io.trino.operator.join.PagesHash Maven / Gradle / Ivy
/*
* 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 io.trino.operator.join;
import io.trino.spi.Page;
import io.trino.spi.PageBuilder;
public interface PagesHash
{
int getPositionCount();
long getInMemorySizeInBytes();
int getAddressIndex(int position, Page hashChannelsPage);
int getAddressIndex(int rightPosition, Page hashChannelsPage, long rawHash);
default int[] getAddressIndex(int[] positions, Page hashChannelsPage)
{
int[] result = new int[positions.length];
for (int i = 0; i < positions.length; i++) {
result[i] = getAddressIndex(positions[i], hashChannelsPage);
}
return result;
}
default int[] getAddressIndex(int[] positions, Page hashChannelsPage, long[] rawHashes)
{
int[] result = new int[positions.length];
for (int i = 0; i < positions.length; i++) {
result[i] = getAddressIndex(positions[i], hashChannelsPage, rawHashes[positions[i]]);
}
return result;
}
void appendTo(long position, PageBuilder pageBuilder, int outputChannelOffset);
static int getHashPosition(long rawHash, long mask)
{
// Avalanches the bits of a long integer by applying the finalisation step of MurmurHash3.
//
// This function implements the finalisation step of Austin Appleby's MurmurHash3.
// Its purpose is to avalanche the bits of the argument to within 0.25% bias. It is used, among other things, to scramble quickly (but deeply) the hash
// values returned by {@link Object#hashCode()}.
//
rawHash ^= rawHash >>> 33;
rawHash *= 0xff51afd7ed558ccdL;
rawHash ^= rawHash >>> 33;
rawHash *= 0xc4ceb9fe1a85ec53L;
rawHash ^= rawHash >>> 33;
return (int) (rawHash & mask);
}
}