| /** |
| * 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 |
| * <p> |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * <p> |
| * 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.hdds.scm; |
| |
| import org.apache.hadoop.hdds.protocol.DatanodeDetails; |
| |
| import java.io.IOException; |
| import java.util.List; |
| |
| /** |
| * A PlacementPolicy support choosing datanodes to build |
| * pipelines or containers with specified constraints. |
| */ |
| public interface PlacementPolicy { |
| |
| /** |
| * Given an initial set of datanodes and the size required, |
| * return set of datanodes that satisfy the nodes and size requirement. |
| * |
| * @param excludedNodes - list of nodes to be excluded. |
| * @param favoredNodes - list of nodes preferred. |
| * @param nodesRequired - number of datanodes required. |
| * @param sizeRequired - size required for the container or block. |
| * @return list of datanodes chosen. |
| * @throws IOException |
| */ |
| List<DatanodeDetails> chooseDatanodes(List<DatanodeDetails> excludedNodes, |
| List<DatanodeDetails> favoredNodes, int nodesRequired, long sizeRequired) |
| throws IOException; |
| } |
