org.elasticsearch.common.bytes.CompositeBytesReference Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of elasticsearch Show documentation
Show all versions of elasticsearch Show documentation
Elasticsearch subproject :server
/*
* Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
* or more contributor license agreements. Licensed under the Elastic License
* 2.0 and the Server Side Public License, v 1; you may not use this file except
* in compliance with, at your election, the Elastic License 2.0 or the Server
* Side Public License, v 1.
*/
package org.elasticsearch.common.bytes;
import org.apache.lucene.util.BytesRef;
import org.apache.lucene.util.BytesRefBuilder;
import org.apache.lucene.util.BytesRefIterator;
import org.apache.lucene.util.RamUsageEstimator;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.Objects;
import java.util.stream.IntStream;
/**
* A composite {@link BytesReference} that allows joining multiple bytes references
* into one without copying.
*
* Note, {@link #toBytesRef()} will materialize all pages in this BytesReference.
*/
public final class CompositeBytesReference extends AbstractBytesReference {
private final BytesReference[] references;
private final int[] offsets; // we use the offsets to seek into the right BytesReference for random access and slicing
private final int length;
private final long ramBytesUsed;
public static BytesReference of(BytesReference... references) {
if (references.length == 0) {
return BytesArray.EMPTY;
} else if (references.length == 1) {
return references[0];
}
return ofMultiple(references);
}
private static BytesReference ofMultiple(BytesReference[] references) {
assert references.length > 1 : "use #of() instead";
final int[] offsets = new int[references.length];
long ramBytesUsed = 0;
int offset = 0;
for (int i = 0; i < references.length; i++) {
final BytesReference reference = references[i];
if (reference == null) {
throw new IllegalArgumentException("references must not be null");
}
if (reference.length() == 0) {
return dropEmptyReferences(references);
}
offsets[i] = offset;
offset += reference.length();
if (offset <= 0) {
throw new IllegalArgumentException("CompositeBytesReference cannot hold more than 2GB");
}
ramBytesUsed += reference.ramBytesUsed();
}
return new CompositeBytesReference(
references,
offsets,
offset,
ramBytesUsed + (Integer.BYTES * offsets.length + RamUsageEstimator.NUM_BYTES_ARRAY_HEADER) // offsets
+ (references.length * RamUsageEstimator.NUM_BYTES_OBJECT_REF + RamUsageEstimator.NUM_BYTES_ARRAY_HEADER) // references
+ Integer.BYTES // length
+ Long.BYTES// ramBytesUsed
);
}
private static BytesReference dropEmptyReferences(BytesReference[] references) {
final BytesReference[] tempArray = new BytesReference[references.length];
int targetIndex = 0;
for (final BytesReference reference : references) {
if (reference.length() != 0) {
tempArray[targetIndex++] = reference;
}
}
assert targetIndex < references.length : "no empty references found";
final BytesReference[] filteredReferences = new BytesReference[targetIndex];
System.arraycopy(tempArray, 0, filteredReferences, 0, targetIndex);
return of(filteredReferences);
}
private CompositeBytesReference(BytesReference[] references, int[] offsets, int length, long ramBytesUsed) {
assert references != null && offsets != null;
assert references.length > 1
: "Should not build composite reference from less than two references but received [" + references.length + "]";
assert Arrays.stream(references).allMatch(r -> r != null && r.length() > 0);
assert offsets[0] == 0;
assert IntStream.range(1, references.length).allMatch(i -> offsets[i] - offsets[i - 1] == references[i - 1].length());
assert length == Arrays.stream(references).mapToLong(BytesReference::length).sum();
assert ramBytesUsed > Arrays.stream(references).mapToLong(BytesReference::ramBytesUsed).sum();
this.references = Objects.requireNonNull(references, "references must not be null");
this.offsets = offsets;
this.length = length;
this.ramBytesUsed = ramBytesUsed;
}
@Override
public byte get(int index) {
final int i = getOffsetIndex(index);
return references[i].get(index - offsets[i]);
}
@Override
public int indexOf(byte marker, int from) {
final int remainingBytes = Math.max(length - from, 0);
Objects.checkFromIndexSize(from, remainingBytes, length);
int result = -1;
if (length == 0) {
return result;
}
final int firstReferenceIndex = getOffsetIndex(from);
for (int i = firstReferenceIndex; i < references.length; ++i) {
final BytesReference reference = references[i];
final int internalFrom;
if (i == firstReferenceIndex) {
internalFrom = from - offsets[firstReferenceIndex];
} else {
internalFrom = 0;
}
result = reference.indexOf(marker, internalFrom);
if (result != -1) {
result += offsets[i];
break;
}
}
return result;
}
@Override
public int length() {
return length;
}
@Override
public BytesReference slice(int from, int length) {
if (from == 0 && this.length == length) {
return this;
}
Objects.checkFromIndexSize(from, length, this.length);
if (length == 0) {
return BytesArray.EMPTY;
}
// for slices we only need to find the start and the end reference
// adjust them and pass on the references in between as they are fully contained
final int to = from + length;
final int limit = getOffsetIndex(to - 1);
final int start = getOffsetIndex(from);
final BytesReference[] inSlice = new BytesReference[1 + (limit - start)];
for (int i = 0, j = start; i < inSlice.length; i++) {
inSlice[i] = references[j++];
}
int inSliceOffset = from - offsets[start];
if (inSlice.length == 1) {
return inSlice[0].slice(inSliceOffset, length);
}
// now adjust slices in front and at the end
inSlice[0] = inSlice[0].slice(inSliceOffset, inSlice[0].length() - inSliceOffset);
inSlice[inSlice.length - 1] = inSlice[inSlice.length - 1].slice(0, to - offsets[limit]);
return CompositeBytesReference.ofMultiple(inSlice);
}
private int getOffsetIndex(int offset) {
final int i = Arrays.binarySearch(offsets, offset);
return i < 0 ? (-(i + 1)) - 1 : i;
}
@Override
public BytesRef toBytesRef() {
BytesRefBuilder builder = new BytesRefBuilder();
builder.grow(length());
BytesRef spare;
BytesRefIterator iterator = iterator();
try {
while ((spare = iterator.next()) != null) {
builder.append(spare);
}
} catch (IOException ex) {
throw new AssertionError("won't happen", ex); // this is really an error since we don't do IO in our bytesreferences
}
return builder.toBytesRef();
}
@Override
public BytesRefIterator iterator() {
return new BytesRefIterator() {
int index = 0;
private BytesRefIterator current = references[index++].iterator();
@Override
public BytesRef next() throws IOException {
BytesRef next = current.next();
if (next == null) {
while (index < references.length) {
current = references[index++].iterator();
next = current.next();
if (next != null) {
break;
}
}
}
return next;
}
};
}
@Override
public void writeTo(OutputStream os) throws IOException {
for (BytesReference reference : references) {
reference.writeTo(os);
}
}
@Override
public long ramBytesUsed() {
return ramBytesUsed;
}
}