Phoenix LiveView hooks telemetry

quatermain · December 11, 2024, 4:28pm

I was thinking that it might be nice to wrap telemetry around hooks as well. Because it can happen that these hooks can be expensive (time, resources…). It would be nice to be able to see these details as well. Or are hooks already executed within the telemetry of the event?
I can implement it if someone will point me where is good start to look around.

steffend · December 11, 2024, 5:25pm

The telemetry calls wrap the whole lifecycle, so hooks are already included:

github.com

phoenixframework/phoenix_live_view/blob/d1250dc6541684fd19f5c8dd3aea692ad4b57950/lib/phoenix_live_view/utils.ex#L341-L355


      
          :telemetry.span(
            [:phoenix, :live_view, :mount],
            %{socket: socket, params: params, session: session, uri: uri},
            fn ->
              socket =
                case Lifecycle.mount(params, session, socket) do
                  {:cont, %Socket{} = socket} when exported? ->
                    view.mount(params, session, socket)
          
                  {_, %Socket{} = socket} ->
                    {:ok, socket}
                end
                |> handle_mount_result!({view, :mount, 3})
          
              {socket, %{socket: socket, params: params, session: session, uri: uri}}

github.com

phoenixframework/phoenix_live_view/blob/d1250dc6541684fd19f5c8dd3aea692ad4b57950/lib/phoenix_live_view/channel.ex#L496-L520


      
          :telemetry.span(
            [:phoenix, :live_view, :handle_event],
            %{socket: socket, event: event, params: val},
            fn ->
              case Lifecycle.handle_event(event, val, socket) do
                {:halt, %Socket{} = socket} ->
                  {{:noreply, socket}, %{socket: socket, event: event, params: val}}
          
                {:halt, reply, %Socket{} = socket} ->
                  {{:reply, reply, socket}, %{socket: socket, event: event, params: val}}
          
                {:cont, %Socket{} = socket} ->
                  case socket.view.handle_event(event, val, socket) do
                    {:noreply, %Socket{} = socket} ->
                      {{:noreply, socket}, %{socket: socket, event: event, params: val}}
          
                    {:reply, reply, %Socket{} = socket} ->
                      {{:reply, reply, socket}, %{socket: socket, event: event, params: val}}
          
                    other ->

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