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package org.postgresql;
/**
* A simple and fast object pool implementation that can pool objects
* of any type. This implementation is not thread safe, it is up to the users
* of this class to assure thread safety.
*/
public class ObjectPool {
int cursize = 0;
int maxsize = 8;
Object arr[] = new Object[8];
/**
* Add object to the pool.
* @param o The object to add.
*/
public void add(Object o){
if(cursize >= maxsize){
Object newarr[] = new Object[maxsize*2];
System.arraycopy(arr, 0, newarr, 0, maxsize);
maxsize = maxsize * 2;
arr = newarr;
}
arr[cursize++] = o;
}
/**
* Remove an object from the pool. If the pool is empty
* ArrayIndexOutOfBoundsException will be thrown.
* @return Returns the removed object.
* @exception If the pool is empty
* ArrayIndexOutOfBoundsException will be thrown.
*/
public Object remove(){
Object o = arr[cursize-1];
// This have to be here, so we don't decrease the counter when
// cursize == 0;
cursize--;
return o;
}
/**
* Check if pool is empty.
* @return true if pool is empty, false otherwise.
*/
public boolean isEmpty(){
return cursize == 0;
}
/**
* Get the size of the pool.
* @return Returns the number of objects in the pool.
*/
public int size(){
return cursize;
}
/**
* Add all the objects from another pool to this pool.
* @pool The pool to add the objects from.
*/
public void addAll(ObjectPool pool){
int srcsize = pool.size();
if(srcsize == 0)
return;
int totalsize = srcsize + cursize;
if(totalsize > maxsize){
Object newarr[] = new Object[totalsize*2];
System.arraycopy(arr, 0, newarr, 0, cursize);
maxsize = maxsize = totalsize * 2;
arr = newarr;
}
System.arraycopy(pool.arr, 0, arr, cursize, srcsize);
cursize = totalsize;
}
/**
* Clear the elements from this pool.
* The method is lazy, so it just resets the index counter without
* removing references to pooled objects. This could possibly
* be an issue with garbage collection, depending on how the
* pool is used.
*/
public void clear(){
cursize = 0;
}
}
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