_server_manager --sup, 会给我们增加sup。然后在mix.exs里增加exactor的依赖如下：

  defp deps do
    [{:exactor, "~> 2.2"}]
  end

跑 mix deps.get,成功了依赖就准备好了。

默认生成的player_server_manager.ex

defmodule PlayerServerManager 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 = [
      # Define workers and child supervisors to be supervised
      # worker(PlayerServerManager.Worker, [arg1, arg2, arg3]),
    ]

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

玩家进程就叫player_server吧。把它改成我需要的。

defmodule PlayerServerManager 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 = [
      # Define workers and child supervisors to be supervised
      worker(PlayerServer, [], restart: :temporary),
    ]

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

因为玩家进程是动态创建的，因此采用simple_one_for_one, 同时我不需要默认传参数，还有我不需要重启。

好了现在让我们编写PlayerServer模块（现在是简单的，而且我还未知有什么需要调整的，后续随着服务器设计而演化吧）。

让我们先增加个查询钻石的接口吧。

defmodule PlayerServer do

    use ExActor.GenServer

    defstart start_link(player), do: initial_state(%{player: player, socket: nil})
    defcall gem, state: state, do: reply(state.player.base_info.gem)
end

我们在PlayerServerManager里增加启动接口如下

 def start_player_server(%Player{} = player) do
    Supervisor.start_child(PlayerServerManager.Supervisor, [player])
  end

在player_server_manager_test.exs里增加测试代码

defmodule PlayerServerManagerTest do
  use ExUnit.Case
  doctest PlayerServerManager
  
  setup do
    Application.stop(:player_server_manager)
    :ok = Application.start(:player_server_manager)
  end

  setup do
      player = Player.new(0)
      {:ok, player: player}
  end
  test "start player_server", %{player: player} do
    assert {:ok, pid} = PlayerServerManager.start_player_server(player)
    assert  PlayerServer.gem(pid) == 0
  end
end

测试通过。

写到这里发现之前Player和BaseInfo @behavior 实际上应该为@hehaviour, 既然之前没报错，我就把它去掉了，测试依然通过。说明其实可能只需要

defdelegate。

好了，这一章就到这。遗留的问题有，我们通常需要给玩家进程一个名字，而不是通过pid，如果是单节点的话, local 注册已经足够，如果是跨服访问，我们需要一个分布式的注册机制（实际上分布式注册机制容易有坑，如无必要，千万别）。比如gporc，比如syn。 前者比较有名，我以前在erlang用过，之前有碰到莫名奇妙的问题。所以下章试试syn吧。