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.cassandra.locator; import java.io.InputStream; import java.net.InetAddress; import java.net.UnknownHostException; import java.util.Arrays; import java.util.HashMap; import java.util.Map; import java.util.Properties; import java.util.Set; import com.google.common.collect.Sets; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.apache.cassandra.exceptions.ConfigurationException; import org.apache.cassandra.service.StorageService; import org.apache.cassandra.utils.FBUtilities; import org.apache.cassandra.utils.ResourceWatcher; import org.apache.cassandra.utils.WrappedRunnable; import org.apache.commons.lang3.StringUtils; /** * <p> * Used to determine if two IP's are in the same datacenter or on the same rack. * </p> * Based on a properties file in the following format: * * 10.0.0.13=DC1:RAC2 * 10.21.119.14=DC3:RAC2 * 10.20.114.15=DC2:RAC2 * default=DC1:r1 */ public class PropertyFileSnitch extends AbstractNetworkTopologySnitch { private static final Logger logger = LoggerFactory.getLogger(PropertyFileSnitch.class); public static final String SNITCH_PROPERTIES_FILENAME = "cassandra-topology.properties"; private static final int DEFAULT_REFRESH_PERIOD_IN_SECONDS = 5; private static volatile Map<InetAddress, String[]> endpointMap; private static volatile String[] defaultDCRack; private volatile boolean gossipStarted; public PropertyFileSnitch() throws ConfigurationException { this(DEFAULT_REFRESH_PERIOD_IN_SECONDS); } public PropertyFileSnitch(int refreshPeriodInSeconds) throws ConfigurationException { reloadConfiguration(false); try { FBUtilities.resourceToFile(SNITCH_PROPERTIES_FILENAME); Runnable runnable = new WrappedRunnable() { protected void runMayThrow() throws ConfigurationException { reloadConfiguration(true); } }; ResourceWatcher.watch(SNITCH_PROPERTIES_FILENAME, runnable, refreshPeriodInSeconds * 1000); } catch (ConfigurationException ex) { logger.error("{} found, but does not look like a plain file. Will not watch it for changes", SNITCH_PROPERTIES_FILENAME); } } /** * Get the raw information about an end point * * @param endpoint endpoint to process * @return a array of string with the first index being the data center and the second being the rack */ public static String[] getEndpointInfo(InetAddress endpoint) { String[] rawEndpointInfo = getRawEndpointInfo(endpoint); if (rawEndpointInfo == null) throw new RuntimeException("Unknown host " + endpoint + " with no default configured"); return rawEndpointInfo; } private static String[] getRawEndpointInfo(InetAddress endpoint) { String[] value = endpointMap.get(endpoint); if (value == null) { logger.trace("Could not find end point information for {}, will use default", endpoint); return defaultDCRack; } return value; } /** * Return the data center for which an endpoint resides in * * @param endpoint the endpoint to process * @return string of data center */ public String getDatacenter(InetAddress endpoint) { String[] info = getEndpointInfo(endpoint); assert info != null : "No location defined for endpoint " + endpoint; return info[0]; } /** * Return the rack for which an endpoint resides in * * @param endpoint the endpoint to process * @return string of rack */ public String getRack(InetAddress endpoint) { String[] info = getEndpointInfo(endpoint); assert info != null : "No location defined for endpoint " + endpoint; return info[1]; } public void reloadConfiguration(boolean isUpdate) throws ConfigurationException { HashMap<InetAddress, String[]> reloadedMap = new HashMap<>(); String[] reloadedDefaultDCRack = null; Properties properties = new Properties(); try (InputStream stream = getClass().getClassLoader().getResourceAsStream(SNITCH_PROPERTIES_FILENAME)) { properties.load(stream); } catch (Exception e) { throw new ConfigurationException("Unable to read " + SNITCH_PROPERTIES_FILENAME, e); } for (Map.Entry<Object, Object> entry : properties.entrySet()) { String key = (String) entry.getKey(); String value = (String) entry.getValue(); if ("default".equals(key)) { String[] newDefault = value.split(":"); if (newDefault.length < 2) reloadedDefaultDCRack = new String[] { "default", "default" }; else reloadedDefaultDCRack = new String[] { newDefault[0].trim(), newDefault[1].trim() }; } else { InetAddress host; String hostString = StringUtils.remove(key, '/'); try { host = InetAddress.getByName(hostString); } catch (UnknownHostException e) { throw new ConfigurationException("Unknown host " + hostString, e); } String[] token = value.split(":"); if (token.length < 2) token = new String[] { "default", "default" }; else token = new String[] { token[0].trim(), token[1].trim() }; reloadedMap.put(host, token); } } if (reloadedDefaultDCRack == null && !reloadedMap.containsKey(FBUtilities.getBroadcastAddress())) throw new ConfigurationException(String.format( "Snitch definitions at %s do not define a location for " + "this node's broadcast address %s, nor does it provides a default", SNITCH_PROPERTIES_FILENAME, FBUtilities.getBroadcastAddress())); if (isUpdate && !livenessCheck(reloadedMap, reloadedDefaultDCRack)) return; if (logger.isTraceEnabled()) { StringBuilder sb = new StringBuilder(); for (Map.Entry<InetAddress, String[]> entry : reloadedMap.entrySet()) sb.append(entry.getKey()).append(':').append(Arrays.toString(entry.getValue())).append(", "); logger.trace("Loaded network topology from property file: {}", StringUtils.removeEnd(sb.toString(), ", ")); } defaultDCRack = reloadedDefaultDCRack; endpointMap = reloadedMap; if (StorageService.instance != null) // null check tolerates circular dependency; see CASSANDRA-4145 { if (isUpdate) StorageService.instance.updateTopology(); else StorageService.instance.getTokenMetadata().invalidateCachedRings(); } if (gossipStarted) StorageService.instance.gossipSnitchInfo(); } /** * We cannot update rack or data-center for a live node, see CASSANDRA-10243. * * @param reloadedMap - the new map of hosts to dc:rack properties * @param reloadedDefaultDCRack - the default dc:rack or null if no default * @return true if we can continue updating (no live host had dc or rack updated) */ private static boolean livenessCheck(HashMap<InetAddress, String[]> reloadedMap, String[] reloadedDefaultDCRack) { // If the default has changed we must check all live hosts but hopefully we will find a live // host quickly and interrupt the loop. Otherwise we only check the live hosts that were either // in the old set or in the new set Set<InetAddress> hosts = Arrays.equals(defaultDCRack, reloadedDefaultDCRack) ? Sets.intersection(StorageService.instance.getLiveRingMembers(), // same default Sets.union(endpointMap.keySet(), reloadedMap.keySet())) : StorageService.instance.getLiveRingMembers(); // default updated for (InetAddress host : hosts) { String[] origValue = endpointMap.containsKey(host) ? endpointMap.get(host) : defaultDCRack; String[] updateValue = reloadedMap.containsKey(host) ? reloadedMap.get(host) : reloadedDefaultDCRack; if (!Arrays.equals(origValue, updateValue)) { logger.error( "Cannot update data center or rack from {} to {} for live host {}, property file NOT RELOADED", origValue, updateValue, host); return false; } } return true; } @Override public void gossiperStarting() { gossipStarted = true; } }