chiragtoor

  # ...
  def init(customer) do
    Process.flag(:trap_exit, true)
    # check for order_contents for the customer
    order_contents = ExCluster.StateHandoff.pickup(customer)
    { :ok, { customer, order_contents } }
  end
  
  # ...

chiragtoor

  # ...
  children = [
    # **it's important that this is the first child in our tree
    { ExCluster.StateHandoff, [] },

    { Horde.Registry, [name: ExCluster.Registry, keys: :unique] },
    { Horde.Supervisor, [name: ExCluster.OrderSupervisor, strategy: :one_for_one ] },
    %{
      id: ExCluster.HordeConnector,
      restart: :transient,

chiragtoor

defmodule ExCluster.StateHandoff do
  use GenServer
  require Logger

  def start_link(opts) do
    GenServer.start_link(__MODULE__, opts, name: __MODULE__)
  end

  def child_spec(opts \\ []) do
    %{

chiragtoor

  # ...
  def init(customer) do
    Process.flag(:trap_exit, true)
    # ...
  end
  # ...
  
  # at the end of the module add a terminate callback
  def terminate(_reason, { customer, order_contents }) do
    # store our order_contents for this customer somwhere

chiragtoor

  # ...
  defp via_tuple(customer) do
    # Order GenServer needs to use Horde.Registry
    { :via, Horde.Registry, { ExCluster.Registry, customer } }
  end
  # ...

chiragtoor

  # ...
  def init(customer) do
    Logger.warn("Starting #{__MODULE__} for #{customer}")
    { :ok, [] }
  end
  # ...

chiragtoor

  # ...
  case System.get_env("NODES") do
    nodes when is_binary(nodes) ->
      nodes
      |> String.split(",")
      |> Enum.map(&String.to_atom/1)
      |> Enum.each(&Node.connect/1)
    _ ->
      nil
  end

chiragtoor

  # ...
  # take in list of nodes from the env
  case System.get_env("NODES") do
    nodes when is_binary(nodes) ->
      nodes
      # convert list of nodes into atoms of node names
      |> String.split(",")
      |> Enum.map(&String.to_atom/1)
      # connect to all nodes to make a cluster
      |> Enum.each(&Node.connect/1)

chiragtoor

defmodule ExCluster.Order do
  use GenServer
  require Logger

  def child_spec(customer), do: %{ id: customer, 
                                   start: { __MODULE__, :start_link, [customer] } }

  def start_link(customer) do
    Logger.info("Starting Order for #{customer}")
    # note the change here in providing a name: instead of [] as the 3rd param

chiragtoor

  # ...
  children = [
    { Registry, keys: :unique, name: ExCluster.Registry },
    { DynamicSupervisor, name: ExCluster.OrderSupervisor, strategy: :one_for_one },
  ]
  # ...