/*
* 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.io.OutputStream;
import java.nio.ByteBuffer;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.util.ByteBufferUtils;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.io.RawComparator;
/**
* Encoder similar to {@link DiffKeyDeltaEncoder} but supposedly faster.
*
* Compress using:
* - store size of common prefix
* - save column family once in the first KeyValue
* - use integer compression for key, value and prefix (7-bit encoding)
* - use bits to avoid duplication key length, value length
* and type if it same as previous
* - store in 3 bits length of prefix timestamp
* with previous KeyValue's timestamp
* - one bit which allow to omit value if it is the same
*
* Format:
* - 1 byte: flag
* - 1-5 bytes: key length (only if FLAG_SAME_KEY_LENGTH is not set in flag)
* - 1-5 bytes: value length (only if FLAG_SAME_VALUE_LENGTH is not set in flag)
* - 1-5 bytes: prefix length
* - ... bytes: rest of the row (if prefix length is small enough)
* - ... bytes: qualifier (or suffix depending on prefix length)
* - 1-8 bytes: timestamp suffix
* - 1 byte: type (only if FLAG_SAME_TYPE is not set in the flag)
* - ... bytes: value (only if FLAG_SAME_VALUE is not set in the flag)
*
*/
@InterfaceAudience.Private
public class FastDiffDeltaEncoder extends BufferedDataBlockEncoder {
final int MASK_TIMESTAMP_LENGTH = (1 << 0) | (1 << 1) | (1 << 2);
final int SHIFT_TIMESTAMP_LENGTH = 0;
final int FLAG_SAME_KEY_LENGTH = 1 << 3;
final int FLAG_SAME_VALUE_LENGTH = 1 << 4;
final int FLAG_SAME_TYPE = 1 << 5;
final int FLAG_SAME_VALUE = 1 << 6;
private static class FastDiffCompressionState extends CompressionState {
byte[] timestamp = new byte[KeyValue.TIMESTAMP_SIZE];
int prevTimestampOffset;
@Override
protected void readTimestamp(ByteBuffer in) {
in.get(timestamp);
}
@Override
void copyFrom(CompressionState state) {
super.copyFrom(state);
FastDiffCompressionState state2 = (FastDiffCompressionState) state;
System.arraycopy(state2.timestamp, 0, timestamp, 0,
KeyValue.TIMESTAMP_SIZE);
prevTimestampOffset = state2.prevTimestampOffset;
}
/**
* Copies the first key/value from the given stream, and initializes
* decompression state based on it. Assumes that we have already read key
* and value lengths. Does not set {@link #qualifierLength} (not used by
* decompression) or {@link #prevOffset} (set by the calle afterwards).
*/
private void decompressFirstKV(ByteBuffer out, DataInputStream in)
throws IOException {
int kvPos = out.position();
out.putInt(keyLength);
out.putInt(valueLength);
prevTimestampOffset = out.position() + keyLength -
KeyValue.TIMESTAMP_TYPE_SIZE;
ByteBufferUtils.copyFromStreamToBuffer(out, in, keyLength + valueLength);
rowLength = out.getShort(kvPos + KeyValue.ROW_OFFSET);
familyLength = out.get(kvPos + KeyValue.ROW_OFFSET +
KeyValue.ROW_LENGTH_SIZE + rowLength);
type = out.get(prevTimestampOffset + KeyValue.TIMESTAMP_SIZE);
}
}
private void compressSingleKeyValue(
FastDiffCompressionState previousState,
FastDiffCompressionState currentState,
OutputStream out, ByteBuffer in) throws IOException {
currentState.prevOffset = in.position();
int keyLength = in.getInt();
int valueOffset =
currentState.prevOffset + keyLength + KeyValue.ROW_OFFSET;
int valueLength = in.getInt();
byte flag = 0;
if (previousState.isFirst()) {
// copy the key, there is no common prefix with none
out.write(flag);
ByteBufferUtils.putCompressedInt(out, keyLength);
ByteBufferUtils.putCompressedInt(out, valueLength);
ByteBufferUtils.putCompressedInt(out, 0);
currentState.readKey(in, keyLength, valueLength);
ByteBufferUtils.moveBufferToStream(out, in, keyLength + valueLength);
} else {
// find a common prefix and skip it
int commonPrefix = ByteBufferUtils.findCommonPrefix(in, in.position(),
previousState.prevOffset + KeyValue.ROW_OFFSET,
Math.min(keyLength, previousState.keyLength) -
KeyValue.TIMESTAMP_TYPE_SIZE);
currentState.readKey(in, keyLength, valueLength,
commonPrefix, previousState);
if (keyLength == previousState.keyLength) {
flag |= FLAG_SAME_KEY_LENGTH;
}
if (valueLength == previousState.valueLength) {
flag |= FLAG_SAME_VALUE_LENGTH;
}
if (currentState.type == previousState.type) {
flag |= FLAG_SAME_TYPE;
}
int commonTimestampPrefix = findCommonTimestampPrefix(
currentState, previousState);
flag |= commonTimestampPrefix << SHIFT_TIMESTAMP_LENGTH;
// Check if current and previous values are the same. Compare value
// length first as an optimization.
