Pistrie

Pistrie

I’m doing some experimentation, and I ran into an issue with my Registry setup.

I have an event where I start some doomed tasks:

def handle_event("start_processes", _, socket) do
  for _ <- 1..5 do
    name = :rand.bytes(5) |> Base.url_encode64(padding: false)

    task =
      TaskSupervisor
      |> Task.Supervisor.async_nolink(fn ->
        Process.sleep(to_timeout(second: :rand.uniform(9)))
        raise "Crash!"
      end)

    Registry.register(ProcessesRegistry, name, task.pid)

    task
  end
  processes = Registry.select(ProcessesRegistry, registry_select_all())
  {:noreply, assign(socket, processes: processes)}
end

I’d like to update my LiveView about the status of these tasks:

<div>
  <p>Current process: {inspect(self())}</p>
  <p>Registry process: {inspect(Process.whereis(ProcessesRegistry))}</p>

  <.button phx-click="get_registered_processes">Refresh Processes</.button>
  <.button phx-click="start_processes">Start Processes</.button>

  <h2>Background Processes</h2>
  <%= for pid <- @processes do %>
    <div>PID: {inspect(pid)}</div>
  <% end %>
</div>
def handle_info({:DOWN, _ref, :process, pid, _reason}, socket) do
  IO.puts("handling DOWN message in #{inspect(socket.root_pid)}")

  [{key, {_, _}}] = Registry.select(ProcessesRegistry, [{{:_, :_, pid}, [], [:"$_"]}])
  Registry.unregister(ProcessesRegistry, key)

  processes = Registry.select(ProcessesRegistry, registry_select_all())
  {:noreply, assign(socket, processes: processes)}
end

But there is a very simple problem: what happens when the LiveView page is refreshed?

The PID of the LiveView is changed, which causes the :DOWN messages to be sent to the old LiveView process instead of the new one.

Is there a simple way to solve this problem?

Thanks :smiley:

Showing Posts 1 to 2

slouchpie

slouchpie

You could use PubSub and broadcast the result of the task. Use the session id in the topic. Just make sure your LV subscribes to that topic on mount.

codeanpeace

codeanpeace

And to add on to this, you could also use user id in the topic if you want it to work across sessions/browsers/devices.

— All posts loaded —

Where Next? Top

Trending in Questions Top

stjefim
Hello! Suppose you are building workflow (order / task / payment) processing system with the following requirements: Each workflow con...
New
jonnycharles
I’m in search of an Elixir library that offers PDF generation capabilities similar to Ruby’s Prawn. While there have been discussions abo...
New
spammy
I’m looking to build a personal workflow to quickly deploy web applications written in elixir/phoenix, for local consumption (ie not on t...
New
dli
Before I dive in myself, did anyone successfully sprinkle Hologram into their existing LiveView app? Looking for hints regarding: Addi...
New
roeland
Kia ora, We have been using elixir-google-api to connect to Google Drive. However, with the updates to Tesla due to CVEs this is now bro...
New
bottlenecked
Hi all, I wanted to ask how the community is dealing with post-release steps. Today we have Ecto migrations, which make sure that the db...
New
rahultumpala
Hello, I have an Elixir backend that implements a custom protocol over TCP. I want to load test the backend and assess the performance o...
New

Other Trending Topics Top

JesseHerrick
Hey, I’m Jesse and I’m the main contributor behind Dexter, a full-featured, lightning-fast Elixir LSP optimized for large codebases. It s...
New
jimsynz
Beam Bots (or just BB for short) is a framework for building fault-tolerant robotics applications in Elixir using familiar OTP patterns. ...
New
mcass19
ExRatatui lets you cook up rich terminal UIs in Elixir, powered by Rust’s ratatui via Rustler NIFs. Build interactive terminal applicatio...
New
Damirados
Hello everyone. After busy few months I am happy to announce v0.1.0 of Emerge &amp; Solve. They are GUI (Emerge) and State management (S...
New
netoum
Corex is an accessible, unstyled UI component library for Phoenix that integrates Zag.js state machines using Vanilla JavaScript and Live...
New
ausimian
Emily is an Elixir library that runs Nx computations on Apple’s MLX. Install it as the default Nx backend and Nx, defn, Axon, Nx.Serving,...
New

We're in Beta

About us Mission Statement

Options

Thread Display Mode




Thread Preview

Skip Thread Previews