PlugStatem

A gen_statem-style event loop that fits the Plug contract.

Elixir HTTP servers using Plug require every write to a Plug.Conn to come from the process that received the request. PlugStatem.enter_loop/6 takes over that process during the execution of a long-lived response, such as when serving SSE.

Over the lifetime of the response, your callback module will be executed just like a standard gen_statem.

On :stop, PlugStatem.enter_loop/5 returns a result instead of exiting the process, so that the rest of the Plug call/2 contract can be fulfilled.

def call(%Plug.Conn{path_info: ["events"]} = conn, _opts) do
  conn = Plug.Conn.put_resp_content_type(conn, "text/event-stream")

  case PlugStatem.enter_loop(MyStream, [], conn, :streaming, %{}) do
    {_reason, _state, conn, _data} -> conn
  end
end

See the PlugStatem module documentation for more details.

Installation

def deps do
  [
    {:plug_statem, "~> 0.1.0"}
  ]
end