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
/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch licenses this file to you 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 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.util.Arrays;
import java.util.Objects;
/**
* 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 BytesReference {
private final BytesReference[] references;
private final int[] offsets;
private final int length;
private final long ramBytesUsed;
public CompositeBytesReference(BytesReference... references) {
this.references = Objects.requireNonNull(references, "references must not be null");
this.offsets = new int[references.length];
long ramBytesUsed = 0;
int offset = 0;
for (int i = 0; i < references.length; i++) {
BytesReference reference = references[i];
if (reference == null) {
throw new IllegalArgumentException("references must not be null");
}
offsets[i] = offset; // we use the offsets to seek into the right BytesReference for random access and slicing
offset += reference.length();
ramBytesUsed += reference.ramBytesUsed();
}
this.ramBytesUsed = 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
length = offset;
}
@Override
public byte get(int index) {
final int i = getOffsetIndex(index);
return references[i].get(index - offsets[i]);
}
@Override
public int length() {
return length;
}
@Override
public BytesReference slice(int from, int length) {
// 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(from + length);
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 new CompositeBytesReference(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() {
if (references.length > 0) {
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;
}
};
} else {
return () -> null;
}
}
@Override
public long ramBytesUsed() {
return ramBytesUsed;
}
}