--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/g1/g1MemoryPool.hpp	Sat Dec 02 06:51:10 2017 +0100
@@ -0,0 +1,109 @@
+/*
+ * Copyright (c) 2007, 2017, 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.
+ *
+ */
+
+#ifndef SHARE_VM_GC_G1_G1MEMORYPOOL_HPP
+#define SHARE_VM_GC_G1_G1MEMORYPOOL_HPP
+
+#include "gc/g1/g1MonitoringSupport.hpp"
+#include "services/memoryPool.hpp"
+#include "services/memoryUsage.hpp"
+
+// This file contains the three classes that represent the memory
+// pools of the G1 spaces: G1EdenPool, G1SurvivorPool, and
+// G1OldGenPool. In G1, unlike our other GCs, we do not have a
+// physical space for each of those spaces. Instead, we allocate
+// regions for all three spaces out of a single pool of regions (that
+// pool basically covers the entire heap). As a result, the eden,
+// survivor, and old gen are considered logical spaces in G1, as each
+// is a set of non-contiguous regions. This is also reflected in the
+// way we map them to memory pools here. The easiest way to have done
+// this would have been to map the entire G1 heap to a single memory
+// pool. However, it's helpful to show how large the eden and survivor
+// get, as this does affect the performance and behavior of G1. Which
+// is why we introduce the three memory pools implemented here.
+//
+// See comments in g1MonitoringSupport.hpp for additional details
+// on this model.
+//
+
+class G1CollectedHeap;
+
+// This class is shared by the three G1 memory pool classes
+// (G1EdenPool, G1SurvivorPool, G1OldGenPool).
+class G1MemoryPoolSuper : public CollectedMemoryPool {
+protected:
+  const static size_t _undefined_max = (size_t) -1;
+  G1MonitoringSupport* _g1mm;
+
+  // Would only be called from subclasses.
+  G1MemoryPoolSuper(G1CollectedHeap* g1h,
+                    const char* name,
+                    size_t init_size,
+                    size_t max_size,
+                    bool support_usage_threshold);
+};
+
+// Memory pool that represents the G1 eden.
+class G1EdenPool : public G1MemoryPoolSuper {
+public:
+  G1EdenPool(G1CollectedHeap* g1h);
+
+  size_t used_in_bytes() {
+    return _g1mm->eden_space_used();
+  }
+  size_t max_size() const {
+    return _undefined_max;
+  }
+  MemoryUsage get_memory_usage();
+};
+
+// Memory pool that represents the G1 survivor.
+class G1SurvivorPool : public G1MemoryPoolSuper {
+public:
+  G1SurvivorPool(G1CollectedHeap* g1h);
+
+  size_t used_in_bytes() {
+    return _g1mm->survivor_space_used();
+  }
+  size_t max_size() const {
+    return _undefined_max;
+  }
+  MemoryUsage get_memory_usage();
+};
+
+// Memory pool that represents the G1 old gen.
+class G1OldGenPool : public G1MemoryPoolSuper {
+public:
+  G1OldGenPool(G1CollectedHeap* g1h);
+
+  size_t used_in_bytes() {
+    return _g1mm->old_space_used();
+  }
+  size_t max_size() const {
+    return _g1mm->old_gen_max();
+  }
+  MemoryUsage get_memory_usage();
+};
+
+#endif // SHARE_VM_GC_G1_G1MEMORYPOOL_HPP