Bug: Hide module reloading behind config flag (#420)

* hide behind config option

* change name, update docs

* fix tests

Author: GuzekAlan

README.md

@@ -108,6 +108,10 @@ config :live_debugger, :disabled?, true
 # Time in ms after tracing will be initialized. Useful in case multi-nodes envs
 config :live_debugger, :tracing_setup_delay, 0
 
+# Used when working with code reloading and traces are not visible.
+# WARNING! This may cause some performance issues.
+config :live_debugger, :tracing_update_on_code_reload?, true
+
 # LiveDebugger endpoint config
 config :live_debugger,
   ip: {127, 0, 0, 1}, # IP on which LiveDebugger will be hosted

docs/config.md

@@ -38,6 +38,10 @@ config :live_debugger, :disabled?, true
 # Time in ms after tracing will be initialized. Useful in case multi-nodes envs
 config :live_debugger, :tracing_setup_delay, 0
 
+# Used when working with code reloading and traces are not visible.
+# WARNING! This may cause some performance issues.
+config :live_debugger, :tracing_update_on_code_reload?, true
+
 # LiveDebugger endpoint config
 config :live_debugger,
   ip: {127, 0, 0, 1}, # IP on which LiveDebugger will be hosted

lib/live_debugger/gen_servers/callback_tracing_server.ex

@@ -53,8 +53,10 @@ defmodule LiveDebugger.GenServers.CallbackTracingServer do
     # We trace it to refresh the components tree
     Dbg.tp({Phoenix.LiveView.Diff, :delete_component, 2}, [])
 
-    # We need to get information when code reloads to properly trace modules
-    Dbg.tp({Mix.Tasks.Compile.Elixir, :run, 1}, [{:_, [], [{:return_trace}]}])
+    if Application.get_env(:live_debugger, :tracing_update_on_code_reload?, false) do
+      # We need to get information when code reloads to properly trace modules
+      Dbg.tp({Mix.Tasks.Compile.Elixir, :run, 1}, [{:_, [], [{:return_trace}]}])
+    end
 
     {:noreply, state}
   end
@@ -64,11 +66,8 @@ defmodule LiveDebugger.GenServers.CallbackTracingServer do
     {:reply, :ok, state}
   end
 
-  # This handler is heavy because of fetching state and we do not care for order because it is not displayed to user
-  # Because of that we do it asynchronously to speed up tracer a bit
-  # We do not persist this trace because it is not displayed to user
   @spec handle_trace(term(), n :: integer()) :: integer()
-  defp handle_trace({_, _, :return_from, {Mix.Tasks.Compile.Elixir, _, _}, _}, n) do
+  defp handle_trace({_, _, :return_from, {Mix.Tasks.Compile.Elixir, _, _}, {:ok, _}}, n) do
     Process.sleep(100)
     add_live_modules_to_tracer()
     n
@@ -78,7 +77,17 @@ defmodule LiveDebugger.GenServers.CallbackTracingServer do
     n
   end
 
-  defp handle_trace({_, pid, _, {Phoenix.LiveView.Diff, :delete_component, [cid | _] = args}}, n) do
+  defp handle_trace({_, _, _, {Mix.Tasks.Compile.Elixir, _, _}, _}, n) do
+    n
+  end
+
+  # This handler is heavy because of fetching state and we do not care for order because it is not displayed to user
+  # Because of that we do it asynchronously to speed up tracer a bit
+  # We do not persist this trace because it is not displayed to user
+  defp handle_trace(
+         {_, pid, _, {Phoenix.LiveView.Diff, :delete_component, [cid | _] = args}},
+         n
+       ) do
     Task.start(fn ->
       with cid <- %Phoenix.LiveComponent.CID{cid: cid},
            {:ok, %{socket: socket}} <- ChannelService.state(pid),

test/gen_servers/callback_tracing_server_test.exs

@@ -49,9 +49,6 @@ defmodule LiveDebugger.GenServers.CallbackTracingServerTest do
 
     MockDbg
     |> expect(:tp, fn {Phoenix.LiveView.Diff, :delete_component, 2}, [] -> :ok end)
-    |> expect(:tp, fn {Mix.Tasks.Compile.Elixir, :run, 1}, [{:_, [], [{:return_trace}]}] ->
-      :ok
-    end)
 
     assert {:noreply, %{}} = CallbackTracingServer.handle_info(:setup_tracing, %{})
   end
@@ -64,9 +61,6 @@ defmodule LiveDebugger.GenServers.CallbackTracingServerTest do
       MockDbg
       |> expect(:p, fn :all, :c -> :ok end)
       |> expect(:tp, fn {Phoenix.LiveView.Diff, :delete_component, 2}, [] -> :ok end)
-      |> expect(:tp, fn {Mix.Tasks.Compile.Elixir, :run, 1}, [{:_, [], [{:return_trace}]}] ->
-        :ok
-      end)
 
       # In order to keep CallbackTracingServer.handle_trace function private we extract it here
       # and send to test process so that we can test it