/**
* 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.hive.ql.exec.vector;
import org.apache.hadoop.hive.ql.metadata.HiveException;
/**
*
*/
public class VectorUtilBatchObjectPool<T extends Object> {
private final T[] buffer;
/**
* Head of the pool. This is where where we should insert the next
* object returned to the pool
*/
private int head = 0;
/**
* Count of available elements. They are behind the head, with wrap-around
* The head itself is not free, is null
*/
private int count = 0;
private IAllocator<T> allocator;
public static interface IAllocator<T> {
public T alloc() throws HiveException;
public void free(T t);
}
@SuppressWarnings("unchecked")
public VectorUtilBatchObjectPool(int size, IAllocator<T> allocator) {
buffer = (T[]) new Object[size];
this.allocator = allocator;
}
public T getFromPool() throws HiveException {
T ret = null;
if (count == 0) {
// Pool is exhausted, return a new object
ret = allocator.alloc();
}
else {
int tail = (head + buffer.length - count) % buffer.length;
ret = buffer[tail];
buffer[tail] = null;
--count;
}
return ret;
}
public void putInPool(T object) {
if (count < buffer.length) {
buffer[head] = object;
++count;
++head;
if (head == buffer.length) {
head = 0;
}
}
else {
allocator.free(object);
}
}
}