--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/jfr/writers/jfrMemoryWriterHost.hpp	Tue May 15 20:24:34 2018 +0200
@@ -0,0 +1,72 @@
+/*
+ * 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.
+ *
+ */
+
+#ifndef SHARE_VM_JFR_WRITERS_JFRMEMORYWRITERHOST_HPP
+#define SHARE_VM_JFR_WRITERS_JFRMEMORYWRITERHOST_HPP
+
+#include "jfr/writers/jfrStorageHost.inline.hpp"
+
+#ifdef ASSERT
+class ExclusiveAccessAssert {
+ private:
+  bool _acquired;
+ public:
+  ExclusiveAccessAssert() : _acquired(false) {}
+  void acquire() { assert_non_acquired(); _acquired = true; }
+  void release() { assert_acquired(); _acquired = false; }
+  bool is_acquired() const { return _acquired; }
+  void assert_acquired() const { assert(_acquired, "Not acquired!"); }
+  void assert_non_acquired() const { assert(!_acquired, "Already acquired!"); }
+};
+#else
+ class ExclusiveAccessAssert {};
+#endif
+
+template <typename Adapter, typename AP, typename AccessAssert = ExclusiveAccessAssert>
+class MemoryWriterHost : public StorageHost<Adapter, AP> {
+  debug_only(AccessAssert _access;)
+ public:
+  typedef typename Adapter::StorageType StorageType;
+ protected:
+  void bytes(void* dest, const void* buf, size_t len);
+  MemoryWriterHost(StorageType* storage, Thread* thread);
+  MemoryWriterHost(StorageType* storage, size_t size);
+  MemoryWriterHost(Thread* thread);
+  debug_only(bool is_acquired() const;)
+ public:
+  void acquire();
+  void release();
+};
+
+template <typename Adapter, typename AP>
+class AcquireReleaseMemoryWriterHost : public MemoryWriterHost<Adapter, AP> {
+ public:
+  typedef typename Adapter::StorageType StorageType;
+  AcquireReleaseMemoryWriterHost(StorageType* storage, Thread* thread);
+  AcquireReleaseMemoryWriterHost(StorageType* storage, size_t size);
+  AcquireReleaseMemoryWriterHost(Thread* thread);
+  ~AcquireReleaseMemoryWriterHost();
+};
+
+#endif // SHARE_VM_JFR_WRITERS_JFRMEMORYWRITERHOST_HPP