/*
* 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 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 com.facebook.presto.operator;
import com.facebook.presto.spi.Page;
import static com.google.common.base.Preconditions.checkState;
public interface HashGenerator
{
long hashPosition(int position, Page page);
default int getPartition(int partitionCount, int position, Page page)
{
long rawHash = hashPosition(position, page);
// clear the sign bit
rawHash &= 0x7fff_ffff_ffff_ffffL;
int partition = (int) (rawHash % partitionCount);
checkState(partition >= 0 && partition < partitionCount);
return partition;
}
}