--- /dev/null	2019-01-28 17:47:47.000000000 +0800
+++ new/src/share/vm/jfr/recorder/storage/jfrBuffer.cpp	2019-01-28 17:47:47.000000000 +0800
@@ -0,0 +1,246 @@
+/*
+ * Copyright (c) 2011, 2019, 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/jfrBuffer.hpp"
+#include "runtime/atomic.hpp"
+#include "runtime/orderAccess.inline.hpp"
+#include "runtime/thread.inline.hpp"
+
+static const u1* const MUTEX_CLAIM = NULL;
+
+JfrBuffer::JfrBuffer() : _next(NULL),
+                         _prev(NULL),
+                         _identity(NULL),
+                         _pos(NULL),
+                         _top(NULL),
+                         _flags(0),
+                         _header_size(0),
+                         _size(0) {}
+
+bool JfrBuffer::initialize(size_t header_size, size_t size, const void* id /* NULL */) {
+  _header_size = (u2)header_size;
+  _size = (u4)(size / BytesPerWord);
+  assert(_identity == NULL, "invariant");
+  _identity = id;
+  set_pos(start());
+  set_top(start());
+  assert(_next == NULL, "invariant");
+  assert(free_size() == size, "invariant");
+  assert(!transient(), "invariant");
+  assert(!lease(), "invariant");
+  assert(!retired(), "invariant");
+  return true;
+}
+
+void JfrBuffer::reinitialize() {
+  assert(!lease(), "invariant");
+  assert(!transient(), "invariant");
+  set_pos(start());
+  set_top(start());
+  clear_retired();
+}
+
+void JfrBuffer::concurrent_reinitialization() {
+  concurrent_top();
+  assert(!lease(), "invariant");
+  assert(!transient(), "invariant");
+  set_pos(start());
+  set_concurrent_top(start()); // StoreStore
+  clear_retired();
+}
+
+size_t JfrBuffer::discard() {
+  size_t discard_size = unflushed_size();
+  set_top(pos());
+  return discard_size;
+}
+
+const u1* JfrBuffer::stable_top() const {
+  const u1* current_top;
+  do {
+    current_top = (const u1*)OrderAccess::load_ptr_acquire((void*)&_top);
+  } while (MUTEX_CLAIM == current_top);
+  return current_top;
+}
+
+void JfrBuffer::clear_flags() {
+  clear_retired();
+}
+
+const u1* JfrBuffer::top() const {
+  return _top;
+}
+
+void JfrBuffer::set_top(const u1* new_top) {
+  _top = new_top;
+}
+
+const u1* JfrBuffer::concurrent_top() const {
+  do {
+    const u1* current_top = stable_top();
+    if ((const u1*)Atomic::cmpxchg_ptr((void*)MUTEX_CLAIM, (void*)&_top, (void*)current_top) == current_top) {
+      return current_top;
+    }
+  } while (true);
+}
+
+void JfrBuffer::set_concurrent_top(const u1* new_top) {
+  assert(new_top != MUTEX_CLAIM, "invariant");
+  assert(new_top <= end(), "invariant");
+  assert(new_top >= start(), "invariant");
+  assert(top() == MUTEX_CLAIM, "invariant");
+  OrderAccess::storestore();
+  set_top(new_top);
+}
+
+size_t JfrBuffer::unflushed_size() const {
+  return pos() - stable_top();
+}
+
+void JfrBuffer::acquire(const void* id) {
+  assert(id != NULL, "invariant");
+  const void* current_id;
+  do {
+    current_id = OrderAccess::load_ptr_acquire(&_identity);
+  } while (current_id != NULL || Atomic::cmpxchg_ptr(const_cast<void*>(id), (void*)&_identity, const_cast<void*>(current_id)) != current_id);
+}
+
+bool JfrBuffer::try_acquire(const void* id) {
+  assert(id != NULL, "invariant");
+  const void* const current_id = OrderAccess::load_ptr_acquire(&_identity);
+  return current_id == NULL && Atomic::cmpxchg_ptr(const_cast<void*>(id), (void*)&_identity, const_cast<void*>(current_id)) == current_id;
+}
+
+void JfrBuffer::release() {
+  OrderAccess::storestore();
+  clear_identity();
+}
+
+void JfrBuffer::clear_identity() {
+  _identity = NULL;
+}
+
+#ifdef ASSERT
+static bool validate_to(const JfrBuffer* const to, size_t size) {
+  assert(to != NULL, "invariant");
+  assert(to->acquired_by_self(), "invariant");
+  assert(to->free_size() >= size, "invariant");
+  return true;
+}
+
+static bool validate_concurrent_this(const JfrBuffer* const t, size_t size) {
+  assert(t->top() == MUTEX_CLAIM, "invariant");
+  return true;
+}
+
+static bool validate_this(const JfrBuffer* const t, size_t size) {
+  assert(t->top() + size <= t->pos(), "invariant");
+  return true;
+}
+
+bool JfrBuffer::acquired_by_self() const {
+  return identity() == Thread::current();
+}
+#endif // ASSERT
+
+void JfrBuffer::move(JfrBuffer* const to, size_t size) {
+  assert(validate_to(to, size), "invariant");
+  assert(validate_this(this, size), "invariant");
+  const u1* current_top = top();
+  assert(current_top != NULL, "invariant");
+  memcpy(to->pos(), current_top, size);
+  to->set_pos(size);
+  to->release(); // StoreStore
+  set_top(current_top + size);
+}
+
+void JfrBuffer::concurrent_move_and_reinitialize(JfrBuffer* const to, size_t size) {
+  assert(validate_to(to, size), "invariant");
+  const u1* current_top = concurrent_top();
+  assert(validate_concurrent_this(this, size), "invariant");
+  const size_t actual_size = MIN2(size, (size_t)(pos() - current_top));
+  assert(actual_size <= size, "invariant");
+  memcpy(to->pos(), current_top, actual_size);
+  to->set_pos(actual_size);
+  set_pos(start());
+  to->release(); // StoreStore
+  clear_retired();
+  set_top(start());
+}
+
+// flags
+enum FLAG {
+  RETIRED = 1,
+  TRANSIENT = 2,
+  LEASE = 4
+};
+
+bool JfrBuffer::transient() const {
+  return (u1)TRANSIENT == (_flags & (u1)TRANSIENT);
+}
+
+void JfrBuffer::set_transient() {
+  _flags |= (u1)TRANSIENT;
+  assert(transient(), "invariant");
+}
+
+void JfrBuffer::clear_transient() {
+  if (transient()) {
+    _flags ^= (u1)TRANSIENT;
+  }
+  assert(!transient(), "invariant");
+}
+
+bool JfrBuffer::lease() const {
+  return (u1)LEASE == (_flags & (u1)LEASE);
+}
+
+void JfrBuffer::set_lease() {
+  _flags |= (u1)LEASE;
+  assert(lease(), "invariant");
+}
+
+void JfrBuffer::clear_lease() {
+  if (lease()) {
+    _flags ^= (u1)LEASE;
+  }
+  assert(!lease(), "invariant");
+}
+
+bool JfrBuffer::retired() const {
+  return (u1)RETIRED == (_flags & (u1)RETIRED);
+}
+
+void JfrBuffer::set_retired() {
+  _flags |= (u1)RETIRED;
+  assert(retired(), "invariant");
+}
+
+void JfrBuffer::clear_retired() {
+  if (retired()) {
+    _flags ^= (u1)RETIRED;
+  }
+  assert(!retired(), "invariant");
+}