dotfiles/app/lib/prymn/messaging/connection.ex
Nikos Papadakis 59945bd2de
terminal
2024-02-02 20:53:52 +02:00

89 lines
2.7 KiB
Elixir

defmodule Prymn.Messaging.Connection do
use GenServer
defstruct [:conn_pid, subscriptions: %{}]
require Logger
alias Prymn.Agents
alias Prymn.Messaging
@dialyzer {:nowarn_function, init: 1}
@subscription_supervisor Prymn.Messaging.SubscriptionSupervisor
@v1_prefix "agents.v1."
def start_link(name) do
GenServer.start_link(__MODULE__, nil, name: name)
end
def publish_to_agent(conn, agent_id, subject, payload \\ "") do
GenServer.call(conn, {:publish, agent_id, subject, payload})
end
def subscribe_to_agent(conn, agent_id, subject) do
GenServer.call(conn, {:subscribe, agent_id, subject})
end
@impl true
def init(_init_arg) do
connection_properties = %{
host: "localhost",
username: "prymn_admin",
password: "prymn_admin",
auth_required: true
}
Process.flag(:trap_exit, true)
case Gnat.start_link(connection_properties) do
{:ok, pid} ->
Logger.info("Connected to NATS")
{:ok, %__MODULE__{conn_pid: pid}, {:continue, :subscribe_to_health}}
{:error, reason} ->
Logger.info("Connection to NATS failed (#{reason}). Attempting reconnect.")
{:ok, nil, {:continue, :attempt_reconnect}}
end
end
@impl true
def handle_continue(:attempt_reconnect, state) do
Process.sleep(3000)
{:stop, {:shutdown, :connection_failure}, state}
end
def handle_continue(:subscribe_to_health, %__MODULE__{} = state) do
{:ok, _subscription} = Gnat.sub(state.conn_pid, self(), @v1_prefix <> "*.health")
{:noreply, state}
end
@impl true
def handle_call({:publish, agent_id, subject, payload}, _from, %{conn_pid: conn_pid} = state) do
:ok = Gnat.pub(conn_pid, @v1_prefix <> "#{agent_id}.#{subject}", payload)
{:reply, :ok, state}
end
def handle_call({:subscribe, agent_id, subject}, {pid, _}, %{conn_pid: conn_pid} = state) do
args = %{agent_id: agent_id, subject: subject, gnat: conn_pid, reply: pid}
case DynamicSupervisor.start_child(@subscription_supervisor, {Messaging.Subscription, args}) do
{:ok, _pid} -> {:reply, :ok, state}
{:error, {:already_started, _pid}} -> {:reply, :ok, state}
{:error, error} -> {:reply, {:error, error}, state}
end
end
@impl true
def handle_info({:EXIT, _pid, _reason}, state) do
Logger.info("Lost connection to NATS. Attempting reconnect.")
{:noreply, state, {:continue, :attempt_reconnect}}
end
def handle_info({:msg, %{body: payload, topic: @v1_prefix <> topic = subject}}, state) do
[agent_id, "health"] = String.split(topic, ".")
health = Messaging.Messages.handle_message(subject, payload)
Agents.update_health(agent_id, health)
{:noreply, state}
end
end