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Send shutdown messages to users when signaltower shuts down #24

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merged 1 commit into from
Jun 6, 2020
Merged

Send shutdown messages to users when signaltower shuts down #24

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17 changes: 12 additions & 5 deletions lib/signal_tower.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -10,11 +10,6 @@ defmodule SignalTower do
|> start_supervisor()
end

@impl Application
def stop(_state) do
:ok
end

defp start_cowboy() do
{port, _} = Integer.parse(System.get_env("SIGNALTOWER_PORT") || "4233")

Expand Down Expand Up @@ -45,4 +40,16 @@ defmodule SignalTower do
Logger.info("SignalTower started")
ret
end

@impl Application
def prep_stop(_state) do
DynamicSupervisor.which_children(Room.Supervisor)
|> Enum.map(fn
{:undefined, pid, :worker, _} when is_pid(pid) ->
send(pid, :shutdown)

_ ->
:ok
end)
end
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Is the signal handler?

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  • this

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... Is this the signal handler

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What do you mean by signal handler? stop(state) is a callback of the Application behaviour ("interface") and it gets called when the application is asked to shut down - is that what you mean?

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Thats what i mean. I was refering to signal handlers used in c++ programms.

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Is the 'asked to shutdown' compareable to unix signal e.g.: sigterm?

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Exactly. "By default, a SIGTERM from the operating system will automatically translate to System.stop/0." https://hexdocs.pm/elixir/Application.html

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Thx a lot for clarification!

end
5 changes: 5 additions & 0 deletions lib/signal_tower/websocket_handler.ex
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Expand Up @@ -67,6 +67,11 @@ defmodule SignalTower.WebsocketHandler do
{:reply, {:text, internal_to_json(msg)}, state}
end

@impl :cowboy_websocket
def websocket_info(:shutdown, state) do
{:reply, {:text, internal_to_json(%{event: "shutdown"})}, state}
end

@impl :cowboy_websocket
def websocket_info(msg, state) do
Logger.warn("Unknown info message: #{inspect(msg)}")
Expand Down