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    private static final String LOG_TAG = "FinitePool";
24
25    /**
26     * Factory used to create new pool objects
27     */
28    private final PoolableManager<T> mManager;
29    /**
30     * Maximum number of objects in the pool
31     */
32    private final int mLimit;
33    /**
34     * If true, mLimit is ignored
35     */
36    private final boolean mInfinite;
37
38    /**
39     * Next object to acquire
40     */
41    private T mRoot;
42    /**
43     * Number of objects in the pool
44     */
45    private int mPoolCount;
46
47    FinitePool(PoolableManager<T> manager) {
48        mManager = manager;
49        mLimit = 0;
50        mInfinite = true;
51    }
52
53    FinitePool(PoolableManager<T> manager, int limit) {
54        if (limit <= 0) throw new IllegalArgumentException("The pool limit must be > 0");
55
56        mManager = manager;
57        mLimit = limit;
58        mInfinite = false;
59    }
60
61    public T acquire() {
62        T element;
63
64        if (mRoot != null) {
65            element = mRoot;
66            mRoot = element.getNextPoolable();
67            mPoolCount--;
68        } else {
69            element = mManager.newInstance();
70        }
71
72        if (element != null) {
73            element.setNextPoolable(null);
74            element.setPooled(false);
75            mManager.onAcquired(element);
76        }
77
78        return element;
79    }
80
81    public void release(T element) {
82        if (!element.isPooled()) {
83            if (mInfinite || mPoolCount < mLimit) {
84                mPoolCount++;
85                element.setNextPoolable(mRoot);
86                element.setPooled(true);
87                mRoot = element;
88            }
89            mManager.onReleased(element);
90        } else {
91            Log.w(LOG_TAG, "Element is already in pool: " + element);
92        }
93    }
94}
95