--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/runtime/threadSMR.cpp	Wed Nov 22 17:54:50 2017 -0800
@@ -0,0 +1,121 @@
+/*
+ * 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 "memory/allocation.inline.hpp"
+#include "runtime/thread.inline.hpp"
+#include "runtime/threadSMR.hpp"
+#include "services/threadService.hpp"
+
+// 'entries + 1' so we always have at least one entry.
+ThreadsList::ThreadsList(int entries) : _length(entries), _threads(NEW_C_HEAP_ARRAY(JavaThread*, entries + 1, mtThread)), _next_list(NULL) {
+  *(JavaThread**)(_threads + entries) = NULL;  // Make sure the extra entry is NULL.
+}
+
+ThreadsList::~ThreadsList() {
+  FREE_C_HEAP_ARRAY(JavaThread*, _threads);
+}
+
+ThreadsListSetter::~ThreadsListSetter() {
+  if (_target_needs_release) {
+    // The hazard ptr in the target needs to be released.
+    Threads::release_stable_list(_target);
+  }
+}
+
+void ThreadsListSetter::set() {
+  assert(_target->get_threads_hazard_ptr() == NULL, "hazard ptr should not already be set");
+  (void) Threads::acquire_stable_list(_target, /* is_ThreadsListSetter */ true);
+  _target_needs_release = true;
+}
+
+ThreadsListHandle::ThreadsListHandle(Thread *self) : _list(Threads::acquire_stable_list(self, /* is_ThreadsListSetter */ false)), _self(self) {
+  assert(self == Thread::current(), "sanity check");
+  if (EnableThreadSMRStatistics) {
+    _timer.start();
+  }
+}
+
+ThreadsListHandle::~ThreadsListHandle() {
+  Threads::release_stable_list(_self);
+  if (EnableThreadSMRStatistics) {
+    _timer.stop();
+    uint millis = (uint)_timer.milliseconds();
+    Threads::inc_smr_tlh_cnt();
+    Threads::add_smr_tlh_times(millis);
+    Threads::update_smr_tlh_time_max(millis);
+  }
+}
+
+// Convert an internal thread reference to a JavaThread found on the
+// associated ThreadsList. This ThreadsListHandle "protects" the
+// returned JavaThread *.
+//
+// If thread_oop_p is not NULL, then the caller wants to use the oop
+// after this call so the oop is returned. On success, *jt_pp is set
+// to the converted JavaThread * and true is returned. On error,
+// returns false.
+//
+bool ThreadsListHandle::cv_internal_thread_to_JavaThread(jobject jthread,
+                                                         JavaThread ** jt_pp,
+                                                         oop * thread_oop_p) {
+  assert(this->list() != NULL, "must have a ThreadsList");
+  assert(jt_pp != NULL, "must have a return JavaThread pointer");
+  // thread_oop_p is optional so no assert()
+
+  // The JVM_* interfaces don't allow a NULL thread parameter; JVM/TI
+  // allows a NULL thread parameter to signify "current thread" which
+  // allows us to avoid calling cv_external_thread_to_JavaThread().
+  // The JVM_* interfaces have no such leeway.
+
+  oop thread_oop = JNIHandles::resolve_non_null(jthread);
+  // Looks like an oop at this point.
+  if (thread_oop_p != NULL) {
+    // Return the oop to the caller; the caller may still want
+    // the oop even if this function returns false.
+    *thread_oop_p = thread_oop;
+  }
+
+  JavaThread *java_thread = java_lang_Thread::thread(thread_oop);
+  if (java_thread == NULL) {
+    // The java.lang.Thread does not contain a JavaThread * so it has
+    // not yet run or it has died.
+    return false;
+  }
+  // Looks like a live JavaThread at this point.
+
+  if (java_thread != JavaThread::current()) {
+    // jthread is not for the current JavaThread so have to verify
+    // the JavaThread * against the ThreadsList.
+    if (EnableThreadSMRExtraValidityChecks && !includes(java_thread)) {
+      // Not on the JavaThreads list so it is not alive.
+      return false;
+    }
+  }
+
+  // Return a live JavaThread that is "protected" by the
+  // ThreadsListHandle in the caller.
+  *jt_pp = java_thread;
+  return true;
+}