package rtc.core.net;
import java.util.Arrays;
public class RingBuffer {
private byte[] array;
private int readPos;//读的起始位置
private int writePos;//写的起始位置
public RingBuffer(int capacity){
array = new byte[capacity];
}
public void clear(){
readPos = writePos = 0;
}
public int remaining(){
if(readPos <= writePos){
return array.length - (writePos - readPos);
}else{
return readPos - writePos;
}
}
public int readable(){
return array.length - remaining();
}
private int reCapacity(int need){
if(need <= array.length){
return array.length;
}
int newCap = array.length;
while (newCap < need){
newCap *= 2;
}
byte[] temp = new byte[newCap];
if(readPos == writePos){
readPos = 0;
writePos = 0;
array = temp;
}else if(readPos < writePos){
int length = readable();
System.arraycopy(array,readPos,temp,0,length);
readPos = 0;
writePos = readPos + length;
array = temp;
}else{
int length = array.length - readPos;
System.arraycopy(array,readPos,temp,0,length);
System.arraycopy(array,0,temp,length,writePos);
writePos = length + writePos;
readPos = 0;
array = temp;
}
return array.length;
}
public int write(byte[] data){
return write(data,0,data.length);
}
public int write(byte[] data,int offset,int length){
if(data == null || data.length == 0 || length == 0) return 0;
if(offset < 0 || length < 0 || (offset + length > data.length)){
throw new IllegalArgumentException(String.format("params error , offset = %s,length = %s,data.length = %s",offset,length,data.length));
}
int remaining = remaining();
if(length > remaining){
reCapacity(array.length + (length - remaining));
}
if(readPos <= writePos){
int wrote = Math.min(array.length - writePos,length);
System.arraycopy(data,offset,array,writePos,wrote);
writePos += wrote;
if(length > wrote){
System.arraycopy(data,offset + wrote,array,0,length - wrote);
writePos = (length - wrote);
}
}else{
System.arraycopy(data,offset,array,writePos,length);
writePos += length;
}
return length;
}
public int peek(byte[] buff){
return peek(buff,0,buff.length);
}
public int peek(byte[] buff,int offset,int length){
return read(buff,offset,length,true);
}
public int read(byte[] buff){
return read(buff,0,buff.length,false);
}
public int read(byte[] buff,int offset,int length,boolean peek){
if(buff == null || buff.length == 0 || length == 0) return 0;
if(offset < 0 || length < 0 || offset >= buff.length){
throw new IllegalArgumentException(String.format("params error , offset = %s,length = %s,buff.length = %s",offset,length,buff.length));
}
length = Math.min(readable(),length);
length = Math.min(buff.length - offset,length);
if(length > 0){
if(readPos <= writePos){
System.arraycopy(array,readPos,buff,offset,length);
if(!peek){
readPos += length;
}
}else{
int read = Math.min(array.length - readPos,length);
System.arraycopy(array,readPos,buff,offset,read);
if(!peek){
readPos += read;
}
if(read < length){
System.arraycopy(array,0,buff,offset + read,length - read);
if(!peek){
readPos = (length - read);
}
}
}
}
return length;
}
public String dump(){
String msg = "array.length = "+array.length + ",";
msg += ("readPos = "+readPos+",");
msg += ("writePos = "+writePos+",");
msg += ("readable = "+readable()+",");
msg += ("remaining = "+remaining());
return msg;
}
public static void main(String[] args){
final RingBuffer buffer = new RingBuffer(8);
final byte[] data = new byte[]{'0','1','2','3','4','5','6','7','8','9'};
buffer.write(data);
System.out.println("write data : "+Arrays.toString(data));
System.out.println("dump : "+buffer.dump());
for(int i = 0 ; i < 100 ; i++){
int readable = buffer.readable();
System.out.println("i = "+ i +",readable = "+buffer.readable());
if(i % 3 == 0){
byte[] readBuff = new byte[readable];
buffer.read(readBuff);
System.out.println("i = " + i+",readBuff = "+ Arrays.toString(readBuff));
System.out.println("dump : "+buffer.dump());
}else{
byte[] temp = data.clone();
if(i % 2 == 0){
temp = data.clone().clone();
}
System.out.println("i = " + i+",write data : "+Arrays.toString(temp));
buffer.write(temp);
System.out.println("dump : "+buffer.dump());
}
}
}
}