if (valueLength == previousState.valueLength) {
int previousValueOffset = previousState.prevOffset
+ previousState.keyLength + KeyValue.ROW_OFFSET;
if (ByteBufferUtils.arePartsEqual(in,
previousValueOffset, previousState.valueLength,
valueOffset, valueLength)) {
flag |= FLAG_SAME_VALUE;
}
}
out.write(flag);
if ((flag & FLAG_SAME_KEY_LENGTH) == 0) {
ByteBufferUtils.putCompressedInt(out, keyLength);
}
if ((flag & FLAG_SAME_VALUE_LENGTH) == 0) {
ByteBufferUtils.putCompressedInt(out, valueLength);
}
ByteBufferUtils.putCompressedInt(out, commonPrefix);
ByteBufferUtils.skip(in, commonPrefix);
if (commonPrefix < currentState.rowLength + KeyValue.ROW_LENGTH_SIZE) {
// Previous and current rows are different. Copy the differing part of
// the row, skip the column family, and copy the qualifier.
ByteBufferUtils.moveBufferToStream(out, in,
currentState.rowLength + KeyValue.ROW_LENGTH_SIZE - commonPrefix);
ByteBufferUtils.skip(in, currentState.familyLength +
KeyValue.FAMILY_LENGTH_SIZE);
ByteBufferUtils.moveBufferToStream(out, in,
currentState.qualifierLength);
} else {
// The common part includes the whole row. As the column family is the
// same across the whole file, it will automatically be included in the
// common prefix, so we need not special-case it here.
int restKeyLength = keyLength - commonPrefix -
KeyValue.TIMESTAMP_TYPE_SIZE;
ByteBufferUtils.moveBufferToStream(out, in, restKeyLength);
}
ByteBufferUtils.skip(in, commonTimestampPrefix);
ByteBufferUtils.moveBufferToStream(out, in,
KeyValue.TIMESTAMP_SIZE - commonTimestampPrefix);
// Write the type if it is not the same as before.
if ((flag & FLAG_SAME_TYPE) == 0) {
out.write(currentState.type);
}
// Write the value if it is not the same as before.
if ((flag & FLAG_SAME_VALUE) == 0) {
ByteBufferUtils.copyBufferToStream(out, in, valueOffset, valueLength);
}
// Skip key type and value in the input buffer.
