Error when sending messages to liveview processes

[PaulOstazeski]

Hi! I heard about bandit on the ThinkingElixir podcast and wanted to give it a try. I found what I think might be a bug.

I am using bandit 0.6.7, thousand_island 0.5.15, phoenix 1.7.0-rc.2, elixir 1.14.0 and erlang 25.0.

I make a new phoenix project via mix archive.install hex phx_new 1.7.0-rc.2 ; mix phx.new foo - then I replace plug_cowboy with {:bandit, "~> 0.6.7"} in hex.exs and add adapter: Bandit.PhoenixAdapter in config/config.exs.

If I send any messages to a liveview process, the first time such a message is sent, I see the error (FunctionClauseError) no function clause matching in Bandit.HTTP1.Handler.handle_info/2 (more lines attached below). Subsequent messages do not repeat the same error. The liveview's handle_info callback is invoked in both cases.

Example liveview code

def mount(_params, _session, socket) do
  :timer.send_interval(1000, :tick)
  {:ok, assign(socket}
end

def handle_info(:tick, socket) do
  IO.inspect("tick happened")
  {:noreply, socket}
end

Full error output:

[error] GenServer #PID<0.2882.0> terminating                                                                                   
** (FunctionClauseError) no function clause matching in Bandit.HTTP1.Handler.handle_info/2
    (bandit 0.6.7) lib/thousand_island/handler.ex:5: Bandit.HTTP1.Handler.handle_info(:tick, {%ThousandIsland.Socket{socket: #Port<0.55>, transport_module: ThousandIsland.Transports.TCP, read_timeout: 15000}, %{handler_module: Bandit.HTTP1.Handler, plug: {Phoenix.Endpoint.SyncCodeReloadPlug, {FartWeb.Endpoint, []}}}})                                                              
    (stdlib 4.0) gen_server.erl:1120: :gen_server.try_dispatch/4                                                               
    (stdlib 4.0) gen_server.erl:1197: :gen_server.handle_msg/6                                                                 
    (stdlib 4.0) proc_lib.erl:240: :proc_lib.init_p_do_apply/3                                                                 
Last message: :tick                                            
State: {%ThousandIsland.Socket{socket: #Port<0.55>, transport_module: ThousandIsland.Transports.TCP, read_timeout: 15000}, %{handler_module: Bandit.HTTP1.Handler, plug: {Phoenix.Endpoint.SyncCodeReloadPlug, {FartWeb.Endpoint, []}}}}
tick happened
tick happened
tick happened
...

[PaulOstazeski]

This is a simplified example, but it happens when sending messages "up" from a livecomponent to the surrounding liveview (via send(self(), ...), and when using pubsub to subscribe to a topic from a liveview.

[PaulOstazeski]

Hahaha. I think the bug is in my code. Calling send or subscribe should only happen when connected?(socket) is true. Disregard.