src/core/org/apache/hadoop/jmx/JMXJsonServlet.java - hadoop - Git at Google

 /*
  * 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
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * 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.hadoop.jmx;

 import java.io.IOException;
 import java.io.PrintWriter;
 import java.lang.management.ManagementFactory;
 import java.lang.reflect.Array;
 import java.util.Iterator;
 import java.util.Set;

 import javax.management.AttributeNotFoundException;
 import javax.management.InstanceNotFoundException;
 import javax.management.IntrospectionException;
 import javax.management.MBeanAttributeInfo;
 import javax.management.MBeanException;
 import javax.management.MBeanInfo;
 import javax.management.MBeanServer;
 import javax.management.MalformedObjectNameException;
 import javax.management.ObjectName;
 import javax.management.ReflectionException;
 import javax.management.RuntimeMBeanException;
 import javax.management.openmbean.CompositeData;
 import javax.management.openmbean.CompositeType;
 import javax.management.openmbean.TabularData;
 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.http.HttpServer;
 import org.codehaus.jackson.JsonFactory;
 import org.codehaus.jackson.JsonGenerator;

 /*
  * This servlet is based off of the JMXProxyServlet from Tomcat 7.0.14. It has
  * been rewritten to be read only and to output in a JSON format so it is not
  * really that close to the original.
  */
 /**
  * Provides Read only web access to JMX.
  * <p>
  * This servlet generally will be placed under the /jmx URL for each
  * HttpServer.  It provides read only
  * access to JMX metrics.  The optional <code>qry</code> parameter
  * may be used to query only a subset of the JMX Beans.  This query
  * functionality is provided through the
  * {@link MBeanServer#queryNames(ObjectName, javax.management.QueryExp)}
  * method.
  * <p>
  * For example <code>http://.../jmx?qry=Hadoop:*</code> will return
  * all hadoop metrics exposed through JMX.
  * <p>
  * If the <code>qry</code> parameter is not formatted correctly then a
  * 400 BAD REQUEST http response code will be returned.
  * <p>
  * The return format is JSON and in the form
  * <p>
  *  <code><pre>
  *  {
  *    "beans" : [
  *      {
  *        "name":"bean-name"
  *        ...
  *      }
  *    ]
  *  }
  *  </pre></code>
  *  <p>
  *  The servlet attempts to convert the the JMXBeans into JSON. Each
  *  bean's attributes will be converted to a JSON object member.
  *
  *  If the attribute is a boolean, a number, a string, or an array
  *  it will be converted to the JSON equivalent.
  *
  *  If the value is a {@link CompositeData} then it will be converted
  *  to a JSON object with the keys as the name of the JSON member and
  *  the value is converted following these same rules.
  *
  *  If the value is a {@link TabularData} then it will be converted
  *  to an array of the {@link CompositeData} elements that it contains.
  *
  *  All other objects will be converted to a string and output as such.
  *
  *  The bean's name and modelerType will be returned for all beans.
  */
 public class JMXJsonServlet extends HttpServlet {
   private static final Log LOG = LogFactory.getLog(JMXJsonServlet.class);

   private static final long serialVersionUID = 1L;

   // ----------------------------------------------------- Instance Variables
   /**
    * MBean server.
    */
   protected transient MBeanServer mBeanServer = null;

   // --------------------------------------------------------- Public Methods
   /**
    * Initialize this servlet.
    */
   @Override
   public void init() throws ServletException {
     // Retrieve the MBean server
     mBeanServer = ManagementFactory.getPlatformMBeanServer();
   }

   /**
    * Process a GET request for the specified resource.
    *
    * @param request
    *          The servlet request we are processing
    * @param response
    *          The servlet response we are creating
    */
   @Override
   public void doGet(HttpServletRequest request, HttpServletResponse response) {
     try {
       // Do the authorization
       if (!HttpServer.hasAdministratorAccess(getServletContext(), request,
           response)) {
         return;
       }

       response.setContentType("application/json; charset=utf8");

       PrintWriter writer = response.getWriter();

