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.metrics2.sink; import java.io.Closeable; import java.io.IOException; import java.net.DatagramPacket; import java.net.DatagramSocket; import java.net.InetSocketAddress; import java.nio.charset.StandardCharsets; import org.apache.commons.configuration.SubsetConfiguration; import org.apache.hadoop.classification.InterfaceAudience; import org.apache.hadoop.classification.InterfaceStability; import org.apache.hadoop.metrics2.AbstractMetric; import org.apache.hadoop.metrics2.MetricType; import org.apache.hadoop.metrics2.MetricsException; import org.apache.hadoop.metrics2.MetricsRecord; import org.apache.hadoop.metrics2.MetricsSink; import org.apache.hadoop.metrics2.MetricsTag; import org.apache.hadoop.metrics2.impl.MsInfo; import org.apache.hadoop.net.NetUtils; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * A metrics sink that writes metrics to a StatsD daemon. * This sink will produce metrics of the form * '[hostname].servicename.context.name.metricname:value|type' * where hostname is optional. This is useful when sending to * a daemon that is running on the localhost and will add the * hostname to the metric (such as the * <a href="https://collectd.org/">CollectD</a> StatsD plugin). * <br/> * To configure this plugin, you will need to add the following * entries to your hadoop-metrics2.properties file: * <br/> * <pre> * *.sink.statsd.class=org.apache.hadoop.metrics2.sink.StatsDSink * [prefix].sink.statsd.server.host= * [prefix].sink.statsd.server.port= * [prefix].sink.statsd.skip.hostname=true|false (optional) * [prefix].sink.statsd.service.name=NameNode (name you want for service) * </pre> */ @InterfaceAudience.Public @InterfaceStability.Evolving public class StatsDSink implements MetricsSink, Closeable { private static final Logger LOG = LoggerFactory.getLogger(StatsDSink.class); private static final String PERIOD = "."; private static final String SERVER_HOST_KEY = "server.host"; private static final String SERVER_PORT_KEY = "server.port"; private static final String HOST_NAME_KEY = "host.name"; private static final String SERVICE_NAME_KEY = "service.name"; private static final String SKIP_HOSTNAME_KEY = "skip.hostname"; private boolean skipHostname = false; private String hostName = null; private String serviceName = null; private StatsD statsd = null; @Override public void init(SubsetConfiguration conf) { // Get StatsD host configurations. final String serverHost = conf.getString(SERVER_HOST_KEY); final int serverPort = Integer.parseInt(conf.getString(SERVER_PORT_KEY)); skipHostname = conf.getBoolean(SKIP_HOSTNAME_KEY, false); if (!skipHostname) { hostName = conf.getString(HOST_NAME_KEY, null); if (null == hostName) { hostName = NetUtils.getHostname(); } } serviceName = conf.getString(SERVICE_NAME_KEY, null); statsd = new StatsD(serverHost, serverPort); } @Override public void putMetrics(MetricsRecord record) { String hn = hostName; String ctx = record.context(); String sn = serviceName; for (MetricsTag tag : record.tags()) { if (tag.info().name().equals(MsInfo.Hostname.name()) && tag.value() != null) { hn = tag.value(); } else if (tag.info().name().equals(MsInfo.Context.name()) && tag.value() != null) { ctx = tag.value(); } else if (tag.info().name().equals(MsInfo.ProcessName.name()) && tag.value() != null) { sn = tag.value(); } } StringBuilder buf = new StringBuilder(); if (!skipHostname && hn != null) { int idx = hn.indexOf("."); if (idx == -1) { buf.append(hn).append(PERIOD); } else { buf.append(hn.substring(0, idx)).append(PERIOD); } } buf.append(sn).append(PERIOD); buf.append(ctx).append(PERIOD); buf.append(record.name().replaceAll("\\.", "-")).append(PERIOD); // Collect datapoints. for (AbstractMetric metric : record.metrics()) { String type = null; if (metric.type().equals(MetricType.COUNTER)) { type = "c"; } else if (metric.type().equals(MetricType.GAUGE)) { type = "g"; } StringBuilder line = new StringBuilder(); line.append(buf.toString()).append(metric.name().replace(' ', '_')).append(":").append(metric.value()) .append("|").append(type); writeMetric(line.toString()); } } public void writeMetric(String line) { try { statsd.write(line); } catch (IOException e) { LOG.warn("Error sending metrics to StatsD", e); throw new MetricsException("Error writing metric to StatsD", e); } } @Override public void flush() { } @Override public void close() throws IOException { statsd.close(); } /** * Class that sends UDP packets to StatsD daemon. * */ public static class StatsD { private DatagramSocket socket = null; private DatagramPacket packet = null; private String serverHost; private int serverPort; public StatsD(String serverHost, int serverPort) { this.serverHost = serverHost; this.serverPort = serverPort; } public void createSocket() throws IOException { try { InetSocketAddress address = new InetSocketAddress(this.serverHost, this.serverPort); socket = new DatagramSocket(); packet = new DatagramPacket("".getBytes(StandardCharsets.UTF_8), 0, 0, address.getAddress(), this.serverPort); } catch (IOException ioe) { throw NetUtils.wrapException(this.serverHost, this.serverPort, "localhost", 0, ioe); } } public void write(String msg) throws IOException { if (null == socket) { createSocket(); } LOG.debug("Sending metric: {}", msg); packet.setData(msg.getBytes(StandardCharsets.UTF_8)); socket.send(packet); } public void close() throws IOException { try { if (socket != null) { socket.close(); } } finally { socket = null; } } } }