change tracing pattern when setting changes

Author: GuzekAlan

lib/live_debugger/gen_servers/callback_tracing_server.ex

@@ -7,6 +7,7 @@ defmodule LiveDebugger.GenServers.CallbackTracingServer do
 
   require Logger
 
+  alias LiveDebugger.GenServers.SettingsServer
   alias LiveDebugger.Services.System.DbgService, as: Dbg
   alias LiveDebugger.Services.ModuleDiscoveryService
   alias LiveDebugger.Services.ChannelService
@@ -49,6 +50,10 @@ defmodule LiveDebugger.GenServers.CallbackTracingServer do
       Dbg.tp(mfa, [{:_, [], [{:exception_trace}]}])
     end)
 
+    if SettingsServer.get(:tracing_update_on_code_reload) do
+      add_code_reload_tracing()
+    end
+
     :ok
   end
 
@@ -67,6 +72,11 @@ defmodule LiveDebugger.GenServers.CallbackTracingServer do
     {:ok, %{}}
   end
 
+  @impl true
+  def handle_call(:ping, _from, state) do
+    {:reply, :ok, state}
+  end
+
   @impl true
   def handle_info(:setup_tracing, state) do
     Dbg.tracer(:process, {&handle_trace/2, 0})
@@ -78,19 +88,25 @@ defmodule LiveDebugger.GenServers.CallbackTracingServer do
     # We trace it to refresh the components tree
     Dbg.tp({Phoenix.LiveView.Diff, :delete_component, 2}, [])
 
-    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
+    PubSubUtils.setting_changed()
+    |> PubSubUtils.subscribe!()
 
     {:noreply, state}
   end
 
-  @impl true
-  def handle_call(:ping, _from, state) do
-    {:reply, :ok, state}
+  def handle_info({:setting_changed, :tracing_update_on_code_reload, reload?}, state)
+      when is_boolean(reload?) do
+    if reload? do
+      add_code_reload_tracing()
+    else
+      remove_code_reload_tracing()
+    end
+
+    {:noreply, state}
   end
 
+  def handle_info(_, state), do: {:noreply, state}
+
   @spec handle_trace(term(), n :: integer()) :: integer()
   defp handle_trace({_, _, :return_from, {Mix.Tasks.Compile.Elixir, _, _}, {:ok, _}, _}, n) do
     Process.sleep(100)
@@ -245,4 +261,12 @@ defmodule LiveDebugger.GenServers.CallbackTracingServer do
     |> PubSubUtils.trace_topic_per_pid(fun, :return)
     |> PubSubUtils.broadcast({:updated_trace, trace})
   end
+
+  defp add_code_reload_tracing() do
+    Dbg.tp({Mix.Tasks.Compile.Elixir, :run, 1}, [{:_, [], [{:return_trace}]}])
+  end
+
+  defp remove_code_reload_tracing() do
+    Dbg.ctp({Mix.Tasks.Compile.Elixir, :run, 1}, [{:_, [], [{:return_trace}]}])
+  end
 end

lib/live_debugger/gen_servers/settings_server.ex

@@ -10,6 +10,8 @@ defmodule LiveDebugger.GenServers.SettingsServer do
 
   @settings [:dead_view_mode, :tracing_update_on_code_reload]
 
+  alias LiveDebugger.Utils.PubSub, as: PubSubUtils
+
   ## API
 
   @spec get(setting :: atom()) :: term()
@@ -64,6 +66,9 @@ defmodule LiveDebugger.GenServers.SettingsServer do
   def handle_cast({:save, setting, value}, state) do
     save_in_dets(setting, value)
 
+    PubSubUtils.setting_changed()
+    |> PubSubUtils.broadcast({:setting_changed, setting, value})
+
     {:noreply, Map.put(state, setting, value)}
   end
 

lib/live_debugger/services/system/dbg_service.ex

@@ -22,6 +22,8 @@ defmodule LiveDebugger.Services.System.DbgService do
 
   @callback tp(module() | mfa(), match_spec :: term()) :: {:ok, match_desc()} | {:error, term()}
 
+  @callback ctp(module() | mfa(), match_spec :: term()) :: {:ok, match_desc()} | {:error, term()}
+
   @doc """
   Wrapper for `:dbg.tracer/2` that starts a tracer for the given type and handler specification.
   """
@@ -46,6 +48,12 @@ defmodule LiveDebugger.Services.System.DbgService do
   @spec tp(module() | mfa(), match_spec :: term()) :: {:ok, match_desc()} | {:error, term()}
   def tp(module, match_spec), do: impl().tp(module, match_spec)
 
+  @doc """
+  Wrapper for `:dbg.ctp/2` that ends tracing for given pattern
+  """
+  @spec ctp(module() | mfa(), match_spec :: term()) :: {:ok, match_desc()} | {:error, term()}
+  def ctp(module, match_spec), do: impl().ctp(module, match_spec)
+
   defp impl() do
     Application.get_env(
       :live_debugger,
@@ -72,5 +80,10 @@ defmodule LiveDebugger.Services.System.DbgService do
     def tp(module, match_spec) do
       :dbg.tp(module, match_spec)
     end
+
+    @impl true
+    def ctp(module, match_spec) do
+      :dbg.ctp(module, match_spec)
+    end
   end
 end

lib/live_debugger/utils/pubsub.ex

@@ -26,6 +26,11 @@ defmodule LiveDebugger.Utils.PubSub do
   @spec unsubscribe(topic :: String.t()) :: :ok
   def unsubscribe(topic), do: impl().unsubscribe(topic)
 
+  @spec setting_changed() :: String.t()
+  def setting_changed() do
+    "lvdbg/setting_changed"
+  end
+
   @doc "Use `{:component_deleted, delete_trace}` for broadcasting"
   @spec component_deleted_topic() :: String.t()
   def component_deleted_topic() do