--- /dev/null	2017-11-09 09:38:01.297999907 +0100
+++ new/src/hotspot/share/jfr/recorder/stringpool/jfrStringPoolBuffer.cpp	2018-04-09 15:19:22.436347302 +0200
@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2016, 2018, 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.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "jfr/recorder/stringpool/jfrStringPoolBuffer.hpp"
+#include "runtime/atomic.hpp"
+#include "runtime/orderAccess.inline.hpp"
+#include "runtime/thread.inline.hpp"
+
+JfrStringPoolBuffer::JfrStringPoolBuffer() : JfrBuffer(), _string_count_pos(0), _string_count_top(0) {}
+
+void JfrStringPoolBuffer::reinitialize() {
+  concurrent_top();
+  set_pos((start()));
+  set_string_pos(0);
+  set_string_top(0);
+  set_concurrent_top(start());
+}
+
+uint64_t JfrStringPoolBuffer::string_pos() const {
+  return OrderAccess::load_acquire(&_string_count_pos);
+}
+
+uint64_t JfrStringPoolBuffer::string_top() const {
+  return OrderAccess::load_acquire(&_string_count_top);
+}
+
+uint64_t JfrStringPoolBuffer::string_count() const {
+  return string_pos() - string_top();
+}
+
+void JfrStringPoolBuffer::set_string_pos(uint64_t value) {
+  Atomic::store(value, &_string_count_pos);
+}
+
+void JfrStringPoolBuffer::increment(uint64_t value) {
+  Atomic::add(value, &_string_count_pos);
+}
+
+void JfrStringPoolBuffer::set_string_top(uint64_t value) {
+  Atomic::store(value, &_string_count_top);
+}