Revert content tracking instead of mtime.

Author: josevalim

lib/mix/lib/mix/compilers/elixir.ex

@@ -1,7 +1,7 @@
 defmodule Mix.Compilers.Elixir do
   @moduledoc false
 
-  @manifest_vsn 9
+  @manifest_vsn 8
 
   import Record
 
@@ -10,7 +10,6 @@ defmodule Mix.Compilers.Elixir do
   defrecord :source,
     source: nil,
     size: 0,
-    digest: nil,
     compile_references: [],
     export_references: [],
     runtime_references: [],
@@ -176,10 +175,6 @@ defmodule Mix.Compilers.Elixir do
     {[], %{}, all_paths, sources_stats}
   end
 
-  # Assume that either all .beam files are missing, or none of them are
-  defp missing_beam_file?(dest, [mod | _]), do: not File.exists?(beam_path(dest, mod))
-  defp missing_beam_file?(_dest, []), do: false
-
   defp compiler_info_from_updated(
          modified,
          all_paths,
@@ -211,16 +206,12 @@ defmodule Mix.Compilers.Elixir do
     # Sources that have changed on disk or
     # any modules associated with them need to be recompiled
     changed =
-      for source(source: source, external: external, size: size, digest: digest, modules: modules) <-
+      for source(source: source, external: external, size: size, modules: modules) <-
             all_sources,
           {last_mtime, last_size} = Map.fetch!(sources_stats, source),
           times = Enum.map(external, &(sources_stats |> Map.fetch!(&1) |> elem(0))),
-          Enum.any?(modules, &Map.has_key?(modules_to_recompile, &1)) or
-            Mix.Utils.stale?(times, [modified]) or
-            (size != last_size or
-               (last_mtime > modified and
-                  (missing_beam_file?(dest, modules) or
-                     digest != digest(source)))),
+          size != last_size or Mix.Utils.stale?([last_mtime | times], [modified]) or
+            Enum.any?(modules, &Map.has_key?(modules_to_recompile, &1)),
           do: source
 
     changed = new_paths ++ changed
@@ -255,12 +246,6 @@ defmodule Mix.Compilers.Elixir do
     end)
   end
 
-  defp digest(file) do
-    file
-    |> File.read!()
-    |> :erlang.md5()
-  end
-
   defp compile_path(stale, dest, timestamp, opts) do
     cwd = File.cwd!()
     long_compilation_threshold = opts[:long_compilation_threshold] || 10
@@ -475,8 +460,6 @@ defmodule Mix.Compilers.Elixir do
     source =
       source(
         source,
-        # We preserve the digest if the file is recompiled but not changed
-        digest: source(source, :digest) || digest(file),
         compile_references: compile_references,
         export_references: export_references,
         runtime_references: runtime_references,
@@ -526,11 +509,11 @@ defmodule Mix.Compilers.Elixir do
   # to be recompiled (but were not changed on disk)
   defp update_stale_sources(sources, changed) do
     Enum.reduce(changed, {sources, %{}}, fn file, {acc_sources, acc_modules} ->
-      {source(size: size, digest: digest, modules: modules), acc_sources} =
+      {source(size: size, modules: modules), acc_sources} =
         List.keytake(acc_sources, file, source(:source))
 
       acc_modules = Enum.reduce(modules, acc_modules, &Map.put(&2, &1, true))
-      {[source(source: file, size: size, digest: digest) | acc_sources], acc_modules}
+      {[source(source: file, size: size) | acc_sources], acc_modules}
     end)
   end
 
@@ -717,15 +700,11 @@ defmodule Mix.Compilers.Elixir do
       {@manifest_vsn, modules, sources, local_exports} ->
         {modules, sources, local_exports}
 
-      # v8-v* (v1.11)
-      {vsn, modules, _sources, _local_exports} when is_integer(vsn) ->
-        purge_old_manifest(compile_path, modules)
-
-      # v5-v7 (v1.10)
+      # From v5 and later
       {vsn, modules, _sources} when is_integer(vsn) ->
         purge_old_manifest(compile_path, modules)
 
-      # v1-v4
+      # From v4 and before
       [vsn | data] when is_integer(vsn) ->
         purge_old_manifest(compile_path, data)
 

lib/mix/test/mix/tasks/compile.elixir_test.exs

@@ -195,7 +195,7 @@ defmodule Mix.Tasks.Compile.ElixirTest do
     end)
   end
 
-  test "compiles mtime changed files if content changed but not length" do
+  test "compiles mtime changed files" do
     in_fixture("no_mixfile", fn ->
       assert Mix.Tasks.Compile.Elixir.run(["--verbose"]) == {:ok, []}
       assert_received {:mix_shell, :info, ["Compiled lib/a.ex"]}
@@ -204,8 +204,6 @@ defmodule Mix.Tasks.Compile.ElixirTest do
       Mix.shell().flush
       purge([A, B])
 
-      same_length_content = "lib/a.ex" |> File.read!() |> String.replace("A", "Z")
-      File.write!("lib/a.ex", same_length_content)
       future = {{2038, 1, 1}, {0, 0, 0}}
       File.touch!("lib/a.ex", future)
       Mix.Tasks.Compile.Elixir.run(["--verbose"])
@@ -227,71 +225,6 @@ defmodule Mix.Tasks.Compile.ElixirTest do
     end)
   end
 
