Enhancement: stabilize LiveDebugger behavior on recompilation (#873)

* Add filesystem dep

* Removed trace after recompile option

* Changed spec

* Working, needs polish

* Removed dbg

* Extracted live_module? function to ModuleAPI

* Changed name of all_paths function

* Better error handling in all_callbacks function

* Better specs

* Cleanup in TracingManager

* Split functions

* Removed obsolete tests

* Removed obsolete handler test

* Cleanup in tracing_manager_test

* Wrapped FileSystem library and added mock for it

* Added tests for paths

* Added tests for all_callbacks/1

* Add tests for live_module? function

* Added tests for refresh_tracing/1

* Add test for monitor recompilation

* Added case for file_event

* Fix settings e2e test

* Installation of inotify-tools

* Updated version in README

* Updated docs with new version

* Revert "Updated docs with new version"

This reverts commit 13a3dae.

* Revert "Updated version in README"

This reverts commit f1c0641.

Author: kraleppa

.github/workflows/backward-compatibility-ci.yaml

@@ -29,6 +29,9 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      - name: Install inotify-tools
+        run: sudo apt-get update && sudo apt-get install -y inotify-tools
+
       - name: Set up Elixir
         uses: erlef/[email protected]
         with:

.github/workflows/elixir-ci.yaml

@@ -29,6 +29,9 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      - name: Install inotify-tools
+        run: sudo apt-get update && sudo apt-get install -y inotify-tools
+
       - name: Set up Elixir
         uses: erlef/[email protected]
         with:

lib/live_debugger/api/settings_storage.ex

@@ -1,7 +1,6 @@
 defmodule LiveDebugger.API.SettingsStorage do
   @available_settings [
     :dead_view_mode,
-    :tracing_update_on_code_reload,
     :garbage_collection,
     :debug_button,
     :tracing_enabled_on_start,
@@ -77,7 +76,6 @@ defmodule LiveDebugger.API.SettingsStorage do
 
     @default_settings %{
       dead_view_mode: true,
-      tracing_update_on_code_reload: false,
       garbage_collection: true,
       debug_button: true,
       tracing_enabled_on_start: true,

lib/live_debugger/api/system/file_system.ex

@@ -0,0 +1,52 @@
+defmodule LiveDebugger.API.System.FileSystem do
+  @moduledoc """
+  API for interacting with file system monitoring functionalities.
+
+  This module wraps the `FileSystem` library to allow for easier testing and mocking.
+  """
+
+  @callback start_link(opts :: keyword()) :: GenServer.on_start()
+  @callback subscribe(name :: atom()) :: :ok
+
+  @doc """
+  Starts a FileSystem monitor process with the given options.
+
+  Options:
+  - `:dirs` - list of directories to monitor
+  - `:name` - name to register the process under
+  """
+  @spec start_link(keyword()) :: GenServer.on_start()
+  def start_link(opts), do: impl().start_link(opts)
+
+  @doc """
+  Subscribes the current process to file system events from the named monitor.
+
+  The subscribing process will receive messages in the format:
+  `{:file_event, pid, {path, events}}`
+  """
+  @spec subscribe(atom()) :: :ok
+  def subscribe(name), do: impl().subscribe(name)
+
+  defp impl() do
+    Application.get_env(
+      :live_debugger,
+      :api_file_system,
+      __MODULE__.Impl
+    )
+  end
+
+  defmodule Impl do
+    @moduledoc false
+    @behaviour LiveDebugger.API.System.FileSystem
+
+    @impl true
+    def start_link(opts) do
+      FileSystem.start_link(opts)
+    end
+
+    @impl true
+    def subscribe(name) do
+      FileSystem.subscribe(name)
+    end
+  end
+end

lib/live_debugger/api/system/module.ex

@@ -6,6 +6,7 @@ defmodule LiveDebugger.API.System.Module do
   @callback all() :: [{charlist(), charlist(), boolean()}]
   @callback loaded?(module :: module()) :: boolean()
   @callback behaviours(module :: module()) :: [module()]
+  @callback live_module?(module :: module()) :: boolean()
 
