/*
* 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.operator.scalar.CombineHashFunction;
import com.facebook.presto.spi.Page;
import com.facebook.presto.spi.type.Type;
import com.facebook.presto.sql.planner.optimizations.HashGenerationOptimizer;
import com.facebook.presto.type.TypeUtils;
import com.google.common.collect.ImmutableList;
import java.util.List;
import static com.google.common.base.MoreObjects.toStringHelper;
import static com.google.common.base.Preconditions.checkArgument;
import static java.util.Objects.requireNonNull;
public class InterpretedHashGenerator
implements HashGenerator
{
private final List<Type> hashChannelTypes;
private final int[] hashChannels;
public InterpretedHashGenerator(List<Type> hashChannelTypes, int[] hashChannels)
{
this.hashChannels = requireNonNull(hashChannels, "hashChannels is null");
this.hashChannelTypes = ImmutableList.copyOf(requireNonNull(hashChannelTypes, "hashChannelTypes is null"));
checkArgument(hashChannelTypes.size() == hashChannels.length);
}
@Override
public long hashPosition(int position, Page page)
{
long result = HashGenerationOptimizer.INITIAL_HASH_VALUE;
for (int i = 0; i < hashChannels.length; i++) {
Type type = hashChannelTypes.get(i);
result = CombineHashFunction.getHash(result, TypeUtils.hashPosition(type, page.getBlock(hashChannels[i]), position));
}
return result;
}
@Override
public String toString()
{
return toStringHelper(this)
.add("hashChannelTypes", hashChannelTypes)
.add("hashChannels", hashChannels)
.toString();
}
}