Support for dynamic mbeans.

README.md

@@ -84,6 +84,22 @@ Create `src/main/resources/jmxtrans.json`, add your mbeans and declare both `Con
 
 In this sample, Graphite host & port are defaulted to `localhost:2003` and can be overwritten with system properties or environment variables, for example in `$CATALINA_BASE/conf/catalina.properties`.
 
+#### Dynamic MBeans
+
+If metrics are provided by a Dynamic MBeans all attributes can be collected by declaring an empty attributes array, for example :
+
+```json
+{
+  "queries": [
+    {
+      "objectName": "com.cocktail:type=CocktailService,name=cocktailService",
+      "resultAlias": "cocktail.controller",
+      "attributes": [ ]
+    }
+  ]
+}
+```
+
 ### Start application and check metrics
 
 #### Check metrics in the Console

src/main/java/org/jmxtrans/embedded/Query.java

@@ -75,7 +75,7 @@ public class Query implements QueryMBean {
      * JMX attributes to collect. As an array for {@link javax.management.MBeanServer#getAttributes(javax.management.ObjectName, String[])}
      */
     @Nonnull
-    private Map<String, QueryAttribute> attributesByName = new HashMap<String, QueryAttribute>();
+    private final Map<String, QueryAttribute> attributesByName = new HashMap<String, QueryAttribute>();
     /**
      * Copy of {@link #attributesByName}'s {@link java.util.Map#entrySet()} for performance optimization
      */
@@ -166,6 +166,11 @@ public void collectMetrics() {
                 logger.trace("Query {} returned {}", matchingObjectName, jmxAttributes);
                 for (Attribute jmxAttribute : jmxAttributes.asList()) {
                     QueryAttribute queryAttribute = this.attributesByName.get(jmxAttribute.getName());
+                    if (queryAttribute == null) { // support for dynamic attributes
+                        logger.trace("Creating query attribute for {}", jmxAttribute.getName());
+                        queryAttribute = new QueryAttribute(jmxAttribute.getName(), null, null);
+                        addAttribute(queryAttribute);
+                    }
                     Object value = jmxAttribute.getValue();
                     int count = queryAttribute.collectMetrics(matchingObjectName, value, epochInMillis, this.queryResults);
                     collectedMetricsCount.addAndGet(count);

src/test/java/org/jmxtrans/embedded/QueryTest.java

@@ -29,10 +29,10 @@
 import org.junit.BeforeClass;
 import org.junit.Test;
 
-import javax.management.MBeanServer;
-import javax.management.ObjectName;
+import javax.management.*;
 import java.lang.management.ManagementFactory;
 import java.util.Arrays;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
 
@@ -93,6 +93,76 @@ public void test_composite_jmx_attribute() throws Exception {
         assertThat(result2.getValue(), instanceOf(Number.class));
     }
 
+    @Test
+    public void testDynamicAttributeSupport() throws Exception {
+        final int count = 42;
+        ObjectName objectName = new ObjectName("test:type=dynamic,category=metrics");
+        mbeanServer.registerMBean(new DynamicMBean() {
+            @Override
+            public Object getAttribute(String attribute) throws AttributeNotFoundException, MBeanException, ReflectionException {
+                if (attribute.equalsIgnoreCase("count1")) {
+                    return count;
+                }
+                if (attribute.equalsIgnoreCase("count2")) {
+                    return count + 1;
+                }
+                return 0;
+            }
+
+            @Override
+            public void setAttribute(Attribute attribute) throws AttributeNotFoundException, InvalidAttributeValueException, MBeanException, ReflectionException {
+                throw new UnsupportedOperationException();
+            }
+
+            @Override
+            public AttributeList getAttributes(String[] attributes) {
+                AttributeList list = new AttributeList();
+                list.add(new Attribute("count1", count));
+                list.add(new Attribute("count2", count + 1));
+                return list;
+            }
+
+            @Override
+            public AttributeList setAttributes(AttributeList attributes) {
+                throw new UnsupportedOperationException();
+            }
+
+            @Override
+            public Object invoke(String actionName, Object[] params, String[] signature) throws MBeanException, ReflectionException {
+                throw new UnsupportedOperationException();
+            }
+
+            @Override
+            public MBeanInfo getMBeanInfo() {
+                MBeanAttributeInfo[] attrs = new MBeanAttributeInfo[2];
+                attrs[0] = new MBeanAttributeInfo("count1", "java.lang.Integer", "Test count 1", true, false, false);
+                attrs[1] = new MBeanAttributeInfo("count2", "java.lang.Integer", "Test count 2", true, false, false);
+                return new MBeanInfo(QueryTest.class.getCanonicalName(), "Provides access to test counts", attrs, null, null, null);
+            }
+        }, objectName);
+        try {
+            EmbeddedJmxTrans embeddedJmxTrans = new EmbeddedJmxTrans();
+
+            Query query = new Query("test:type=dynamic,category=metrics");
+
+            embeddedJmxTrans.addQuery(query);
+            query.collectMetrics();
+            assertThat(query.getResults().size(), is(2));
+
+            QueryResult result1 = query.getResults().poll();
+            assertThat(result1.getValue(), instanceOf(Number.class));
+            assertEquals("test.category__metrics.type__dynamic.count1", String.valueOf(result1.getName()));
+            assertEquals(count, Integer.parseInt(String.valueOf(result1.getValue())));
+
+            QueryResult result2 = query.getResults().poll();
+            assertThat(result2.getValue(), instanceOf(Number.class));
+            assertEquals("test.category__metrics.type__dynamic.count2", String.valueOf(result2.getName()));
+            assertEquals(count + 1, Integer.parseInt(String.valueOf(result2.getValue())));
+        } finally {
+            mbeanServer.unregisterMBean(objectName);
+        }
+    }
+
     @Test
     public void testExportResults() {
         EmbeddedJmxTrans embeddedJmxTrans = new EmbeddedJmxTrans();