Java tutorial
/** * Licensed to DigitalPebble Ltd under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * DigitalPebble 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 com.digitalpebble.storm.crawler.metrics; import java.io.IOException; import java.util.Collection; import java.util.Date; import java.util.Map; import java.util.SortedMap; import java.util.concurrent.ConcurrentHashMap; import java.util.concurrent.ConcurrentMap; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.storm.guava.base.Joiner; import org.apache.storm.guava.collect.ImmutableMap; import org.apache.storm.guava.collect.ImmutableSortedMap; import org.mortbay.jetty.Server; import org.mortbay.jetty.servlet.Context; import org.mortbay.jetty.servlet.ServletHolder; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import backtype.storm.metric.api.IMetricsConsumer; import backtype.storm.task.IErrorReporter; import backtype.storm.task.TopologyContext; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.ObjectWriter; /** * Displays metrics at JSON format in a servlet running on * http://localhost:7070/metrics * * @author Enno Shioji (enno.shioji@peerindex.com) */ public class DebugMetricsConsumer implements IMetricsConsumer { private static final Logger log = LoggerFactory.getLogger(DebugMetricsConsumer.class); private IErrorReporter errorReporter; private Server server; // Make visible to servlet threads private volatile ConcurrentMap<String, Number> metrics; private volatile ConcurrentMap<String, Map<String, Object>> metrics_metadata; @Override public void prepare(Map stormConf, Object registrationArgument, TopologyContext context, IErrorReporter errorReporter) { this.errorReporter = errorReporter; this.metrics = new ConcurrentHashMap<String, Number>(); this.metrics_metadata = new ConcurrentHashMap<String, Map<String, Object>>(); try { // TODO Config file not tested final String PORT_CONFIG_STRING = "topology.metrics.consumers.debug.servlet.port"; Integer port = (Integer) stormConf.get(PORT_CONFIG_STRING); if (port == null) { log.warn("Metrics debug servlet's port not specified, defaulting to 7070. You can specify it via " + PORT_CONFIG_STRING + " in storm.yaml"); port = 7070; } server = startServlet(port); } catch (Exception e) { log.error("Failed to start metrics server", e); throw new AssertionError(e); } } private static final Joiner ON_COLONS = Joiner.on("::"); @Override public void handleDataPoints(TaskInfo taskInfo, Collection<DataPoint> dataPoints) { // In order String componentId = taskInfo.srcComponentId; Integer taskId = taskInfo.srcTaskId; Integer updateInterval = taskInfo.updateIntervalSecs; Long timestamp = taskInfo.timestamp; for (DataPoint point : dataPoints) { String metric_name = point.name; try { Map<String, Number> metric = (Map<String, Number>) point.value; for (Map.Entry<String, Number> entry : metric.entrySet()) { String metricId = ON_COLONS.join(componentId, taskId, metric_name, entry.getKey()); Number val = entry.getValue(); metrics.put(metricId, val); metrics_metadata.put(metricId, ImmutableMap.<String, Object>of("updateInterval", updateInterval, "lastreported", timestamp)); } } catch (RuntimeException e) { // One can easily send something else than a Map<String,Number> // down the __metrics stream and make this part break. // If you ask me either the message should carry type // information or there should be different stream per message // type // This is one of the reasons why I want to write a further // abstraction on this facility errorReporter.reportError(e); metrics_metadata.putIfAbsent("ERROR_METRIC_CONSUMER_" + e.getClass().getSimpleName(), ImmutableMap.of("offending_message_sample", point.value)); } } } private static final ObjectMapper OM = new ObjectMapper(); private Server startServlet(int serverPort) throws Exception { // Setup HTTP server Server server = new Server(serverPort); Context root = new Context(server, "/"); server.start(); HttpServlet servlet = new HttpServlet() { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { SortedMap<String, Number> metrics = ImmutableSortedMap.copyOf(DebugMetricsConsumer.this.metrics); SortedMap<String, Map<String, Object>> metrics_metadata = ImmutableSortedMap .copyOf(DebugMetricsConsumer.this.metrics_metadata); Map<String, Object> toplevel = ImmutableMap.of("retrieved", new Date(), // TODO this call fails with mysterious // exception // "java.lang.IllegalArgumentException: Could not find component common for __metrics" // Mailing list suggests it's a library version // issue but couldn't find anything suspicious // Need to eventually investigate // "sources", // context.getThisSources().toString(), "metrics", metrics, "metric_metadata", metrics_metadata); ObjectWriter prettyPrinter = OM.writerWithDefaultPrettyPrinter(); prettyPrinter.writeValue(resp.getWriter(), toplevel); } }; root.addServlet(new ServletHolder(servlet), "/metrics"); log.info("Started metric server..."); return server; } @Override public void cleanup() { try { server.stop(); } catch (Exception e) { throw new AssertionError(e); } } }