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/**
* Copyright 2013-2016 Guoqiang Chen, Shanghai, China. All rights reserved.
*
* Author: Guoqiang Chen
* Email: [email protected]
* WebURL: https://github.com/subchen
*
* Licensed 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 jetbrick.io.buffer;
/**
* Fast, fast byte buffer.
* This buffer implementation does not store all data
* in single array, but in array of chunks.
*/
public class FastByteBuffer {
private byte[][] buffers = new byte[16][];
private int buffersCount;
private int currentBufferIndex = -1;
private byte[] currentBuffer;
private int offset;
private int size;
private final int minChunkLen;
/**
* Creates a new byte buffer. The buffer capacity is
* initially 1024 bytes, though its size increases if necessary.
*/
public FastByteBuffer() {
this.minChunkLen = 1024;
}
/**
* Creates a new byte buffer, with a buffer capacity of
* the specified size, in bytes.
*
* @param size the initial size.
* @throws IllegalArgumentException if size is negative.
*/
public FastByteBuffer(int size) {
if (size < 0) {
throw new IllegalArgumentException("Invalid size: " + size);
}
this.minChunkLen = size;
}
/**
* Prepares next chunk to match new size.
* The minimal length of new chunk is minChunkLen.
*/
private void needNewBuffer(int newSize) {
int delta = newSize - size;
int newBufferSize = Math.max(minChunkLen, delta);
currentBufferIndex++;
currentBuffer = new byte[newBufferSize];
offset = 0;
// add buffer
if (currentBufferIndex >= buffers.length) {
int newLen = buffers.length << 1;
byte[][] newBuffers = new byte[newLen][];
System.arraycopy(buffers, 0, newBuffers, 0, buffers.length);
buffers = newBuffers;
}
buffers[currentBufferIndex] = currentBuffer;
buffersCount++;
}
/**
* Appends byte array to buffer.
*/
public FastByteBuffer append(byte[] array, int off, int len) {
int end = off + len;
if ((off < 0) || (len < 0) || (end > array.length)) {
throw new IndexOutOfBoundsException();
}
if (len == 0) {
return this;
}
int newSize = size + len;
int remaining = len;
if (currentBuffer != null) {
// first try to fill current buffer
int part = Math.min(remaining, currentBuffer.length - offset);
System.arraycopy(array, end - remaining, currentBuffer, offset, part);
remaining -= part;
offset += part;
size += part;
}
if (remaining > 0) {
// still some data left
// ask for new buffer
needNewBuffer(newSize);
// then copy remaining
// but this time we are sure that it will fit
int part = Math.min(remaining, currentBuffer.length - offset);
System.arraycopy(array, end - remaining, currentBuffer, offset, part);
offset += part;
size += part;
}
return this;
}
/**
* Appends byte array to buffer.
*/
public FastByteBuffer append(byte[] array) {
return append(array, 0, array.length);
}
/**
* Appends single byte to buffer.
*/
public FastByteBuffer append(byte element) {
if ((currentBuffer == null) || (offset == currentBuffer.length)) {
needNewBuffer(size + 1);
}
currentBuffer[offset] = element;
offset++;
size++;
return this;
}
/**
* Appends another fast buffer to this one.
*/
public FastByteBuffer append(FastByteBuffer buff) {
if (buff.size == 0) {
return this;
}
for (int i = 0; i < buff.currentBufferIndex; i++) {
append(buff.buffers[i]);
}
append(buff.currentBuffer, 0, buff.offset);
return this;
}
/**
* Returns buffer size.
*/
public int size() {
return size;
}
/**
* Tests if this buffer has no elements.
*/
public boolean isEmpty() {
return size == 0;
}
/**
* Returns current index of inner byte array chunk.
* Represents the index of last used inner array chunk.
*/
public int index() {
return currentBufferIndex;
}
/**
* Returns the offset of last used element in current inner array chunk.
*/
public int offset() {
return offset;
}
/**
* Returns byte inner array chunk at given index.
* May be used for iterating inner chunks in fast manner.
*/
public byte[] array(int index) {
return buffers[index];
}
/**
* Resets the buffer content.
*/
public void clear() {
size = 0;
offset = 0;
currentBufferIndex = -1;
currentBuffer = null;
buffersCount = 0;
}
/**
* Creates byte array from buffered content.
*/
public byte[] toArray() {
int pos = 0;
byte[] array = new byte[size];
if (currentBufferIndex == -1) {
return array;
}
for (int i = 0; i < currentBufferIndex; i++) {
int len = buffers[i].length;
System.arraycopy(buffers[i], 0, array, pos, len);
pos += len;
}
System.arraycopy(buffers[currentBufferIndex], 0, array, pos, offset);
return array;
}
/**
* Creates byte subarray from buffered content.
*/
public byte[] toArray(int start, int len) {
int remaining = len;
int pos = 0;
byte[] array = new byte[len];
if (len == 0) {
return array;
}
int i = 0;
while (start >= buffers[i].length) {
start -= buffers[i].length;
i++;
}
while (i < buffersCount) {
byte[] buf = buffers[i];
int c = Math.min(buf.length - start, remaining);
System.arraycopy(buf, start, array, pos, c);
pos += c;
remaining -= c;
if (remaining == 0) {
break;
}
start = 0;
i++;
}
return array;
}
/**
* Returns byte element at given index.
*/
public byte get(int index) {
if ((index >= size) || (index < 0)) {
throw new IndexOutOfBoundsException();
}
int ndx = 0;
while (true) {
byte[] b = buffers[ndx];
if (index < b.length) {
return b[index];
}
ndx++;
index -= b.length;
}
}
}
