--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/shared/hSpaceCounters.hpp	Sat Dec 02 06:51:10 2017 +0100
@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2011, 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_SHARED_HSPACECOUNTERS_HPP
+#define SHARE_VM_GC_SHARED_HSPACECOUNTERS_HPP
+
+#include "memory/allocation.hpp"
+#include "runtime/perfData.hpp"
+#include "utilities/macros.hpp"
+
+// A HSpaceCounter is a holder class for performance counters
+// that track a collections (logical spaces) in a heap;
+
+class HSpaceCounters: public CHeapObj<mtGC> {
+  friend class VMStructs;
+
+ private:
+  PerfVariable* _capacity;
+  PerfVariable* _used;
+
+  // Constant PerfData types don't need to retain a reference.
+  // However, it's a good idea to document them here.
+
+  char*         _name_space;
+
+ public:
+
+  HSpaceCounters(const char* name_space, const char* name, int ordinal,
+                 size_t max_size, size_t initial_capacity);
+
+  ~HSpaceCounters();
+
+  void update_capacity(size_t v);
+  void update_used(size_t v);
+
+  void update_all(size_t capacity, size_t used);
+
+  debug_only(
+    // for security reasons, we do not allow arbitrary reads from
+    // the counters as they may live in shared memory.
+    jlong used();
+    jlong capacity();
+  )
+
+  const char* name_space() const        { return _name_space; }
+};
+#endif // SHARE_VM_GC_SHARED_HSPACECOUNTERS_HPP