--- /dev/null	2019-01-25 10:20:53.925519614 +0100
+++ new/src/hotspot/share/gc/g1/g1CollectionSetCandidates.cpp	2019-01-25 14:25:11.553893625 +0100
@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) 2019, 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 "gc/g1/collectionSetChooser.hpp"
+#include "gc/g1/g1CollectionSetCandidates.hpp"
+#include "gc/g1/heapRegion.inline.hpp"
+
+HeapRegion* G1CollectionSetCandidates::pop_front() {
+  assert(_front_idx < _num_regions, "pre-condition");
+  HeapRegion* hr = _regions[_front_idx];
+  assert(hr != NULL, "pre-condition");
+  _regions[_front_idx] = NULL;
+  assert(hr->reclaimable_bytes() <= _remaining_reclaimable_bytes,
+         "Remaining reclaimable bytes inconsistent "
+         "from region: " SIZE_FORMAT " remaining: " SIZE_FORMAT,
+         hr->reclaimable_bytes(), _remaining_reclaimable_bytes);
+  _remaining_reclaimable_bytes -= hr->reclaimable_bytes();
+  _front_idx++;
+  return hr;
+}
+
+void G1CollectionSetCandidates::push_front(HeapRegion* hr) {
+  assert(hr != NULL, "Can't put back a NULL region");
+  assert(_front_idx >= 1, "Too many regions have been put back.");
+  _front_idx--;
+  _regions[_front_idx] = hr;
+  _remaining_reclaimable_bytes += hr->reclaimable_bytes();
+}
+
+void G1CollectionSetCandidates::iterate(HeapRegionClosure* cl) {
+  for (uint i = _front_idx; i < _num_regions; i++) {
+    HeapRegion* r = _regions[i];
+    if (cl->do_heap_region(r)) {
+      cl->set_incomplete();
+      break;
+    }
+  }
+}
+
+#ifndef PRODUCT
+void G1CollectionSetCandidates::verify() const {
+  guarantee(_front_idx <= _num_regions, "Index: %u Num_regions: %u", _front_idx, _num_regions);
+  uint idx = 0;
+  size_t sum_of_reclaimable_bytes = 0;
+  while (idx < _front_idx) {
+    guarantee(_regions[idx] == NULL, "All entries before _front_idx %u should be NULL, but %u is not",
+              _front_idx, idx);
+    idx++;
+  }
+  HeapRegion *prev = NULL;
+  for (; idx < _num_regions; idx++) {
+    HeapRegion *cur = _regions[idx];
+    guarantee(cur != NULL, "Regions after _front_idx %u cannot be NULL but %u is", _front_idx, idx);
+    guarantee(CollectionSetChooser::should_add(cur), "Region %u should be eligible for addition.", cur->hrm_index());
+    if (prev != NULL) {
+      guarantee(prev->gc_efficiency() >= cur->gc_efficiency(),
+                "GC efficiency for region %u: %1.4f smaller than for region %u: %1.4f",
+                prev->hrm_index(), prev->gc_efficiency(), cur->hrm_index(), cur->gc_efficiency());
+    }
+    sum_of_reclaimable_bytes += cur->reclaimable_bytes();
+    prev = cur;
+  }
+  guarantee(sum_of_reclaimable_bytes == _remaining_reclaimable_bytes,
+            "Inconsistent remaining_reclaimable bytes, remaining " SIZE_FORMAT " calculated " SIZE_FORMAT,
+            _remaining_reclaimable_bytes, sum_of_reclaimable_bytes);
+}
+#endif // !PRODUCT