| /* |
| * 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.iotdb.tsfile.encoding.decoder; |
| |
| import org.apache.iotdb.tsfile.encoding.encoder.DeltaBinaryEncoder; |
| import org.apache.iotdb.tsfile.file.metadata.enums.TSEncoding; |
| import org.apache.iotdb.tsfile.utils.BytesUtils; |
| import org.apache.iotdb.tsfile.utils.ReadWriteIOUtils; |
| |
| import java.io.IOException; |
| import java.nio.ByteBuffer; |
| |
| /** |
| * This class is a decoder for decoding the byte array that encoded by {@code |
| * DeltaBinaryEncoder}.DeltaBinaryDecoder just supports integer and long values.<br> |
| * . |
| * |
| * @see DeltaBinaryEncoder |
| */ |
| public abstract class DeltaBinaryDecoder extends Decoder { |
| |
| protected long count = 0; |
| protected byte[] deltaBuf; |
| |
| /** the first value in one pack. */ |
| protected int readIntTotalCount = 0; |
| |
| protected int nextReadIndex = 0; |
| /** max bit length of all value in a pack. */ |
| protected int packWidth; |
| /** data number in this pack. */ |
| protected int packNum; |
| |
| /** how many bytes data takes after encoding. */ |
| protected int encodingLength; |
| |
| public DeltaBinaryDecoder() { |
| super(TSEncoding.TS_2DIFF); |
| } |
| |
| protected abstract void readHeader(ByteBuffer buffer) throws IOException; |
| |
| protected abstract void allocateDataArray(); |
| |
| protected abstract void readValue(int i); |
| |
| /** |
| * calculate the bytes length containing v bits. |
| * |
| * @param v - number of bits |
| * @return number of bytes |
| */ |
| protected int ceil(int v) { |
| return (int) Math.ceil((double) (v) / 8.0); |
| } |
| |
| @Override |
| public boolean hasNext(ByteBuffer buffer) throws IOException { |
| return (nextReadIndex < readIntTotalCount) || buffer.remaining() > 0; |
| } |
| |
| public static class IntDeltaDecoder extends DeltaBinaryDecoder { |
| |
| private int firstValue; |
| private int[] data; |
| private int previous; |
| /** minimum value for all difference. */ |
| private int minDeltaBase; |
| |
| public IntDeltaDecoder() { |
| super(); |
| } |
| |
| /** |
| * if there's no decoded data left, decode next pack into {@code data}. |
| * |
| * @param buffer ByteBuffer |
| * @return int |
| */ |
| protected int readT(ByteBuffer buffer) { |
| if (nextReadIndex == readIntTotalCount) { |
| return loadIntBatch(buffer); |
| } |
| return data[nextReadIndex++]; |
| } |
| |
| @Override |
| public int readInt(ByteBuffer buffer) { |
| return readT(buffer); |
| } |
| |
| /** |
| * if remaining data has been run out, load next pack from InputStream. |
| * |
| * @param buffer ByteBuffer |
| * @return int |
| */ |
| protected int loadIntBatch(ByteBuffer buffer) { |
| packNum = ReadWriteIOUtils.readInt(buffer); |
| packWidth = ReadWriteIOUtils.readInt(buffer); |
| count++; |
| readHeader(buffer); |
| |
| encodingLength = ceil(packNum * packWidth); |
| deltaBuf = new byte[encodingLength]; |
| buffer.get(deltaBuf); |
| allocateDataArray(); |
| |
| previous = firstValue; |
| readIntTotalCount = packNum; |
| nextReadIndex = 0; |
| readPack(); |
| return firstValue; |
| } |
| |
| private void readPack() { |
| for (int i = 0; i < packNum; i++) { |
| readValue(i); |
| previous = data[i]; |
| } |
| } |
| |
| @Override |
| protected void readHeader(ByteBuffer buffer) { |
| minDeltaBase = ReadWriteIOUtils.readInt(buffer); |
| firstValue = ReadWriteIOUtils.readInt(buffer); |
| } |
| |
| @Override |
| protected void allocateDataArray() { |
| data = new int[packNum]; |
| } |
| |
| @Override |
| protected void readValue(int i) { |
| int v = BytesUtils.bytesToInt(deltaBuf, packWidth * i, packWidth); |
| data[i] = previous + minDeltaBase + v; |
| } |
| |
| @Override |
| public void reset() { |
| // do nothing |
| } |
| } |
| |
| public static class LongDeltaDecoder extends DeltaBinaryDecoder { |
| |
| private long firstValue; |
| private long[] data; |
| private long previous; |
| /** minimum value for all difference. */ |
| private long minDeltaBase; |
| |
| public LongDeltaDecoder() { |
| super(); |
| } |
| |
| /** |
| * if there's no decoded data left, decode next pack into {@code data}. |
| * |
| * @param buffer ByteBuffer |
| * @return long value |
| */ |
| protected long readT(ByteBuffer buffer) { |
| if (nextReadIndex == readIntTotalCount) { |
| return loadIntBatch(buffer); |
| } |
| return data[nextReadIndex++]; |
| } |
| |
| /** |
| * if remaining data has been run out, load next pack from InputStream. |
| * |
| * @param buffer ByteBuffer |
| * @return long value |
| */ |
| protected long loadIntBatch(ByteBuffer buffer) { |
| packNum = ReadWriteIOUtils.readInt(buffer); |
| packWidth = ReadWriteIOUtils.readInt(buffer); |
| count++; |
| readHeader(buffer); |
| |
| encodingLength = ceil(packNum * packWidth); |
| deltaBuf = new byte[encodingLength]; |
| buffer.get(deltaBuf); |
| allocateDataArray(); |
| |
| previous = firstValue; |
| readIntTotalCount = packNum; |
| nextReadIndex = 0; |
| readPack(); |
| return firstValue; |
| } |
| |
| private void readPack() { |
| for (int i = 0; i < packNum; i++) { |
| readValue(i); |
| previous = data[i]; |
| } |
| } |
| |
| @Override |
| public long readLong(ByteBuffer buffer) { |
| |
| return readT(buffer); |
| } |
| |
| @Override |
| protected void readHeader(ByteBuffer buffer) { |
| minDeltaBase = ReadWriteIOUtils.readLong(buffer); |
| firstValue = ReadWriteIOUtils.readLong(buffer); |
| } |
| |
| @Override |
| protected void allocateDataArray() { |
| data = new long[packNum]; |
| } |
| |
| @Override |
| protected void readValue(int i) { |
| long v = BytesUtils.bytesToLong(deltaBuf, packWidth * i, packWidth); |
| data[i] = previous + minDeltaBase + v; |
| } |
| |
| @Override |
| public void reset() { |
| // do nothing |
| } |
| } |
| } |