org.elasticsearch.common.compress.CompressedXContent 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.compress;
import org.apache.lucene.util.BytesRef;
import org.elasticsearch.common.bytes.BytesArray;
import org.elasticsearch.common.bytes.BytesReference;
import org.elasticsearch.common.io.stream.BytesStreamOutput;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.xcontent.ToXContent;
import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.common.xcontent.XContentFactory;
import org.elasticsearch.common.xcontent.XContentType;
import java.io.IOException;
import java.io.OutputStream;
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.
*/
public final class CompressedXContent {
private static int crc32(BytesReference data) {
OutputStream dummy = new OutputStream() {
@Override
public void write(int b) throws IOException {
// no-op
}
@Override
public void write(byte[] b, int off, int len) throws IOException {
// no-op
}
};
CRC32 crc32 = new CRC32();
try {
data.writeTo(new CheckedOutputStream(dummy, 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, XContentType type, ToXContent.Params params) throws IOException {
BytesStreamOutput bStream = new BytesStreamOutput();
OutputStream compressedStream = CompressorFactory.COMPRESSOR.streamOutput(bStream);
CRC32 crc32 = new CRC32();
OutputStream checkedStream = new CheckedOutputStream(compressedStream, crc32);
try (XContentBuilder builder = XContentFactory.contentBuilder(type, checkedStream)) {
builder.startObject();
xcontent.toXContent(builder, params);
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 = CompressorFactory.compressor(data);
if (compressor != null) {
// already compressed...
this.bytes = BytesReference.toBytes(data);
this.crc32 = crc32(new BytesArray(uncompressed()));
} else {
BytesStreamOutput out = new BytesStreamOutput();
try (OutputStream compressedOutput = CompressorFactory.COMPRESSOR.streamOutput(out)) {
data.writeTo(compressedOutput);
}
this.bytes = BytesReference.toBytes(out.bytes());
this.crc32 = crc32(data);
}
assertConsistent();
}
private void assertConsistent() {
assert CompressorFactory.compressor(new BytesArray(bytes)) != null;
assert this.crc32 == crc32(new BytesArray(uncompressed()));
}
public CompressedXContent(byte[] data) throws IOException {
this(new BytesArray(data));
}
public CompressedXContent(String str) throws IOException {
this(new BytesArray(new BytesRef(str)));
}
/** 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 byte[] uncompressed() {
try {
return BytesReference.toBytes(CompressorFactory.uncompress(new BytesArray(bytes)));
} catch (IOException e) {
throw new IllegalStateException("Cannot decompress compressed string", e);
}
}
public String string() {
return new BytesRef(uncompressed()).utf8ToString();
}
public static CompressedXContent readCompressedString(StreamInput in) throws IOException {
int crc32 = in.readInt();
byte[] compressed = new byte[in.readVInt()];
in.readBytes(compressed, 0, compressed.length);
return new CompressedXContent(compressed, crc32);
}
public void writeTo(StreamOutput out) throws IOException {
out.writeInt(crc32);
out.writeVInt(bytes.length);
out.writeBytes(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 Arrays.equals(uncompressed(), that.uncompressed());
}
@Override
public int hashCode() {
return crc32;
}
@Override
public String toString() {
return string();
}
}