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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.vespa.hosted.node.admin.maintenance.sync;
import com.yahoo.compress.ZstdCompressor;
import java.io.IOException;
import java.io.InputStream;
/**
* InputStream that outputs given InputStream compressed with the ZStandard.
*
* @author freva
*/
public class ZstdCompressingInputStream extends InputStream {
public static final int DEFAULT_INPUT_BUFFER_SIZE = 8 * 1024;
static final ZstdCompressor compressor = new ZstdCompressor();
private final InputStream is;
private final byte[] inputBuffer;
private final byte[] outputBuffer;
private boolean firstRead = true;
private boolean eof = false;
private int outputPosition = 0;
private int outputLength = 0;
private boolean isClosed = false;
public ZstdCompressingInputStream(InputStream is, int inputBufferSize) {
this.is = is;
this.inputBuffer = new byte[inputBufferSize];
this.outputBuffer = new byte[ZstdCompressor.getMaxCompressedLength(inputBufferSize)];
}
public ZstdCompressingInputStream(InputStream is) {
this(is, DEFAULT_INPUT_BUFFER_SIZE);
}
@Override
public int read() throws IOException {
throwIfClosed();
if (outputPosition >= outputLength) {
int readLength = eof ? -1 : is.read(inputBuffer);
if (readLength == -1) {
if (!firstRead)
return -1;
// zstd compressing an empty file results in a 13 bytes file.
eof = true;
readLength = 0;
}
firstRead = false;
outputLength = compressor.compress(inputBuffer, 0, readLength, outputBuffer, 0, outputBuffer.length);
outputPosition = 0;
}
return Byte.toUnsignedInt(outputBuffer[outputPosition++]);
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
int first = read();
if (first == -1) return -1;
b[off++] = (byte) first;
len = Math.min(Math.min(len, outputLength - outputPosition), b.length - off);
System.arraycopy(outputBuffer, outputPosition, b, off, len);
outputPosition += len;
return len + 1;
}
@Override
public void close() throws IOException {
throwIfClosed();
is.close();
isClosed = true;
}
private void throwIfClosed() {
if (isClosed) throw new IllegalArgumentException("Input stream is already closed");
}
}
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