Add `GC.auto_compact= true/false` and `GC.auto_compact`

* `GC.auto_compact=`, `GC.auto_compact` can be used to control when
  compaction runs.  Setting `auto_compact=` to true will cause
  compaction to occurr duing major collections.  At the moment,
  compaction adds significant overhead to major collections, so please
  test first!

[Feature #17176]

1 files changed, 65 insertions, 0 deletions

diff --git a/test/ruby/test_gc_compact.rb b/test/ruby/test_gc_compact.rb
index 75d9b01f2c..0ceb54dba7 100644
--- a/test/ruby/test_gc_compact.rb
+++ b/test/ruby/test_gc_compact.rb
@@ -3,6 +3,71 @@ require 'test/unit'
 require 'fiddle'
 
 class TestGCCompact < Test::Unit::TestCase
+  def test_enable_autocompact
+    before = GC.auto_compact
+    GC.auto_compact = true
+    assert GC.auto_compact
+  ensure
+    GC.auto_compact = before
+  end
+
+  def test_disable_autocompact
+    before = GC.auto_compact
+    GC.auto_compact = false
+    refute GC.auto_compact
+  ensure
+    GC.auto_compact = before
+  end
+
+  def test_major_compacts
+    before = GC.auto_compact
+    GC.auto_compact = true
+    compact = GC.stat :compact_count
+    GC.start
+    assert_operator GC.stat(:compact_count), :>, compact
+  ensure
+    GC.auto_compact = before
+  end
+
+  def test_implicit_compaction_does_something
+    before = GC.auto_compact
+    list = []
+    list2 = []
+
+    # Try to make some fragmentation
+    500.times {
+      list << Object.new
+      Object.new
+      Object.new
+    }
+    count = GC.stat :compact_count
+    GC.auto_compact = true
+    loop do
+      break if count < GC.stat(:compact_count)
+      list2 << Object.new
+    end
+    compact_stats = GC.latest_compact_info
+    refute_predicate compact_stats[:considered], :empty?
+    refute_predicate compact_stats[:moved], :empty?
+  ensure
+    GC.auto_compact = before
+  end
+
+  def test_gc_compact_stats
+    list = []
+    list2 = []
+
+    # Try to make some fragmentation
+    500.times {
+      list << Object.new
+      Object.new
+      Object.new
+    }
+    compact_stats = GC.compact
+    refute_predicate compact_stats[:considered], :empty?
+    refute_predicate compact_stats[:moved], :empty?
+  end
+
   def memory_location(obj)
     (Fiddle.dlwrap(obj) >> 1)
   end