From e8b36e7711d44bf23a39426b3d766c08528573b3 Mon Sep 17 00:00:00 2001
From: Matthew Draper <matthew@trebex.net>
Date: Mon, 3 Oct 2016 01:34:27 +1030
Subject: Avoid bumping the class serial when invoking executor

---
 .../lib/active_support/execution_wrapper.rb        | 33 ++++++++-----
 activesupport/test/executor_test.rb                | 55 ++++++++++++++++++++++
 2 files changed, 76 insertions(+), 12 deletions(-)

(limited to 'activesupport')

diff --git a/activesupport/lib/active_support/execution_wrapper.rb b/activesupport/lib/active_support/execution_wrapper.rb
index 4c8b03c9df..3384d12d5b 100644
--- a/activesupport/lib/active_support/execution_wrapper.rb
+++ b/activesupport/lib/active_support/execution_wrapper.rb
@@ -19,6 +19,23 @@ module ActiveSupport
       set_callback(:complete, *args, &block)
     end
 
+    class RunHook < Struct.new(:hook) # :nodoc:
+      def before(target)
+        hook_state = target.send(:hook_state)
+        hook_state[hook] = hook.run
+      end
+    end
+
+    class CompleteHook < Struct.new(:hook) # :nodoc:
+      def before(target)
+        hook_state = target.send(:hook_state)
+        if hook_state.key?(hook)
+          hook.complete hook_state[hook]
+        end
+      end
+      alias after before
+    end
+
     # Register an object to be invoked during both the +run+ and
     # +complete+ steps.
     #
@@ -29,19 +46,11 @@ module ActiveSupport
     # invoked in that situation.)
     def self.register_hook(hook, outer: false)
       if outer
-        run_args = [prepend: true]
-        complete_args = [:after]
+        to_run RunHook.new(hook), prepend: true
+        to_complete :after, CompleteHook.new(hook)
       else
-        run_args = complete_args = []
-      end
-
-      to_run(*run_args) do
-        hook_state[hook] = hook.run
-      end
-      to_complete(*complete_args) do
-        if hook_state.key?(hook)
-          hook.complete hook_state[hook]
-        end
+        to_run RunHook.new(hook)
+        to_complete CompleteHook.new(hook)
       end
     end
 
diff --git a/activesupport/test/executor_test.rb b/activesupport/test/executor_test.rb
index 0b56ea008f..d409216206 100644
--- a/activesupport/test/executor_test.rb
+++ b/activesupport/test/executor_test.rb
@@ -158,6 +158,61 @@ class ExecutorTest < ActiveSupport::TestCase
     assert_equal :some_state, supplied_state
   end
 
+  def test_hook_insertion_order
+    invoked = []
+    supplied_state = []
+
+    hook_class = Class.new do
+      attr_accessor :letter
+
+      define_method(:initialize) do |letter|
+        self.letter = letter
+      end
+
+      define_method(:run) do
+        invoked << :"run_#{letter}"
+        :"state_#{letter}"
+      end
+
+      define_method(:complete) do |state|
+        invoked << :"complete_#{letter}"
+        supplied_state << state
+      end
+    end
+
+    executor.register_hook(hook_class.new(:a))
+    executor.register_hook(hook_class.new(:b))
+    executor.register_hook(hook_class.new(:c), outer: true)
+    executor.register_hook(hook_class.new(:d))
+
+    executor.wrap {}
+
+    assert_equal [:run_c, :run_a, :run_b, :run_d, :complete_a, :complete_b, :complete_d, :complete_c], invoked
+    assert_equal [:state_a, :state_b, :state_d, :state_c], supplied_state
+  end
+
+  def test_class_serial_is_unaffected
+    hook = Class.new do
+      define_method(:run) do
+        nil
+      end
+
+      define_method(:complete) do |state|
+        nil
+      end
+    end.new
+
+    executor.register_hook(hook)
+
+    before = RubyVM.stat(:class_serial)
+    executor.wrap {}
+    executor.wrap {}
+    executor.wrap {}
+    after = RubyVM.stat(:class_serial)
+
+    assert_equal before, after
+  end
+
   def test_separate_classes_can_wrap
     other_executor = Class.new(ActiveSupport::Executor)
 
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