Java tutorial
/* * 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.hbase.util; import java.io.Closeable; import java.io.IOException; import java.io.PrintWriter; import java.io.StringWriter; 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.RuntimeErrorException; import javax.management.RuntimeMBeanException; import javax.management.openmbean.CompositeData; import javax.management.openmbean.CompositeType; import javax.management.openmbean.TabularData; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.codehaus.jackson.JsonFactory; import org.codehaus.jackson.JsonGenerationException; import org.codehaus.jackson.JsonGenerator; /** * Utility for doing JSON and MBeans. */ public class JSONBean { private static final Log LOG = LogFactory.getLog(JSONBean.class); private final JsonFactory jsonFactory; public JSONBean() { this.jsonFactory = new JsonFactory(); } /** * Use dumping out mbeans as JSON. */ public interface Writer extends Closeable { void write(final String key, final String value) throws JsonGenerationException, IOException; int write(final MBeanServer mBeanServer, ObjectName qry, String attribute, final boolean description) throws IOException; void flush() throws IOException; } public Writer open(final PrintWriter writer) throws IOException { final JsonGenerator jg = jsonFactory.createJsonGenerator(writer); jg.disable(JsonGenerator.Feature.AUTO_CLOSE_TARGET); jg.useDefaultPrettyPrinter(); jg.writeStartObject(); return new Writer() { @Override public void flush() throws IOException { jg.flush(); } @Override public void close() throws IOException { jg.close(); } @Override public void write(String key, String value) throws JsonGenerationException, IOException { jg.writeStringField(key, value); } @Override public int write(MBeanServer mBeanServer, ObjectName qry, String attribute, boolean description) throws IOException { return JSONBean.write(jg, mBeanServer, qry, attribute, description); } }; } /** * @param mBeanServer * @param qry * @param attribute * @param description * @return Return non-zero if failed to find bean. 0 * @throws IOException */ private static int write(final JsonGenerator jg, final MBeanServer mBeanServer, ObjectName qry, String attribute, final boolean description) throws IOException { LOG.trace("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 = ""; String descriptionStr = null; Object attributeinfo = null; try { minfo = mBeanServer.getMBeanInfo(oname); code = minfo.getClassName(); if (description) descriptionStr = minfo.getDescription(); String prs = ""; try { if ("org.apache.commons.modeler.BaseModelMBean".equals(code)) { prs = "modelerType"; code = (String) mBeanServer.getAttribute(oname, prs); } if (attribute != null) { prs = attribute; attributeinfo = mBeanServer.getAttribute(oname, prs); } } 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) { if (LOG.isTraceEnabled()) { LOG.trace("Getting attribute " + prs + " of " + oname + " threw " + e); } } else { LOG.error("Getting attribute " + prs + " of " + oname + " threw an exception", e); } return 0; } catch (AttributeNotFoundException e) { // If the modelerType attribute was not found, the class name is used // instead. LOG.error("getting attribute " + prs + " of " + oname + " threw an exception", e); } 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 " + prs + " of " + oname + " threw an exception", e); } catch (RuntimeException e) { // For some reason even with an MBeanException available to them // Runtime exceptionscan still find their way through, so treat them // the same as MBeanException LOG.error("getting attribute " + prs + " 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 " + prs + " 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()); if (description && descriptionStr != null && descriptionStr.length() > 0) { jg.writeStringField("description", descriptionStr); } jg.writeStringField("modelerType", code); if (attribute != null && attributeinfo == null) { jg.writeStringField("result", "ERROR"); jg.writeStringField("message", "No attribute with name " + attribute + " was found."); jg.writeEndObject(); jg.writeEndArray(); jg.close(); return -1; } if (attribute != null) { writeAttribute(jg, attribute, descriptionStr, attributeinfo); } else { MBeanAttributeInfo[] attrs = minfo.getAttributes(); for (int i = 0; i < attrs.length; i++) { writeAttribute(jg, mBeanServer, oname, description, attrs[i]); } } jg.writeEndObject(); } jg.writeEndArray(); return 0; } private static void writeAttribute(final JsonGenerator jg, final MBeanServer mBeanServer, ObjectName oname, final boolean description, final 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; } String descriptionStr = description ? attr.getDescription() : null; 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) { if (LOG.isTraceEnabled()) { LOG.trace("Getting attribute " + attName + " of " + oname + " threw " + e); } } else { LOG.error("getting attribute " + attName + " of " + oname + " threw an exception", e); } return; } catch (RuntimeErrorException e) { // RuntimeErrorException happens when an unexpected failure occurs in getAttribute // for example https://issues.apache.org/jira/browse/DAEMON-120 LOG.debug("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, descriptionStr, value); } private static void writeAttribute(JsonGenerator jg, String attName, final String descriptionStr, Object value) throws IOException { boolean description = false; if (descriptionStr != null && descriptionStr.length() > 0 && !attName.equals(descriptionStr)) { description = true; jg.writeFieldName(attName); jg.writeStartObject(); jg.writeFieldName("description"); jg.writeString(descriptionStr); jg.writeFieldName("value"); writeObject(jg, description, value); jg.writeEndObject(); } else { jg.writeFieldName(attName); writeObject(jg, description, value); } } private static void writeObject(final JsonGenerator jg, final boolean description, 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, description, 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, null, cds.get(key)); } jg.writeEndObject(); } else if (value instanceof TabularData) { TabularData tds = (TabularData) value; jg.writeStartArray(); for (Object entry : tds.values()) { writeObject(jg, description, entry); } jg.writeEndArray(); } else { jg.writeString(value.toString()); } } } /** * Dump out a subset of regionserver mbeans only, not all of them, as json on System.out. * @throws MalformedObjectNameException * @throws IOException */ public static String dumpRegionServerMetrics() throws MalformedObjectNameException, IOException { StringWriter sw = new StringWriter(1024 * 100); // Guess this size try (PrintWriter writer = new PrintWriter(sw)) { JSONBean dumper = new JSONBean(); try (JSONBean.Writer jsonBeanWriter = dumper.open(writer)) { MBeanServer mbeanServer = ManagementFactory.getPlatformMBeanServer(); jsonBeanWriter.write(mbeanServer, new ObjectName("java.lang:type=Memory"), null, false); jsonBeanWriter.write(mbeanServer, new ObjectName("Hadoop:service=HBase,name=RegionServer,sub=IPC"), null, false); jsonBeanWriter.write(mbeanServer, new ObjectName("Hadoop:service=HBase,name=RegionServer,sub=Replication"), null, false); jsonBeanWriter.write(mbeanServer, new ObjectName("Hadoop:service=HBase,name=RegionServer,sub=Server"), null, false); } } sw.close(); return sw.toString(); } /** * Dump out all registered mbeans as json on System.out. * @throws IOException * @throws MalformedObjectNameException */ public static void dumpAllBeans() throws IOException, MalformedObjectNameException { try (PrintWriter writer = new PrintWriter(System.out)) { JSONBean dumper = new JSONBean(); try (JSONBean.Writer jsonBeanWriter = dumper.open(writer)) { MBeanServer mbeanServer = ManagementFactory.getPlatformMBeanServer(); jsonBeanWriter.write(mbeanServer, new ObjectName("*:*"), null, false); } } } public static void main(String[] args) throws IOException, MalformedObjectNameException { String str = dumpRegionServerMetrics(); System.out.println(str); } }