io.craft.atom.nio.NioByteBufferAllocator Maven / Gradle / Ivy
package io.craft.atom.nio;
import java.nio.ByteBuffer;
import lombok.ToString;
/**
* Allocate byte buffer and reuse original buffer as far as possible. A trade
* off for memory waste and efficiency.
*
* Not thread safe
*
* @author mindwind
* @version 1.0, Jan 25, 2013
*/
@ToString(of = { "buf", "exceedCount", "maxExceedCount", "percentual" })
public class NioByteBufferAllocator {
private ByteBuffer buf ;
private int exceedCount ;
private final int maxExceedCount;
private final int percentual ;
// ~ -------------------------------------------------------------------------------------------------------------
NioByteBufferAllocator() {
this(16, 80);
}
NioByteBufferAllocator(int maxExceedCount, int percentual) {
this.maxExceedCount = maxExceedCount;
this.percentual = percentual;
}
// ~ -------------------------------------------------------------------------------------------------------------
ByteBuffer allocate(int size) {
if (buf == null) {
return newBuffer(size);
}
if (buf.capacity() < size) {
return newBuffer(size);
}
if (buf.capacity() * percentual / 100 > size) {
if (++exceedCount == maxExceedCount) {
return newBuffer(size);
} else {
buf.clear();
}
} else {
exceedCount = 0;
buf.clear();
}
return buf;
}
private ByteBuffer newBuffer(int size) {
if (buf != null) {
exceedCount = 0;
}
buf = ByteBuffer.allocate(normalizeCapacity(size));
return buf;
}
private static int normalizeCapacity(int capacity) {
// Normalize to multiple of 1024
int q = capacity >>> 10;
int r = capacity & 1023;
if (r != 0) {
q ++;
}
return q << 10;
}
}