ByteBufferUtils.skip(in, KeyValue.TYPE_SIZE + currentState.valueLength);
}
}
private int findCommonTimestampPrefix(FastDiffCompressionState left,
FastDiffCompressionState right) {
int prefixTimestamp = 0;
while (prefixTimestamp < (KeyValue.TIMESTAMP_SIZE - 1) &&
left.timestamp[prefixTimestamp]
== right.timestamp[prefixTimestamp]) {
prefixTimestamp++;
}
return prefixTimestamp; // has to be at most 7 bytes
}
private void uncompressSingleKeyValue(DataInputStream source,
ByteBuffer out, FastDiffCompressionState state)
throws IOException, EncoderBufferTooSmallException {
byte flag = source.readByte();
int prevKeyLength = state.keyLength;
if ((flag & FLAG_SAME_KEY_LENGTH) == 0) {
state.keyLength = ByteBufferUtils.readCompressedInt(source);
}
if ((flag & FLAG_SAME_VALUE_LENGTH) == 0) {
state.valueLength = ByteBufferUtils.readCompressedInt(source);
}
int commonLength = ByteBufferUtils.readCompressedInt(source);
ensureSpace(out, state.keyLength + state.valueLength + KeyValue.ROW_OFFSET);
int kvPos = out.position();
if (!state.isFirst()) {
// copy the prefix
int common;
int prevOffset;
if ((flag & FLAG_SAME_VALUE_LENGTH) == 0) {
out.putInt(state.keyLength);
out.putInt(state.valueLength);
prevOffset = state.prevOffset + KeyValue.ROW_OFFSET;
common = commonLength;
} else {
if ((flag & FLAG_SAME_KEY_LENGTH) != 0) {
prevOffset = state.prevOffset;
common = commonLength + KeyValue.ROW_OFFSET;
} else {
out.putInt(state.keyLength);
prevOffset = state.prevOffset + KeyValue.KEY_LENGTH_SIZE;
common = commonLength + KeyValue.KEY_LENGTH_SIZE;
}
}
ByteBufferUtils.copyFromBufferToBuffer(out, out, prevOffset, common);
// copy the rest of the key from the buffer
int keyRestLength;
if (commonLength < state.rowLength + KeyValue.ROW_LENGTH_SIZE) {
// omit the family part of the key, it is always the same
int rowWithSizeLength;
int rowRestLength;
// check length of row
if (commonLength < KeyValue.ROW_LENGTH_SIZE) {
// not yet copied, do it now
ByteBufferUtils.copyFromStreamToBuffer(out, source,
KeyValue.ROW_LENGTH_SIZE - commonLength);
rowWithSizeLength = out.getShort(out.position() -
KeyValue.ROW_LENGTH_SIZE) + KeyValue.ROW_LENGTH_SIZE;
rowRestLength = rowWithSizeLength - KeyValue.ROW_LENGTH_SIZE;
} else {
// already in kvBuffer, just read it
rowWithSizeLength = out.getShort(kvPos + KeyValue.ROW_OFFSET) +
KeyValue.ROW_LENGTH_SIZE;
rowRestLength = rowWithSizeLength - commonLength;
}
// copy the rest of row
ByteBufferUtils.copyFromStreamToBuffer(out, source, rowRestLength);
// copy the column family
ByteBufferUtils.copyFromBufferToBuffer(out, out,
state.prevOffset + KeyValue.ROW_OFFSET + KeyValue.ROW_LENGTH_SIZE
+ state.rowLength, state.familyLength
+ KeyValue.FAMILY_LENGTH_SIZE);
state.rowLength = (short) (rowWithSizeLength -
KeyValue.ROW_LENGTH_SIZE);
keyRestLength = state.keyLength - rowWithSizeLength -
state.familyLength -
(KeyValue.FAMILY_LENGTH_SIZE + KeyValue.TIMESTAMP_TYPE_SIZE);
} else {
// prevRowWithSizeLength is the same as on previous row
keyRestLength = state.keyLength - commonLength -
KeyValue.TIMESTAMP_TYPE_SIZE;
}
// copy the rest of the key, after column family == column qualifier
ByteBufferUtils.copyFromStreamToBuffer(out, source, keyRestLength);
// copy timestamp
int prefixTimestamp =
(flag & MASK_TIMESTAMP_LENGTH) >>> SHIFT_TIMESTAMP_LENGTH;
ByteBufferUtils.copyFromBufferToBuffer(out, out,
state.prevTimestampOffset, prefixTimestamp);
state.prevTimestampOffset = out.position() - prefixTimestamp;
ByteBufferUtils.copyFromStreamToBuffer(out, source,
KeyValue.TIMESTAMP_SIZE - prefixTimestamp);
// copy the type and value
if ((flag & FLAG_SAME_TYPE) != 0) {
