package org.exist.util;
/**
* A pool for byte arrays.
*
* This pool is primarily used while parsing documents: serializing the
* DOM nodes generates a lot of small byte chunks. Only byte arrays
* with length < MAX are kept in the pool. Large arrays are rarely
* reused.
*/
public class ByteArrayPool {
public static final int POOL_SIZE = 32;
public static final int MAX = 128;
public static final ThreadLocal<byte[][]> pools_ = new PoolThreadLocal();
private static int slot_ = 0;
public ByteArrayPool() {
//Nothing to do
}
public static byte[] getByteArray(int size) {
final byte[][] pool = pools_.get();
if(size < MAX) {
for(int i = pool.length; i-- > 0; ) {
if(pool[i] != null && pool[i].length == size) {
//System.out.println("found byte[" + size + "]");
final byte[] b = pool[i];
pool[i] = null;
return b;
}
}
}
return new byte[size];
}
public static void releaseByteArray(final byte[] b) {
if(b == null || b.length > MAX)
{return;}
//System.out.println("releasing byte[" + b.length + "]");
final byte[][] pool = pools_.get();
for(int i = pool.length; i-- > 0;) {
if(pool[i] == null) {
pool[i] = b;
return;
}
}
int s = slot_++;
if (s < 0)
{s = -s;}
pool[s % pool.length] = b;
}
private static final class PoolThreadLocal extends ThreadLocal<byte[][]> {
@Override
protected byte[][] initialValue() {
return new byte[POOL_SIZE][];
}
}
}