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BlockStorage.java
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BlockStorage.java
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/*
* Copyright (c) 2002-2019 "Neo4j,"
* Neo4j Sweden AB [http://neo4j.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.kernel.impl.index.schema;
import org.eclipse.collections.api.list.MutableList;
import org.eclipse.collections.impl.factory.Lists;
import java.io.Closeable;
import java.io.File;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.Comparator;
import org.neo4j.index.internal.gbptree.Layout;
import org.neo4j.io.IOUtils;
import org.neo4j.io.fs.FileSystemAbstraction;
import org.neo4j.io.fs.StoreChannel;
import org.neo4j.io.pagecache.ByteArrayPageCursor;
import static org.neo4j.index.internal.gbptree.DynamicSizeUtil.getOverhead;
import static org.neo4j.index.internal.gbptree.DynamicSizeUtil.putKeyValueSize;
class BlockStorage<KEY, VALUE> implements Closeable
{
static final int BLOCK_HEADER_SIZE = Long.BYTES; // keyCount
private final Layout<KEY,VALUE> layout;
private final FileSystemAbstraction fs;
private final File blockFile;
private final MutableList<BlockEntry<KEY,VALUE>> bufferedEntries;
private final ByteBuffer byteBuffer;
private final Comparator<BlockEntry<KEY,VALUE>> comparator;
private final StoreChannel storeChannel;
private final Monitor monitor;
private final int bufferSize;
private final ByteBufferFactory bufferFactory;
private int currentBufferSize;
private int mergeIteration;
BlockStorage( Layout<KEY,VALUE> layout, ByteBufferFactory bufferFactory, FileSystemAbstraction fs, File blockFile, Monitor monitor, int bufferSize )
throws IOException
{
this.layout = layout;
this.fs = fs;
this.blockFile = blockFile;
this.monitor = monitor;
this.bufferSize = bufferSize;
this.bufferedEntries = Lists.mutable.empty();
this.bufferFactory = bufferFactory;
this.byteBuffer = bufferFactory.newBuffer( bufferSize );
this.comparator = ( e0, e1 ) -> layout.compare( e0.key(), e1.key() );
this.storeChannel = fs.create( blockFile );
resetBuffer();
}
public void add( KEY key, VALUE value ) throws IOException
{
int keySize = layout.keySize( key );
int valueSize = layout.valueSize( value );
int overhead = getOverhead( keySize, valueSize );
int entrySize = keySize + valueSize + overhead;
if ( currentBufferSize + entrySize > bufferSize )
{
// append buffer to file and clear buffers
flushAndResetBuffer();
}
bufferedEntries.add( new BlockEntry<>( key, value ) );
currentBufferSize += entrySize;
monitor.entryAdded( entrySize );
}
public void doneAdding() throws IOException
{
if ( !bufferedEntries.isEmpty() )
{
flushAndResetBuffer();
}
}
private void resetBuffer()
{
byteBuffer.clear();
bufferedEntries.clear();
currentBufferSize = BLOCK_HEADER_SIZE;
}
private void flushAndResetBuffer() throws IOException
{
bufferedEntries.sortThis( comparator );
ByteArrayPageCursor pageCursor = new ByteArrayPageCursor( byteBuffer );
// Header
pageCursor.putLong( bufferedEntries.size() );
// Entries
for ( BlockEntry<KEY,VALUE> entry : bufferedEntries )
{
int keySize = layout.keySize( entry.key() );
int valueSize = layout.valueSize( entry.value() );
putKeyValueSize( pageCursor, keySize, valueSize );
layout.writeKey( pageCursor, entry.key() );
layout.writeValue( pageCursor, entry.value() );
}
// TODO solve the BIG padding problem
// Zero pad
pageCursor.putBytes( bufferSize - currentBufferSize, (byte) 0 );
// Append to file
byteBuffer.flip();
storeChannel.writeAll( byteBuffer );
monitor.blockFlushed( bufferedEntries.size(), currentBufferSize, storeChannel.position() );
resetBuffer();
}
@Override
public void close() throws IOException
{
IOUtils.closeAll( storeChannel );
}
private long calculateBlockSize()
{
return (long) Math.pow( 2, mergeIteration ) * bufferSize;
}
public BlockStorageReader<KEY,VALUE> reader() throws IOException
{
return new BlockStorageReader<>( fs, blockFile, calculateBlockSize(), layout );
}
public interface Monitor
{
void entryAdded( int entrySize );
void blockFlushed( long keyCount, int bufferSize, long positionAfterFlush );
class Adapter implements Monitor
{
@Override
public void entryAdded( int entrySize )
{ // no-op
}
@Override
public void blockFlushed( long keyCount, int bufferSize, long positionAfterFlush )
{ // no-op
}
}
Monitor NO_MONITOR = new Adapter();
}
}