That sounds promising, indeed. Thanks. I’ll look into it.
coen.bakker
al2o3cr
One thing to watch out for - mount gets called by two processes during normal operation:
- in the Cowboy acceptor, with
connected?(socket)false for the initial “dead view” render - in the channel handler, with
connected?(socket)true for subsequent updates
Do you get a different result if you capture self in assigns instead of calling it directly here? I’m wondering if the change from being called from a different process isn’t getting picked up by the diff algorithm…
1
coen.bakker
Oh. I meant to remove that line, since it is from back when I passed the pid as a string to the server. But, yes, let me check.
# Inside mount
IO.inspect self()
# Inside assign()
assign(socket,
pid: self()
)
# Inside controller
pid = Process.whereis(:temp_name)
IO.inspect pid
They log the same pid number. But when I render @pid inside the template I get this quick jump from one pid to another.
I reckon that is what you referred to in the first part of your message.
Haven’t thought of this behaviour as a possible explanation. Glad you mentioned it.
0
coen.bakker
Oh, and the handle_info({:form_error, payload}, socket does get triggered if I send a message from within the LiveView itself, by the way. Thought I might mention that also.
0
axelson
Scenic Core Team
FYI mix phx.gen.auth —live was announced at ElixirConf this year. I’m not sure if the code for it is available yet but that may provide some patterns that you can use here.
2
coen.bakker
Nicd
One thing I didn’t see mentioned here is the danger factor. You’re firstly exposing a PID to the user (not really bad in itself) but also allowing the user to send a message to any PID in the system. This can crash processes and lead to at least DoS.
2
benwilson512
Author of Craft GraphQL APIs in Elixir with Absinthe
This is normal. LiveViews are rendered twice. The first time from the HTTP request, the second time from the websocket process.
Usually you’d wrap your registration call in a connected? conditional:
if connected?(socket) do
case Process.whereis(:temp_name) do
nil -> nil
_ -> Process.unregister(:temp_name)
end
end
As @Nicd notes though %{"sender_pid" => sender_pid} = changeset.params is pretty dangerous. You should consider encrypting this value.
1
coen.bakker
Thank you for replies. I’m soaking in all the input. Appreciate all the lessons learnt during this project.
0