/*
* 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.serde;
import com.facebook.presto.operator.Page;
import com.facebook.presto.spi.block.Block;
import com.facebook.presto.spi.block.BlockEncoding;
import com.facebook.presto.spi.block.BlockEncodingSerde;
import com.google.common.collect.AbstractIterator;
import io.airlift.slice.SliceInput;
import io.airlift.slice.SliceOutput;
import java.util.Iterator;
import static com.google.common.base.Preconditions.checkNotNull;
import static java.util.Arrays.asList;
public final class PagesSerde
{
private PagesSerde() {}
public static void writePages(BlockEncodingSerde blockEncodingSerde, SliceOutput sliceOutput, Page... pages)
{
writePages(blockEncodingSerde, sliceOutput, asList(pages).iterator());
}
public static void writePages(BlockEncodingSerde blockEncodingSerde, SliceOutput sliceOutput, Iterable<Page> pages)
{
writePages(blockEncodingSerde, sliceOutput, pages.iterator());
}
public static void writePages(BlockEncodingSerde blockEncodingSerde, SliceOutput sliceOutput, Iterator<Page> pages)
{
PagesWriter pagesWriter = new PagesWriter(blockEncodingSerde, sliceOutput);
while (pages.hasNext()) {
pagesWriter.append(pages.next());
}
}
public static Iterator<Page> readPages(BlockEncodingSerde blockEncodingSerde, SliceInput sliceInput)
{
return new PagesReader(blockEncodingSerde, sliceInput);
}
private static class PagesWriter
{
private final BlockEncodingSerde blockEncodingSerde;
private final SliceOutput sliceOutput;
private BlockEncoding[] blockEncodings;
private PagesWriter(BlockEncodingSerde blockEncodingSerde, SliceOutput sliceOutput)
{
this.blockEncodingSerde = checkNotNull(blockEncodingSerde, "blockEncodingSerde is null");
this.sliceOutput = checkNotNull(sliceOutput, "sliceOutput is null");
}
public PagesWriter append(Page page)
{
checkNotNull(page, "page is null");
if (blockEncodings == null) {
Block[] blocks = page.getBlocks();
blockEncodings = new BlockEncoding[blocks.length];
sliceOutput.writeInt(blocks.length);
for (int i = 0; i < blocks.length; i++) {
Block block = blocks[i];
BlockEncoding blockEncoding = block.getEncoding();
blockEncodings[i] = blockEncoding;
blockEncodingSerde.writeBlockEncoding(sliceOutput, blockEncoding);
}
}
sliceOutput.writeInt(page.getPositionCount());
Block[] blocks = page.getBlocks();
for (int i = 0; i < blocks.length; i++) {
blockEncodings[i].writeBlock(sliceOutput, blocks[i]);
}
return this;
}
}
private static class PagesReader
extends AbstractIterator<Page>
{
private final BlockEncoding[] blockEncodings;
private final SliceInput sliceInput;
public PagesReader(BlockEncodingSerde blockEncodingSerde, SliceInput sliceInput)
{
this.sliceInput = sliceInput;
if (!sliceInput.isReadable()) {
endOfData();
blockEncodings = new BlockEncoding[0];
return;
}
int channelCount = sliceInput.readInt();
blockEncodings = new BlockEncoding[channelCount];
for (int i = 0; i < blockEncodings.length; i++) {
blockEncodings[i] = blockEncodingSerde.readBlockEncoding(sliceInput);
}
}
@Override
protected Page computeNext()
{
if (!sliceInput.isReadable()) {
return endOfData();
}
int positions = sliceInput.readInt();
Block[] blocks = new Block[blockEncodings.length];
for (int i = 0; i < blocks.length; i++) {
blocks[i] = blockEncodings[i].readBlock(sliceInput);
}
@SuppressWarnings("UnnecessaryLocalVariable")
Page page = new Page(positions, blocks);
return page;
}
}
}