ARTEMIS-3741 Cache MBeanInfoHelper results

The utility methods in
`org.apache.activemq.artemis.core.management.impl.MBeanInfoHelper` are
executed *a lot* - especially for Jolokia which is used by the web
console. The `MBeanOperationInfo` and `MBeanAttributeInfo` results are
static and reflection is slow therefore they should not be calculated
over and over again. Rather they should be calculated once and cached
for later use.

Caching these results significantly improves performance. Over the
course of 1,000,000 invocations the difference is several orders of
magnitude. This improves usability substantially when dealing with,
for example, tens of thousands of addresses and/or queues.

artemis-server/src/main/java/org/apache/activemq/artemis/core/management/impl/MBeanInfoHelper.java

@@ -23,6 +23,7 @@ import java.lang.annotation.Annotation;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.ConcurrentHashMap;
 
 import org.apache.activemq.artemis.api.core.management.Attribute;
 import org.apache.activemq.artemis.api.core.management.Operation;
@@ -30,9 +31,13 @@ import org.apache.activemq.artemis.api.core.management.Parameter;
 
 public class MBeanInfoHelper {
 
-
+   private static ConcurrentHashMap<Class, MBeanAttributeInfo[]> attributesInfoCache = new ConcurrentHashMap<>();
+   private static ConcurrentHashMap<Class, MBeanOperationInfo[]> operationsInfoCache = new ConcurrentHashMap<>();
 
    public static MBeanOperationInfo[] getMBeanOperationsInfo(final Class mbeanInterface) {
+      if (operationsInfoCache.containsKey(mbeanInterface)) {
+         return operationsInfoCache.get(mbeanInterface);
+      } else {
          List<MBeanOperationInfo> operations = new ArrayList<>();
 
          for (Method method : mbeanInterface.getMethods()) {
@@ -41,11 +46,16 @@ public class MBeanInfoHelper {
                operations.add(MBeanInfoHelper.getOperationInfo(method));
             }
          }
-
-      return operations.toArray(new MBeanOperationInfo[operations.size()]);
+         MBeanOperationInfo[] result = operations.toArray(new MBeanOperationInfo[operations.size()]);
+         operationsInfoCache.put(mbeanInterface, result);
+         return result;
+      }
    }
 
    public static MBeanAttributeInfo[] getMBeanAttributesInfo(final Class mbeanInterface) {
+      if (attributesInfoCache.containsKey(mbeanInterface)) {
+         return attributesInfoCache.get(mbeanInterface);
+      } else {
          List<MBeanAttributeInfo> tempAttributes = new ArrayList<>();
          List<MBeanAttributeInfo> finalAttributes = new ArrayList<>();
          List<String> alreadyAdded = new ArrayList<>();
@@ -70,12 +80,27 @@ public class MBeanInfoHelper {
                alreadyAdded.add(infoToCopy.getName());
             }
          }
-
-      return finalAttributes.toArray(new MBeanAttributeInfo[finalAttributes.size()]);
+         MBeanAttributeInfo[] result = finalAttributes.toArray(new MBeanAttributeInfo[finalAttributes.size()]);
+         attributesInfoCache.put(mbeanInterface, result);
+         return result;
+      }
    }
 
+   public static int getAttributesInfoCacheSize() {
+      return attributesInfoCache.size();
+   }
 
+   public static int getOperationsInfoCacheSize() {
+      return operationsInfoCache.size();
+   }
 
+   public static void clearAttributesInfoCache() {
+      attributesInfoCache.clear();
+   }
+
+   public static void clearOperationsInfoCache() {
+      operationsInfoCache.clear();
+   }
 
    private static boolean isGetterMethod(final Method method) {
       if (!method.getName().equals("get") && method.getName().startsWith("get") &&

artemis-server/src/test/java/org/apache/activemq/artemis/core/management/impl/MBeanInfoHelperTest.java

@@ -0,0 +1,46 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.activemq.artemis.core.management.impl;
+
+import org.apache.activemq.artemis.api.core.management.AddressControl;
+import org.apache.activemq.artemis.api.core.management.QueueControl;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class MBeanInfoHelperTest extends Assert {
+
+   @Test
+   public void testOperationsInfosCache() {
+      MBeanInfoHelper.clearOperationsInfoCache();
+      for (int i = 0; i < 10; i++) {
+         MBeanInfoHelper.getMBeanOperationsInfo(QueueControl.class);
+         MBeanInfoHelper.getMBeanOperationsInfo(AddressControl.class);
+      }
+      assertEquals(2, MBeanInfoHelper.getOperationsInfoCacheSize());
+   }
+
+   @Test
+   public void testAttributesInfosCache() {
+      MBeanInfoHelper.clearAttributesInfoCache();
+      for (int i = 0; i < 10; i++) {
+         MBeanInfoHelper.getMBeanAttributesInfo(QueueControl.class);
+         MBeanInfoHelper.getMBeanAttributesInfo(AddressControl.class);
+      }
+      assertEquals(2, MBeanInfoHelper.getAttributesInfoCacheSize());
+   }
+}