       JsonFactory jsonFactory = new JsonFactory();
       JsonGenerator jg = jsonFactory.createJsonGenerator(writer);
       jg.useDefaultPrettyPrinter();
       jg.writeStartObject();
       if (mBeanServer == null) {
         jg.writeStringField("result", "ERROR");
         jg.writeStringField("message", "No MBeanServer could be found");
         jg.close();
         return;
       }
       String qry = request.getParameter("qry");
       if (qry == null) {
         qry = "*:*";
       }
       listBeans(jg, new ObjectName(qry));
       jg.close();
     } catch (IOException e) {
       LOG.error("Caught an exception while processing JMX request", e);
       response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
     } catch (MalformedObjectNameException e) {
       LOG.error("Caught an exception while processing JMX request", e);
       response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
     }
   }

   // --------------------------------------------------------- Private Methods
   private void listBeans(JsonGenerator jg, ObjectName qry) throws IOException {
     LOG.debug("Listing beans for "+qry);
     Set<ObjectName> names = null;
     names = mBeanServer.queryNames(qry, null);

     jg.writeArrayFieldStart("beans");
     Iterator<ObjectName> it = names.iterator();
     while (it.hasNext()) {
       ObjectName oname = it.next();
       MBeanInfo minfo;
       String code;
       try {
         minfo = mBeanServer.getMBeanInfo(oname);
         code = minfo.getClassName();
         try {
           if ("org.apache.commons.modeler.BaseModelMBean".equals(code)) {
             code = (String) mBeanServer.getAttribute(oname, "modelerType");
           }
         } catch (AttributeNotFoundException e) {
           //Ignored the modelerType attribute was not found, so use the class name instead.
         } catch (MBeanException e) {
           //The code inside the attribute getter threw an exception so log it, and
           // fall back on the class name
           LOG.error("getting attribute modelerType of "+oname+" threw an exception", e);
         } catch (RuntimeException e) {
           //For some reason even with an MBeanException available to them Runtime exceptions
           //can still find their way through, so treat them the same as MBeanException
           LOG.error("getting attribute modelerType of "+oname+" threw an exception", e);
         } catch (ReflectionException e) {
           //This happens when the code inside the JMX bean (setter?? from the java docs)
           //threw an exception, so log it and fall back on the class name
           LOG.error("getting attribute modelerType of "+oname+" threw an exception", e);
         }
       } catch (InstanceNotFoundException e) {
         //Ignored for some reason the bean was not found so don't output it
         continue;
       } catch (IntrospectionException e) {
         //This is an internal error, something odd happened with reflection so log it and
         //don't output the bean.
         LOG.error("Problem while trying to process JMX query: "+qry+" with MBean "+oname, e);
         continue;
       } catch (ReflectionException e) {
         //This happens when the code inside the JMX bean threw an exception, so log it and
         //don't output the bean.
         LOG.error("Problem while trying to process JMX query: "+qry+" with MBean "+oname, e);
         continue;
       }

       jg.writeStartObject();
       jg.writeStringField("name", oname.toString());
       // can't be null - I think

       jg.writeStringField("modelerType", code);

       MBeanAttributeInfo attrs[] = minfo.getAttributes();
       for (int i = 0; i < attrs.length; i++) {
         writeAttribute(jg, oname, attrs[i]);
       }
       //  LOG.error("Caught Error writing value ",t);
       //  ExceptionUtils.handleThrowable(t);
       //}
       jg.writeEndObject();
     }
     jg.writeEndArray();
   }

   private void writeAttribute(JsonGenerator jg, ObjectName oname, MBeanAttributeInfo attr) throws IOException {
     if (!attr.isReadable()) {
       return;
     }
     String attName = attr.getName();
     if ("modelerType".equals(attName)) {
       return;
     }
     if (attName.indexOf("=") >= 0 || attName.indexOf(":") >= 0
         || attName.indexOf(" ") >= 0) {
       return;
     }
     Object value = null;
     try {
       value = mBeanServer.getAttribute(oname, attName);
     } catch (RuntimeMBeanException e) {
       // UnsupportedOperationExceptions happen in the normal course of business,
       // so no need to log them as errors all the time.
       if (e.getCause() instanceof UnsupportedOperationException) {
         LOG.debug("getting attribute "+attName+" of "+oname+" threw an exception", e);
       } else {
         LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);
       }
       return;
     } catch (AttributeNotFoundException e) {
       //Ignored the attribute was not found, which should never happen because the bean
       //just told us that it has this attribute, but if this happens just don't output
       //the attribute.
       return;
     } catch (MBeanException e) {
       //The code inside the attribute getter threw an exception so log it, and
       // skip outputting the attribute
       LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);
       return;
     } catch (RuntimeException e) {
       //For some reason even with an MBeanException available to them Runtime exceptions
       //can still find their way through, so treat them the same as MBeanException
       LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);
       return;
     } catch (ReflectionException e) {
       //This happens when the code inside the JMX bean (setter?? from the java docs)
       //threw an exception, so log it and skip outputting the attribute
       LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);
       return;
     } catch (InstanceNotFoundException e) {
       //Ignored the mbean itself was not found, which should never happen because we
       //just accessed it (perhaps something unregistered in-between) but if this
       //happens just don't output the attribute.
       return;
     }

