1 /*
2  * Copyright (C) 2008 Esmertec AG.
3  * Copyright (C) 2008 The Android Open Source Project
4  *
5  * Licensed under the Apache License, Version 2.0 (the "License");
6  * you may not use this file except in compliance with the License.
7  * You may obtain a copy of the License at
8  *
9  *      http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17 
18 package com.android.messaging.mmslib.util;
19 
20 import androidx.collection.SimpleArrayMap;
21 import android.util.Log;
22 
23 public abstract class AbstractCache<K, V> {
24     private static final String TAG = "AbstractCache";
25     private static final boolean LOCAL_LOGV = false;
26 
27     private static final int MAX_CACHED_ITEMS = 500;
28 
29     private final SimpleArrayMap<K, CacheEntry<V>> mCacheMap;
30 
AbstractCache()31     protected AbstractCache() {
32         mCacheMap = new SimpleArrayMap<K, CacheEntry<V>>();
33     }
34 
put(K key, V value)35     public boolean put(K key, V value) {
36         if (LOCAL_LOGV) {
37             Log.v(TAG, "Trying to put " + key + " into cache.");
38         }
39 
40         if (mCacheMap.size() >= MAX_CACHED_ITEMS) {
41             // TODO: Should remove the oldest or least hit cached entry
42             // and then cache the new one.
43             if (LOCAL_LOGV) {
44                 Log.v(TAG, "Failed! size limitation reached.");
45             }
46             return false;
47         }
48 
49         if (key != null) {
50             CacheEntry<V> cacheEntry = new CacheEntry<V>();
51             cacheEntry.value = value;
52             mCacheMap.put(key, cacheEntry);
53 
54             if (LOCAL_LOGV) {
55                 Log.v(TAG, key + " cached, " + mCacheMap.size() + " items total.");
56             }
57             return true;
58         }
59         return false;
60     }
61 
get(K key)62     public V get(K key) {
63         if (LOCAL_LOGV) {
64             Log.v(TAG, "Trying to get " + key + " from cache.");
65         }
66 
67         if (key != null) {
68             CacheEntry<V> cacheEntry = mCacheMap.get(key);
69             if (cacheEntry != null) {
70                 cacheEntry.hit++;
71                 if (LOCAL_LOGV) {
72                     Log.v(TAG, key + " hit " + cacheEntry.hit + " times.");
73                 }
74                 return cacheEntry.value;
75             }
76         }
77         return null;
78     }
79 
purge(K key)80     public V purge(K key) {
81         if (LOCAL_LOGV) {
82             Log.v(TAG, "Trying to purge " + key);
83         }
84 
85         CacheEntry<V> v = mCacheMap.remove(key);
86 
87         if (LOCAL_LOGV) {
88             Log.v(TAG, mCacheMap.size() + " items cached.");
89         }
90 
91         return v != null ? v.value : null;
92     }
93 
purgeAll()94     public void purgeAll() {
95         if (LOCAL_LOGV) {
96             Log.v(TAG, "Purging cache, " + mCacheMap.size()
97                     + " items dropped.");
98         }
99         mCacheMap.clear();
100     }
101 
size()102     public int size() {
103         return mCacheMap.size();
104     }
105 
106     private static class CacheEntry<V> {
107 
108         int hit;
109 
110         V value;
111     }
112 }
113