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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.transport;
import org.elasticsearch.core.internal.io.IOUtils;
import org.elasticsearch.common.bytes.BytesReference;
import org.elasticsearch.common.compress.CompressorFactory;
import org.elasticsearch.common.io.Streams;
import org.elasticsearch.common.io.stream.BytesStream;
import org.elasticsearch.common.io.stream.StreamOutput;
import java.io.IOException;
import java.util.zip.DeflaterOutputStream;
/**
* This class exists to provide a stream with optional compression. This is useful as using compression
* requires that the underlying {@link DeflaterOutputStream} be closed to write EOS bytes. However, the
* {@link BytesStream} should not be closed yet, as we have not used the bytes. This class handles these
* intricacies.
*
* {@link CompressibleBytesOutputStream#materializeBytes()} should be called when all the bytes have been
* written to this stream. If compression is enabled, the proper EOS bytes will be written at that point.
* The underlying {@link BytesReference} will be returned.
*
* {@link CompressibleBytesOutputStream#close()} will NOT close the underlying stream. The byte stream passed
* in the constructor must be closed individually.
*/
final class CompressibleBytesOutputStream extends StreamOutput {
private final StreamOutput stream;
private final BytesStream bytesStreamOutput;
private final boolean shouldCompress;
CompressibleBytesOutputStream(BytesStream bytesStreamOutput, boolean shouldCompress) throws IOException {
this.bytesStreamOutput = bytesStreamOutput;
this.shouldCompress = shouldCompress;
if (shouldCompress) {
this.stream = CompressorFactory.COMPRESSOR.streamOutput(Streams.flushOnCloseStream(bytesStreamOutput));
} else {
this.stream = bytesStreamOutput;
}
}
/**
* This method ensures that compression is complete and returns the underlying bytes.
*
* @return bytes underlying the stream
* @throws IOException if an exception occurs when writing or flushing
*/
BytesReference materializeBytes() throws IOException {
// If we are using compression the stream needs to be closed to ensure that EOS marker bytes are written.
// The actual ReleasableBytesStreamOutput will not be closed yet as it is wrapped in flushOnCloseStream when
// passed to the deflater stream.
if (shouldCompress) {
stream.close();
}
return bytesStreamOutput.bytes();
}
@Override
public void writeByte(byte b) throws IOException {
stream.write(b);
}
@Override
public void writeBytes(byte[] b, int offset, int length) throws IOException {
stream.writeBytes(b, offset, length);
}
@Override
public void flush() throws IOException {
stream.flush();
}
@Override
public void close() throws IOException {
if (stream != bytesStreamOutput) {
assert shouldCompress : "If the streams are different we should be compressing";
IOUtils.close(stream);
}
}
@Override
public void reset() throws IOException {
throw new UnsupportedOperationException();
}
}