Elixir：使用 Dynamic Supervisor 启动 child 的正确方法

Question

我正在尝试创建一个动态主管来启动子进程。我使用三个模块来执行此操作，一个是主模块，第二个是动态管理器，第三个是 genserver。我没有收到任何错误，但我看不到任何子进程运行.

这是我的代码。第一个是有 main 方法的模块

defmodule Simulator do
    def main(args) do
        {:ok, super_pid} = PersonManager.start_link(args)
        num_of_persons = 1
        start_persons(num_of_persons)
        IO.inspect PersonManager.count_children, label: "The Persons started in main method are"
    end

    def start_persons(num_of_persons) when num_of_persons >=1 do
        PersonManager.add_node(private_key, public_key, 0)
        start_persons(num_of_persons-1)    
    end
    # num_of_persons == 0 case handled
end

以下为动态Supervisor

defmodule PersonManager do
  use DynamicSupervisor

  def start_link(args) do
    DynamicSupervisor.start_link(__MODULE__, :ok, name: __MODULE__)
  end

  def add_node(private_key, public_key, num_of_coins) do
    # The code flow does come here, used inspect to check
    child_spec = {Person, {private_key, public_key, num_of_coins}}
    DynamicSupervisor.start_child(__MODULE__, child_spec)
    #The code flow does come here, used inpect to check.   
  end
end

以下是工作人员应该创建的 GenServers

defmodule Person do
  use GenServer

  def init({private_key, public_key, address, num_of_coins}) do
    IO.puts "Starting a person"
    {:ok, %{private_key: private_key, public_key: public_key, num_of_coins: num_of_coins}}
  end

  def start_link({private_key, public_key, address, num_of_coins}) do
    IO.puts "Starting a person"
    GenServer.start_link(
      __MODULE__,
      {private_key, public_key, address, num_of_coins}
      name: {:global, "node:#{public_key}"},
    )
  end
end

我希望 genserver 是运行但我得到 The Persons started in main method are: %{active: 0, specs: 0, supervisors: 0, workers: 0}

我不知道主管为什么不能启动genserver。任何帮助都会很好。 TIA

Answer 1

对于您的情况，您需要做三件事：

在从 DynamicSupervisor 开始之前正确设置 child 规范：

child_spec = {Person, [private_key, public_key, num_of_coins]}

强制child开始失败，如果不成功：

case DynamicSupervisor.start_child do
  {:ok, _pid} -> {}
  {:error, {:already_started, _pid}} -> {}
  error -> raise error
end

并且，确保 child 进程能够处理主管给它的确切参数：

defmodule Person do
  use GenServer

  def start_link([], private_key, public_key, num_of_coins) do
    GenServer.start_link(
      __MODULE__,
      {private_key, public_key, num_of_coins},
      name: {:global, "node:#{public_key}"}
    )
  end

  def init({private_key, public_key, num_of_coins}) do
    {:ok, %{private_key: private_key, public_key: public_key, num_of_coins: num_of_coins}}
  end
end

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