Implemented a Performance Counter class

src/zutil/ClassUtil.java

@@ -169,7 +169,8 @@ public class ClassUtil {
      * @return the first class in the stack that do not match the filter
      */
     public static String getCallingClass(Class... filter){
-        ArrayList filterStr = new ArrayList();
+        ArrayList filterStr = new ArrayList(filter.length + 1);
+        filterStr.add(ClassUtil.class.getName());
         for (Class clazz : filter)
             filterStr.add(clazz.getName());
 

src/zutil/log/CounterManager.java

@@ -0,0 +1,170 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Ziver Koc
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package zutil.log;
+
+import zutil.ClassUtil;
+
+import javax.management.MBeanServer;
+import javax.management.ObjectName;
+import java.lang.management.ManagementFactory;
+import java.util.HashMap;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * This class is used for performance measurements on an application.
+ * The counter values will be published in JMX and can be viewed in JConsole.
+ */
+public class CounterManager {
+    /** a two dimensional map [Class][Counter ID] for storing singleton objects **/
+    private static HashMap<String, HashMap<String, Counter>> counters = new HashMap<>();
+
+    /**
+     * @param   name    a unique name/id of the counter
+     * @return a singleton instance of the counter name with the calling class as context. Will always return a valid object.
+     */
+    public static Counter getCounter(String name) {
+        return getCounter(ClassUtil.getCallingClass(CounterManager.class), name);
+    }
+    /**
+     * @param   clazz   the counter context
+     * @param   name    a unique name/id of the counter
+     * @return a singleton instance of the counter name. Will always return a valid object.
+     */
+    public static Counter getCounter(Class clazz, String name) {
+        return getCounter(clazz.getName(), name);
+    }
+    private static synchronized Counter getCounter(String clazz, String name) {
+        Counter counter;
+        if ( ! counters.containsKey(clazz) || ! counters.get(clazz).containsKey(name)) {
+            // Get the platform MBeanServer
+            MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
+            // Unique identification of MBeans
+            counter = new Counter(name);
+
+            try {
+                // Uniquely identify the MBeans and register them with the platform MBeanServer
+                ObjectName objectName = new ObjectName(clazz + ":name=" + counter.getName());
+                mbs.registerMBean(counter, objectName);
+                // Register the singleton
+                if ( ! counters.containsKey(clazz))
+                    counters.put(clazz, new HashMap<String, Counter>());
+                counters.get(clazz).put(name, counter);
+            } catch (Exception e) {
+                e.printStackTrace();
+            }
+        }
+        else
+            counter = counters.get(clazz).get(name);
+        return counter;
+    }
+
+
+    /**
+     * MBean Counter definition for publishing data in JMX
+     */
+    public interface CounterMBean {
+        String getName();
+
+        int getValue();
+        int getMax();
+        int getMin();
+        double getAverage();
+    }
+
+
+    public static class Counter implements CounterMBean{
+        private final String name;
+        private int max;
+        private int min;
+        private double average;
+        private int sampleCount;
+        private AtomicInteger counter = new AtomicInteger();
+
+
+        protected Counter(String name){
+            this.name = name;
+        }
+
+
+        public void add(int i){
+            int prev = counter.getAndAdd(i);
+            updateMetaData(prev + i);
+        }
+        public void set(int i){
+            counter.getAndSet(i);
+            updateMetaData(i);
+        }
+        public void increment(){
+            int i = counter.incrementAndGet();
+            updateMetaData(i);
+        }
+        public void decrement(){
+            int i = counter.decrementAndGet();
+            updateMetaData(i);
+        }
+        private void updateMetaData(int i){
+            if (max < i)
+                max = i;
+            if (min > i)
+                min = i;
+
+            average = (average*sampleCount + i) / ++sampleCount;
+        }
+
+
+        @Override
+        public String getName() {
+            return name;
+        }
+        /**
+         * @return current value of the counter
+         */
+        @Override
+        public int getValue(){
+            return counter.intValue();
+        }
+        /**
+         * @return the maximum registered value over the lifetime of the counter
+         */
+        @Override
+        public int getMax() {
+            return max;
+        }
+        /**
+         * @return the minimum registered value over the lifetime of the counter
+         */
+        @Override
+        public int getMin() {
+            return min;
+        }
+        /**
+         * @return the average value of the counter
+         */
+        @Override
+        public double getAverage() {
+            return average;
+        }
+    }
+}

