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      1 /*
      2  * Copyright (C) 2009 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.util;
     18 
     19 /**
     20  * @hide
     21  */
     22 class FinitePool<T extends Poolable<T>> implements Pool<T> {
     23     /**
     24      * Factory used to create new pool objects
     25      */
     26     private final PoolableManager<T> mManager;
     27     /**
     28      * Maximum number of objects in the pool
     29      */
     30     private final int mLimit;
     31     /**
     32      * If true, mLimit is ignored
     33      */
     34     private final boolean mInfinite;
     35 
     36     /**
     37      * Next object to acquire
     38      */
     39     private T mRoot;
     40     /**
     41      * Number of objects in the pool
     42      */
     43     private int mPoolCount;
     44 
     45     FinitePool(PoolableManager<T> manager) {
     46         mManager = manager;
     47         mLimit = 0;
     48         mInfinite = true;
     49     }
     50 
     51     FinitePool(PoolableManager<T> manager, int limit) {
     52         if (limit <= 0) throw new IllegalArgumentException("The pool limit must be > 0");
     53 
     54         mManager = manager;
     55         mLimit = limit;
     56         mInfinite = false;
     57     }
     58 
     59     public T acquire() {
     60         T element;
     61 
     62         if (mRoot != null) {
     63             element = mRoot;
     64             mRoot = element.getNextPoolable();
     65             mPoolCount--;
     66         } else {
     67             element = mManager.newInstance();
     68         }
     69 
     70         if (element != null) {
     71             element.setNextPoolable(null);
     72             mManager.onAcquired(element);
     73         }
     74 
     75         return element;
     76     }
     77 
     78     public void release(T element) {
     79         if (mInfinite || mPoolCount < mLimit) {
     80             mPoolCount++;
     81             element.setNextPoolable(mRoot);
     82             mRoot = element;
     83         }
     84         mManager.onReleased(element);
     85     }
     86 }
     87