Mix.install [:gen_state_machine]
defmodule Server do
use GenStateMachine, callback_mode: :state_functions
def start_link(opts \\ []) do
GenStateMachine.start_link(__MODULE__, opts)
end
def init(opts) do
Process.flag(:trap_exit, true)
{:ok, :state, opts}
end
def state(:info, message, data) do
IO.inspect(message, label: :received)
:keep_state_and_data
end
def terminate(reason, :state, data) do
IO.inspect(reason, label: :terminating)
end
end
DynamicSupervisor.start_link(name: Sup)
{:ok, child} = DynamicSupervisor.start_child(Sup, Server)
And in iex
iex(3)> Process.exit(child, :normal)
received: {:EXIT, #PID<0.112.0>, :normal}
true
iex(4)> Process.exit(child, :kill)
true
iex(5)> Process.info child
nil
As you can see, with trap_exit, normal exit results in just a message being sent. But if you call this
iex(3)> DynamicSupervisor.terminate_child Sup, child
terminating: :shutdown
:ok
It initiates the terminate callback
P.S. don’t forget to mark the correct answer
