| /* |
| * 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.samza.container.grouper.stream; |
| |
| import com.google.common.base.Preconditions; |
| import org.apache.samza.Partition; |
| import org.apache.samza.system.SystemStreamPartition; |
| |
| /** |
| * A SystemStreamPartitionMapper that uses the hash partitioning function of the producer to map a {@link SystemStreamPartition} to |
| * correct previous {@link SystemStreamPartition} after the stream expansion. |
| */ |
| public class HashSystemStreamPartitionMapper implements SystemStreamPartitionMapper { |
| |
| @Override |
| public SystemStreamPartition getPreviousSSP(SystemStreamPartition currentSystemStreamPartition, int previousPartitionCount, int currentPartitionCount) { |
| Preconditions.checkNotNull(currentSystemStreamPartition); |
| Preconditions.checkArgument(currentPartitionCount % previousPartitionCount == 0, |
| String.format("New partition count: %d should be a multiple of previous partition count: %d.", currentPartitionCount, previousPartitionCount)); |
| Partition partition = currentSystemStreamPartition.getPartition(); |
| Preconditions.checkNotNull(partition, String.format("SystemStreamPartition: %s cannot have null partition", currentSystemStreamPartition)); |
| int currentPartitionId = partition.getPartitionId(); |
| int previousPartitionId = currentPartitionId % previousPartitionCount; |
| return new SystemStreamPartition(currentSystemStreamPartition.getSystemStream(), new Partition(previousPartitionId)); |
| } |
| } |