/*
* 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.block.BlockCursor;
import com.facebook.presto.spi.block.RandomAccessBlock;
import com.google.common.collect.ImmutableList;
import java.util.List;
public class SimplePagesHashStrategy
implements PagesHashStrategy
{
private final List<List<RandomAccessBlock>> channels;
private final List<List<RandomAccessBlock>> hashChannels;
public SimplePagesHashStrategy(List<List<RandomAccessBlock>> channels, List<Integer> hashChannels)
{
this.channels = ImmutableList.copyOf(channels);
ImmutableList.Builder<List<RandomAccessBlock>> hashChannelsBuilder = ImmutableList.builder();
for (int hashChannel : hashChannels) {
hashChannelsBuilder.add(channels.get(hashChannel));
}
this.hashChannels = hashChannelsBuilder.build();
}
@Override
public int getChannelCount()
{
return channels.size();
}
@Override
public void appendTo(int blockIndex, int blockPosition, PageBuilder pageBuilder, int outputChannelOffset)
{
for (List<RandomAccessBlock> channel : channels) {
RandomAccessBlock block = channel.get(blockIndex);
block.appendTo(blockPosition, pageBuilder.getBlockBuilder(outputChannelOffset));
outputChannelOffset++;
}
}
@Override
public int hashPosition(int blockIndex, int blockPosition)
{
int result = 0;
for (List<RandomAccessBlock> channel : hashChannels) {
RandomAccessBlock block = channel.get(blockIndex);
result = result * 31 + block.hash(blockPosition);
}
return result;
}
@Override
public boolean positionEqualsCursors(int blockIndex, int blockPosition, BlockCursor[] cursors)
{
for (int i = 0; i < hashChannels.size(); i++) {
List<RandomAccessBlock> channel = hashChannels.get(i);
RandomAccessBlock block = channel.get(blockIndex);
if (!block.equalTo(blockPosition, cursors[i])) {
return false;
}
}
return true;
}
@Override
public boolean positionEqualsPosition(int leftBlockIndex, int leftBlockPosition, int rightBlockIndex, int rightBlockPosition)
{
for (List<RandomAccessBlock> channel : hashChannels) {
RandomAccessBlock leftBlock = channel.get(leftBlockIndex);
RandomAccessBlock rightBlock = channel.get(rightBlockIndex);
if (!leftBlock.equalTo(leftBlockPosition, rightBlock, rightBlockPosition)) {
return false;
}
}
return true;
}
}