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
17package android.util;
18
19/**
20 * @hide
21 */
22class 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