Reshape put_in/update_in calls in crashgroups (#811)

* Reshape put_in/update_in calls in crashgroups

* Add debug log about error in handling actions

* Fix test

* Add comment

lib/membrane/core/callback_handler.ex

@@ -185,6 +185,8 @@ defmodule Membrane.Core.CallbackHandler do
           Error handling actions returned by callback #{inspect(state.module)}.#{callback}
           """)
 
+          log_debug_orginal_error(actions, e, __STACKTRACE__)
+
           reraise e, __STACKTRACE__
       end
 
@@ -198,10 +200,29 @@ defmodule Membrane.Core.CallbackHandler do
             Error handling action #{inspect(action)} returned by callback #{inspect(state.module)}.#{callback}
             """)
 
+            log_debug_orginal_error(action, e, __STACKTRACE__)
+
             reraise e, __STACKTRACE__
         end
       end)
 
     handler_module.handle_end_of_actions(state)
   end
+
+  # We log it, because sometimes, for some reason, crashing process doesn't cause
+  # printing error logs on stderr, so this debug log allows us to get some info
+  # about what happened in case of process crash
+  defp log_debug_orginal_error(action_or_actions, error, stacktrace) do
+    action_or_actions =
+      if(is_list(action_or_actions), do: "actions ", else: "action ") <>
+        inspect(action_or_actions, limit: :infinity)
+
+    Membrane.Logger.debug("""
+    Error while handling #{action_or_actions}
+
+    Orginal error:
+    #{inspect(error, pretty: true, limit: :infinity)}
+    #{Exception.format_stacktrace(stacktrace)}
+    """)
+  end
 end

lib/membrane/core/parent/child_life_controller/crash_group_utils.ex

@@ -16,8 +16,7 @@ defmodule Membrane.Core.Parent.ChildLifeController.CrashGroupUtils do
   def add_crash_group(group_name, mode, children, state)
       when not is_map_key(state.crash_groups, group_name) do
     put_in(
-      state,
-      [:crash_groups, group_name],
+      state.crash_groups[group_name],
       %CrashGroup{
         name: group_name,
         mode: mode,
@@ -28,7 +27,7 @@ defmodule Membrane.Core.Parent.ChildLifeController.CrashGroupUtils do
 
   @spec extend_crash_group(Child.group(), [Child.name()], Parent.state()) :: Parent.state()
   def extend_crash_group(group_name, children, state) do
-    update_in(state, [:crash_groups, group_name, :members], &(children ++ &1))
+    update_in(state.crash_groups[group_name].members, &(children ++ &1))
   end
 
   @spec get_child_crash_group(Child.name(), Parent.state()) :: {:ok, CrashGroup.t()} | :error
@@ -44,7 +43,7 @@ defmodule Membrane.Core.Parent.ChildLifeController.CrashGroupUtils do
     # and we will not want to have it in :crash_group_members in the callback context in handle_crash_group_down/3,
     # so this child is removed from :members in crash group struct
     members = List.delete(group.members, child_name)
-    state = put_in(state, [:crash_groups, group.name, :members], members)
+    state = put_in(state.crash_groups[group.name].members, members)
 
     if group.detonating? and Enum.all?(members, &(not Map.has_key?(state.children, &1))) do
       cleanup_crash_group(group.name, state)
@@ -83,8 +82,7 @@ defmodule Membrane.Core.Parent.ChildLifeController.CrashGroupUtils do
     end)
 
     update_in(
-      state,
-      [:crash_groups, group.name],
+      state.crash_groups[group.name],
       &%CrashGroup{
         &1
         | detonating?: true,
@@ -96,15 +94,15 @@ defmodule Membrane.Core.Parent.ChildLifeController.CrashGroupUtils do
 
   defp cleanup_crash_group(group_name, state) do
     state = exec_handle_crash_group_down(group_name, state)
-    {_group, state} = pop_in(state, [:crash_groups, group_name])
+    {_group, state} = pop_in(state.crash_groups[group_name])
     state
   end
 
   defp exec_handle_crash_group_down(
          group_name,
          state
        ) do
-    crash_group = get_in(state, [:crash_groups, group_name])
+    crash_group = state.crash_groups[group_name]
 
     context_generator =
       &Component.context_from_state(&1,