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.hdfs.qjournal.server; import java.io.IOException; import java.net.InetSocketAddress; import java.net.URI; import java.util.ArrayList; import java.util.Collection; import java.util.HashMap; import java.util.HashSet; import java.util.List; import java.util.Map; import java.util.Map.Entry; import java.util.Set; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.hdfs.DFSUtil; import org.codehaus.jackson.map.ObjectMapper; import org.codehaus.jackson.type.TypeReference; /** * Class used for connecting to journal nodes and obtaining * statistics about the underlying journals. */ public class JournalNodeJspHelper { private static final Log LOG = LogFactory.getLog(JournalNodeJspHelper.class); public static final ObjectMapper mapper = new ObjectMapper(); private static final int HTTP_CONNECT_TIMEOUT = 2000; // 2 secs private static final int HTTP_READ_TIMEOUT = 5000; // 5 secs private final Configuration conf; private final String name; public JournalNodeJspHelper(JournalNode jn) { conf = jn.getConf(); StringBuilder tempName = new StringBuilder(""); for (InetSocketAddress addr : getJournals()) { tempName = tempName.append(getHostAddress(addr)).append(","); } if (tempName.length() > 0) { // Removing last , tempName.deleteCharAt(tempName.length() - 1); } name = tempName.toString(); } public String getName() { return name; } public QJMStatus generateQJMStatusReport() throws IOException { QJMStatus status = new QJMStatus(getJournals()); Map<InetSocketAddress, Map<String, Map<String, String>>> temp = new HashMap<InetSocketAddress, Map<String, Map<String, String>>>(); Map<InetSocketAddress, Boolean> aliveMap = new HashMap<InetSocketAddress, Boolean>(); Set<String> allJournals = new HashSet<String>(); for (InetSocketAddress jn : status.journalNodes) { LOG.info("Connecting to journal node: " + jn); // mapping from a single journal to key,value stats String json = fetchStats(jn); aliveMap.put(jn, json != null); Map<String, Map<String, String>> map = getStatsMap(json); // update the list of all available journals allJournals.addAll(map.keySet()); // store the retrieved results temp.put(jn, map); } for (InetSocketAddress jn : temp.keySet()) { // if we haven't fetch anything, we need to handle this Map<String, Map<String, String>> stats = temp.get(jn); for (String journal : allJournals) { // for each journal // we create (node, stats) mapping status.addJournalStats(journal, jn, stats.get(journal), aliveMap.get(jn)); } } return status; } public static class QJMStatus { // all journal nodes private final Collection<InetSocketAddress> journalNodes; // all stats exposed by journals private final Set<String> statNames; // all journal nodes private final Map<String, Boolean> aliveStatus; // (journalid) -> (list(node -> (k,v))) mapping final Map<String, List<StatsDescriptor>> stats; public QJMStatus(Collection<InetSocketAddress> jns) { statNames = new HashSet<String>(); aliveStatus = new HashMap<String, Boolean>(); journalNodes = jns; stats = new HashMap<String, List<StatsDescriptor>>(); } void addJournalStats(String journal, InetSocketAddress jn, Map<String, String> stat, boolean alive) { StatsDescriptor sd = new StatsDescriptor(jn, stat); // update the set of available stats statNames.addAll(sd.statsPerJournal.keySet()); // and the names of journalnodes aliveStatus.put(sd.journalNode, alive); // we add the mapping to the list of mappings for each journal List<StatsDescriptor> currentList = stats.get(journal); if (currentList == null) { currentList = new ArrayList<StatsDescriptor>(); stats.put(journal, currentList); } currentList.add(sd); } public Map<String, List<StatsDescriptor>> getStatus() { return stats; } public Collection<String> getJournalIds() { return stats.keySet(); } public Map<String, Boolean> getAliveMap() { return aliveStatus; } } public static class StatsDescriptor { String journalNode; Map<String, String> statsPerJournal; public