Refactor diamond detection code

lib/membrane/core/element/diamond_detection_controller.ex

@@ -6,10 +6,11 @@ defmodule Membrane.Core.Element.DiamondDetectionController do
   require Membrane.Pad, as: Pad
 
   alias __MODULE__.{DiamondLogger, PathInGraph}
+  alias __MODULE__.PathInGraph.Vertex
   alias Membrane.Core.Element.State
   alias Membrane.Element.PadData
 
-  @component_path_suffix "__membrane_component_path_64_byte_suffix________________________"
+  @component_path_prefix "__membrane_component_path_64_byte_prefix________________________"
 
   @spec start_diamond_detection(State.t()) :: :ok
   def start_diamond_detection(state) do
@@ -61,11 +62,14 @@ defmodule Membrane.Core.Element.DiamondDetectionController do
         state
 
       true ->
+        old_diamond_detection_path =
+          state.diamond_detection_ref_to_path[diamond_detection_ref]
+          |> remove_component_path_prefix()
+
         :ok =
-          DiamondLogger.log_diamond(
-            diamond_detecton_path |> cut_suffixes_in_path(),
-            state.diamond_detection_ref_to_path[diamond_detection_ref] |> cut_suffixes_in_path()
-          )
+          diamond_detecton_path
+          |> remove_component_path_prefix()
+          |> DiamondLogger.log_diamond(old_diamond_detection_path)
 
         state
     end
@@ -186,18 +190,18 @@ defmodule Membrane.Core.Element.DiamondDetectionController do
   end
 
   defp get_component_path() do
-    # adding @component_path_suffix to component path will cause that component path will
+    # adding @component_path_prefix to component path will cause that component path will
     # always have more than 64 bytes, so it won't be copied during sending a message
-    (Membrane.ComponentPath.get() ++ [@component_path_suffix])
+    [@component_path_prefix | Membrane.ComponentPath.get()]
     |> Enum.join()
   end
 
   defp have_common_prefix?(path_a, path_b), do: List.last(path_a) == List.last(path_b)
 
-  defp cut_suffixes_in_path(path_in_graph) do
+  defp remove_component_path_prefix(path_in_graph) do
     path_in_graph
-    |> Enum.map(
-      &%{&1 | component_path: String.replace(&1.component_path, @component_path_suffix, "")}
-    )
+    |> Enum.map(fn %Vertex{component_path: @component_path_prefix <> component_path} = vertex ->
+      %{vertex | component_path: component_path}
+    end)
   end
 end

lib/membrane/core/element/diamond_detection_controller/diamond_logger.ex

@@ -6,6 +6,8 @@ defmodule Membrane.Core.Element.DiamondDetectionController.DiamondLogger do
   alias Membrane.Core.Element.DiamondDetectionController.PathInGraph
   alias Membrane.Core.Element.DiamondDetectionController.PathInGraph.Vertex
 
+  # logging a diamond is moved to the separate module due to testing
+
   @spec log_diamond(PathInGraph.t(), PathInGraph.t()) :: :ok
   def log_diamond(path_a, path_b) do
     Membrane.Logger.debug("""

test/membrane/integration/diamond_detection_test.exs

@@ -29,6 +29,7 @@ defmodule Membrane.Integration.DiamondDetectionTest do
     def handle_demand(_pad, _demand, _unit, _ctx, state), do: {[], state}
   end
 
+  @tag :xd
   test "logging a diamond" do
     with_mock DiamondLogger, log_diamond: fn _path_a, _path_b -> :ok end do
       # a -> b -> c and a -> c
@@ -112,7 +113,7 @@ defmodule Membrane.Integration.DiamondDetectionTest do
       Process.sleep(1500)
 
       assert [_old_entry | new_entries] = call_history(DiamondLogger)
-      assert new_entries != []
+      assert length(new_entries) in [1, 2]
 
       new_entries
       |> Enum.flat_map(fn {_element_pid, {DiamondLogger, :log_diamond, [path_a, path_b]}, :ok} ->