/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with this
* work for additional information regarding copyright ownership. The ASF
* 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.apache.hadoop.hbase.io.encoding;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.CellUtil;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.KeyValue.KVComparator;
import org.apache.hadoop.hbase.KeyValueUtil;
import org.apache.hadoop.hbase.util.ByteBufferUtils;
import org.apache.hadoop.hbase.util.Bytes;
/**
* Compress key by storing size of common prefix with previous KeyValue
* and storing raw size of rest.
*
* Format:
* 1-5 bytes: compressed key length minus prefix (7-bit encoding)
* 1-5 bytes: compressed value length (7-bit encoding)
* 1-3 bytes: compressed length of common key prefix
* ... bytes: rest of key (including timestamp)
* ... bytes: value
*
* In a worst case compressed KeyValue will be three bytes longer than original.
*
*/
@InterfaceAudience.Private
public class PrefixKeyDeltaEncoder extends BufferedDataBlockEncoder {
@Override
public int internalEncode(Cell cell, HFileBlockDefaultEncodingContext encodingContext,
DataOutputStream out) throws IOException {
int klength = KeyValueUtil.keyLength(cell);
int vlength = cell.getValueLength();
EncodingState state = encodingContext.getEncodingState();
if (state.prevCell == null) {
// copy the key, there is no common prefix with none
ByteBufferUtils.putCompressedInt(out, klength);
ByteBufferUtils.putCompressedInt(out, vlength);
ByteBufferUtils.putCompressedInt(out, 0);
CellUtil.writeFlatKey(cell, out);
} else {
// find a common prefix and skip it
int common = CellUtil.findCommonPrefixInFlatKey(cell, state.prevCell, true, true);
ByteBufferUtils.putCompressedInt(out, klength - common);
ByteBufferUtils.putCompressedInt(out, vlength);
ByteBufferUtils.putCompressedInt(out, common);
writeKeyExcludingCommon(cell, common, out);
}
// Write the value part
out.write(cell.getValueArray(), cell.getValueOffset(), vlength);
int size = klength + vlength + KeyValue.KEYVALUE_INFRASTRUCTURE_SIZE;
size += afterEncodingKeyValue(cell, out, encodingContext);
state.prevCell = cell;
return size;
}
private void writeKeyExcludingCommon(Cell cell, int commonPrefix, DataOutputStream out)
throws IOException {
short rLen = cell.getRowLength();
if (commonPrefix < rLen + KeyValue.ROW_LENGTH_SIZE) {
// Previous and current rows are different. Need to write the differing part followed by
// cf,q,ts and type
CellUtil.writeRowKeyExcludingCommon(cell, rLen, commonPrefix, out);
byte fLen = cell.getFamilyLength();
out.writeByte(fLen);
out.write(cell.getFamilyArray(), cell.getFamilyOffset(), fLen);
out.write(cell.getQualifierArray(), cell.getQualifierOffset(), cell.getQualifierLength());
out.writeLong(cell.getTimestamp());
out.writeByte(cell.getTypeByte());
} else {
// The full row key part is common. CF part will be common for sure as we deal with Cells in
// same family. Just need write the differing part in q, ts and type
commonPrefix = commonPrefix - (rLen + KeyValue.ROW_LENGTH_SIZE)
- (cell.getFamilyLength() + KeyValue.FAMILY_LENGTH_SIZE);
int qLen = cell.getQualifierLength();
int commonQualPrefix = Math.min(commonPrefix, qLen);
int qualPartLenToWrite = qLen - commonQualPrefix;
if (qualPartLenToWrite > 0) {
out.write(cell.getQualifierArray(), cell.getQualifierOffset() + commonQualPrefix,
qualPartLenToWrite);
}
commonPrefix -= commonQualPrefix;
// Common part in TS also?