StatsDescriptor(InetSocketAddress jn, Map<String, String> statsPerJournal) { this.journalNode = getHostAddress(jn) + " : " + jn.getPort(); this.statsPerJournal = statsPerJournal == null ? new HashMap<String, String>() : statsPerJournal; } public String toString() { return journalNode + ":" + statsPerJournal.toString(); } } /** * Retrieve value from the map corresponding to the given key. */ private static String getValue(Map<String, String> map, String keyName) { String value = map.get(keyName); return value == null ? "-" : value; } /** * Fetch stats from a single given journal node over http. */ private String fetchStats(InetSocketAddress jn) throws IOException { try { return DFSUtil.getHTMLContentWithTimeout(new URI("http", null, jn.getAddress().getHostAddress(), jn.getPort(), "/journalStats", null, null).toURL(), HTTP_CONNECT_TIMEOUT, HTTP_READ_TIMEOUT); } catch (Exception e) { LOG.error("Problem connecting to " + getHostAddress(jn), e); return null; } } /** * Get the map corresponding to the JSON string */ private static Map<String, Map<String, String>> getStatsMap(String json) throws IOException { if (json == null || json.isEmpty()) { return new HashMap<String, Map<String, String>>(); } TypeReference<Map<String, Map<String, String>>> type = new TypeReference<Map<String, Map<String, String>>>() { }; return mapper.readValue(json, type); } /** * Get the list of journal addresses to connect. */ private Collection<InetSocketAddress> getJournals() { return JournalNode.getJournalHttpAddresses(conf); } /** * Generate health report for journal nodes */ public static String getNodeReport(QJMStatus status) { StringBuilder sb = new StringBuilder(); sb.append("<table border=1 cellpadding=1 cellspacing=0 title=\"Journals\">"); sb.append("<thead><tr><td><b>Journal node</b></td><td><b>Alive</b></td></tr></thead>"); for (Entry<String, Boolean> e : status.getAliveMap().entrySet()) { if (e.getValue()) { sb.append("<tr><td>" + e.getKey() + "</td><td><font color=green>Active</font></td></tr>"); } else { sb.append("<tr><td>" + e.getKey() + "</td><td><font color=red>Failed</font></td></tr>"); } } sb.append("</table>"); return sb.toString(); } /** * Generate report for all journals and all journal nodes */ public static String getJournalReport(QJMStatus status) { StringBuilder sb = new StringBuilder(); sb.append("<table border=1 cellpadding=1 cellspacing=0 title=\"Journals\">"); sb.append("<thead><tr><td><b>JournalId</b></td><td><b>Statistics</b></td></tr></thead>"); for (String journalId : status.getJournalIds()) { sb.append("<tr><td>" + journalId + "</td><td>"); getHTMLTableForASingleJournal(status, journalId, sb); sb.append("</td></tr>"); } sb.append("</table>"); return sb.toString(); } /** * Render html table for a single journal. */ public static void getHTMLTableForASingleJournal(QJMStatus status, String journalName, StringBuilder sb) { List<StatsDescriptor> stats = status.stats.get(journalName); if (stats == null) { return; } Set<String> statsNames = status.statNames; // header sb.append("<table border=1 align=\"right\" cellpadding=1 " + "cellspacing=0 title=\"Journal statistics\">"); sb.append("<thead><tr><td></td>"); for (StatsDescriptor sd : stats) { sb.append("<td><b>" + sd.journalNode + "</b></td>"); } sb.append("</tr></thead>"); // contents for (String st : statsNames) { // for each available stat sb.append("<tr><td>" + st + "</td>"); // for each available node for (StatsDescriptor sd : stats) { sb.append("<td align=\"right\">" + getValue(sd.statsPerJournal, st) + "</td>"); } sb.append("</tr>"); } sb.append("</table>"); } /** * Returns the address of the host minimizing DNS lookups. * @param addr * @return */ private static String getHostAddress(InetSocketAddress addr) { String hostToAppend = ""; if (addr.isUnresolved()) { hostToAppend = addr.getHostName(); } else { hostToAppend = addr.getAddress().getHostAddress(); } return hostToAppend; } }