package org.apache.cassandra.locator; /* * * 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. * */ import java.net.InetAddress; import java.net.UnknownHostException; import java.util.*; /** * An endpoint snitch tells Cassandra information about network topology that it can use to route * requests more efficiently (with "sortByProximity"). Of the abstract methods, isOnSameRack * and isInSameDataCenter are always required; getLocation is only used by DatacenterShardStrategy. */ public abstract class AbstractEndpointSnitch implements IEndPointSnitch { /** * Determines if 2 nodes are in the same rack in the data center. * @param host a specified endpoint * @param host2 another specified endpoint * @return true if on the same rack false otherwise * @throws UnknownHostException */ abstract public boolean isOnSameRack(InetAddress host, InetAddress host2) throws UnknownHostException; /** * Determines if 2 nodes are in the same data center. * @param host a specified endpoint * @param host2 another specified endpoint * @return true if in the same data center false otherwise * @throws UnknownHostException */ abstract public boolean isInSameDataCenter(InetAddress host, InetAddress host2) throws UnknownHostException; /** * Determines the name of the datacenter this endpoint lives in. * @param endpoint * @return the name of the datacenter the endpoint lives in */ abstract public String getLocation(InetAddress endpoint) throws UnknownHostException; public List<InetAddress> getSortedListByProximity(final InetAddress address, Collection<InetAddress> unsortedAddress) { List<InetAddress> preferred = new ArrayList<InetAddress>(unsortedAddress); sortByProximity(address, preferred); return preferred; } public List<InetAddress> sortByProximity(final InetAddress address, List<InetAddress> addresses) { Collections.sort(addresses, new Comparator<InetAddress>() { public int compare(InetAddress a1, InetAddress a2) { return compareEndpoints(address, a1, a2); } }); return addresses; } public int compareEndpoints(InetAddress target, InetAddress a1, InetAddress a2) { try { if (target.equals(a1) && !target.equals(a2)) return -1; if (target.equals(a2) && !target.equals(a1)) return 1; if (isOnSameRack(target, a1) && !isOnSameRack(target, a2)) return -1; if (isOnSameRack(target, a2) && !isOnSameRack(target, a1)) return 1; if (isInSameDataCenter(target, a1) && !isInSameDataCenter(target, a2)) return -1; if (isInSameDataCenter(target, a2) && !isInSameDataCenter(target, a1)) return 1; return 0; } catch (UnknownHostException e) { throw new RuntimeException(e); } } }