--- /dev/null	2020-01-17 11:46:19.065201212 +0100
+++ new/src/hotspot/share/gc/shenandoah/shenandoahNumberSeq.hpp	2020-01-17 17:10:25.555129628 +0100
@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2018, 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_VM_GC_SHENANDOAH_SHENANDOAHNUMBERSEQ_HPP
+#define SHARE_VM_GC_SHENANDOAH_SHENANDOAHNUMBERSEQ_HPP
+
+#include "utilities/numberSeq.hpp"
+
+// HDR sequence stores the low-resolution high-dynamic-range values.
+// It does so by maintaining the double array, where first array defines
+// the magnitude of the value being stored, and the second array maintains
+// the low resolution histogram within that magnitude. For example, storing
+// 4.352819 * 10^3 increments the bucket _hdr[3][435]. This allows for
+// memory efficient storage of huge amount of samples.
+//
+// Accepts positive numbers only.
+class HdrSeq: public NumberSeq {
+private:
+  enum PrivateConstants {
+    ValBuckets = 512,
+    MagBuckets = 24,
+    MagMinimum = -12
+  };
+  int** _hdr;
+
+public:
+  HdrSeq();
+  ~HdrSeq();
+
+  virtual void add(double val);
+  double percentile(double level) const;
+};
+
+// Binary magnitude sequence stores the power-of-two histogram.
+// It has very low memory requirements, and is thread-safe. When accuracy
+// is not needed, it is preferred over HdrSeq.
+class BinaryMagnitudeSeq {
+private:
+  size_t  _sum;
+  size_t* _mags;
+
+public:
+  BinaryMagnitudeSeq();
+  ~BinaryMagnitudeSeq();
+
+  void add(size_t val);
+  size_t num() const;
+  size_t level(int level) const;
+  size_t sum() const;
+  int min_level() const;
+  int max_level() const;
+};
+
+#endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHNUMBERSEQ_HPP