src.it.unimi.dsi.util.ByteBufferLongBigList Maven / Gradle / Ivy
/*
* DSI utilities
*
* Copyright (C) 2012-2023 Sebastiano Vigna
*
* This program and the accompanying materials are made available under the
* terms of the GNU Lesser General Public License v2.1 or later,
* which is available at
* http://www.gnu.org/licenses/old-licenses/lgpl-2.1-standalone.html,
* or the Apache Software License 2.0, which is available at
* https://www.apache.org/licenses/LICENSE-2.0.
*
* 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.
*
* SPDX-License-Identifier: LGPL-2.1-or-later OR Apache-2.0
*/
package it.unimi.dsi.util;
import java.io.DataOutput;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;
import java.util.Arrays;
import it.unimi.dsi.fastutil.longs.AbstractLongBigList;
import it.unimi.dsi.fastutil.longs.LongBigList;
import it.unimi.dsi.fastutil.longs.LongMappedBigList;
import it.unimi.dsi.lang.FlyweightPrototype;
/**
* A bridge between byte {@linkplain ByteBuffer buffers} and {@linkplain LongBigList long big
* lists}.
*
*
* Java's {@linkplain FileChannel#map(MapMode, long, long) memory-mapping facilities} have the
* severe limitation of mapping at most {@link Integer#MAX_VALUE} bytes, as they expose the content
* of a file using a {@link MappedByteBuffer}. This class can
* {@linkplain #map(FileChannel, ByteOrder, FileChannel.MapMode) expose a file of longs of arbitrary
* length} as a {@link LongBigList} that is actually based on an array of {@link MappedByteBuffer}s,
* each mapping a chunk of {@link #CHUNK_SIZE} longs.
*
*
* Instances of this class are not thread safe, but the {@link #copy()} method provides a
* lightweight duplicate that can be accessed independently by another thread. Only chunks that are
* actually used will be {@linkplain ByteBuffer#duplicate() duplicated} lazily.
*
* @author Sebastiano Vigna
* @deprecated Use {@link LongMappedBigList} instead.
*/
@Deprecated
public class ByteBufferLongBigList extends AbstractLongBigList implements FlyweightPrototype {
private static int CHUNK_SHIFT = 27;
/** The size in longs of a chunk created by {@link #map(FileChannel, ByteOrder, FileChannel.MapMode)}. */
public static final long CHUNK_SIZE = 1L << CHUNK_SHIFT;
/** The mask used to compute the offset in the chunk in longs. */
private static final long CHUNK_MASK = CHUNK_SIZE - 1;
/** The underlying byte buffers. */
private final ByteBuffer[] byteBuffer;
/** An array parallel to {@link #byteBuffer} specifying which buffers do not need to be
* {@linkplain ByteBuffer#duplicate() duplicated} before being used. */
private final boolean[] readyToUse;
/** The number of byte buffers. */
private final int n;
/** The overall size in longs. */
private final long size;
/** Creates a new byte-buffer long big list from a single {@link ByteBuffer}.
*
* @param byteBuffer the underlying byte buffer.
*/
public ByteBufferLongBigList(final ByteBuffer byteBuffer) {
this(new ByteBuffer[] { byteBuffer }, byteBuffer.capacity() / 8, new boolean[1]);
}
/** Creates a new byte-buffer long big list.
*
* @param byteBuffer the underlying byte buffers.
* @param size the overall number of longs in the underlying byte buffers (i.e., the
* sum of the {@linkplain ByteBuffer#capacity() capacities} of the byte buffers divided by eight).
* @param readyToUse an array parallel to byteBuffer specifying which buffers do not need to be
* {@linkplain ByteBuffer#duplicate() duplicated} before being used (the process will happen lazily); the array
* will be used internally by the newly created byte-buffer long big list.
*/
protected ByteBufferLongBigList(final ByteBuffer[] byteBuffer, final long size, final boolean[] readyToUse) {
this.byteBuffer = byteBuffer;
this.n = byteBuffer.length;
this.size = size;
this.readyToUse = readyToUse;
for(int i = 0; i < n; i++) if (i < n - 1 && byteBuffer[i].capacity() / 8 != CHUNK_SIZE) throw new IllegalArgumentException();
}
/** Creates a new byte-buffer long big list by read-only mapping a given file channel using the standard Java (i.e., {@link DataOutput}) byte order ({@link ByteOrder#BIG_ENDIAN}).
*
* @param fileChannel the file channel that will be mapped.
* @return a new read-only byte-buffer long big list over the contents of fileChannel.
*
* @see #map(FileChannel, ByteOrder, MapMode)
*/
public static ByteBufferLongBigList map(final FileChannel fileChannel) throws IOException {
return map(fileChannel, ByteOrder.BIG_ENDIAN);
}
/** Creates a new byte-buffer long big list by read-only mapping a given file channel.
*
* @param fileChannel the file channel that will be mapped.
* @param byteOrder a prescribed byte order.
* @return a new read-only byte-buffer long big list over the contents of fileChannel.
*
* @see #map(FileChannel, ByteOrder, MapMode)
*/
public static ByteBufferLongBigList map(final FileChannel fileChannel, final ByteOrder byteOrder) throws IOException {
return map(fileChannel, byteOrder, MapMode.READ_ONLY);
}
/** Creates a new byte-buffer long big list by mapping a given file channel.
*
* @param fileChannel the file channel that will be mapped.
* @param byteOrder a prescribed byte order.
* @param mapMode the mapping mode: usually {@link MapMode#READ_ONLY}, but if intend to make the list
* {@linkplain #set(long, long) mutable}, you have to pass {@link MapMode#READ_WRITE}.
* @return a new byte-buffer long big list over the contents of fileChannel.
*/
public static ByteBufferLongBigList map(final FileChannel fileChannel, final ByteOrder byteOrder, final MapMode mapMode) throws IOException {
final long size = fileChannel.size() / 8;
final int chunks = (int)((size + (CHUNK_SIZE - 1)) / CHUNK_SIZE);
final ByteBuffer[] byteBuffer = new ByteBuffer[chunks];
for(int i = 0; i < chunks; i++) byteBuffer[i] = fileChannel.map(mapMode, i * CHUNK_SIZE * 8, Math.min(CHUNK_SIZE, size - i * CHUNK_SIZE) * 8).order(byteOrder);
final boolean[] readyToUse = new boolean[chunks];
Arrays.fill(readyToUse, true);
return new ByteBufferLongBigList(byteBuffer, size, readyToUse);
}
private ByteBuffer byteBuffer(final int n) {
if (readyToUse[n]) return byteBuffer[n];
readyToUse[n] = true;
return byteBuffer[n] = byteBuffer[n].duplicate().order(byteBuffer[n].order());
}
@Override
public ByteBufferLongBigList copy() {
return new ByteBufferLongBigList(byteBuffer.clone(), size, new boolean[n]);
}
@Override
public long getLong(final long index) {
return byteBuffer((int)(index >>> CHUNK_SHIFT)).getLong((int)(index & CHUNK_MASK) << 3);
}
@Override
public long set(final long index, final long value) {
final ByteBuffer b = byteBuffer((int)(index >>> CHUNK_SHIFT));
final int i = (int)(index & CHUNK_MASK) << 3;
final long previousValue = b.getLong(i);
b.putLong(i, value);
return previousValue;
}
@Override
public long size64() {
return size;
}
}