/* * 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.net.UnknownHostException; import java.util.ArrayList; import java.util.Collections; import java.util.Iterator; import java.util.List; import org.apache.cassandra.config.DatabaseDescriptor; import org.apache.cassandra.dht.Token; import java.net.InetAddress; import org.apache.cassandra.service.StorageService; /* * This class returns the nodes responsible for a given * key but does respects rack awareness. It makes a best * effort to get a node from a different data center and * a node in a different rack in the same datacenter as * the primary. */ public class RackAwareStrategy extends AbstractReplicationStrategy { public RackAwareStrategy(TokenMetadata tokenMetadata, IEndPointSnitch snitch) { super(tokenMetadata, snitch); if (!(snitch instanceof EndPointSnitch)) throw new IllegalArgumentException(("RackAwareStrategy requires EndPointSnitch.")); } public ArrayList<InetAddress> getNaturalEndpoints(Token token, TokenMetadata metadata, String table) { int replicas = DatabaseDescriptor.getReplicationFactor(table); ArrayList<InetAddress> endpoints = new ArrayList<InetAddress>(replicas); List<Token> tokens = metadata.sortedTokens(); if (tokens.isEmpty()) return endpoints; Iterator<Token> iter = TokenMetadata.ringIterator(tokens, token); Token primaryToken = iter.next(); endpoints.add(metadata.getEndPoint(primaryToken)); boolean bDataCenter = false; boolean bOtherRack = false; while (endpoints.size() < replicas && iter.hasNext()) { try { // First try to find one in a different data center Token t = iter.next(); if (!((EndPointSnitch)snitch_).isInSameDataCenter(metadata.getEndPoint(primaryToken), metadata.getEndPoint(t))) { // If we have already found something in a diff datacenter no need to find another if (!bDataCenter) { endpoints.add(metadata.getEndPoint(t)); bDataCenter = true; } continue; } // Now try to find one on a different rack if (!((EndPointSnitch)snitch_).isOnSameRack(metadata.getEndPoint(primaryToken), metadata.getEndPoint(t)) && ((EndPointSnitch)snitch_).isInSameDataCenter(metadata.getEndPoint(primaryToken), metadata.getEndPoint(t))) { // If we have already found something in a diff rack no need to find another if (!bOtherRack) { endpoints.add(metadata.getEndPoint(t)); bOtherRack = true; } } } catch (UnknownHostException e) { throw new RuntimeException(e); } } // If we found N number of nodes we are good. This loop wil just exit. Otherwise just // loop through the list and add until we have N nodes. if (endpoints.size() < replicas) { iter = TokenMetadata.ringIterator(tokens, token); while (endpoints.size() < replicas && iter.hasNext()) { Token t = iter.next(); if (!endpoints.contains(metadata.getEndPoint(t))) endpoints.add(metadata.getEndPoint(t)); } } return endpoints; } }