org.elasticsearch.common.bytes.AbstractBytesReference Maven / Gradle / Ivy
/*
* 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.BytesRefIterator;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.xcontent.XContentBuilder;
import java.io.IOException;
import java.io.OutputStream;
import java.util.function.ToIntBiFunction;
public abstract class AbstractBytesReference implements BytesReference {
private int hash; // we cache the hash of this reference since it can be quite costly to re-calculated it
private boolean hashIsZero; // if the calculated hash is actually zero
@Override
public int getInt(int index) {
return (get(index) & 0xFF) << 24 | (get(index + 1) & 0xFF) << 16 | (get(index + 2) & 0xFF) << 8 | get(index + 3) & 0xFF;
}
@Override
public int indexOf(byte marker, int from) {
final int to = length();
for (int i = from; i < to; i++) {
if (get(i) == marker) {
return i;
}
}
return -1;
}
@Override
public StreamInput streamInput() throws IOException {
return new BytesReferenceStreamInput(this);
}
@Override
public void writeTo(OutputStream os) throws IOException {
final BytesRefIterator iterator = iterator();
BytesRef ref;
while ((ref = iterator.next()) != null) {
os.write(ref.bytes, ref.offset, ref.length);
}
}
@Override
public String utf8ToString() {
return toBytesRef().utf8ToString();
}
@Override
public BytesRefIterator iterator() {
return new BytesRefIterator() {
BytesRef ref = length() == 0 ? null : toBytesRef();
@Override
public BytesRef next() {
BytesRef r = ref;
ref = null; // only return it once...
return r;
}
};
}
@Override
public boolean equals(Object other) {
if (this == other) {
return true;
}
if (other instanceof final BytesReference otherRef) {
if (length() != otherRef.length()) {
return false;
}
return compareIterators(
this,
otherRef,
(a, b) -> a.bytesEquals(b) ? 0 : 1 // this is a call to BytesRef#bytesEquals - this method is the hot one in the comparison
) == 0;
}
return false;
}
@Override
public int hashCode() {
if (hash == 0 && hashIsZero == false) {
final BytesRefIterator iterator = iterator();
BytesRef ref;
int result = 1;
try {
while ((ref = iterator.next()) != null) {
for (int i = 0; i < ref.length; i++) {
result = 31 * result + ref.bytes[ref.offset + i];
}
}
} catch (IOException ex) {
throw new AssertionError("wont happen", ex);
}
if (result == 0) {
hashIsZero = true;
} else {
hash = result;
}
}
return hash;
}
@Override
public int compareTo(final BytesReference other) {
return compareIterators(this, other, BytesRef::compareTo);
}
/**
* Compares the two references using the given int function.
*/
private static int compareIterators(final BytesReference a, final BytesReference b, final ToIntBiFunction f) {
try {
// we use the iterators since it's a 0-copy comparison where possible!
final long lengthToCompare = Math.min(a.length(), b.length());
final BytesRefIterator aIter = a.iterator();
final BytesRefIterator bIter = b.iterator();
BytesRef aRef = aIter.next();
BytesRef bRef = bIter.next();
if (aRef != null && bRef != null) { // do we have any data?
aRef = aRef.clone(); // we clone since we modify the offsets and length in the iteration below
bRef = bRef.clone();
if (aRef.length == a.length() && bRef.length == b.length()) { // is it only one array slice we are comparing?
return f.applyAsInt(aRef, bRef);
} else {
for (int i = 0; i < lengthToCompare;) {
if (aRef.length == 0) {
aRef = aIter.next().clone(); // must be non null otherwise we have a bug
}
if (bRef.length == 0) {
bRef = bIter.next().clone(); // must be non null otherwise we have a bug
}
final int aLength = aRef.length;
final int bLength = bRef.length;
final int length = Math.min(aLength, bLength); // shrink to the same length and use the fast compare in lucene
aRef.length = bRef.length = length;
// now we move to the fast comparison - this is the hot part of the loop
int diff = f.applyAsInt(aRef, bRef);
aRef.length = aLength;
bRef.length = bLength;
if (diff != 0) {
return diff;
}
advance(aRef, length);
advance(bRef, length);
i += length;
}
}
}
// One is a prefix of the other, or, they are equal:
return a.length() - b.length();
} catch (IOException ex) {
throw new AssertionError("can not happen", ex);
}
}
private static void advance(final BytesRef ref, final int length) {
assert ref.length >= length : " ref.length: " + ref.length + " length: " + length;
assert ref.offset + length < ref.bytes.length || (ref.offset + length == ref.bytes.length && ref.length - length == 0)
: "offset: " + ref.offset + " ref.bytes.length: " + ref.bytes.length + " length: " + length + " ref.length: " + ref.length;
ref.length -= length;
ref.offset += length;
}
@Override
public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
BytesRef bytes = toBytesRef();
return builder.value(bytes.bytes, bytes.offset, bytes.length);
}
}