JmxIndex.java

package org.vafer.jmx2snmp.jmx;

import java.lang.management.ManagementFactory;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.atomic.AtomicReference;

import javax.management.MBeanAttributeInfo;
import javax.management.MBeanInfo;
import javax.management.MBeanServer;
import javax.management.ObjectInstance;
import javax.management.ObjectName;

/**
 *  Represents an index of all bean paths of the MBeanServer to the individual
 *  JMX attributes. Use the expression to formulate a javax.management.QueryExp
 *  for MBean selection.
 *
 *  @threadsafe yes
 */
public final class JmxIndex {

  private final AtomicReference<Map<String, JmxAttribute>> attributesRef = new AtomicReference<Map<String, JmxAttribute>>(Collections.unmodifiableMap(new HashMap<String, JmxAttribute>()));
  private final MBeanServer mbeanServer;
  private final String expression;

  public JmxIndex() throws Exception {
    this(ManagementFactory.getPlatformMBeanServer(), "bean:*");
  }

  public JmxIndex(MBeanServer pMbeanServer, String pExpression) throws Exception {
    mbeanServer = pMbeanServer;
    expression = pExpression;

    update();
  }

  public void update() throws Exception {

    final HashMap<String, JmxAttribute> newAttributes = new HashMap<String, JmxAttribute>();
    final Collection<ObjectInstance> mbeans = mbeanServer.queryMBeans(new ObjectName(expression), null);

    for (Iterator<ObjectInstance> it = mbeans.iterator(); it.hasNext();) {
      final ObjectInstance mbean = it.next();

      final MBeanInfo mbeanInfo = mbeanServer.getMBeanInfo(mbean.getObjectName());

      final MBeanAttributeInfo[] attributes = mbeanInfo.getAttributes();
      for (final MBeanAttributeInfo attribute : attributes) {

        if (attribute.isReadable()) {
          final String attributeName = attribute.getName();

          final JmxAttribute jmxAttribute = new JmxAttribute(attributeName, attribute.getType(), mbean.getObjectName(), mbeanServer);

          newAttributes.put(jmxAttribute.getPath(), jmxAttribute);
        }
      }
    }

    attributesRef.set(Collections.unmodifiableMap(newAttributes));
  }

  public Set<String> getAttributePaths() {
    final Map<String, JmxAttribute> mapping = attributesRef.get();
    return Collections.unmodifiableSet(mapping.keySet());
  }

  public JmxAttribute getAttributeAtPath(String pPath) {
    final Map<String, JmxAttribute> attributes = attributesRef.get();
    return attributes.get(pPath);
  }

  public String toString() {
    final StringBuilder sb = new StringBuilder();
    sb.append(super.toString());
    sb.append('{').append(attributesRef.get()).append('}');
    return sb.toString();
  }
}