Java tutorial
/* * Copyright 2015 Open Networking Laboratory * * Licensed 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.onosproject.store.consistent.impl; import com.google.common.collect.ImmutableMap; import com.google.common.collect.ImmutableSet; import com.google.common.collect.Maps; import org.onosproject.store.cluster.impl.NodeInfo; import java.util.ArrayList; import java.util.Collections; import java.util.HashSet; import java.util.List; import java.util.Map; import java.util.Set; import static com.google.common.base.Preconditions.checkNotNull; /** * Partitioned database configuration. */ public class DatabaseDefinition { private Map<String, Set<NodeInfo>> partitions; private Set<NodeInfo> nodes; /** * Creates a new DatabaseDefinition. * * @param partitions partition map * @param nodes set of nodes * @return database definition */ public static DatabaseDefinition from(Map<String, Set<NodeInfo>> partitions, Set<NodeInfo> nodes) { checkNotNull(partitions); checkNotNull(nodes); DatabaseDefinition definition = new DatabaseDefinition(); definition.partitions = ImmutableMap.copyOf(partitions); definition.nodes = ImmutableSet.copyOf(nodes); return definition; } /** * Creates a new DatabaseDefinition using default partitions. * * @param nodes set of nodes * @return database definition */ public static DatabaseDefinition from(Set<NodeInfo> nodes) { return from(generateDefaultPartitions(nodes), nodes); } /** * Returns the map of database partitions. * * @return db partition map */ public Map<String, Set<NodeInfo>> getPartitions() { return partitions; } /** * Returns the set of nodes. * * @return nodes */ public Set<NodeInfo> getNodes() { return nodes; } /** * Generates set of default partitions using permutations of the nodes. * * @param nodes information about cluster nodes * @return default partition map */ private static Map<String, Set<NodeInfo>> generateDefaultPartitions(Set<NodeInfo> nodes) { List<NodeInfo> sorted = new ArrayList<>(nodes); Collections.sort(sorted, (o1, o2) -> o1.getId().compareTo(o2.getId())); Map<String, Set<NodeInfo>> partitions = Maps.newHashMap(); int length = nodes.size(); int count = 3; for (int i = 0; i < length; i++) { Set<NodeInfo> set = new HashSet<>(count); for (int j = 0; j < count; j++) { set.add(sorted.get((i + j) % length)); } partitions.put("p" + (i + 1), set); } return partitions; } }