   @doc """
   Wrapper for `:code.all_available/0`.
@@ -26,6 +27,12 @@ defmodule LiveDebugger.API.System.Module do
   @spec behaviours(module :: module()) :: [module()]
   def behaviours(module), do: impl().behaviours(module)
 
+  @doc """
+  Returns true if the module implements Phoenix.LiveView or Phoenix.LiveComponent behaviour.
+  """
+  @spec live_module?(module :: module()) :: boolean()
+  def live_module?(module), do: impl().live_module?(module)
+
   defp impl() do
     Application.get_env(
       :live_debugger,
@@ -58,5 +65,12 @@ defmodule LiveDebugger.API.System.Module do
       # It is safe to return empty list in this case
       UndefinedFunctionError -> []
     end
+
+    @impl true
+    def live_module?(module) do
+      module
+      |> behaviours()
+      |> Enum.any?(&(&1 == Phoenix.LiveView || &1 == Phoenix.LiveComponent))
+    end
   end
 end

lib/live_debugger/app/events.ex

@@ -8,7 +8,7 @@ defmodule LiveDebugger.App.Events do
   alias LiveDebugger.Structs.LvProcess
 
   defevent(UserChangedSettings,
-    key: :dead_view_mode | :tracing_update_on_code_reload | :garbage_collection,
+    key: :dead_view_mode | :garbage_collection,
     value: term(),
     from: pid()
   )

lib/live_debugger/app/settings/web/settings_live.ex

@@ -69,14 +69,6 @@ defmodule LiveDebugger.App.Settings.Web.SettingsLive do
               phx-value-setting="dead_view_mode"
             />
 
-            <SettingsComponents.settings_switch
-              id="tracing-update-on-reload-switch"
-              label="Refresh tracing after recompilation"
-              description="Tracing in LiveDebugger may be interrupted when modules are recompiled. With this option enabled, LiveDebugger will refresh tracing after project recompilation. It may have a negative impact on application performance."
-              checked={@settings[:tracing_update_on_code_reload]}
-              phx-click="update"
-              phx-value-setting="tracing_update_on_code_reload"
-            />
             <SettingsComponents.settings_switch
               id="garbage-collection-switch"
               label="Garbage Collection"

lib/live_debugger/services/callback_tracer/actions/tracing.ex

@@ -2,11 +2,15 @@ defmodule LiveDebugger.Services.CallbackTracer.Actions.Tracing do
   @moduledoc """
   This module provides actions for tracing.
   """
+  require Logger
 
   alias LiveDebugger.Services.CallbackTracer.Queries.Callbacks, as: CallbackQueries
   alias LiveDebugger.Services.CallbackTracer.Process.Tracer
   alias LiveDebugger.API.System.Dbg
-  alias LiveDebugger.API.SettingsStorage
+  alias LiveDebugger.API.System.FileSystem, as: FileSystemAPI
+  alias LiveDebugger.API.System.Module, as: ModuleAPI
+  alias LiveDebugger.Utils.Modules, as: UtilsModules
+  alias LiveDebugger.Services.CallbackTracer.Queries.Paths, as: PathQueries
 
   @spec setup_tracing!() :: :ok
   def setup_tracing!() do
@@ -21,33 +25,40 @@ defmodule LiveDebugger.Services.CallbackTracer.Actions.Tracing do
     Dbg.process([:c, :timestamp])
     apply_trace_patterns()
 
-    if SettingsStorage.get(:tracing_update_on_code_reload) do
-      Dbg.trace_pattern(
-        {Mix.Tasks.Compile.Elixir, :run, 1},
-        Dbg.flag_to_match_spec(:return_trace)
-      )
-    end
-
     :ok
   end
 
