com.liferay.petra.io.unsync.UnsyncBufferedReader Maven / Gradle / Ivy
/**
* Copyright (c) 2000-present Liferay, Inc. All rights reserved.
*
* This library is free software; you can redistribute it and/or modify it under
* the terms of the GNU Lesser General Public License as published by the Free
* Software Foundation; either version 2.1 of the License, or (at your option)
* any later version.
*
* This library is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
* details.
*/
package com.liferay.petra.io.unsync;
import com.liferay.petra.string.CharPool;
import com.liferay.petra.string.StringBundler;
import java.io.IOException;
import java.io.Reader;
/**
*
* See https://issues.liferay.com/browse/LPS-6648.
*
*
* @author Shuyang Zhou
*/
public class UnsyncBufferedReader extends Reader {
public UnsyncBufferedReader(Reader reader) {
this(reader, _DEFAULT_BUFFER_SIZE);
}
public UnsyncBufferedReader(Reader reader, int size) {
if (size <= 0) {
throw new IllegalArgumentException("Size is less than 1");
}
_reader = reader;
_buffer = new char[size];
}
@Override
public void close() throws IOException {
if (_reader != null) {
_reader.close();
_reader = null;
_buffer = null;
}
}
@Override
public void mark(int markLimit) throws IOException {
if (markLimit < 0) {
throw new IllegalArgumentException("Mark limit is less than 0");
}
if (_reader == null) {
throw new IOException("Reader is null");
}
if (markLimit == 0) {
return;
}
_markLimitIndex = markLimit;
if (_index == 0) {
return;
}
int available = _firstInvalidIndex - _index;
if (available > 0) {
// Shuffle mark beginning to buffer beginning
System.arraycopy(_buffer, _index, _buffer, 0, available);
_index = 0;
_firstInvalidIndex = available;
}
else {
// Reset buffer states
_index = _firstInvalidIndex = 0;
}
}
@Override
public boolean markSupported() {
return true;
}
@Override
public int read() throws IOException {
if (_reader == null) {
throw new IOException("Reader is null");
}
if (_index >= _firstInvalidIndex) {
_fillInBuffer();
if (_index >= _firstInvalidIndex) {
return -1;
}
}
return _buffer[_index++];
}
@Override
public int read(char[] chars) throws IOException {
return read(chars, 0, chars.length);
}
@Override
public int read(char[] chars, int offset, int length) throws IOException {
if (_reader == null) {
throw new IOException("Reader is null");
}
BoundaryCheckerUtil.check(chars.length, offset, length);
if (length == 0) {
return 0;
}
int read = 0;
while (true) {
// Try to at least read some data
int currentRead = _readOnce(chars, offset + read, length - read);
if (currentRead <= 0) {
if (read == 0) {
read = currentRead;
}
break;
}
read += currentRead;
if (!_reader.ready() || (read >= length)) {
// Read enough or further reading may be blocked, stop reading
break;
}
}
return read;
}
public String readLine() throws IOException {
if (_reader == null) {
throw new IOException("Reader is null");
}
StringBundler sb = null;
while (true) {
if (_index >= _firstInvalidIndex) {
_fillInBuffer();
}
if (_index >= _firstInvalidIndex) {
if (sb == null) {
return null;
}
return sb.toString();
}
boolean hasLineBreak = false;
char lineEndChar = 0;
int x = _index;
int y = _index;
while (y < _firstInvalidIndex) {
lineEndChar = _buffer[y];
if ((lineEndChar == CharPool.NEW_LINE) ||
(lineEndChar == CharPool.RETURN)) {
hasLineBreak = true;
break;
}
y++;
}
String line = new String(_buffer, x, y - x);
_index = y;
if (hasLineBreak) {
_index++;
if ((lineEndChar == CharPool.RETURN) &&
(_index < _buffer.length) &&
(_buffer[_index] == CharPool.NEW_LINE)) {
_index++;
}
if (sb == null) {
return line;
}
sb.append(line);
return sb.toString();
}
if (sb == null) {
sb = new StringBundler();
}
sb.append(line);
}
}
@Override
public boolean ready() throws IOException {
if (_reader == null) {
throw new IOException("Reader is null");
}
if ((_index < _firstInvalidIndex) || _reader.ready()) {
return true;
}
return false;
}
@Override
public void reset() throws IOException {
if (_reader == null) {
throw new IOException("Reader is null");
}
if (_markLimitIndex < 0) {
throw new IOException("Resetting to invalid mark");
}
_index = 0;
}
@Override
public long skip(long skip) throws IOException {
if (skip < 0) {
throw new IllegalArgumentException("Skip is less than 0");
}
if (_reader == null) {
throw new IOException("Reader is null");
}
if (skip == 0) {
return 0;
}
long available = _firstInvalidIndex - _index;
if (available <= 0) {
if (_markLimitIndex < 0) {
// No mark required, skip the underlying input stream
return _reader.skip(skip);
}
// Mark required, save the skipped data
_fillInBuffer();
available = _firstInvalidIndex - _index;
if (available <= 0) {
return 0;
}
}
// Skip the data in buffer
if (available < skip) {
skip = available;
}
_index += skip;
return skip;
}
private void _fillInBuffer() throws IOException {
if (_markLimitIndex < 0) {
// No mark required, fill the buffer
_index = _firstInvalidIndex = 0;
int number = _reader.read(_buffer);
if (number > 0) {
_firstInvalidIndex = number;
}
return;
}
// Mark required
if (_index >= _markLimitIndex) {
// Passed mark limit indexs, get rid of all cache data
_markLimitIndex = -1;
_index = _firstInvalidIndex = 0;
}
else if (_index == _buffer.length) {
// Cannot get rid of cache data and there is no room to read in any
// more data, so grow the buffer
int newBufferSize = _buffer.length * 2;
if (newBufferSize > _markLimitIndex) {
newBufferSize = _markLimitIndex;
}
char[] newBuffer = new char[newBufferSize];
System.arraycopy(_buffer, 0, newBuffer, 0, _buffer.length);
_buffer = newBuffer;
}
// Read the underlying input stream since the buffer has more space
_firstInvalidIndex = _index;
int number = _reader.read(_buffer, _index, _buffer.length - _index);
if (number > 0) {
_firstInvalidIndex += number;
}
}
private int _readOnce(char[] chars, int offset, int length)
throws IOException {
int available = _firstInvalidIndex - _index;
if (available <= 0) {
// Buffer is empty, read from underlying reader
if ((_markLimitIndex < 0) && (length >= _buffer.length)) {
// No mark required, left read block is no less than buffer,
// read through buffer is inefficient, so directly read from
// underlying reader
return _reader.read(chars, offset, length);
}
// Mark is required, has to read through the buffer to remember
// data
_fillInBuffer();
available = _firstInvalidIndex - _index;
if (available <= 0) {
return -1;
}
}
if (length > available) {
length = available;
}
System.arraycopy(_buffer, _index, chars, offset, length);
_index += length;
return length;
}
private static final int _DEFAULT_BUFFER_SIZE = 8192;
private char[] _buffer;
private int _firstInvalidIndex;
private int _index;
private int _markLimitIndex = -1;
private Reader _reader;
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