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/*
* SPDX-License-Identifier: Apache-2.0
*
* The OpenSearch Contributors require contributions made to
* this file be licensed under the Apache-2.0 license or a
* compatible open source license.
*/
/*
* 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.
*/
/*
* Modifications Copyright OpenSearch Contributors. See
* GitHub history for details.
*/
package org.opensearch.common.compress;
import org.opensearch.common.annotation.PublicApi;
import org.opensearch.common.io.Streams;
import org.opensearch.common.io.stream.BytesStreamOutput;
import org.opensearch.common.xcontent.XContentFactory;
import org.opensearch.core.common.bytes.BytesArray;
import org.opensearch.core.common.bytes.BytesReference;
import org.opensearch.core.common.io.stream.StreamInput;
import org.opensearch.core.common.io.stream.StreamOutput;
import org.opensearch.core.compress.Compressor;
import org.opensearch.core.compress.CompressorRegistry;
import org.opensearch.core.xcontent.ToXContent;
import org.opensearch.core.xcontent.XContentBuilder;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.zip.CRC32;
import java.util.zip.CheckedOutputStream;
/**
* Similar class to the {@link String} class except that it internally stores
* data using a compressed representation in order to require less permanent
* memory. Note that the compressed string might still sometimes need to be
* decompressed in order to perform equality checks or to compute hash codes.
*
* @opensearch.api
*/
@PublicApi(since = "1.0.0")
public final class CompressedXContent {
private static int crc32(BytesReference data) {
CRC32 crc32 = new CRC32();
try {
data.writeTo(new CheckedOutputStream(Streams.NULL_OUTPUT_STREAM, crc32));
} catch (IOException bogus) {
// cannot happen
throw new Error(bogus);
}
return (int) crc32.getValue();
}
private final byte[] bytes;
private final int crc32;
// Used for serialization
private CompressedXContent(byte[] compressed, int crc32) {
this.bytes = compressed;
this.crc32 = crc32;
assertConsistent();
}
/**
* Create a {@link CompressedXContent} out of a {@link ToXContent} instance.
*/
public CompressedXContent(ToXContent xcontent, ToXContent.Params params) throws IOException {
BytesStreamOutput bStream = new BytesStreamOutput();
OutputStream compressedStream = CompressorRegistry.defaultCompressor().threadLocalOutputStream(bStream);
CRC32 crc32 = new CRC32();
OutputStream checkedStream = new CheckedOutputStream(compressedStream, crc32);
try (XContentBuilder builder = XContentFactory.jsonBuilder(checkedStream)) {
if (xcontent.isFragment()) {
builder.startObject();
}
xcontent.toXContent(builder, params);
if (xcontent.isFragment()) {
builder.endObject();
}
}
this.bytes = BytesReference.toBytes(bStream.bytes());
this.crc32 = (int) crc32.getValue();
assertConsistent();
}
/**
* Create a {@link CompressedXContent} out of a serialized {@link ToXContent}
* that may already be compressed.
*/
public CompressedXContent(BytesReference data) throws IOException {
Compressor compressor = CompressorRegistry.compressor(data);
if (compressor != null) {
// already compressed...
this.bytes = BytesReference.toBytes(data);
this.crc32 = crc32(uncompressed());
} else {
this.bytes = BytesReference.toBytes(CompressorRegistry.defaultCompressor().compress(data));
this.crc32 = crc32(data);
}
assertConsistent();
}
private void assertConsistent() {
assert CompressorRegistry.compressor(new BytesArray(bytes)) != null;
assert this.crc32 == crc32(uncompressed());
}
public CompressedXContent(byte[] data) throws IOException {
this(new BytesArray(data));
}
public CompressedXContent(String str) throws IOException {
this(new BytesArray(str.getBytes(StandardCharsets.UTF_8)));
}
/** Return the compressed bytes. */
public byte[] compressed() {
return this.bytes;
}
/** Return the compressed bytes as a {@link BytesReference}. */
public BytesReference compressedReference() {
return new BytesArray(bytes);
}
/** Return the uncompressed bytes. */
public BytesReference uncompressed() {
try {
return CompressorRegistry.uncompress(new BytesArray(bytes));
} catch (IOException e) {
throw new IllegalStateException("Cannot decompress compressed string", e);
}
}
public String string() {
return uncompressed().utf8ToString();
}
public static CompressedXContent readCompressedString(StreamInput in) throws IOException {
int crc32 = in.readInt();
return new CompressedXContent(in.readByteArray(), crc32);
}
public void writeTo(StreamOutput out) throws IOException {
out.writeInt(crc32);
out.writeByteArray(bytes);
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
CompressedXContent that = (CompressedXContent) o;
if (Arrays.equals(compressed(), that.compressed())) {
return true;
}
if (crc32 != that.crc32) {
return false;
}
return uncompressed().equals(that.uncompressed());
}
@Override
public int hashCode() {
return crc32;
}
@Override
public String toString() {
return string();
}
}