/**
* 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.hadoop.record;
import java.io.UnsupportedEncodingException;
/**
* A byte sequence that is used as a Java native type for buffer.
* It is resizable and distinguishes between the count of the seqeunce and
* the current capacity.
*
*/
public class Buffer implements Comparable, Cloneable {
/** Number of valid bytes in this.bytes. */
private int count;
/** Backing store for Buffer. */
private byte[] bytes = null;
/**
* Create a zero-count sequence.
*/
public Buffer() {
this.count = 0;
}
/**
* Create a Buffer using the byte array as the initial value.
*
* @param bytes This array becomes the backing storage for the object.
*/
public Buffer(byte[] bytes) {
this.bytes = bytes;
this.count = (bytes == null) ? 0 : bytes.length;
}
/**
* Create a Buffer using the byte range as the initial value.
*
* @param bytes Copy of this array becomes the backing storage for the object.
* @param offset offset into byte array
* @param length length of data
*/
public Buffer(byte[] bytes, int offset, int length) {
copy(bytes, offset, length);
}
/**
* Use the specified bytes array as underlying sequence.
*
* @param bytes byte sequence
*/
public void set(byte[] bytes) {
this.count = (bytes == null) ? 0 : bytes.length;
this.bytes = bytes;
}
/**
* Copy the specified byte array to the Buffer. Replaces the current buffer.
*
* @param bytes byte array to be assigned
* @param offset offset into byte array
* @param length length of data
*/
public final void copy(byte[] bytes, int offset, int length) {
if (this.bytes == null || this.bytes.length < length) {
this.bytes = new byte[length];
}
System.arraycopy(bytes, offset, this.bytes, 0, length);
this.count = length;
}
/**
* Get the data from the Buffer.
*
* @return The data is only valid between 0 and getCount() - 1.
*/
public byte[] get() {
if (bytes == null) {
bytes = new byte[0];
}
return bytes;
}
/**
* Get the current count of the buffer.
*/
public int getCount() {
return count;
}
/**
* Get the capacity, which is the maximum count that could handled without
* resizing the backing storage.
*
* @return The number of bytes
*/
public int getCapacity() {
return this.get().length;
}
/**
* Change the capacity of the backing storage.
* The data is preserved if newCapacity >= getCount().
* @param newCapacity The new capacity in bytes.
*/
public void setCapacity(int newCapacity) {
if (newCapacity < 0) {
throw new IllegalArgumentException("Invalid capacity argument "+newCapacity);
}
if (newCapacity == 0) {
this.bytes = null;
this.count = 0;
return;
}
if (newCapacity != getCapacity()) {
byte[] data = new byte[newCapacity];
if (newCapacity < count) {
count = newCapacity;
}
if (count != 0) {
System.arraycopy(this.get(), 0, data, 0, count);
}
bytes = data;
}
}
/**
* Reset the buffer to 0 size
*/
public void reset() {
setCapacity(0);
}
/**
* Change the capacity of the backing store to be the same as the current
* count of buffer.
*/
public void truncate() {
setCapacity(count);
}
/**
* Append specified bytes to the buffer.
*
* @param bytes byte array to be appended
* @param offset offset into byte array
* @param length length of data
*/
public void append(byte[] bytes, int offset, int length) {
setCapacity(count+length);
System.arraycopy(bytes, offset, this.get(), count, length);
count = count + length;
}
/**
* Append specified bytes to the buffer
*
* @param bytes byte array to be appended
*/
public void append(byte[] bytes) {
append(bytes, 0, bytes.length);
}
// inherit javadoc
public int hashCode() {
int hash = 1;
byte[] b = this.get();
for (int i = 0; i < count; i++)
hash = (31 * hash) + (int)b[i];
return hash;
}
/**
* Define the sort order of the Buffer.
*
* @param other The other buffer
* @return Positive if this is bigger than other, 0 if they are equal, and
* negative if this is smaller than other.
*/
public int compareTo(Object other) {
Buffer right = ((Buffer) other);
byte[] lb = this.get();
byte[] rb = right.get();
for (int i = 0; i < count && i < right.count; i++) {
int a = (lb[i] & 0xff);
int b = (rb[i] & 0xff);
if (a != b) {
return a - b;
}
}
return count - right.count;
}
// inherit javadoc
public boolean equals(Object other) {
if (other instanceof Buffer && this != other) {
return compareTo(other) == 0;
}
return (this == other);
}
// inheric javadoc
public String toString() {
StringBuffer sb = new StringBuffer(2*count);
for(int idx = 0; idx < count; idx++) {
sb.append(Character.forDigit((bytes[idx] & 0xF0) >> 4, 16));
sb.append(Character.forDigit(bytes[idx] & 0x0F, 16));
}
return sb.toString();
}
/**
* Convert the byte buffer to a string an specific character encoding
*
* @param charsetName Valid Java Character Set Name
*/
public String toString(String charsetName)
throws UnsupportedEncodingException {
return new String(this.get(), 0, this.getCount(), charsetName);
}
// inherit javadoc
public Object clone() throws CloneNotSupportedException {
Buffer result = (Buffer) super.clone();
result.copy(this.get(), 0, this.getCount());
return result;
}
}