if (commonPrefix > 0) {
int commonTimestampPrefix = Math.min(commonPrefix, KeyValue.TIMESTAMP_SIZE);
if (commonTimestampPrefix < KeyValue.TIMESTAMP_SIZE) {
byte[] curTsBuf = Bytes.toBytes(cell.getTimestamp());
out.write(curTsBuf, commonTimestampPrefix, KeyValue.TIMESTAMP_SIZE
- commonTimestampPrefix);
}
commonPrefix -= commonTimestampPrefix;
if (commonPrefix == 0) {
out.writeByte(cell.getTypeByte());
}
} else {
out.writeLong(cell.getTimestamp());
out.writeByte(cell.getTypeByte());
}
}
}
@Override
protected ByteBuffer internalDecodeKeyValues(DataInputStream source, int allocateHeaderLength,
int skipLastBytes, HFileBlockDefaultDecodingContext decodingCtx) throws IOException {
int decompressedSize = source.readInt();
ByteBuffer buffer = ByteBuffer.allocate(decompressedSize +
allocateHeaderLength);
buffer.position(allocateHeaderLength);
int prevKeyOffset = 0;
while (source.available() > skipLastBytes) {
prevKeyOffset = decodeKeyValue(source, buffer, prevKeyOffset);
afterDecodingKeyValue(source, buffer, decodingCtx);
}
if (source.available() != skipLastBytes) {
throw new IllegalStateException("Read too many bytes.");
}
buffer.limit(buffer.position());
return buffer;
}
private int decodeKeyValue(DataInputStream source, ByteBuffer buffer,
int prevKeyOffset)
throws IOException, EncoderBufferTooSmallException {
int keyLength = ByteBufferUtils.readCompressedInt(source);
int valueLength = ByteBufferUtils.readCompressedInt(source);
int commonLength = ByteBufferUtils.readCompressedInt(source);
int keyOffset;
keyLength += commonLength;
ensureSpace(buffer, keyLength + valueLength + KeyValue.ROW_OFFSET);
buffer.putInt(keyLength);
buffer.putInt(valueLength);
// copy the prefix
if (commonLength > 0) {
keyOffset = buffer.position();
ByteBufferUtils.copyFromBufferToBuffer(buffer, buffer, prevKeyOffset,
commonLength);
} else {
keyOffset = buffer.position();
}
// copy rest of the key and value
int len = keyLength - commonLength + valueLength;
ByteBufferUtils.copyFromStreamToBuffer(buffer, source, len);
return keyOffset;
}
@Override
public ByteBuffer getFirstKeyInBlock(ByteBuffer block) {
block.mark();
block.position(Bytes.SIZEOF_INT);
int keyLength = ByteBufferUtils.readCompressedInt(block);
ByteBufferUtils.readCompressedInt(block);
int commonLength = ByteBufferUtils.readCompressedInt(block);
if (commonLength != 0) {
throw new AssertionError("Nonzero common length in the first key in "
+ "block: " + commonLength);
}
int pos = block.position();
block.reset();
ByteBuffer dup = block.duplicate();
dup.position(pos);
dup.limit(pos + keyLength);
return dup.slice();
}
@Override
public String toString() {
return PrefixKeyDeltaEncoder.class.getSimpleName();
}
@Override
public EncodedSeeker createSeeker(KVComparator comparator,
final HFileBlockDecodingContext decodingCtx) {
return new BufferedEncodedSeeker<SeekerState>(comparator, decodingCtx) {
@Override
protected void decodeNext() {
current.keyLength = ByteBufferUtils.readCompressedInt(currentBuffer);
current.valueLength = ByteBufferUtils.readCompressedInt(currentBuffer);
current.lastCommonPrefix =
ByteBufferUtils.readCompressedInt(currentBuffer);
current.keyLength += current.lastCommonPrefix;
current.ensureSpaceForKey();
currentBuffer.get(current.keyBuffer, current.lastCommonPrefix,
current.keyLength - current.lastCommonPrefix);
current.valueOffset = currentBuffer.position();
ByteBufferUtils.skip(currentBuffer, current.valueLength);
if (includesTags()) {
decodeTags();
}
if (includesMvcc()) {
current.memstoreTS = ByteBufferUtils.readVLong(currentBuffer);
} else {
current.memstoreTS = 0;
}
current.nextKvOffset = currentBuffer.position();
}
@Override
protected void decodeFirst() {
ByteBufferUtils.skip(currentBuffer, Bytes.SIZEOF_INT);
decodeNext();
}
};
}
}