-  @spec start_tracing_recompile_pattern() :: :ok
-  def start_tracing_recompile_pattern() do
-    Dbg.trace_pattern({Mix.Tasks.Compile.Elixir, :run, 1}, Dbg.flag_to_match_spec(:return_trace))
+  @spec refresh_tracing() :: :ok
+  def refresh_tracing() do
+    apply_trace_patterns()
 
     :ok
   end
 
-  @spec stop_tracing_recompile_pattern() :: :ok
-  def stop_tracing_recompile_pattern() do
-    Dbg.clear_trace_pattern({Mix.Tasks.Compile.Elixir, :run, 1})
+  @spec refresh_tracing(String.t()) :: :ok
+  def refresh_tracing(path) do
+    with true <- beam_file?(path),
+         module <- path |> Path.basename(".beam") |> String.to_existing_atom(),
+         true <- ModuleAPI.loaded?(module),
+         false <- UtilsModules.debugger_module?(module),
+         true <- ModuleAPI.live_module?(module) do
+      refresh_tracing_for_module(module)
+    end
 
     :ok
   end
 
-  @spec refresh_tracing() :: :ok
-  def refresh_tracing() do
-    apply_trace_patterns()
+  @doc """
+  Starts FileSystem monitor and subscribes to it for compiled modules directories.
+  When changes are detected in the monitored directories,
+  process will receive `{:file_event, _pid, {path, events}}` message.
+  """
+
+  @spec monitor_recompilation() :: :ok
+  def monitor_recompilation() do
+    directories = PathQueries.compiled_modules_directories()
+    FileSystemAPI.start_link(dirs: directories, name: :lvdbg_file_system_monitor)
+    FileSystemAPI.subscribe(:lvdbg_file_system_monitor)
 
     :ok
   end
@@ -59,6 +70,22 @@ defmodule LiveDebugger.Services.CallbackTracer.Actions.Tracing do
     :ok
   end
 
+  defp refresh_tracing_for_module(module) do
+    module
+    |> CallbackQueries.all_callbacks()
+    |> case do
+      {:error, error} ->
+        Logger.error("Error refreshing tracing for module #{module}: #{error}")
+
+      callbacks ->
+        callbacks
+        |> Enum.each(fn mfa ->
+          Dbg.trace_pattern(mfa, Dbg.flag_to_match_spec(:return_trace))
+          Dbg.trace_pattern(mfa, Dbg.flag_to_match_spec(:exception_trace))
+        end)
+    end
+  end
+
   defp apply_trace_patterns() do
     # This is not a callback created by user
     # We trace it to refresh the components tree
@@ -70,4 +97,8 @@ defmodule LiveDebugger.Services.CallbackTracer.Actions.Tracing do
       Dbg.trace_pattern(mfa, Dbg.flag_to_match_spec(:exception_trace))
     end)
   end
+
+  defp beam_file?(path) do
+    String.ends_with?(path, ".beam")
+  end
 end

lib/live_debugger/services/callback_tracer/gen_servers/trace_handler.ex

@@ -9,7 +9,6 @@ defmodule LiveDebugger.Services.CallbackTracer.GenServers.TraceHandler do
 
   alias LiveDebugger.Utils.Callbacks, as: CallbackUtils
   alias LiveDebugger.Services.CallbackTracer.Actions.FunctionTrace, as: TraceActions
-  alias LiveDebugger.Services.CallbackTracer.Actions.Tracing, as: TracingActions
   alias LiveDebugger.Services.CallbackTracer.Actions.State, as: StateActions
   alias LiveDebugger.Services.CallbackTracer.Actions.DiffTrace, as: DiffActions
   alias LiveDebugger.Structs.Trace.FunctionTrace
@@ -53,39 +52,6 @@ defmodule LiveDebugger.Services.CallbackTracer.GenServers.TraceHandler do
     {:ok, %{}}
   end
 
