--- /dev/null	2017-11-09 09:38:01.297999907 +0100
+++ new/src/hotspot/share/jfr/recorder/service/jfrPostBox.hpp	2018-04-09 15:12:10.131651146 +0200
@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2013, 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_SERVICE_JFRPOSTBOX_HPP
+#define SHARE_VM_JFR_RECORDER_SERVICE_JFRPOSTBOX_HPP
+
+#include "jfr/utilities/jfrAllocation.hpp"
+
+#define MSGBIT(e) (1<<(e))
+
+enum JFR_Msg {
+  MSG_ALL_MSGS = -1,
+  MSG_CLONE_IN_MEMORY = 0,
+  MSG_START,
+  MSG_STOP,
+  MSG_ROTATE,
+  MSG_FULLBUFFER,
+  MSG_CHECKPOINT,
+  MSG_WAKEUP,
+  MSG_SHUTDOWN,
+  MSG_VM_ERROR,
+  MSG_DEADBUFFER,
+  MSG_NO_OF_MSGS
+};
+
+/**
+ *  Jfr messaging.
+ *
+ *  Synchronous messages (posting thread waits for message completion):
+ *
+ *  MSG_CLONE_IN_MEMORY (0) ; MSGBIT(MSG_CLONE_IN_MEMORY) == (1 << 0) == 0x1
+ *  MSG_START(1)            ; MSGBIT(MSG_START) == (1 << 0x1) == 0x2
+ *  MSG_STOP (2)            ; MSGBIT(MSG_STOP) == (1 << 0x2) == 0x4
+ *  MSG_ROTATE (3)          ; MSGBIT(MSG_ROTATE) == (1 << 0x3) == 0x8
+ *  MSG_VM_ERROR (8)        ; MSGBIT(MSG_VM_ERROR) == (1 << 8) == 0x100
+ *
+ *  Asynchronous messages (posting thread returns immediately upon deposit):
+ *
+ *  MSG_FULLBUFFER (4)      ; MSGBIT(MSG_FULLBUFFER) == (1 << 0x4) == 0x10
+ *  MSG_CHECKPOINT (5)      ; MSGBIT(CHECKPOINT) == (1 << 5) == 0x20
+ *  MSG_WAKEUP (6)          ; MSGBIT(WAKEUP) == (1 << 6) == 0x40
+ *  MSG_SHUTDOWN (7)        ; MSGBIT(MSG_SHUTDOWN) == (1 << 7) == 0x80
+ *  MSG_DEADBUFFER (9)      ; MSGBIT(MSG_DEADBUFFER) == (1 << 9) == 0x200
+ */
+
+class JfrPostBox : public JfrCHeapObj {
+  friend class JfrRecorder;
+ public:
+  void post(JFR_Msg msg);
+
+ private:
+  uintptr_t _msg_read_serial;
+  uintptr_t _msg_handled_serial;
+  volatile int _messages;
+  bool _has_waiters;
+
+  JfrPostBox();
+  static JfrPostBox& instance();
+  static JfrPostBox* create();
+  static void destroy();
+
+  void asynchronous_post(int msg);
+  void synchronous_post(int msg);
+  void deposit(int new_messages);
+  bool is_message_processed(uintptr_t serial_id) const;
+
+  friend void recorderthread_entry(JavaThread*, Thread*);
+  // for the friend declaration above
+  bool is_empty() const;
+  int collect();
+  bool check_waiters(int messages) const;
+  void notify_waiters();
+  void notify_collection_stop();
+};
+
+#endif // SHARE_VM_JFR_RECORDER_SERVICE_JFRPOSTBOX_HPP