Java tutorial
/* * Copyright 2016 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.primitives.impl; import static com.google.common.base.Preconditions.checkNotNull; import java.util.List; import java.util.Map; import java.util.TreeMap; import org.apache.commons.lang.StringUtils; import org.onlab.util.Tools; import org.onosproject.cluster.PartitionId; import org.onosproject.store.primitives.DistributedPrimitiveCreator; import org.onosproject.store.service.AsyncAtomicCounter; import org.onosproject.store.service.AsyncAtomicValue; import org.onosproject.store.service.AsyncConsistentMap; import org.onosproject.store.service.AsyncDistributedSet; import org.onosproject.store.service.AsyncLeaderElector; import org.onosproject.store.service.DistributedQueue; import org.onosproject.store.service.Serializer; import com.google.common.collect.Lists; import com.google.common.collect.Maps; import com.google.common.hash.HashCode; import com.google.common.hash.Hashing; import com.google.common.primitives.Bytes; /** * {@code DistributedPrimitiveCreator} that federates responsibility for creating * distributed primitives to a collection of other {@link DistributedPrimitiveCreator creators}. */ public class FederatedDistributedPrimitiveCreator implements DistributedPrimitiveCreator { private final TreeMap<PartitionId, DistributedPrimitiveCreator> members; private final List<PartitionId> sortedMemberPartitionIds; public FederatedDistributedPrimitiveCreator(Map<PartitionId, DistributedPrimitiveCreator> members) { this.members = Maps.newTreeMap(); this.members.putAll(checkNotNull(members)); this.sortedMemberPartitionIds = Lists.newArrayList(members.keySet()); } @Override public <K, V> AsyncConsistentMap<K, V> newAsyncConsistentMap(String name, Serializer serializer) { checkNotNull(name); checkNotNull(serializer); Map<PartitionId, AsyncConsistentMap<K, V>> maps = Maps.transformValues(members, partition -> partition.newAsyncConsistentMap(name, serializer)); Hasher<K> hasher = key -> { long hashCode = HashCode.fromBytes(Bytes.ensureCapacity(serializer.encode(key), 8, 0)).asLong(); return sortedMemberPartitionIds.get(Hashing.consistentHash(hashCode, members.size())); }; return new PartitionedAsyncConsistentMap<>(name, maps, hasher); } @Override public <E> AsyncDistributedSet<E> newAsyncDistributedSet(String name, Serializer serializer) { return DistributedPrimitives.newSetFromMap(newAsyncConsistentMap(name, serializer)); } @Override public AsyncAtomicCounter newAsyncCounter(String name) { return getCreator(name).newAsyncCounter(name); } @Override public <V> AsyncAtomicValue<V> newAsyncAtomicValue(String name, Serializer serializer) { return getCreator(name).newAsyncAtomicValue(name, serializer); } @Override public <E> DistributedQueue<E> newDistributedQueue(String name, Serializer serializer) { return getCreator(name).newDistributedQueue(name, serializer); } @Override public AsyncLeaderElector newAsyncLeaderElector(String name) { return getCreator(name).newAsyncLeaderElector(name); } /** * Returns the {@code DistributedPrimitiveCreator} to use for hosting a primitive. * @param name primitive name * @return primitive creator */ private DistributedPrimitiveCreator getCreator(String name) { long hashCode = HashCode.fromBytes(Tools.getBytesUtf8(StringUtils.leftPad(name, 8))).asLong(); int index = Hashing.consistentHash(hashCode, members.size()); return members.get(sortedMemberPartitionIds.get(index)); } }