     writeAttribute(jg, attName, value);
   }

   private void writeAttribute(JsonGenerator jg, String attName, Object value) throws IOException {
     jg.writeFieldName(attName);
     writeObject(jg, value);
   }

   private void writeObject(JsonGenerator jg, Object value) throws IOException {
     if(value == null) {
       jg.writeNull();
     } else {
       Class<?> c = value.getClass();
       if (c.isArray()) {
         jg.writeStartArray();
         int len = Array.getLength(value);
         for (int j = 0; j < len; j++) {
           Object item = Array.get(value, j);
           writeObject(jg, item);
         }
         jg.writeEndArray();
       } else if(value instanceof Number) {
         Number n = (Number)value;
         jg.writeNumber(n.toString());
       } else if(value instanceof Boolean) {
         Boolean b = (Boolean)value;
         jg.writeBoolean(b);
       } else if(value instanceof CompositeData) {
         CompositeData cds = (CompositeData)value;
         CompositeType comp = cds.getCompositeType();
         Set<String> keys = comp.keySet();
         jg.writeStartObject();
         for(String key: keys) {
           writeAttribute(jg, key, cds.get(key));
         }
         jg.writeEndObject();
       } else if(value instanceof TabularData) {
         TabularData tds = (TabularData)value;
         jg.writeStartArray();
         for(Object entry : tds.values()) {
           writeObject(jg, entry);
         }
         jg.writeEndArray();
       } else {
         jg.writeString(value.toString());
       }
     }
   }
 }
	/*
	* 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
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* 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.hadoop.jmx;

	import java.io.IOException;
	import java.io.PrintWriter;
	import java.lang.management.ManagementFactory;
	import java.lang.reflect.Array;
	import java.util.Iterator;
	import java.util.Set;

	import javax.management.AttributeNotFoundException;
	import javax.management.InstanceNotFoundException;
	import javax.management.IntrospectionException;
	import javax.management.MBeanAttributeInfo;
	import javax.management.MBeanException;
	import javax.management.MBeanInfo;
	import javax.management.MBeanServer;
	import javax.management.MalformedObjectNameException;
	import javax.management.ObjectName;
	import javax.management.ReflectionException;
	import javax.management.RuntimeMBeanException;
	import javax.management.openmbean.CompositeData;
	import javax.management.openmbean.CompositeType;
	import javax.management.openmbean.TabularData;
	import javax.servlet.ServletException;
	import javax.servlet.http.HttpServlet;
	import javax.servlet.http.HttpServletRequest;
	import javax.servlet.http.HttpServletResponse;

	import org.apache.commons.logging.Log;
	import org.apache.commons.logging.LogFactory;
	import org.apache.hadoop.http.HttpServer;
	import org.codehaus.jackson.JsonFactory;
	import org.codehaus.jackson.JsonGenerator;

	/*
	* This servlet is based off of the JMXProxyServlet from Tomcat 7.0.14. It has
	* been rewritten to be read only and to output in a JSON format so it is not
	* really that close to the original.
	*/
	/**
	* Provides Read only web access to JMX.
	* <p>
	* This servlet generally will be placed under the /jmx URL for each
	* HttpServer. It provides read only
	* access to JMX metrics. The optional <code>qry</code> parameter
	* may be used to query only a subset of the JMX Beans. This query
	* functionality is provided through the
	* {@link MBeanServer#queryNames(ObjectName, javax.management.QueryExp)}
	* method.
	* <p>
	* For example <code>http://.../jmx?qry=Hadoop:*</code> will return
	* all hadoop metrics exposed through JMX.
	* <p>
	* If the <code>qry</code> parameter is not formatted correctly then a
	* 400 BAD REQUEST http response code will be returned.
	* <p>
	* The return format is JSON and in the form
	* <p>
	* <code><pre>
	* {
	* "beans" : [
	* {
	* "name":"bean-name"
	* ...
	* }
	* ]
	* }
	* </pre></code>
	* <p>
	* The servlet attempts to convert the the JMXBeans into JSON. Each
	* bean's attributes will be converted to a JSON object member.
	*
	* If the attribute is a boolean, a number, a string, or an array
	* it will be converted to the JSON equivalent.
	*
	* If the value is a {@link CompositeData} then it will be converted
	* to a JSON object with the keys as the name of the JSON member and
	* the value is converted following these same rules.
	*
	* If the value is a {@link TabularData} then it will be converted
	* to an array of the {@link CompositeData} elements that it contains.
	*
	* All other objects will be converted to a string and output as such.
	*
	* The bean's name and modelerType will be returned for all beans.
	*/
	public class JMXJsonServlet extends HttpServlet {
	private static final Log LOG = LogFactory.getLog(JMXJsonServlet.class);

