livebook/lib/livebook_web/channels/js_output_channel.ex
Jonatan Kłosko 19baf013d5
Introduce a dedicated channel for JS widget communication (#843)
* Introduce a dedicated channel for JS widget communication

* Handle payload serialization errors

* Tie channel lifetime to the session

* Catch serialization errors instead of encoding twice

* Merge JS static and dynamic outputs

* Authenticate socket connection from session

* Update JS output format

* Remove unused helper

* Apply review comments
2022-01-06 16:31:26 +01:00

74 lines
2.5 KiB
Elixir

defmodule LivebookWeb.JSOutputChannel do
use Phoenix.Channel
@impl true
def join("js_output", %{}, socket) do
{:ok, assign(socket, ref_with_pid: %{}, ref_with_count: %{})}
end
@impl true
def handle_in("connect", %{"session_token" => session_token, "ref" => ref}, socket) do
{:ok, data} = Phoenix.Token.verify(LivebookWeb.Endpoint, "js output", session_token)
%{pid: pid} = data
send(pid, {:connect, self(), %{origin: self(), ref: ref}})
ref_with_pid = Map.put(socket.assigns.ref_with_pid, ref, pid)
ref_with_count = Map.update(socket.assigns.ref_with_count, ref, 1, &(&1 + 1))
socket = assign(socket, ref_with_pid: ref_with_pid, ref_with_count: ref_with_count)
{:noreply, socket}
end
def handle_in("event", %{"event" => event, "payload" => payload, "ref" => ref}, socket) do
pid = socket.assigns.ref_with_pid[ref]
send(pid, {:event, event, payload, %{origin: self(), ref: ref}})
{:noreply, socket}
end
def handle_in("disconnect", %{"ref" => ref}, socket) do
socket =
if socket.assigns.ref_with_count[ref] == 1 do
{_, ref_with_count} = Map.pop!(socket.assigns.ref_with_count, ref)
{_, ref_with_pid} = Map.pop!(socket.assigns.ref_with_pid, ref)
assign(socket, ref_with_count: ref_with_count, ref_with_pid: ref_with_pid)
else
ref_with_count = Map.update!(socket.assigns.ref_with_count, ref, &(&1 - 1))
assign(socket, ref_with_count: ref_with_count)
end
{:noreply, socket}
end
@impl true
def handle_info({:connect_reply, data, %{ref: ref}}, socket) do
with {:error, error} <- try_push(socket, "init:#{ref}", %{"data" => data}) do
message = "Failed to serialize initial widget data, " <> error
push(socket, "error:#{ref}", %{"message" => message})
end
{:noreply, socket}
end
def handle_info({:event, event, payload, %{ref: ref}}, socket) do
with {:error, error} <-
try_push(socket, "event:#{ref}", %{"event" => event, "payload" => payload}) do
message = "Failed to serialize event payload, " <> error
push(socket, "error:#{ref}", %{"message" => message})
end
{:noreply, socket}
end
# In case the payload fails to encode we catch the error
defp try_push(socket, event, payload) do
try do
push(socket, event, payload)
catch
:error, %Protocol.UndefinedError{protocol: Jason.Encoder, value: value} ->
{:error, "value #{inspect(value)} is not JSON-serializable, use another data type"}
:error, error ->
{:error, Exception.message(error)}
end
end
end