-  #########################################################
-  # Handling recompile events
-  #
-  # We catch this trace to know when modules were recompiled.
-  # We do not display this trace to user, so we do not have to care about order
-  # We need to catch that case because tracer disconnects from modules that were recompiled
-  # and we need to reapply tracing patterns to them.
-  # This will be replaced in the future with a more efficient way to handle this.
-  # https://github.com/software-mansion/live-debugger/issues/592
-  #
-  #########################################################
-
-  @impl true
-  def handle_cast(
-        {:new_trace, {_, _, :return_from, {Mix.Tasks.Compile.Elixir, _, _}, {:ok, _}, _}, _n},
-        state
-      ) do
-    Task.start(fn ->
-      Process.sleep(100)
-      TracingActions.refresh_tracing()
-    end)
-
-    {:noreply, state}
-  end
-
-  def handle_cast({:new_trace, {_, _, _, {Mix.Tasks.Compile.Elixir, _, _}, _}, _}, state) do
-    {:noreply, state}
-  end
-
-  def handle_cast({:new_trace, {_, _, _, {Mix.Tasks.Compile.Elixir, _, _}, _, _}, _}, state) do
-    {:noreply, state}
-  end
-
   #########################################################
   # Handling component deletion traces
   #
@@ -96,6 +62,7 @@ defmodule LiveDebugger.Services.CallbackTracer.GenServers.TraceHandler do
   #
   #########################################################
 
+  @impl true
   def handle_cast(
         {:new_trace,
          {_, pid, _, {Phoenix.LiveView.Diff, :delete_component, [cid | _] = args}, ts}, n},

lib/live_debugger/services/callback_tracer/gen_servers/tracing_manager.ex

@@ -6,7 +6,6 @@ defmodule LiveDebugger.Services.CallbackTracer.GenServers.TracingManager do
   use GenServer
 
   alias LiveDebugger.Bus
-  alias LiveDebugger.App.Events.UserChangedSettings
   alias LiveDebugger.App.Events.UserRefreshedTrace
   alias LiveDebugger.Services.ProcessMonitor.Events.LiveViewBorn
 
@@ -41,40 +40,36 @@ defmodule LiveDebugger.Services.CallbackTracer.GenServers.TracingManager do
   @impl true
   def handle_info(:setup_tracing, state) do
     TracingActions.setup_tracing!()
+    TracingActions.monitor_recompilation()
 
     {:noreply, state}
   end
 
-  @impl true
-  def handle_info(%UserChangedSettings{key: :tracing_update_on_code_reload, value: true}, state) do
-    TracingActions.start_tracing_recompile_pattern()
+  def handle_info(%LiveViewBorn{pid: pid}, state) do
+    TracingActions.start_outgoing_messages_tracing(pid)
 
     {:noreply, state}
   end
 
-  @impl true
-  def handle_info(%UserChangedSettings{key: :tracing_update_on_code_reload, value: false}, state) do
-    TracingActions.stop_tracing_recompile_pattern()
+  def handle_info(%UserRefreshedTrace{}, state) do
+    TracingActions.refresh_tracing()
 
     {:noreply, state}
   end
 
-  @impl true
-  def handle_info(%LiveViewBorn{pid: pid}, state) do
-    TracingActions.start_outgoing_messages_tracing(pid)
+  def handle_info({:file_event, _pid, {path, events}}, state) do
+    if correct_event?(events) do
+      TracingActions.refresh_tracing(path)
+    end
 
     {:noreply, state}
   end
 
-  @impl true
-  def handle_info(%UserRefreshedTrace{}, state) do
-    TracingActions.refresh_tracing()
-
+  def handle_info(_, state) do
     {:noreply, state}
   end
 
-  @impl true
-  def handle_info(_, state) do
-    {:noreply, state}
+  defp correct_event?(events) do
+    Enum.any?(events, &(&1 == :modified || &1 == :created))
   end
 end