catalyst/expressions/HiveHasher.java

0001 /*
0002  * Licensed to the Apache Software Foundation (ASF) under one or more
0003  * contributor license agreements.  See the NOTICE file distributed with
0004  * this work for additional information regarding copyright ownership.
0005  * The ASF licenses this file to You under the Apache License, Version 2.0
0006  * (the "License"); you may not use this file except in compliance with
0007  * the License.  You may obtain a copy of the License at
0008  *
0009  *    http://www.apache.org/licenses/LICENSE-2.0
0010  *
0011  * Unless required by applicable law or agreed to in writing, software
0012  * distributed under the License is distributed on an "AS IS" BASIS,
0013  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
0014  * See the License for the specific language governing permissions and
0015  * limitations under the License.
0016  */
0017
0018 package org.apache.spark.sql.catalyst.expressions;
0019
0020 import org.apache.spark.unsafe.Platform;
0021
0022 /**
0023  * Simulates Hive's hashing function from Hive v1.2.1
0024  * org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorUtils#hashcode()
0025  */
0026 public class HiveHasher {
0027
0028   @Override
0029   public String toString() {
0030     return HiveHasher.class.getSimpleName();
0031   }
0032
0033   public static int hashInt(int input) {
0034     return input;
0035   }
0036
0037   public static int hashLong(long input) {
0038     return (int) ((input >>> 32) ^ input);
0039   }
0040
0041   public static int hashUnsafeBytes(Object base, long offset, int lengthInBytes) {
0042     assert (lengthInBytes >= 0): "lengthInBytes cannot be negative";
0043     int result = 0;
0044     for (int i = 0; i < lengthInBytes; i++) {
0045       result = (result * 31) + (int) Platform.getByte(base, offset + i);
0046     }
0047     return result;
0048   }
0049 }