| /* |
| * Copyright 2009-2010 by The Regents of the University of California |
| * 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 from |
| * |
| * 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 edu.uci.ics.hyracks.dataflow.common.data.partition; |
| |
| import edu.uci.ics.hyracks.api.comm.IFrameTupleAccessor; |
| import edu.uci.ics.hyracks.api.dataflow.value.IBinaryHashFunction; |
| import edu.uci.ics.hyracks.api.dataflow.value.IBinaryHashFunctionFactory; |
| import edu.uci.ics.hyracks.api.dataflow.value.ITuplePartitionComputer; |
| import edu.uci.ics.hyracks.api.dataflow.value.ITuplePartitionComputerFactory; |
| |
| public class FieldHashPartitionComputerFactory implements ITuplePartitionComputerFactory { |
| private static final long serialVersionUID = 1L; |
| private final int[] hashFields; |
| private final IBinaryHashFunctionFactory[] hashFunctionFactories; |
| |
| public FieldHashPartitionComputerFactory(int[] hashFields, IBinaryHashFunctionFactory[] hashFunctionFactories) { |
| this.hashFields = hashFields; |
| this.hashFunctionFactories = hashFunctionFactories; |
| } |
| |
| @Override |
| public ITuplePartitionComputer createPartitioner() { |
| final IBinaryHashFunction[] hashFunctions = new IBinaryHashFunction[hashFunctionFactories.length]; |
| for (int i = 0; i < hashFunctionFactories.length; ++i) { |
| hashFunctions[i] = hashFunctionFactories[i].createBinaryHashFunction(); |
| } |
| return new ITuplePartitionComputer() { |
| @Override |
| public int partition(IFrameTupleAccessor accessor, int tIndex, int nParts) { |
| int h = 0; |
| int startOffset = accessor.getTupleStartOffset(tIndex); |
| int slotLength = accessor.getFieldSlotsLength(); |
| for (int j = 0; j < hashFields.length; ++j) { |
| int fIdx = hashFields[j]; |
| IBinaryHashFunction hashFn = hashFunctions[j]; |
| int fStart = accessor.getFieldStartOffset(tIndex, fIdx); |
| int fEnd = accessor.getFieldEndOffset(tIndex, fIdx); |
| int fh = hashFn |
| .hash(accessor.getBuffer().array(), startOffset + slotLength + fStart, fEnd - fStart); |
| h += fh; |
| } |
| if (h < 0) { |
| h = -h; |
| } |
| return h % nParts; |
| } |
| }; |
| } |
| } |