--- /dev/null	2017-11-09 09:38:01.297999907 +0100
+++ new/src/hotspot/share/jfr/recorder/storage/jfrStorageControl.cpp	2018-04-09 15:16:52.385424354 +0200
@@ -0,0 +1,137 @@
+/*
+ * Copyright (c) 2012, 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/storage/jfrStorageControl.hpp"
+#include "runtime/atomic.hpp"
+#include "runtime/orderAccess.inline.hpp"
+
+// returns the updated value
+static jlong atomic_add(size_t value, size_t volatile* const dest) {
+  size_t compare_value;
+  size_t exchange_value;
+  do {
+    compare_value = OrderAccess::load_acquire(dest);
+    exchange_value = compare_value + value;
+  } while (Atomic::cmpxchg(exchange_value, dest, compare_value) != compare_value);
+  return exchange_value;
+}
+
+static jlong atomic_dec(size_t volatile* const dest) {
+  size_t compare_value;
+  size_t exchange_value;
+  do {
+    compare_value = OrderAccess::load_acquire(dest);
+    assert(compare_value >= 1, "invariant");
+    exchange_value = compare_value - 1;
+  } while (Atomic::cmpxchg(exchange_value, dest, compare_value) != compare_value);
+  return exchange_value;
+}
+
+const size_t max_lease_factor = 2;
+JfrStorageControl::JfrStorageControl(size_t global_count_total, size_t in_memory_discard_threshold) :
+  _global_count_total(global_count_total),
+  _full_count(0),
+  _global_lease_count(0),
+  _dead_count(0),
+  _to_disk_threshold(0),
+  _in_memory_discard_threshold(in_memory_discard_threshold),
+  _global_lease_threshold(global_count_total / max_lease_factor),
+  _scavenge_threshold(0),
+  _to_disk(false) {}
+
+bool JfrStorageControl::to_disk() const {
+  return _to_disk;
+}
+
+void JfrStorageControl::set_to_disk(bool enable) {
+  _to_disk = enable;
+}
+
+// concurrent with lax requirement
+
+size_t JfrStorageControl::full_count() const {
+  return _full_count;
+}
+
+size_t JfrStorageControl::increment_full() {
+  return atomic_add(1, &_full_count);
+}
+
+size_t JfrStorageControl::decrement_full() {
+  return atomic_dec(&_full_count);
+}
+
+void JfrStorageControl::reset_full() {
+  Atomic::store((size_t)0, &_full_count);
+}
+
+bool JfrStorageControl::should_post_buffer_full_message() const {
+  return to_disk() && (full_count() > _to_disk_threshold);
+}
+
+bool JfrStorageControl::should_discard() const {
+  return !to_disk() && full_count() >= _in_memory_discard_threshold;
+}
+
+// concurrent with accuracy requirement
+
+size_t JfrStorageControl::global_lease_count() const {
+  return OrderAccess::load_acquire(&_global_lease_count);
+}
+
+size_t JfrStorageControl::increment_leased() {
+  return atomic_add(1, &_global_lease_count);
+}
+
+size_t JfrStorageControl::decrement_leased() {
+  return atomic_dec(&_global_lease_count);
+}
+
+bool JfrStorageControl::is_global_lease_allowed() const {
+  return global_lease_count() <= _global_lease_threshold;
+}
+
+// concurrent with lax requirement
+
+size_t JfrStorageControl::dead_count() const {
+  return _dead_count;
+}
+
+size_t JfrStorageControl::increment_dead() {
+  return atomic_add(1, &_dead_count);
+}
+
+size_t JfrStorageControl::decrement_dead() {
+  return atomic_dec(&_dead_count);
+}
+
+bool JfrStorageControl::should_scavenge() const {
+  return dead_count() >= _scavenge_threshold;
+}
+
+void JfrStorageControl::set_scavenge_threshold(size_t number_of_dead_buffers) {
+  _scavenge_threshold = number_of_dead_buffers;
+}
+