Remove an extra Deployment preload during after_join (#1618)

- Preload the deployment, along with its firmware and archive, at the start of `after_join`
- Preload all the required bits again in `Deployments.set_deployment`
- And only use `:force` if the deployment has changed.
- This approach saves 100ms during `after_join`, which is over 15% of the total time.

lib/nerves_hub/deployments.ex

@@ -6,6 +6,7 @@ defmodule NervesHub.Deployments do
   alias NervesHub.AuditLogs
   alias NervesHub.Deployments.Deployment
   alias NervesHub.Deployments.InflightDeploymentCheck
+  alias NervesHub.Devices
   alias NervesHub.Devices.Device
   alias NervesHub.Products.Product
   alias NervesHub.Repo
@@ -498,25 +499,25 @@ defmodule NervesHub.Deployments do
 
       [deployment] ->
         device
-        |> Ecto.Changeset.change()
-        |> Ecto.Changeset.put_change(:deployment_id, deployment.id)
-        |> Repo.update!()
-        |> Repo.preload([:deployment])
+        |> Devices.update_deployment(deployment)
+        |> preload_with_firmware_and_archive(true)
 
       [deployment | _] ->
         Logger.debug(
           "More than one deployment matches for #{device.identifier}, setting to the first"
         )
 
         device
-        |> Ecto.Changeset.change()
-        |> Ecto.Changeset.put_change(:deployment_id, deployment.id)
-        |> Repo.update!()
-        |> Repo.preload([:deployment])
+        |> Devices.update_deployment(deployment)
+        |> preload_with_firmware_and_archive(true)
     end
   end
 
   def set_deployment(device) do
-    Repo.preload(device, [:deployment])
+    preload_with_firmware_and_archive(device)
+  end
+
+  def preload_with_firmware_and_archive(device, force \\ false) do
+    Repo.preload(device, [deployment: [:archive, :firmware]], force: force)
   end
 end

lib/nerves_hub/devices.ex

@@ -839,6 +839,13 @@ defmodule NervesHub.Devices do
 
   def matches_deployment?(_, _), do: false
 
+  def update_deployment(device, deployment) do
+    device
+    |> Ecto.Changeset.change()
+    |> Ecto.Changeset.put_change(:deployment_id, deployment.id)
+    |> Repo.update!()
+  end
+
   @spec failure_threshold_met?(Device.t(), Deployment.t()) :: boolean()
   def failure_threshold_met?(%Device{} = device, %Deployment{} = deployment) do
     Enum.count(device.update_attempts) >= deployment.device_failure_threshold

lib/nerves_hub_web/channels/device_channel.ex

@@ -32,11 +32,7 @@ defmodule NervesHubWeb.DeviceChannel do
   end
 
   def handle_info({:after_join, params}, %{assigns: %{device: device}} = socket) do
-    device =
-      device
-      |> Devices.verify_deployment()
-      |> Deployments.set_deployment()
-      |> deployment_preload()
+    device = maybe_update_deployment(device)
 
     maybe_send_public_keys(device, socket, params)
 
@@ -476,6 +472,13 @@ defmodule NervesHubWeb.DeviceChannel do
     :ok
   end
 
+  defp maybe_update_deployment(device) do
+    device
+    |> Deployments.preload_with_firmware_and_archive()
+    |> Devices.verify_deployment()
+    |> Deployments.set_deployment()
+  end
+
   defp log_to_sentry(device, message, extra \\ %{}) do
     Sentry.Context.set_tags_context(%{
       device_identifier: device.identifier,