-  test "does not recompile mtime changed but identical files" do
-    in_fixture("no_mixfile", fn ->
-      assert Mix.Tasks.Compile.Elixir.run(["--verbose"]) == {:ok, []}
-      assert_received {:mix_shell, :info, ["Compiled lib/a.ex"]}
-      assert_received {:mix_shell, :info, ["Compiled lib/b.ex"]}
-
-      Mix.shell().flush
-      purge([A, B])
-
-      future = {{2038, 1, 1}, {0, 0, 0}}
-      File.touch!("lib/a.ex", future)
-      Mix.Tasks.Compile.Elixir.run(["--verbose"])
-
-      message =
-        "warning: mtime (modified time) for \"lib/a.ex\" was set to the future, resetting to now"
-
-      assert_received {:mix_shell, :error, [^message]}
-
-      message =
-        "warning: mtime (modified time) for \"lib/b.ex\" was set to the future, resetting to now"
-
-      refute_received {:mix_shell, :error, [^message]}
-      refute_received {:mix_shell, :info, ["Compiled lib/a.ex"]}
-      refute_received {:mix_shell, :info, ["Compiled lib/b.ex"]}
-
-      File.touch!("_build/dev/lib/sample/.mix/compile.elixir", future)
-      assert Mix.Tasks.Compile.Elixir.run([]) == {:noop, []}
-    end)
-  end
-
-  test "does recompile a file restored after a compile error (and .beam file were deleted)" do
-    in_fixture("no_mixfile", fn ->
-      assert Mix.Tasks.Compile.Elixir.run(["--verbose"]) == {:ok, []}
-      assert_received {:mix_shell, :info, ["Compiled lib/a.ex"]}
-      assert_received {:mix_shell, :info, ["Compiled lib/b.ex"]}
-
-      Mix.shell().flush
-      purge([A, B])
-
-      # Compile with error
-      original_content = File.read!("lib/b.ex")
-      File.write!("lib/b.ex", "this will not compile")
-
-      assert capture_io(fn ->
-               {:error, _} = Mix.Tasks.Compile.Elixir.run(["--verbose"])
-             end) =~ "Compilation error in file lib/b.ex"
-
-      assert_received {:mix_shell, :info, ["Compiling 1 file (.ex)"]}
-
-      # Revert change
-      File.write!("lib/b.ex", original_content)
-      future = {{2038, 1, 1}, {0, 0, 0}}
-      File.touch!("lib/b.ex", future)
-
-      Mix.Tasks.Compile.Elixir.run(["--verbose"])
-
-      message =
-        "warning: mtime (modified time) for \"lib/b.ex\" was set to the future, resetting to now"
-
-      assert_received {:mix_shell, :error, [^message]}
-      assert_received {:mix_shell, :info, ["Compiled lib/b.ex"]}
-      refute_received {:mix_shell, :info, ["Compiled lib/a.ex"]}
-    end)
-  end
-
   test "compiles size changed files" do
     in_fixture("no_mixfile", fn ->
       past = {{2010, 1, 1}, {0, 0, 0}}
@@ -324,7 +257,8 @@ defmodule Mix.Tasks.Compile.ElixirTest do
       Mix.shell().flush
       purge([A, B])
 
-      force_recompilation("lib/b.ex")
+      future = {{2038, 1, 1}, {0, 0, 0}}
+      File.touch!("lib/b.ex", future)
       Mix.Tasks.Compile.Elixir.run(["--verbose"])
 
       assert_received {:mix_shell, :info, ["Compiled lib/a.ex"]}
@@ -349,7 +283,7 @@ defmodule Mix.Tasks.Compile.ElixirTest do
 
       Code.put_compiler_option(:ignore_module_conflict, true)
       Code.compile_file("lib/b.ex")
-      force_recompilation("lib/a.ex")
+      File.touch!("lib/a.ex", {{2038, 1, 1}, {0, 0, 0}})
 
       Mix.Tasks.Compile.Elixir.run(["--verbose"])
       assert_received {:mix_shell, :info, ["Compiled lib/a.ex"]}
@@ -538,7 +472,8 @@ defmodule Mix.Tasks.Compile.ElixirTest do
       assert_received {:mix_shell, :info, ["Compiled lib/b.ex"]}
       purge([A, B])
 
-      force_recompilation("lib/a.ex")
+      future = {{2038, 1, 1}, {0, 0, 0}}
+      File.touch!("lib/a.ex", future)
 
       assert Mix.Tasks.Compile.Elixir.run(["--verbose"]) == {:ok, []}
       assert_received {:mix_shell, :info, ["Compiled lib/a.ex"]}
@@ -680,7 +615,8 @@ defmodule Mix.Tasks.Compile.ElixirTest do
       Mix.shell().flush
       purge([A, B])
 
-      force_recompilation("lib/a.ex")
+      future = {{2038, 1, 1}, {0, 0, 0}}
+      File.touch!("lib/a.ex", future)
       Mix.Tasks.Compile.Elixir.run(["--verbose"])
 
       assert_received {:mix_shell, :info, ["Compiled lib/a.ex"]}

lib/mix/test/mix/tasks/test_test.exs

@@ -68,12 +68,12 @@ defmodule Mix.Tasks.TestTest do
         assert_stale_run_output("2 tests, 0 failures")
 
         set_all_mtimes()
-        force_recompilation("lib/b.ex")
+        File.touch!("lib/b.ex")
 
         assert_stale_run_output("1 test, 0 failures")
 
         set_all_mtimes()
-        force_recompilation("lib/a.ex")
+        File.touch!("lib/a.ex")
 
         assert_stale_run_output("2 tests, 0 failures")
       end)

lib/mix/test/test_helper.exs

@@ -179,10 +179,6 @@ defmodule MixTest.Case do
     ])
   end
 
-  def force_recompilation(file) do
-    File.write!(file, File.read!(file) <> "\n")
-  end
-
   defp mix_executable do
     Path.expand("../../../bin/mix", __DIR__)
   end