--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/runtime/threadHeapSampler.hpp	Fri Jun 15 02:31:37 2018 -0700
@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2018, Google 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 RUNTIME_THREADHEAPSAMPLER_HPP
+#define RUNTIME_THREADHEAPSAMPLER_HPP
+
+#include "memory/allocation.hpp"
+
+class ThreadHeapSampler {
+ private:
+  size_t _bytes_until_sample;
+  // Cheap random number generator
+  static uint64_t _rnd;
+
+  void pick_next_geometric_sample();
+  void pick_next_sample(size_t overflowed_bytes = 0);
+  static int _enabled;
+  static int _sampling_rate;
+
+  // Used for assertion mode to determine if there is a path to a TLAB slow path
+  // without a collector present.
+  size_t _collectors_present;
+
+  static void init_log_table();
+
+ public:
+  ThreadHeapSampler() : _bytes_until_sample(0) {
+    _rnd = static_cast<uint32_t>(reinterpret_cast<uintptr_t>(this));
+    if (_rnd == 0) {
+      _rnd = 1;
+    }
+
+    _collectors_present = 0;
+  }
+
+  size_t bytes_until_sample()                    { return _bytes_until_sample;   }
+  void set_bytes_until_sample(size_t bytes)      { _bytes_until_sample = bytes;  }
+
+  void check_for_sampling(HeapWord* obj, size_t size_in_bytes, size_t bytes_allocated_before = 0);
+
+  static int enabled();
+  static void enable();
+  static void disable();
+
+  static void set_sampling_rate(int sampling_rate);
+  static int get_sampling_rate();
+
+  bool sampling_collector_present() const;
+  bool remove_sampling_collector();
+  bool add_sampling_collector();
+};
+
+#endif // SHARE_RUNTIME_THREADHEAPSAMPLER_HPP