io.trino.hive.formats.rcfile.PageSplitterUtil 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.hive.formats.rcfile;
import com.google.common.collect.ImmutableList;
import io.trino.spi.Page;
import java.util.List;
import static com.google.common.base.Preconditions.checkArgument;
/**
* Copy of io.trino.execution.buffer.PageSplitterUtil
*/
public final class PageSplitterUtil
{
private PageSplitterUtil() {}
public static List splitPage(Page page, long maxPageSizeInBytes)
{
return splitPage(page, maxPageSizeInBytes, Long.MAX_VALUE);
}
private static List splitPage(Page page, long maxPageSizeInBytes, long previousPageSize)
{
checkArgument(page.getPositionCount() > 0, "page is empty");
checkArgument(maxPageSizeInBytes > 0, "maxPageSizeInBytes must be > 0");
// for Pages with certain types of Blocks (e.g., RLE blocks) the size in bytes may remain constant
// through the recursive calls, which causes the recursion to only terminate when page.getPositionCount() == 1
// and create potentially a large number of Page's of size 1. So we check here that
// if the size of the page doesn't improve from the previous call we terminate the recursion.
if (page.getSizeInBytes() == previousPageSize || page.getSizeInBytes() <= maxPageSizeInBytes || page.getPositionCount() == 1) {
return ImmutableList.of(page);
}
ImmutableList.Builder outputPages = ImmutableList.builder();
long previousSize = page.getSizeInBytes();
int positionCount = page.getPositionCount();
int half = positionCount / 2;
Page leftHalf = page.getRegion(0, half);
outputPages.addAll(splitPage(leftHalf, maxPageSizeInBytes, previousSize));
Page rightHalf = page.getRegion(half, positionCount - half);
outputPages.addAll(splitPage(rightHalf, maxPageSizeInBytes, previousSize));
return outputPages.build();
}
}