--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/hotspot/jtreg/gc/testlibrary/PerfCounter.java	Mon Nov 27 10:51:31 2017 +0100
@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2013, 2015, 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.
+ */
+
+package gc.testlibrary;
+
+import sun.jvmstat.monitor.Monitor;
+
+/**
+ * Represents a performance counter in the JVM.
+ *
+ * See http://openjdk.java.net/groups/hotspot/docs/Serviceability.html#bjvmstat
+ * for more details about performance counters.
+ */
+public class PerfCounter {
+    private final Monitor monitor;
+    private final String name;
+
+    PerfCounter(Monitor monitor, String name) {
+        this.monitor = monitor;
+        this.name = name;
+    }
+
+    /**
+     * Returns the value of this performance counter as a long.
+     *
+     * @return The long value of this performance counter
+     * @throws RuntimeException If the value of the performance counter isn't a long
+     */
+    public long longValue() {
+        Object value = monitor.getValue();
+        if (value instanceof Long) {
+            return ((Long) value).longValue();
+        }
+        throw new RuntimeException("Expected " + monitor.getName() + " to have a long value");
+    }
+
+    /**
+     * Returns the name of the performance counter.
+     *
+     * @return The name of the performance counter.
+     */
+    public String getName() {
+        return name;
+    }
+
+    @Override
+    public String toString() {
+        return name;
+    }
+}