--- /dev/null	2018-11-30 10:10:44.238550338 +0100
+++ new/src/hotspot/share/gc/shenandoah/shenandoahHeuristics.hpp	2018-11-30 21:09:12.501782463 +0100
@@ -0,0 +1,167 @@
+/*
+ * 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_SHENANDOAHHEURISTICS_HPP
+#define SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEURISTICS_HPP
+
+#include "gc/shenandoah/shenandoahHeap.hpp"
+#include "gc/shenandoah/shenandoahPhaseTimings.hpp"
+#include "gc/shenandoah/shenandoahSharedVariables.hpp"
+#include "memory/allocation.hpp"
+#include "runtime/globals_extension.hpp"
+
+#define SHENANDOAH_ERGO_DISABLE_FLAG(name)                                  \
+  do {                                                                      \
+    if (FLAG_IS_DEFAULT(name) && (name)) {                                  \
+      log_info(gc)("Heuristics ergonomically sets -XX:-" #name);            \
+      FLAG_SET_DEFAULT(name, false);                                        \
+    }                                                                       \
+  } while (0)
+
+#define SHENANDOAH_ERGO_ENABLE_FLAG(name)                                   \
+  do {                                                                      \
+    if (FLAG_IS_DEFAULT(name) && !(name)) {                                 \
+      log_info(gc)("Heuristics ergonomically sets -XX:+" #name);            \
+      FLAG_SET_DEFAULT(name, true);                                         \
+    }                                                                       \
+  } while (0)
+
+#define SHENANDOAH_ERGO_OVERRIDE_DEFAULT(name, value)                       \
+  do {                                                                      \
+    if (FLAG_IS_DEFAULT(name)) {                                            \
+      log_info(gc)("Heuristics ergonomically sets -XX:" #name "=" #value);  \
+      FLAG_SET_DEFAULT(name, value);                                        \
+    }                                                                       \
+  } while (0)
+
+#define SHENANDOAH_CHECK_FLAG_SET(name)                                     \
+  do {                                                                      \
+    if (!name) {                                                            \
+      err_msg message("Heuristics needs -XX:+" #name " to work correctly"); \
+      vm_exit_during_initialization("Error", message);                      \
+    }                                                                       \
+  } while (0)
+
+class ShenandoahCollectionSet;
+class ShenandoahHeapRegion;
+
+class ShenandoahHeuristics : public CHeapObj<mtGC> {
+  static const intx Concurrent_Adjust   =  1; // recover from penalties
+  static const intx Degenerated_Penalty = 10; // how much to penalize average GC duration history on Degenerated GC
+  static const intx Full_Penalty        = 20; // how much to penalize average GC duration history on Full GC
+
+protected:
+  typedef struct {
+    ShenandoahHeapRegion* _region;
+    size_t _garbage;
+    uint64_t _seqnum_last_alloc;
+  } RegionData;
+
+  bool _update_refs_early;
+  bool _update_refs_adaptive;
+
+  RegionData* _region_data;
+  size_t _region_data_size;
+
+  uint _degenerated_cycles_in_a_row;
+  uint _successful_cycles_in_a_row;
+
+  size_t _bytes_in_cset;
+
+  double _cycle_start;
+  double _last_cycle_end;
+
+  size_t _gc_times_learned;
+  size_t _gc_time_penalties;
+  TruncatedSeq* _gc_time_history;
+
+  // There may be many threads that contend to set this flag
+  ShenandoahSharedFlag _metaspace_oom;
+
+  static int compare_by_garbage(RegionData a, RegionData b);
+  static int compare_by_garbage_then_alloc_seq_ascending(RegionData a, RegionData b);
+  static int compare_by_alloc_seq_ascending(RegionData a, RegionData b);
+  static int compare_by_alloc_seq_descending(RegionData a, RegionData b);
+
+  RegionData* get_region_data_cache(size_t num);
+
+  virtual void choose_collection_set_from_regiondata(ShenandoahCollectionSet* set,
+                                                     RegionData* data, size_t data_size,
+                                                     size_t free) = 0;
+
+public:
+  ShenandoahHeuristics();
+  virtual ~ShenandoahHeuristics();
+
+  void record_gc_start();
+
+  void record_gc_end();
+
+  void record_metaspace_oom()     { _metaspace_oom.set(); }
+  void clear_metaspace_oom()      { _metaspace_oom.unset(); }
+  bool has_metaspace_oom() const  { return _metaspace_oom.is_set(); }
+
+  virtual void record_cycle_start();
+
+  virtual void record_cycle_end();
+
+  virtual void record_phase_time(ShenandoahPhaseTimings::Phase phase, double secs);
+
+  virtual bool should_start_normal_gc() const;
+
+  virtual bool should_start_update_refs();
+
+  virtual bool should_start_traversal_gc();
+
+  virtual bool can_do_traversal_gc();
+
+  virtual bool should_degenerate_cycle();
+
+  virtual void record_success_concurrent();
+
+  virtual void record_success_degenerated();
+
+  virtual void record_success_full();
+
+  virtual void record_allocation_failure_gc();
+
+  virtual void record_requested_gc();
+
+  virtual void choose_collection_set(ShenandoahCollectionSet* collection_set);
+
+  virtual bool can_process_references();
+  virtual bool should_process_references();
+
+  virtual bool can_unload_classes();
+  virtual bool can_unload_classes_normal();
+  virtual bool should_unload_classes();
+
+  virtual const char* name() = 0;
+  virtual bool is_diagnostic() = 0;
+  virtual bool is_experimental() = 0;
+  virtual void initialize();
+
+  double time_since_last_gc() const;
+};
+
+#endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEURISTICS_HPP