/*
* Copyright (c) 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017 David Berkman
*
* This file is part of the SmallMind Code Project.
*
* The SmallMind Code Project is free software, you can redistribute
* it and/or modify it under either, at your discretion...
*
* 1) The terms of GNU Affero General Public License as published by the
* Free Software Foundation, either version 3 of the License, or (at
* your option) any later version.
*
* ...or...
*
* 2) The terms of the Apache License, Version 2.0.
*
* The SmallMind Code Project 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
* General Public License or Apache License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* and the Apache License along with the SmallMind Code Project. If not, see
* <http://www.gnu.org/licenses/> or <http://www.apache.org/licenses/LICENSE-2.0>.
*
* Additional permission under the GNU Affero GPL version 3 section 7
* ------------------------------------------------------------------
* If you modify this Program, or any covered work, by linking or
* combining it with other code, such other code is not for that reason
* alone subject to any of the requirements of the GNU Affero GPL
* version 3.
*/
package org.smallmind.nutsnbolts.util;
public class CircularBuffer {
private static enum State {
READ, WRITE
}
private RangeSegment[] segments;
private boolean closed = false;
private int position = 0;
private int filled = 0;
private byte[] buffer;
public CircularBuffer (int size) {
buffer = new byte[size];
segments = new RangeSegment[2];
}
public synchronized boolean isClosed () {
return closed;
}
public synchronized void close () {
closed = true;
notifyAll();
}
public synchronized int available () {
return (buffer.length - filled);
}
public int read (byte[] data) {
return read(data, 0);
}
public synchronized int read (byte[] data, long millis) {
int bytesRead;
if (data.length == 0) {
return 0;
}
while ((bytesRead = get(data)) == 0) {
if (closed) {
return -1;
}
try {
wait(millis);
} catch (InterruptedException interruptedException) {
throw new RuntimeException(interruptedException);
}
}
notifyAll();
return bytesRead;
}
public void write (byte[] data) {
write(data, 0, data.length);
}
public synchronized void write (byte[] data, int off, int length) {
int totalBytes = off;
int bytesWritten;
if (closed) {
throw new IllegalStateException("The close() method has previously been called");
}
do {
if ((bytesWritten = put(data, totalBytes, length - totalBytes)) > 0) {
totalBytes += bytesWritten;
notifyAll();
}
if (totalBytes < length) {
try {
wait();
} catch (InterruptedException interruptedException) {
throw new RuntimeException(interruptedException);
}
}
} while (totalBytes < length);
}
private int put (byte[] data, int off, int length) {
int totalBytes = 0;
int writeBytes;
setSegments(State.WRITE);
for (int count = 0; count < segments.length; count++) {
if (segments[count] != null) {
writeBytes = Math.min(segments[count].getStop() - segments[count].getStart(), length - totalBytes);
if (writeBytes > 0) {
System.arraycopy(data, off + totalBytes, buffer, segments[count].getStart(), writeBytes);
totalBytes += writeBytes;
}
}
}
filled += totalBytes;
return totalBytes;
}
private int get (byte[] data) {
int totalBytes = 0;
int readBytes;
setSegments(State.READ);
for (int count = 0; count < segments.length; count++) {
if (segments[count] != null) {
readBytes = Math.min(segments[count].getStop() - segments[count].getStart(), data.length - totalBytes);
if (readBytes > 0) {
System.arraycopy(buffer, segments[count].getStart(), data, totalBytes, readBytes);
totalBytes += readBytes;
}
}
}
filled -= totalBytes;
position += totalBytes;
if (position > buffer.length) {
position -= buffer.length;
}
return totalBytes;
}
private void setSegments (State state) {
if (position + filled <= buffer.length) {
switch (state) {
case READ:
segments[0] = new RangeSegment(position, position + filled);
segments[1] = null;
break;
case WRITE:
segments = new RangeSegment[2];
segments[0] = new RangeSegment(position + filled, buffer.length);
segments[1] = new RangeSegment(0, position);
}
} else {
switch (state) {
case READ:
segments = new RangeSegment[2];
segments[0] = new RangeSegment(position, buffer.length);
segments[1] = new RangeSegment(0, position + filled - buffer.length);
break;
case WRITE:
segments[0] = new RangeSegment(position + filled - buffer.length, position);
segments[1] = null;
}
}
}
public class RangeSegment {
private int start;
private int stop;
public RangeSegment (int start, int stop) {
this.start = start;
this.stop = stop;
}
public int getStart () {
return start;
}
public int getStop () {
return stop;
}
}
}