Process JMX beans with an ArrayList value by returning the size of the list

Signed-off-by: Stephen Darlington <stephen.darlington@gridgain.com>

Author: sdarlington

collector/src/main/java/io/prometheus/jmx/JmxScraper.java

@@ -20,14 +20,7 @@
 import javax.rmi.ssl.SslRMIClientSocketFactory;
 import java.io.IOException;
 import java.lang.management.ManagementFactory;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.LinkedHashMap;
-import java.util.LinkedList;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
-import java.util.TreeSet;
+import java.util.*;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
@@ -157,28 +150,22 @@ private void scrapeBean(MBeanServerConnection beanConn, ObjectName mbeanName) {
             logScrape(mbeanName, name2AttrInfo.keySet(), "Fail: " + e);
             return;
         }
-        try {
-            for (Object attributeObj : attributes.asList()) {
-                if (Attribute.class.isInstance(attributeObj)) {
-                    Attribute attribute = (Attribute)(attributeObj);
-                    MBeanAttributeInfo attr = name2AttrInfo.get(attribute.getName());
-                    logScrape(mbeanName, attr, "process");
-                    processBeanValue(
-                            mbeanName.getDomain(),
-                            jmxMBeanPropertyCache.getKeyPropertyList(mbeanName),
-                            new LinkedList<String>(),
-                            attr.getName(),
-                            attr.getType(),
-                            attr.getDescription(),
-                            attribute.getValue()
-                    );
-                }
+        for (Object attributeObj : attributes) {
+            if (Attribute.class.isInstance(attributeObj)) {
+                Attribute attribute = (Attribute)(attributeObj);
+                MBeanAttributeInfo attr = name2AttrInfo.get(attribute.getName());
+                logScrape(mbeanName, attr, "process");
+                processBeanValue(
+                        mbeanName.getDomain(),
+                        jmxMBeanPropertyCache.getKeyPropertyList(mbeanName),
+                        new LinkedList<String>(),
+                        attr.getName(),
+                        attr.getType(),
+                        attr.getDescription(),
+                        attribute.getValue()
+                );
             }
         }
-        catch (Exception e) {
-            logScrape(mbeanName.toString(), "failed to process attribute");
-            return;
-        }
     }
 
 
@@ -288,6 +275,18 @@ private void processBeanValue(
             }
         } else if (value.getClass().isArray()) {
             logScrape(domain, "arrays are unsupported");
+        } else if (value instanceof ArrayList<?>) {
+            // We can't output a list of values here, so instead let's send the count of entries
+            ArrayList<?> list = (ArrayList<?>)value;
+            logScrape(domain + beanProperties + attrName, String.valueOf(list.size()));
+            this.receiver.recordBean(
+                    domain,
+                    beanProperties,
+                    attrKeys,
+                    attrName,
+                    attrType,
+                    attrDescription,
+                    list.size());
         } else {
             logScrape(domain + beanProperties, attrType + " is not exported");
         }