--- /dev/null	2017-02-06 22:16:02.409658130 -0500
+++ new/src/share/vm/gc/shared/concurrentGCPhaseManager.cpp	2017-02-17 20:09:49.330238562 -0500
@@ -0,0 +1,163 @@
+/*
+ * Copyright (c) 2017, 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 "gc/shared/concurrentGCPhaseManager.hpp"
+#include "runtime/mutexLocker.hpp"
+#include "runtime/thread.hpp"
+
+#define assert_ConcurrentGC_thread() \
+  assert(Thread::current()->is_ConcurrentGC_thread(), "precondition")
+
+#define assert_not_enter_unconstrained(phase) \
+  assert((phase) != UNCONSTRAINED_PHASE, "Cannot enter \"unconstrained\" phase")
+
+#define assert_manager_is_tos(manager, stack, kind)  \
+  assert((manager) == *(stack), kind " manager is not top of stack")
+
+ConcurrentGCPhaseManager::ConcurrentGCPhaseManager(int phase,
+                                                   ConcurrentGCPhaseManager** stack,
+                                                   int* request) :
+  _phase(phase),
+  _active(true),
+  _request(request),
+  _link(NULL),
+  _stack(stack)
+{
+  assert_ConcurrentGC_thread();
+  assert_not_enter_unconstrained(phase);
+  assert(stack != NULL, "NULL stack pointer");
+  assert(request != NULL, "NULL request pointer");
+  MonitorLockerEx ml(CGCPhaseManager_lock, Mutex::_no_safepoint_check_flag);
+  assert(*stack == NULL, "Non-empty stack");
+  *stack = this;
+  ml.notify_all();
+}
+
+ConcurrentGCPhaseManager::ConcurrentGCPhaseManager(int phase,
+                                                   ConcurrentGCPhaseManager* prev) :
+  _phase(phase),
+  _active(true),
+  _request(NULL),
+  _link(prev),
+  _stack(NULL)
+{
+  assert_ConcurrentGC_thread();
+  assert_not_enter_unconstrained(phase);
+  assert(prev != NULL, "NULL previous stack entry");
+  MonitorLockerEx ml(CGCPhaseManager_lock, Mutex::_no_safepoint_check_flag);
+  assert_manager_is_tos(prev, prev->_stack, "Previous");
+  assert(prev->_active, "Previous manager is inactive");
+  _stack = prev->_stack;
+  _request = prev->_request;
+  *_stack = this;
+  ml.notify_all();
+}
+
+ConcurrentGCPhaseManager::~ConcurrentGCPhaseManager() {
+  assert_ConcurrentGC_thread();
+  MonitorLockerEx ml(CGCPhaseManager_lock, Mutex::_no_safepoint_check_flag);
+  assert_manager_is_tos(this, _stack, "This");
+  wait_when_requested_impl();
+  *_stack = _link;
+  ml.notify_all();
+}
+
+bool ConcurrentGCPhaseManager::is_requested() const {
+  assert_ConcurrentGC_thread();
+  MonitorLockerEx ml(CGCPhaseManager_lock, Mutex::_no_safepoint_check_flag);
+  assert_manager_is_tos(this, _stack, "This");
+  return _active && (*_request == _phase);
+}
+
+bool ConcurrentGCPhaseManager::wait_when_requested_impl() const {
+  assert_ConcurrentGC_thread();
+  assert_lock_strong(CGCPhaseManager_lock);
+  bool waited = false;
+  while (_active && (*_request == _phase)) {
+    waited = true;
+    CGCPhaseManager_lock->wait(Mutex::_no_safepoint_check_flag);
+  }
+  return waited;
+}
+
+bool ConcurrentGCPhaseManager::wait_when_requested() const {
+  assert_ConcurrentGC_thread();
+  MonitorLockerEx ml(CGCPhaseManager_lock, Mutex::_no_safepoint_check_flag);
+  assert_manager_is_tos(this, _stack, "This");
+  return wait_when_requested_impl();
+}
+
+void ConcurrentGCPhaseManager::set_phase(int phase, bool force) {
+  assert_ConcurrentGC_thread();
+  assert_not_enter_unconstrained(phase);
+  MonitorLockerEx ml(CGCPhaseManager_lock, Mutex::_no_safepoint_check_flag);
+  assert_manager_is_tos(this, _stack, "This");
+  if (!force) wait_when_requested_impl();
+  _phase = phase;
+  ml.notify_all();
+}
+
+void ConcurrentGCPhaseManager::deactivate() {
+  assert_ConcurrentGC_thread();
+  MonitorLockerEx ml(CGCPhaseManager_lock, Mutex::_no_safepoint_check_flag);
+  assert_manager_is_tos(this, _stack, "This");
+  _active = false;
+  ml.notify_all();
+}
+
+bool ConcurrentGCPhaseManager::wait_for_phase(int phase,
+                                              ConcurrentGCPhaseManager** stack,
+                                              int* request) {
+  assert(Thread::current()->is_Java_thread(), "precondition");
+  MonitorLockerEx ml(CGCPhaseManager_lock);
+  // Update request and notify service of change.
+  if (*request != phase) {
+    *request = phase;
+    ml.notify_all();
+  }
+
+  if (phase == UNCONSTRAINED_PHASE) {
+    return true;
+  }
+
+  // Wait until phase or IDLE is active.
+  while (true) {
+    bool idle = false;
+    for (ConcurrentGCPhaseManager* manager = *stack;
+         manager != NULL;
+         manager = manager->_link) {
+      if (manager->_phase == phase) {
+        return true;            // phase is active.
+      } else if (manager->_phase == IDLE_PHASE) {
+        idle = true;            // Note idle active, continue search for phase.
+      }
+    }
+    if (idle) {
+      return false;             // idle is active and phase is not.
+    } else {
+      ml.wait();                // Wait for phase change.
+    }
+  }
+}