	private static final long serialVersionUID = 1L;

	// ----------------------------------------------------- Instance Variables
	/**
	* MBean server.
	*/
	protected transient MBeanServer mBeanServer = null;

	// --------------------------------------------------------- Public Methods
	/**
	* Initialize this servlet.
	*/
	@Override
	public void init() throws ServletException {
	// Retrieve the MBean server
	mBeanServer = ManagementFactory.getPlatformMBeanServer();
	}

	/**
	* Process a GET request for the specified resource.
	*
	* @param request
	* The servlet request we are processing
	* @param response
	* The servlet response we are creating
	*/
	@Override
	public void doGet(HttpServletRequest request, HttpServletResponse response) {
	try {
	// Do the authorization
	if (!HttpServer.hasAdministratorAccess(getServletContext(), request,
	response)) {
	return;
	}

	response.setContentType("application/json; charset=utf8");

	PrintWriter writer = response.getWriter();

	JsonFactory jsonFactory = new JsonFactory();
	JsonGenerator jg = jsonFactory.createJsonGenerator(writer);
	jg.useDefaultPrettyPrinter();
	jg.writeStartObject();
	if (mBeanServer == null) {
	jg.writeStringField("result", "ERROR");
	jg.writeStringField("message", "No MBeanServer could be found");
	jg.close();
	return;
	}
	String qry = request.getParameter("qry");
	if (qry == null) {
	qry = ":";
	}
	listBeans(jg, new ObjectName(qry));
	jg.close();
	} catch (IOException e) {
	LOG.error("Caught an exception while processing JMX request", e);
	response.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
	} catch (MalformedObjectNameException e) {
	LOG.error("Caught an exception while processing JMX request", e);
	response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
	}
	}

	// --------------------------------------------------------- Private Methods
	private void listBeans(JsonGenerator jg, ObjectName qry) throws IOException {
	LOG.debug("Listing beans for "+qry);
	Set<ObjectName> names = null;
	names = mBeanServer.queryNames(qry, null);

	jg.writeArrayFieldStart("beans");
	Iterator<ObjectName> it = names.iterator();
	while (it.hasNext()) {
	ObjectName oname = it.next();
	MBeanInfo minfo;
	String code;
	try {
	minfo = mBeanServer.getMBeanInfo(oname);
	code = minfo.getClassName();
	try {
	if ("org.apache.commons.modeler.BaseModelMBean".equals(code)) {
	code = (String) mBeanServer.getAttribute(oname, "modelerType");
	}
	} catch (AttributeNotFoundException e) {
	//Ignored the modelerType attribute was not found, so use the class name instead.
	} catch (MBeanException e) {
	//The code inside the attribute getter threw an exception so log it, and
	// fall back on the class name
	LOG.error("getting attribute modelerType of "+oname+" threw an exception", e);
	} catch (RuntimeException e) {
	//For some reason even with an MBeanException available to them Runtime exceptions
	//can still find their way through, so treat them the same as MBeanException
	LOG.error("getting attribute modelerType of "+oname+" threw an exception", e);
	} catch (ReflectionException e) {
	//This happens when the code inside the JMX bean (setter?? from the java docs)
	//threw an exception, so log it and fall back on the class name
	LOG.error("getting attribute modelerType of "+oname+" threw an exception", e);
	}
	} catch (InstanceNotFoundException e) {
	//Ignored for some reason the bean was not found so don't output it
	continue;
	} catch (IntrospectionException e) {
	//This is an internal error, something odd happened with reflection so log it and
	//don't output the bean.
	LOG.error("Problem while trying to process JMX query: "+qry+" with MBean "+oname, e);
	continue;
	} catch (ReflectionException e) {
	//This happens when the code inside the JMX bean threw an exception, so log it and
	//don't output the bean.
	LOG.error("Problem while trying to process JMX query: "+qry+" with MBean "+oname, e);
	continue;
	}

	jg.writeStartObject();
	jg.writeStringField("name", oname.toString());
	// can't be null - I think

	jg.writeStringField("modelerType", code);