out.put(state.type);
if ((flag & FLAG_SAME_VALUE) != 0) {
ByteBufferUtils.copyFromBufferToBuffer(out, out, state.prevOffset +
KeyValue.ROW_OFFSET + prevKeyLength, state.valueLength);
} else {
ByteBufferUtils.copyFromStreamToBuffer(out, source,
state.valueLength);
}
} else {
if ((flag & FLAG_SAME_VALUE) != 0) {
ByteBufferUtils.copyFromStreamToBuffer(out, source,
KeyValue.TYPE_SIZE);
ByteBufferUtils.copyFromBufferToBuffer(out, out, state.prevOffset +
KeyValue.ROW_OFFSET + prevKeyLength, state.valueLength);
} else {
ByteBufferUtils.copyFromStreamToBuffer(out, source,
state.valueLength + KeyValue.TYPE_SIZE);
}
state.type = out.get(state.prevTimestampOffset +
KeyValue.TIMESTAMP_SIZE);
}
} else { // this is the first element
state.decompressFirstKV(out, source);
}
state.prevOffset = kvPos;
}
@Override
public void internalEncodeKeyValues(DataOutputStream out,
ByteBuffer in, boolean includesMemstoreTS) throws IOException {
in.rewind();
ByteBufferUtils.putInt(out, in.limit());
FastDiffCompressionState previousState = new FastDiffCompressionState();
FastDiffCompressionState currentState = new FastDiffCompressionState();
while (in.hasRemaining()) {
compressSingleKeyValue(previousState, currentState,
out, in);
afterEncodingKeyValue(in, out, includesMemstoreTS);
// swap previousState <-> currentState
FastDiffCompressionState tmp = previousState;
previousState = currentState;
currentState = tmp;
}
}
@Override
public ByteBuffer decodeKeyValues(DataInputStream source,
int allocHeaderLength, int skipLastBytes, boolean includesMemstoreTS)
throws IOException {
int decompressedSize = source.readInt();
ByteBuffer buffer = ByteBuffer.allocate(decompressedSize +
allocHeaderLength);
buffer.position(allocHeaderLength);
FastDiffCompressionState state = new FastDiffCompressionState();
while (source.available() > skipLastBytes) {
uncompressSingleKeyValue(source, buffer, state);
afterDecodingKeyValue(source, buffer, includesMemstoreTS);
}
if (source.available() != skipLastBytes) {
throw new IllegalStateException("Read too much bytes.");
}
return buffer;
}
@Override
public ByteBuffer getFirstKeyInBlock(ByteBuffer block) {
block.mark();
block.position(Bytes.SIZEOF_INT + Bytes.SIZEOF_BYTE);
int keyLength = ByteBufferUtils.readCompressedInt(block);
ByteBufferUtils.readCompressedInt(block); // valueLength
ByteBufferUtils.readCompressedInt(block); // commonLength
int pos = block.position();
block.reset();
return ByteBuffer.wrap(block.array(), pos, keyLength).slice();
}
@Override
public String toString() {
return FastDiffDeltaEncoder.class.getSimpleName();
}
protected static class FastDiffSeekerState extends SeekerState {
private byte[] prevTimestampAndType =
new byte[KeyValue.TIMESTAMP_TYPE_SIZE];
private int rowLengthWithSize;
private int familyLengthWithSize;
@Override
protected void copyFromNext(SeekerState that) {
super.copyFromNext(that);
FastDiffSeekerState other = (FastDiffSeekerState) that;
System.arraycopy(other.prevTimestampAndType, 0,
prevTimestampAndType, 0,
KeyValue.TIMESTAMP_TYPE_SIZE);
rowLengthWithSize = other.rowLengthWithSize;
familyLengthWithSize = other.familyLengthWithSize;
}
}
@Override
public EncodedSeeker createSeeker(RawComparator<byte[]> comparator,
final boolean includesMemstoreTS) {
return new BufferedEncodedSeeker<FastDiffSeekerState>(comparator) {
private void decode(boolean isFirst) {
byte flag = currentBuffer.get();
if ((flag & FLAG_SAME_KEY_LENGTH) == 0) {
if (!isFirst) {
System.arraycopy(current.keyBuffer,
current.keyLength - current.prevTimestampAndType.length,
current.prevTimestampAndType, 0,
current.prevTimestampAndType.length);
}
