--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/jfr/recorder/storage/jfrBuffer.hpp	Tue May 15 20:24:34 2018 +0200
@@ -0,0 +1,188 @@
+/*
+ * 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.
+ *
+ */
+
+#ifndef SHARE_VM_JFR_RECORDER_STORAGE_JFRBUFFER_HPP
+#define SHARE_VM_JFR_RECORDER_STORAGE_JFRBUFFER_HPP
+
+#include "jni.h"
+#include "memory/allocation.hpp"
+
+//
+// Represents a piece of committed memory.
+//
+// u1* _pos <-- next store position
+// u1* _top <-- next unflushed position
+//
+// const void* _identity <<-- acquired by
+//
+// Must be the owner before attempting stores.
+// Use acquire() and/or try_acquire() for exclusive access
+// to the (entire) buffer (cas identity).
+//
+// Stores to the buffer should uphold transactional semantics.
+// A new _pos must be updated only after all intended stores have completed.
+// The relation between _pos and _top must hold atomically,
+// e.g. the delta must always be fully parsable.
+// _top can move concurrently by other threads but is always <= _pos.
+//
+class JfrBuffer {
+ private:
+  JfrBuffer* _next;
+  JfrBuffer* _prev;
+  const void* volatile _identity;
+  u1* _pos;
+  mutable const u1* volatile _top;
+  u2 _flags;
+  u2 _header_size;
+  u4 _size;
+
+  const u1* stable_top() const;
+  void clear_flags();
+
+ public:
+  JfrBuffer();
+  bool initialize(size_t header_size, size_t size, const void* id = NULL);
+  void reinitialize();
+  void concurrent_reinitialization();
+  size_t discard();
+  JfrBuffer* next() const {
+    return _next;
+  }
+
+  JfrBuffer* prev() const {
+    return _prev;
+  }
+
+  void set_next(JfrBuffer* next) {
+    _next = next;
+  }
+
+  void set_prev(JfrBuffer* prev) {
+    _prev = prev;
+  }
+
+  const u1* start() const {
+    return ((const u1*)this) + _header_size;
+  }
+
+  u1* start() {
+    return ((u1*)this) + _header_size;
+  }
+
+  const u1* end() const {
+    return start() + size();
+  }
+
+  const u1* pos() const {
+    return _pos;
+  }
+
+  u1* pos() {
+    return _pos;
+  }
+
+  u1** pos_address() {
+    return (u1**)&_pos;
+  }
+
+  void set_pos(u1* new_pos) {
+    assert(new_pos <= end(), "invariant");
+    _pos = new_pos;
+  }
+
+  void set_pos(size_t size) {
+    assert(_pos + size <= end(), "invariant");
+    _pos += size;
+  }
+
+  const u1* top() const;
+  void set_top(const u1* new_top);
+  const u1* concurrent_top() const;
+  void set_concurrent_top(const u1* new_top);
+
+  size_t header_size() const {
+    return _header_size;
+  }
+
+  size_t size() const {
+    return _size * BytesPerWord;
+  }
+
+  size_t total_size() const {
+    return header_size() + size();
+  }
+
+  size_t free_size() const {
+    return end() - pos();
+  }
+
+  size_t unflushed_size() const;
+
+  bool empty() const {
+    return pos() == start();
+  }
+
+  const void* identity() const {
+    return _identity;
+  }
+
+  void clear_identity();
+
+  void acquire(const void* id);
+  bool try_acquire(const void* id);
+  void release();
+
+  void move(JfrBuffer* const to, size_t size);
+  void concurrent_move_and_reinitialize(JfrBuffer* const to, size_t size);
+
+  bool transient() const;
+  void set_transient();
+  void clear_transient();
+
+  bool lease() const;
+  void set_lease();
+  void clear_lease();
+
+  bool retired() const;
+  void set_retired();
+  void clear_retired();
+
+  debug_only(bool acquired_by_self() const;)
+};
+
+class JfrAgeNode : public JfrBuffer {
+ private:
+  JfrBuffer* _retired;
+
+ public:
+  JfrAgeNode() : _retired(NULL) {}
+  void set_retired_buffer(JfrBuffer* retired) {
+    _retired = retired;
+  }
+  JfrBuffer* retired_buffer() const {
+    return _retired;
+  }
+};
+
+#endif // SHARE_VM_JFR_RECORDER_STORAGE_JFRBUFFER_HPP