| /** |
| * 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.tajo.storage.thirdparty.orc; |
| |
| import java.io.IOException; |
| |
| /** |
| * A streamFactory that writes a sequence of bytes. A control byte is written before |
| * each run with positive values 0 to 127 meaning 2 to 129 repetitions. If the |
| * bytes is -1 to -128, 1 to 128 literal byte values follow. |
| */ |
| class RunLengthByteWriter { |
| static final int MIN_REPEAT_SIZE = 3; |
| static final int MAX_LITERAL_SIZE = 128; |
| static final int MAX_REPEAT_SIZE= 127 + MIN_REPEAT_SIZE; |
| private final PositionedOutputStream output; |
| private final byte[] literals = new byte[MAX_LITERAL_SIZE]; |
| private int numLiterals = 0; |
| private boolean repeat = false; |
| private int tailRunLength = 0; |
| |
| RunLengthByteWriter(PositionedOutputStream output) { |
| this.output = output; |
| } |
| |
| private void writeValues() throws IOException { |
| if (numLiterals != 0) { |
| if (repeat) { |
| output.write(numLiterals - MIN_REPEAT_SIZE); |
| output.write(literals, 0, 1); |
| } else { |
| output.write(-numLiterals); |
| output.write(literals, 0, numLiterals); |
| } |
| repeat = false; |
| tailRunLength = 0; |
| numLiterals = 0; |
| } |
| } |
| |
| void flush() throws IOException { |
| writeValues(); |
| output.flush(); |
| } |
| |
| void write(byte value) throws IOException { |
| if (numLiterals == 0) { |
| literals[numLiterals++] = value; |
| tailRunLength = 1; |
| } else if (repeat) { |
| if (value == literals[0]) { |
| numLiterals += 1; |
| if (numLiterals == MAX_REPEAT_SIZE) { |
| writeValues(); |
| } |
| } else { |
| writeValues(); |
| literals[numLiterals++] = value; |
| tailRunLength = 1; |
| } |
| } else { |
| if (value == literals[numLiterals - 1]) { |
| tailRunLength += 1; |
| } else { |
| tailRunLength = 1; |
| } |
| if (tailRunLength == MIN_REPEAT_SIZE) { |
| if (numLiterals + 1 == MIN_REPEAT_SIZE) { |
| repeat = true; |
| numLiterals += 1; |
| } else { |
| numLiterals -= MIN_REPEAT_SIZE - 1; |
| writeValues(); |
| literals[0] = value; |
| repeat = true; |
| numLiterals = MIN_REPEAT_SIZE; |
| } |
| } else { |
| literals[numLiterals++] = value; |
| if (numLiterals == MAX_LITERAL_SIZE) { |
| writeValues(); |
| } |
| } |
| } |
| } |
| |
| void getPosition(PositionRecorder recorder) throws IOException { |
| output.getPosition(recorder); |
| recorder.addPosition(numLiterals); |
| } |
| } |