| /** |
| * 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.metrics; |
| |
| import java.net.InetAddress; |
| import java.net.UnknownHostException; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| |
| /** |
| * Utility class to simplify creation and reporting of hadoop metrics. |
| * |
| * For examples of usage, see NameNodeMetrics. |
| * @see org.apache.hadoop.metrics.MetricsRecord |
| * @see org.apache.hadoop.metrics.MetricsContext |
| * @see org.apache.hadoop.metrics.ContextFactory |
| */ |
| @InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"}) |
| @InterfaceStability.Evolving |
| public class MetricsUtil { |
| |
| public static final Log LOG = |
| LogFactory.getLog(MetricsUtil.class); |
| |
| /** |
| * Don't allow creation of a new instance of Metrics |
| */ |
| private MetricsUtil() {} |
| |
| public static MetricsContext getContext(String contextName) { |
| return getContext(contextName, contextName); |
| } |
| |
| /** |
| * Utility method to return the named context. |
| * If the desired context cannot be created for any reason, the exception |
| * is logged, and a null context is returned. |
| */ |
| public static MetricsContext getContext(String refName, String contextName) { |
| MetricsContext metricsContext; |
| try { |
| metricsContext = |
| ContextFactory.getFactory().getContext(refName, contextName); |
| if (!metricsContext.isMonitoring()) { |
| metricsContext.startMonitoring(); |
| } |
| } catch (Exception ex) { |
| LOG.error("Unable to create metrics context " + contextName, ex); |
| metricsContext = ContextFactory.getNullContext(contextName); |
| } |
| return metricsContext; |
| } |
| |
| /** |
| * Utility method to create and return new metrics record instance within the |
| * given context. This record is tagged with the host name. |
| * |
| * @param context the context |
| * @param recordName name of the record |
| * @return newly created metrics record |
| */ |
| public static MetricsRecord createRecord(MetricsContext context, |
| String recordName) |
| { |
| MetricsRecord metricsRecord = context.createRecord(recordName); |
| metricsRecord.setTag("hostName", getHostName()); |
| return metricsRecord; |
| } |
| |
| /** |
| * Returns the host name. If the host name is unobtainable, logs the |
| * exception and returns "unknown". |
| */ |
| private static String getHostName() { |
| String hostName = null; |
| try { |
| hostName = InetAddress.getLocalHost().getHostName(); |
| } catch (UnknownHostException ex) { |
| LOG.info("Unable to obtain hostName", ex); |
| hostName = "unknown"; |
| } |
| return hostName; |
| } |
| |
| } |