--- /dev/null	2013-02-01 15:46:04.000000000 +0100
+++ new/src/share/vm/gc_implementation/g1/g1PreserveMarkQueue.hpp	2013-02-01 15:46:04.000000000 +0100
@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2013, 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_IMPLEMENTATION_G1_PRESERVEMARKQUEUE_HPP
+#define SHARE_VM_GC_IMPLEMENTATION_G1_PRESERVEMARKQUEUE_HPP
+
+#include "oops/oopsHierarchy.hpp"
+
+struct G1PreserveMarkQueueEntry {
+  oop obj;
+  markOop mark;
+};
+
+class G1PreserveMarkChunk;
+
+class G1PreserveMarkQueue {
+  const size_t _initial_chunk_capacity;
+  const size_t _max_chunk_capacity;
+  size_t _current_capacity;
+  G1PreserveMarkChunk* _current_write_chunk;
+  G1PreserveMarkChunk* _current_read_chunk;
+
+ public:
+  G1PreserveMarkQueue(size_t initial_chunk_capacity, size_t max_chunk_capacity) :
+    _initial_chunk_capacity(initial_chunk_capacity), _max_chunk_capacity(max_chunk_capacity),
+    _current_write_chunk(NULL), _current_read_chunk(NULL) {
+    assert(_initial_chunk_capacity <= _max_chunk_capacity, "initial must be <= max");
+  }
+
+  bool has_data();
+  void append(const oop& obj, const markOop& mark);
+  G1PreserveMarkQueueEntry remove_first();
+
+  size_t new_chunk_capacity() {
+    if (_current_write_chunk == NULL) {
+      _current_capacity = _initial_chunk_capacity;
+    } else if (_current_capacity == _max_chunk_capacity) {
+      // do nothing. already at max capacity
+    } else {
+      // Grow with 50%, similar to java.util.ArrayList
+      _current_capacity += _current_capacity >> 1;
+      _current_capacity = MIN2(_current_capacity, _max_chunk_capacity);
+    }
+
+    assert(_current_capacity >= _initial_chunk_capacity, "too small capacity");
+    assert(_current_capacity <= _max_chunk_capacity, "too large capacity");
+
+    return _current_capacity;
+  }
+
+  NOT_PRODUCT(void verify_empty());
+};
+
+NOT_PRODUCT(void g1PreserveMarkChunkTests());
+NOT_PRODUCT(void g1PreserveMarkQueueTests());
+
+#endif // SHARE_VM_GC_IMPLEMENTATION_G1_PRESERVEMARKQUEUE_HPP