	MBeanAttributeInfo attrs[] = minfo.getAttributes();
	for (int i = 0; i < attrs.length; i++) {
	writeAttribute(jg, oname, attrs[i]);
	}
	// LOG.error("Caught Error writing value ",t);
	// ExceptionUtils.handleThrowable(t);
	//}
	jg.writeEndObject();
	}
	jg.writeEndArray();
	}

	private void writeAttribute(JsonGenerator jg, ObjectName oname, MBeanAttributeInfo attr) throws IOException {
	if (!attr.isReadable()) {
	return;
	}
	String attName = attr.getName();
	if ("modelerType".equals(attName)) {
	return;
	}
	if (attName.indexOf("=") >= 0 \|\| attName.indexOf(":") >= 0
	\|\| attName.indexOf(" ") >= 0) {
	return;
	}
	Object value = null;
	try {
	value = mBeanServer.getAttribute(oname, attName);
	} catch (RuntimeMBeanException e) {
	// UnsupportedOperationExceptions happen in the normal course of business,
	// so no need to log them as errors all the time.
	if (e.getCause() instanceof UnsupportedOperationException) {
	LOG.debug("getting attribute "+attName+" of "+oname+" threw an exception", e);
	} else {
	LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);
	}
	return;
	} catch (AttributeNotFoundException e) {
	//Ignored the attribute was not found, which should never happen because the bean
	//just told us that it has this attribute, but if this happens just don't output
	//the attribute.
	return;
	} catch (MBeanException e) {
	//The code inside the attribute getter threw an exception so log it, and
	// skip outputting the attribute
	LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);
	return;
	} catch (RuntimeException e) {
	//For some reason even with an MBeanException available to them Runtime exceptions
	//can still find their way through, so treat them the same as MBeanException
	LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);
	return;
	} catch (ReflectionException e) {
	//This happens when the code inside the JMX bean (setter?? from the java docs)
	//threw an exception, so log it and skip outputting the attribute
	LOG.error("getting attribute "+attName+" of "+oname+" threw an exception", e);
	return;
	} catch (InstanceNotFoundException e) {
	//Ignored the mbean itself was not found, which should never happen because we
	//just accessed it (perhaps something unregistered in-between) but if this
	//happens just don't output the attribute.
	return;
	}

	writeAttribute(jg, attName, value);
	}

	private void writeAttribute(JsonGenerator jg, String attName, Object value) throws IOException {
	jg.writeFieldName(attName);
	writeObject(jg, value);
	}

	private void writeObject(JsonGenerator jg, Object value) throws IOException {
	if(value == null) {
	jg.writeNull();
	} else {
	Class<?> c = value.getClass();
	if (c.isArray()) {
	jg.writeStartArray();
	int len = Array.getLength(value);
	for (int j = 0; j < len; j++) {
	Object item = Array.get(value, j);
	writeObject(jg, item);
	}
	jg.writeEndArray();
	} else if(value instanceof Number) {
	Number n = (Number)value;
	jg.writeNumber(n.toString());
	} else if(value instanceof Boolean) {
	Boolean b = (Boolean)value;
	jg.writeBoolean(b);
	} else if(value instanceof CompositeData) {
	CompositeData cds = (CompositeData)value;
	CompositeType comp = cds.getCompositeType();
	Set<String> keys = comp.keySet();
	jg.writeStartObject();
	for(String key: keys) {
	writeAttribute(jg, key, cds.get(key));
	}
	jg.writeEndObject();
	} else if(value instanceof TabularData) {
	TabularData tds = (TabularData)value;
	jg.writeStartArray();
	for(Object entry : tds.values()) {
	writeObject(jg, entry);
	}
	jg.writeEndArray();
	} else {
	jg.writeString(value.toString());
	}
	}
	}
	}