MetricsUtil.java
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上传日期:2018-01-08
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- /**
- * 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;
- /**
- * 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
- */
- 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;
- }
- }