test/zutil/log/CounterManagerTest.java

@@ -0,0 +1,148 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Ziver Koc
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package zutil.log;
+
+import org.junit.Test;
+import zutil.log.CounterManager.Counter;
+
+import static org.junit.Assert.*;
+
+public class CounterManagerTest {
+
+    @Test
+    public void singletonTest(){
+        Counter c1 = CounterManager.getCounter("TestCounter");
+        Counter c2 = CounterManager.getCounter("TestCounter");
+        assertSame(c1, c2);
+
+        c1 = CounterManager.getCounter("TestCounter");
+        c2 = CounterManager.getCounter(CounterManagerTest.class, "TestCounter");
+        assertSame(c1, c2);
+
+        c1 = CounterManager.getCounter(CounterManagerTest.class, "TestCounter");
+        c2 = CounterManager.getCounter(CounterManagerTest.class, "TestCounter");
+        assertSame(c1, c2);
+    }
+
+    @Test
+    public void addTest(){
+        Counter c1 = CounterManager.getCounter("AddTestCounter");
+        assertEquals(0, c1.getValue());
+
+        c1.add(10);
+        assertEquals(10, c1.getValue());
+
+        c1.add(20);
+        c1.add(30);
+        assertEquals(60, c1.getValue());
+    }
+
+    @Test
+    public void setTest(){
+        Counter c1 = CounterManager.getCounter("SetTestCounter");
+        assertEquals(0, c1.getValue());
+
+        c1.set(10);
+        assertEquals(10, c1.getValue());
+
+        c1.set(20);
+        c1.set(30);
+        assertEquals(30, c1.getValue());
+    }
+
+    @Test
+    public void incrementTest(){
+        Counter c1 = CounterManager.getCounter("IncrementTestCounter");
+        assertEquals(0, c1.getValue());
+
+        c1.increment();
+        assertEquals(1, c1.getValue());
+
+        c1.increment();
+        c1.increment();
+        c1.increment();
+        assertEquals(4, c1.getValue());
+    }
+
+    @Test
+    public void decrementTest(){
+        Counter c1 = CounterManager.getCounter("DecrementTestCounter");
+        assertEquals(0, c1.getValue());
+
+        c1.decrement();
+        assertEquals(-1, c1.getValue());
+
+        c1.decrement();
+        c1.decrement();
+        c1.decrement();
+        assertEquals(-4, c1.getValue());
+    }
+
+    @Test
+    public void maxTest(){
+        Counter c1 = CounterManager.getCounter("MaxTestCounter");
+        assertEquals(0, c1.getMax());
+
+        c1.set(10);
+        assertEquals(10, c1.getMax());
+
+        c1.set(50);
+        assertEquals(50, c1.getMax());
+
+        c1.set(0);
+        assertEquals(50, c1.getMax());
+    }
+
+    @Test
+    public void minTest(){
+        Counter c1 = CounterManager.getCounter("MinTestCounter");
+        assertEquals(0, c1.getMin());
+
+        c1.set(10);
+        assertEquals(0, c1.getMin());
+
+        c1.set(-50);
+        assertEquals(-50, c1.getMin());
+
+        c1.set(0);
+        assertEquals(-50, c1.getMin());
+    }
+
+    @Test
+    public void averageTest(){
+        Counter c1 = CounterManager.getCounter("MinTestCounter");
+        assertEquals(0, (int)c1.getAverage());
+
+        c1.set(10);
+        assertEquals(10, (int)c1.getAverage());
+
+        c1.set(10);
+        assertEquals(10, (int)c1.getAverage());
+
+        c1.set(70);
+        assertEquals(30, (int)c1.getAverage());
+    }
+
+}