Revert "Use a monotonically increasing number for object_id"

This reverts commit bd2b314a05ae9192b3143e1e678a37c370d8a9ce.

1 files changed, 90 insertions, 0 deletions

diff --git a/test/ruby/test_gc_compact.rb b/test/ruby/test_gc_compact.rb
index bc26897386..eaffccda08 100644
--- a/test/ruby/test_gc_compact.rb
+++ b/test/ruby/test_gc_compact.rb
@@ -7,6 +7,13 @@ class TestGCCompact < Test::Unit::TestCase
     (Fiddle.dlwrap(obj) >> 1)
   end
 
+  def assert_object_ids(list)
+    same_count = list.find_all { |obj|
+      memory_location(obj) == obj.object_id
+    }.count
+    list.count - same_count
+  end
+
   def big_list(level = 10)
     if level > 0
       big_list(level - 1)
@@ -34,6 +41,89 @@ class TestGCCompact < Test::Unit::TestCase
     new_object
   end
 
+  def try_to_move_objects
+    10.times do
+      list_of_objects = big_list
+
+      ids       = list_of_objects.map(&:object_id) # store id in map
+      addresses = list_of_objects.map(&self.:memory_location)
+
+      assert_equal ids, addresses
+
+      # All object ids should be equal
+      assert_equal 0, assert_object_ids(list_of_objects) # should be 0
+
+      GC.verify_compaction_references(toward: :empty)
+
+      # Some should have moved
+      id_count = assert_object_ids(list_of_objects)
+      skip "couldn't get objects to move" if id_count == 0
+      assert_operator id_count, :>, 0
+
+      new_ids = list_of_objects.map(&:object_id)
+
+      # Object ids should not change after compaction
+      assert_equal ids, new_ids
+
+      new_tenant = find_object_in_recycled_slot(addresses)
+      return [list_of_objects, addresses, new_tenant] if new_tenant
+    end
+
+    flunk "Couldn't get objects to move"
+  end
+
+  def test_find_collided_object
+    skip "figure out how to guarantee move"
+
+    list_of_objects, addresses, new_tenant = try_to_move_objects
+
+    # This is the object that used to be in new_object's position
+    loc = memory_location(new_tenant)
+    assert loc, "should have a memory location"
+
+    if (ENV['TRAVIS'] && RUBY_PLATFORM =~ /darwin/)
+      skip "tests are failing on Travis osx / Wercker from here"
+    end
+
+    address_idx = addresses.index(loc)
+    assert address_idx, "should have an address index"
+
+    previous_tenant = list_of_objects[address_idx]
+    assert previous_tenant, "should have a previous tenant"
+
+    assert_not_equal previous_tenant.object_id, new_tenant.object_id
+
+    # Should be able to look up object by object_id
+    assert_equal new_tenant, ObjectSpace._id2ref(new_tenant.object_id)
+
+    # Should be able to look up object by object_id
+    assert_equal previous_tenant, ObjectSpace._id2ref(previous_tenant.object_id)
+
+    int = (new_tenant.object_id >> 1)
+    # These two should be the same! but they are not :(
+    assert_equal int, ObjectSpace._id2ref(int.object_id)
+  end
+
+  def test_many_collisions
+    list_of_objects = big_list
+    ids       = list_of_objects.map(&:object_id)
+    addresses = list_of_objects.map(&self.:memory_location)
+
+    GC.verify_compaction_references(toward: :empty)
+
+    skip "time consuming"
+
+    new_tenants = 10.times.map {
+      find_object_in_recycled_slot(addresses)
+    }
+
+    collisions = GC.stat(:object_id_collisions)
+    skip "couldn't get objects to collide" if collisions == 0
+    assert_operator collisions, :>, 0
+    ids.clear
+    new_tenants.clear
+  end
+
   def test_complex_hash_keys
     list_of_objects = big_list
     hash = list_of_objects.hash