| /** |
| * 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.orc.impl; |
| |
| import java.io.EOFException; |
| import java.io.IOException; |
| |
| import org.apache.hadoop.hive.ql.exec.vector.ColumnVector; |
| |
| /** |
| * A reader that reads a sequence of bytes. A control byte is read before |
| * each run with positive values 0 to 127 meaning 3 to 130 repetitions. If the |
| * byte is -1 to -128, 1 to 128 literal byte values follow. |
| */ |
| public class RunLengthByteReader { |
| private InStream input; |
| private final byte[] literals = |
| new byte[RunLengthByteWriter.MAX_LITERAL_SIZE]; |
| private int numLiterals = 0; |
| private int used = 0; |
| private boolean repeat = false; |
| |
| public RunLengthByteReader(InStream input) { |
| this.input = input; |
| } |
| |
| public void setInStream(InStream input) { |
| this.input = input; |
| } |
| |
| private void readValues(boolean ignoreEof) throws IOException { |
| int control = input.read(); |
| used = 0; |
| if (control == -1) { |
| if (!ignoreEof) { |
| throw new EOFException("Read past end of buffer RLE byte from " + input); |
| } |
| used = numLiterals = 0; |
| return; |
| } else if (control < 0x80) { |
| repeat = true; |
| numLiterals = control + RunLengthByteWriter.MIN_REPEAT_SIZE; |
| int val = input.read(); |
| if (val == -1) { |
| throw new EOFException("Reading RLE byte got EOF"); |
| } |
| literals[0] = (byte) val; |
| } else { |
| repeat = false; |
| numLiterals = 0x100 - control; |
| int bytes = 0; |
| while (bytes < numLiterals) { |
| int result = input.read(literals, bytes, numLiterals - bytes); |
| if (result == -1) { |
| throw new EOFException("Reading RLE byte literal got EOF in " + this); |
| } |
| bytes += result; |
| } |
| } |
| } |
| |
| public boolean hasNext() throws IOException { |
| return used != numLiterals || input.available() > 0; |
| } |
| |
| public byte next() throws IOException { |
| byte result; |
| if (used == numLiterals) { |
| readValues(false); |
| } |
| if (repeat) { |
| result = literals[0]; |
| } else { |
| result = literals[used]; |
| } |
| ++used; |
| return result; |
| } |
| |
| public void nextVector(ColumnVector previous, long[] data, long size) |
| throws IOException { |
| previous.isRepeating = true; |
| for (int i = 0; i < size; i++) { |
| if (!previous.isNull[i]) { |
| data[i] = next(); |
| } else { |
| // The default value of null for int types in vectorized |
| // processing is 1, so set that if the value is null |
| data[i] = 1; |
| } |
| |
| // The default value for nulls in Vectorization for int types is 1 |
| // and given that non null value can also be 1, we need to check for isNull also |
| // when determining the isRepeating flag. |
| if (previous.isRepeating |
| && i > 0 |
| && ((data[0] != data[i]) || |
| (previous.isNull[0] != previous.isNull[i]))) { |
| previous.isRepeating = false; |
| } |
| } |
| } |
| |
| /** |
| * Read the next size bytes into the data array, skipping over any slots |
| * where isNull is true. |
| * @param isNull if non-null, skip any rows where isNull[r] is true |
| * @param data the array to read into |
| * @param size the number of elements to read |
| * @throws IOException |
| */ |
| public void nextVector(boolean[] isNull, int[] data, |
| long size) throws IOException { |
| if (isNull == null) { |
| for(int i=0; i < size; ++i) { |
| data[i] = next(); |
| } |
| } else { |
| for(int i=0; i < size; ++i) { |
| if (!isNull[i]) { |
| data[i] = next(); |
| } |
| } |
| } |
| } |
| |
| public void seek(PositionProvider index) throws IOException { |
| input.seek(index); |
| int consumed = (int) index.getNext(); |
| if (consumed != 0) { |
| // a loop is required for cases where we break the run into two parts |
| while (consumed > 0) { |
| readValues(false); |
| used = consumed; |
| consumed -= numLiterals; |
| } |
| } else { |
| used = 0; |
| numLiterals = 0; |
| } |
| } |
| |
| public void skip(long items) throws IOException { |
| while (items > 0) { |
| if (used == numLiterals) { |
| readValues(false); |
| } |
| long consume = Math.min(items, numLiterals - used); |
| used += consume; |
| items -= consume; |
| } |
| } |
| |
| @Override |
| public String toString() { |
| return "byte rle " + (repeat ? "repeat" : "literal") + " used: " + |
| used + "/" + numLiterals + " from " + input; |
| } |
| } |