org.apache.hadoop.hive.ql.udf.generic.GenericUDFHash Maven / Gradle / Ivy
/**
* 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.hadoop.hive.ql.udf.generic;
import org.apache.commons.lang.StringUtils;
import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDFArgumentTypeException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorUtils;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.io.IntWritable;
/**
* GenericUDF Class for computing hash values.
*/
@Description(name = "hash", value = "_FUNC_(a1, a2, ...) - Returns a hash value of the arguments")
public class GenericUDFHash extends GenericUDF {
private transient ObjectInspector[] argumentOIs;
@Override
public ObjectInspector initialize(ObjectInspector[] arguments) throws UDFArgumentTypeException {
argumentOIs = arguments;
return PrimitiveObjectInspectorFactory.writableIntObjectInspector;
}
private final IntWritable result = new IntWritable();
@Override
public Object evaluate(DeferredObject[] arguments) throws HiveException {
// See
// http://java.sun.com/j2se/1.5.0/docs/api/java/util/List.html#hashCode()
int r = 0;
for (int i = 0; i < arguments.length; i++) {
r = r * 31
+ ObjectInspectorUtils.hashCode(arguments[i].get(), argumentOIs[i]);
}
result.set(r);
return result;
}
@Override
public String getDisplayString(String[] children) {
return getStandardDisplayString("hash", children, ",");
}
}