/*
* 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.pig.piggybank.evaluation.string;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import org.apache.pig.EvalFunc;
import org.apache.pig.FuncSpec;
import org.apache.pig.data.DataType;
import org.apache.pig.data.Tuple;
import org.apache.pig.impl.logicalLayer.FrontendException;
import org.apache.pig.impl.logicalLayer.schema.Schema;
/**
* <dl>
* <dt><b>Syntax:</b></dt>
* <dd><code>long HashFNV(String string_to_hash, [int mod])</code>.</dd>
* </dl>
*/
public class HashFNV extends EvalFunc<Long> {
static final int FNV1_32_INIT = 33554467;
static final int FNV_32_PRIME = 0x01000193;
public Schema outputSchema(Schema input) {
try {
return new Schema(new Schema.FieldSchema(getSchemaName(this.getClass().getName().toLowerCase(), input), DataType.LONG));
} catch (Exception e) {
return null;
}
}
long hashFnv32Init(int init, String s)
{
int hval = init;
byte[] bytes = null;
try {
bytes = s.getBytes("UTF-8");
} catch (java.io.UnsupportedEncodingException e) {
// shall not happen
}
for (int i=0;i<bytes.length;i++)
{
/* multiply by the 32 bit FNV magic prime mod 2^32 */
hval *= FNV_32_PRIME;
hval ^= bytes[i];
}
return hval;
}
long hashFnv32(String s)
{
return hashFnv32Init(FNV1_32_INIT, s);
}
public Long exec(Tuple input) throws IOException { throw new IOException("HashFNV: internal error, try to use HashFNV directly"); }
@Override
public List<FuncSpec> getArgToFuncMapping() throws FrontendException {
List<FuncSpec> funcList = new ArrayList<FuncSpec>();
Schema s = new Schema();
s.add(new Schema.FieldSchema(null, DataType.CHARARRAY));
funcList.add(new FuncSpec(HashFNV1.class.getName(), s));
s = new Schema();
s.add(new Schema.FieldSchema(null, DataType.CHARARRAY));
s.add(new Schema.FieldSchema(null, DataType.INTEGER));
funcList.add(new FuncSpec(HashFNV2.class.getName(), s));
return funcList;
}
}