不处理强制转换的事件处理程序的 GenServer 实现

Question

我正在尝试在我的 Phoenix 应用程序中使用 GenServer as an event handler for EventBus，但出于某种原因，我似乎无法弄清楚为什么没有调用句柄转换函数。我用 :observer.start().

检查了进程是否还活着

为了让 GenServer 正确处理 cast 调用，我缺少什么吗？

本质上，流程函数应该处理传入事件并将其转换为 GenServer，其中 GenServer 将处理转换并对该事件执行域逻辑。

----生成服务器模块----

defmodule App.Notifications.EventHandler do
  use GenServer
  require Logger


  def start_link(opts \ []) do
    {:ok, pid} = GenServer.start_link(__MODULE__, [], opts)
  end

  def init([]) do
    {:ok, []}
  end

  def process({topic_id, event_id}) do
    Logger.info("event notification process recieved!!") <---- THIS IS GETTING PRINTED!

    GenServer.cast(__MODULE__, {topic_id, event_id})
  end



def handle_cast({topic_id, event_id}, state) do
  Logger.info("event  notification data Recieved!!") <----- THIS IS NOT

  # do stuff

  {:noreply, state}
end


end

----应用模块-----

defmodule App.Application do
  # See https://hexdocs.pm/elixir/Application.html
  # for more information on OTP Applications
  @moduledoc false

  use Application


  def start(_type, _args) do

    EventBus.subscribe({App.Notifications.EventHandler, ["^event_notification_created$"]})

    # List all child processes to be supervised
    children = [
      # Start the Ecto repository
      App.Repo,
      # Start the endpoint when the application starts
      AppWeb.Endpoint,
      # Starts a worker by calling: App.Worker.start_link(arg)
      # {App.Worker, arg},,
      App.Notifications.EventHandler <--- STARTING THE GEN SERVER HERE
    ]

    # See https://hexdocs.pm/elixir/Supervisor.html
    # for other strategies and supported options
    opts = [strategy: :one_for_one, name: App.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
    App.Endpoint.config_change(changed, removed)
    :ok
  end
end

Answer 1

关于 GenServer.cast/2 states, that the first parameter in call to GenServer.cast/2 must be of a type server() 的文档是：

any of the values described in the “Name registration” section of the documentation for this module.

在您的代码中，您启动 link 未命名：

GenServer.start_link(__MODULE__, [], opts)

但随后您投射到指定的 GenServer:

#              ⇓⇓⇓⇓⇓⇓⇓⇓⇓⇓
GenServer.cast(__MODULE__, {topic_id, event_id})

修复它的最简单方法，启动名为的服务器：

GenServer.start_link(__MODULE__, [], name: __MODULE__)

不处理强制转换的事件处理程序的 GenServer 实现

GenServer implementation of an event handler not handling casts

elixir

gen-server

phoenix-framework