--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/services/threadStackTracker.hpp	Tue Mar 26 15:50:34 2019 -0400
@@ -0,0 +1,114 @@
+/*
+ * Copyright (c) 2019, Red Hat, Inc. All rights reserved.
+ *
+ * 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_SERVICES_THREADSTACKTRACKER_HPP
+#define SHARE_SERVICES_THREADSTACKTRACKER_HPP
+
+#if INCLUDE_NMT
+
+#include "services/allocationSite.hpp"
+#include "services/mallocSiteTable.hpp"
+#include "services/nmtCommon.hpp"
+#include "utilities/nativeCallStack.hpp"
+#include "utilities/linkedlist.hpp"
+
+class SimpleThreadStackSite;
+
+class SimpleThreadStack {
+  friend class SimpleThreadStackSite;
+private:
+  address _base;
+  size_t  _size;
+public:
+  SimpleThreadStack() : _base(NULL), _size(0) { }
+  bool equals(const SimpleThreadStack& s) const {
+    return base() == s.base();
+  }
+
+  size_t  size() const { return _size; }
+  address base() const { return _base; }
+private:
+  void set_size(size_t size)  { _size = size; }
+  void set_base(address base) { _base = base; }
+};
+
+class SimpleThreadStackSite : public AllocationSite<SimpleThreadStack> {
+public:
+  SimpleThreadStackSite(address base, size_t size, const NativeCallStack& stack) :
+    AllocationSite<SimpleThreadStack>(stack, mtThreadStack) {
+    data()->set_size(size);
+    data()->set_base(base);
+  }
+
+  SimpleThreadStackSite(address base, size_t size) :
+    AllocationSite<SimpleThreadStack>(NativeCallStack::empty_stack(), mtThreadStack) {
+    data()->set_base(base);
+    data()->set_size(size);
+  }
+
+  bool equals(const SimpleThreadStackSite& mts) const {
+    bool eq = base() == mts.base();
+    assert(!eq || size() == mts.size(), "Must match");
+    return eq;
+  }
+
+  size_t  size() const { return peek()->size(); }
+  address base() const { return peek()->base(); }
+};
+
+  /*
+   * Most of platforms, that hotspot support, have their thread stacks backed by
+   * virtual memory by default. For these cases, thread stack tracker simply
+   * delegates tracking to virtual memory tracker.
+   * However, there are exceptions, (e.g. AIX), that platforms can provide stacks
+   * that are not page aligned. A hypothetical VM implementation, it can provide
+   * it own stacks. In these case, track_as_vm() should return false and manage
+   * stack tracking by this tracker internally.
+   * During memory snapshot, tracked thread stacks memory data is walked and stored
+   * along with malloc'd data inside baseline. The regions are not scanned and assumed
+   * all committed for now. Can add scanning phase when there is a need.
+   */
+class ThreadStackTracker : AllStatic {
+private:
+  static volatile size_t _thread_count;
+
+  static int compare_thread_stack_base(const SimpleThreadStackSite& s1, const SimpleThreadStackSite& s2);
+  static SortedLinkedList<SimpleThreadStackSite, compare_thread_stack_base>* _simple_thread_stacks;
+public:
+  // Late phase initialization
+  static bool late_initialize(NMT_TrackingLevel level);
+  static bool transition(NMT_TrackingLevel from, NMT_TrackingLevel to);
+
+  static void new_thread_stack(void* base, size_t size, const NativeCallStack& stack);
+  static void delete_thread_stack(void* base, size_t size);
+
+  static bool   track_as_vm()  { return AIX_ONLY(false) NOT_AIX(true); }
+  static size_t thread_count() { return _thread_count; }
+
+  // Snapshot support. Piggyback thread stack data in malloc slot, NMT always handles
+  // thread stack slot specially since beginning.
+  static bool walk_simple_thread_stack_site(MallocSiteWalker* walker);
+};
+
+#endif // INCLUDE_NMT
+#endif // SHARE_SERVICES_THREADSTACKTRACKER_HPP