--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc/g1/youngList.hpp	Tue Oct 13 08:37:44 2015 +0200
@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_GC_G1_YOUNGLIST_HPP
+#define SHARE_VM_GC_G1_YOUNGLIST_HPP
+
+#include "memory/allocation.hpp"
+#include "runtime/globals.hpp"
+
+class YoungList : public CHeapObj<mtGC> {
+private:
+  G1CollectedHeap* _g1h;
+
+  HeapRegion* _head;
+
+  HeapRegion* _survivor_head;
+  HeapRegion* _survivor_tail;
+
+  HeapRegion* _curr;
+
+  uint        _length;
+  uint        _survivor_length;
+
+  size_t      _last_sampled_rs_lengths;
+  size_t      _sampled_rs_lengths;
+
+  void         empty_list(HeapRegion* list);
+
+public:
+  YoungList(G1CollectedHeap* g1h);
+
+  void         push_region(HeapRegion* hr);
+  void         add_survivor_region(HeapRegion* hr);
+
+  void         empty_list();
+  bool         is_empty() { return _length == 0; }
+  uint         length() { return _length; }
+  uint         eden_length() { return length() - survivor_length(); }
+  uint         survivor_length() { return _survivor_length; }
+
+  // Currently we do not keep track of the used byte sum for the
+  // young list and the survivors and it'd be quite a lot of work to
+  // do so. When we'll eventually replace the young list with
+  // instances of HeapRegionLinkedList we'll get that for free. So,
+  // we'll report the more accurate information then.
+  size_t       eden_used_bytes() {
+    assert(length() >= survivor_length(), "invariant");
+    return (size_t) eden_length() * HeapRegion::GrainBytes;
+  }
+  size_t       survivor_used_bytes() {
+    return (size_t) survivor_length() * HeapRegion::GrainBytes;
+  }
+
+  void rs_length_sampling_init();
+  bool rs_length_sampling_more();
+  void rs_length_sampling_next();
+
+  void reset_sampled_info() {
+    _last_sampled_rs_lengths =   0;
+  }
+  size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }
+
+  // for development purposes
+  void reset_auxilary_lists();
+  void clear() { _head = NULL; _length = 0; }
+
+  void clear_survivors() {
+    _survivor_head    = NULL;
+    _survivor_tail    = NULL;
+    _survivor_length  = 0;
+  }
+
+  HeapRegion* first_region() { return _head; }
+  HeapRegion* first_survivor_region() { return _survivor_head; }
+  HeapRegion* last_survivor_region() { return _survivor_tail; }
+
+  // debugging
+  bool          check_list_well_formed();
+  bool          check_list_empty(bool check_sample = true);
+  void          print();
+};
+
+#endif // SHARE_VM_GC_G1_YOUNGLIST_HPP