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/*
* Copyright (C) 2017, Google Inc. and others
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0 which is available at
* https://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.eclipse.jgit.internal.storage.reftable;
import static java.nio.charset.StandardCharsets.UTF_8;
import static org.eclipse.jgit.internal.storage.reftable.ReftableConstants.FILE_HEADER_LEN;
import static org.eclipse.jgit.internal.storage.reftable.ReftableConstants.INDEX_BLOCK_TYPE;
import static org.eclipse.jgit.internal.storage.reftable.ReftableConstants.LOG_BLOCK_TYPE;
import static org.eclipse.jgit.lib.Constants.OBJECT_ID_LENGTH;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.zip.Deflater;
import java.util.zip.DeflaterOutputStream;
import org.eclipse.jgit.internal.JGitText;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.util.NB;
import org.eclipse.jgit.util.io.CountingOutputStream;
/**
* Wrapper to assist formatting a reftable to an {@link OutputStream}.
* <p>
* Internally buffers at block size boundaries, flushing only complete blocks to
* the {@code OutputStream}.
*/
class ReftableOutputStream extends OutputStream {
private final byte[] tmp = new byte[10];
private final CountingOutputStream out;
private final boolean alignBlocks;
private Deflater deflater;
private DeflaterOutputStream compressor;
private int blockType;
private int blockSize;
private int blockStart;
private byte[] blockBuf;
private int cur;
private long paddingUsed;
ReftableOutputStream(OutputStream os, int bs, boolean align) {
blockSize = bs;
blockBuf = new byte[bs];
alignBlocks = align;
out = new CountingOutputStream(os);
}
void setBlockSize(int bs) {
blockSize = bs;
}
@Override
public void write(int b) {
ensureBytesAvailableInBlockBuf(1);
blockBuf[cur++] = (byte) b;
}
@Override
public void write(byte[] b, int off, int cnt) {
ensureBytesAvailableInBlockBuf(cnt);
System.arraycopy(b, off, blockBuf, cur, cnt);
cur += cnt;
}
int bytesWrittenInBlock() {
return cur;
}
int bytesAvailableInBlock() {
return blockSize - cur;
}
long paddingUsed() {
return paddingUsed;
}
/**
* Get size
*
* @return bytes flushed; excludes {@link #bytesWrittenInBlock()}.
*/
long size() {
return out.getCount();
}
static int computeVarintSize(long val) {
int n = 1;
for (; (val >>>= 7) != 0; n++) {
val--;
}
return n;
}
void writeVarint(long val) {
int n = tmp.length;
tmp[--n] = (byte) (val & 0x7f);
while ((val >>>= 7) != 0) {
tmp[--n] = (byte) (0x80 | (--val & 0x7F));
}
write(tmp, n, tmp.length - n);
}
void writeInt16(int val) {
ensureBytesAvailableInBlockBuf(2);
NB.encodeInt16(blockBuf, cur, val);
cur += 2;
}
void writeInt24(int val) {
ensureBytesAvailableInBlockBuf(3);
NB.encodeInt24(blockBuf, cur, val);
cur += 3;
}
void writeId(ObjectId id) {
ensureBytesAvailableInBlockBuf(OBJECT_ID_LENGTH);
id.copyRawTo(blockBuf, cur);
cur += OBJECT_ID_LENGTH;
}
void writeVarintString(String s) {
writeVarintString(s.getBytes(UTF_8));
}
void writeVarintString(byte[] msg) {
writeVarint(msg.length);
write(msg, 0, msg.length);
}
private void ensureBytesAvailableInBlockBuf(int cnt) {
if (cur + cnt > blockBuf.length) {
int n = Math.max(cur + cnt, blockBuf.length * 2);
blockBuf = Arrays.copyOf(blockBuf, n);
}
}
void flushFileHeader() throws IOException {
if (cur == FILE_HEADER_LEN && out.getCount() == 0) {
out.write(blockBuf, 0, cur);
cur = 0;
}
}
void beginBlock(byte type) {
blockType = type;
blockStart = cur;
cur += 4; // reserve space for 4-byte block header.
}
void flushBlock() throws IOException {
if (cur > blockSize && blockType != INDEX_BLOCK_TYPE) {
throw new IOException(JGitText.get().overflowedReftableBlock);
}
NB.encodeInt32(blockBuf, blockStart, (blockType << 24) | cur);
if (blockType == LOG_BLOCK_TYPE) {
// Log blocks are deflated after the block header.
out.write(blockBuf, 0, 4);
if (deflater != null) {
deflater.reset();
} else {
deflater = new Deflater(Deflater.BEST_COMPRESSION);
compressor = new DeflaterOutputStream(out, deflater);
}
compressor.write(blockBuf, 4, cur - 4);
compressor.finish();
} else {
// Other blocks are uncompressed.
out.write(blockBuf, 0, cur);
}
cur = 0;
blockType = 0;
blockStart = 0;
}
void padBetweenBlocksToNextBlock() throws IOException {
if (alignBlocks) {
long m = size() % blockSize;
if (m > 0) {
int pad = blockSize - (int) m;
ensureBytesAvailableInBlockBuf(pad);
Arrays.fill(blockBuf, 0, pad, (byte) 0);
out.write(blockBuf, 0, pad);
paddingUsed += pad;
}
}
}
int estimatePadBetweenBlocks(int currentBlockSize) {
if (alignBlocks) {
long m = (size() + currentBlockSize) % blockSize;
return m > 0 ? blockSize - (int) m : 0;
}
return 0;
}
void finishFile() throws IOException {
// File footer doesn't need patching for the block start.
// Just flush what has been buffered.
out.write(blockBuf, 0, cur);
cur = 0;
if (deflater != null) {
deflater.end();
}
}
}
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