current.keyLength = ByteBufferUtils.readCompressedInt(currentBuffer);
}
if ((flag & FLAG_SAME_VALUE_LENGTH) == 0) {
current.valueLength =
ByteBufferUtils.readCompressedInt(currentBuffer);
}
current.lastCommonPrefix =
ByteBufferUtils.readCompressedInt(currentBuffer);
current.ensureSpaceForKey();
if (isFirst) {
// copy everything
currentBuffer.get(current.keyBuffer, current.lastCommonPrefix,
current.keyLength - current.prevTimestampAndType.length);
current.rowLengthWithSize = Bytes.toShort(current.keyBuffer, 0) +
Bytes.SIZEOF_SHORT;
current.familyLengthWithSize =
current.keyBuffer[current.rowLengthWithSize] + Bytes.SIZEOF_BYTE;
} else if (current.lastCommonPrefix < Bytes.SIZEOF_SHORT) {
// length of row is different, copy everything except family
// copy the row size
int oldRowLengthWithSize = current.rowLengthWithSize;
currentBuffer.get(current.keyBuffer, current.lastCommonPrefix,
Bytes.SIZEOF_SHORT - current.lastCommonPrefix);
current.rowLengthWithSize = Bytes.toShort(current.keyBuffer, 0) +
Bytes.SIZEOF_SHORT;
// move the column family
System.arraycopy(current.keyBuffer, oldRowLengthWithSize,
current.keyBuffer, current.rowLengthWithSize,
current.familyLengthWithSize);
// copy the rest of row
currentBuffer.get(current.keyBuffer, Bytes.SIZEOF_SHORT,
current.rowLengthWithSize - Bytes.SIZEOF_SHORT);
// copy the qualifier
currentBuffer.get(current.keyBuffer, current.rowLengthWithSize
+ current.familyLengthWithSize, current.keyLength
- current.rowLengthWithSize - current.familyLengthWithSize
- current.prevTimestampAndType.length);
} else if (current.lastCommonPrefix < current.rowLengthWithSize) {
// We have to copy part of row and qualifier, but the column family
// is in the right place.
// before column family (rest of row)
currentBuffer.get(current.keyBuffer, current.lastCommonPrefix,
current.rowLengthWithSize - current.lastCommonPrefix);
// after column family (qualifier)
currentBuffer.get(current.keyBuffer, current.rowLengthWithSize
+ current.familyLengthWithSize, current.keyLength
- current.rowLengthWithSize - current.familyLengthWithSize
- current.prevTimestampAndType.length);
} else {
// copy just the ending
currentBuffer.get(current.keyBuffer, current.lastCommonPrefix,
current.keyLength - current.prevTimestampAndType.length
- current.lastCommonPrefix);
}
// timestamp
int pos = current.keyLength - current.prevTimestampAndType.length;
int commonTimestampPrefix = (flag & MASK_TIMESTAMP_LENGTH) >>>
SHIFT_TIMESTAMP_LENGTH;
if ((flag & FLAG_SAME_KEY_LENGTH) == 0) {
System.arraycopy(current.prevTimestampAndType, 0, current.keyBuffer,
pos, commonTimestampPrefix);
}
pos += commonTimestampPrefix;
currentBuffer.get(current.keyBuffer, pos,
Bytes.SIZEOF_LONG - commonTimestampPrefix);
pos += Bytes.SIZEOF_LONG - commonTimestampPrefix;
// type
if ((flag & FLAG_SAME_TYPE) == 0) {
currentBuffer.get(current.keyBuffer, pos, Bytes.SIZEOF_BYTE);
} else if ((flag & FLAG_SAME_KEY_LENGTH) == 0) {
current.keyBuffer[pos] =
current.prevTimestampAndType[Bytes.SIZEOF_LONG];
}
// handle value
if ((flag & FLAG_SAME_VALUE) == 0) {
current.valueOffset = currentBuffer.position();
ByteBufferUtils.skip(currentBuffer, current.valueLength);
}
if (includesMemstoreTS) {
current.memstoreTS = ByteBufferUtils.readVLong(currentBuffer);
} else {
current.memstoreTS = 0;
}
current.nextKvOffset = currentBuffer.position();
}
@Override
protected void decodeFirst() {
ByteBufferUtils.skip(currentBuffer, Bytes.SIZEOF_INT);
decode(true);
}
@Override
protected void decodeNext() {
decode(false);
}
@Override
protected FastDiffSeekerState createSeekerState() {
return new FastDiffSeekerState();
}
};
}
}