How to manage state for each player in Phoenix

[amnu3387]

Yes indeed - it would require opening two tabs/connections at the same time tough, and the channel crash would make a rejoin which wouldn’t then crash, but I agree, it’s better to take care of it right there as well.

[madclaws]

@idi527 @amnu3387
Hi, one doubt, how do we take care of the above mentioned race condition?

[kokolegorille]

Just use this part…

case GenServer.start(__MODULE__, {n_id, self()}, name: gen_serv_ref(id)) do
  {:ok, pid} -> {:ok, pid}
  {:error, {:already_started, pid}} -> {:ok, pid}
end

PS: The BEAM forbid processes with the same name, there is no need to check if there is already one present. See this post for a longer response

How to check globally named Agent?

As was already pointed out, the BEAM won’t let you start a second process with the same name. Since in your code you’re not handling the return: you could just have Agent.start_link(fn -> %{} end, [name: {:global, user_id}]) and get the same result. Assuming that’s just example code and you do care about the response, you can do something like: def ensure_agent(user_id) do case Agent.start_link(fn -> %{} end, [name: {:global, user_id}]) do {:ok, pid} -> {:ok, pid} {:error, {:already…