1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
|
/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed 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.
*/
#ifndef ANDROID_UTILS_GENERATION_CACHE_H
#define ANDROID_UTILS_GENERATION_CACHE_H
#include <utils/KeyedVector.h>
#include <utils/RefBase.h>
namespace android {
/**
* GenerationCache callback used when an item is removed
*/
template<typename EntryKey, typename EntryValue>
class OnEntryRemoved {
public:
virtual ~OnEntryRemoved() { };
virtual void operator()(EntryKey& key, EntryValue& value) = 0;
}; // class OnEntryRemoved
template<typename EntryKey, typename EntryValue>
struct Entry: public LightRefBase<Entry<EntryKey, EntryValue> > {
Entry() { }
Entry(const Entry<EntryKey, EntryValue>& e):
key(e.key), value(e.value), parent(e.parent), child(e.child) { }
Entry(sp<Entry<EntryKey, EntryValue> > e):
key(e->key), value(e->value), parent(e->parent), child(e->child) { }
EntryKey key;
EntryValue value;
sp<Entry<EntryKey, EntryValue> > parent;
sp<Entry<EntryKey, EntryValue> > child;
}; // struct Entry
/**
* A LRU type cache
*/
template<typename K, typename V>
class GenerationCache {
public:
GenerationCache(uint32_t maxCapacity);
virtual ~GenerationCache();
enum Capacity {
kUnlimitedCapacity,
};
void setOnEntryRemovedListener(OnEntryRemoved<K, V>* listener);
void clear();
bool contains(K key) const;
V get(K key);
K getKeyAt(uint32_t index) const;
bool put(K key, V value);
V remove(K key);
V removeOldest();
V getValueAt(uint32_t index) const;
uint32_t size() const;
void addToCache(sp<Entry<K, V> > entry, K key, V value);
void attachToCache(sp<Entry<K, V> > entry);
void detachFromCache(sp<Entry<K, V> > entry);
V removeAt(ssize_t index);
private:
KeyedVector<K, sp<Entry<K, V> > > mCache;
uint32_t mMaxCapacity;
OnEntryRemoved<K, V>* mListener;
sp<Entry<K, V> > mOldest;
sp<Entry<K, V> > mYoungest;
}; // class GenerationCache
template<typename K, typename V>
GenerationCache<K, V>::GenerationCache(uint32_t maxCapacity): mMaxCapacity(maxCapacity),
mListener(NULL) {
};
template<typename K, typename V>
GenerationCache<K, V>::~GenerationCache() {
clear();
};
template<typename K, typename V>
uint32_t GenerationCache<K, V>::size() const {
return mCache.size();
}
/**
* Should be set by the user of the Cache so that the callback is called whenever an item is
* removed from the cache
*/
template<typename K, typename V>
void GenerationCache<K, V>::setOnEntryRemovedListener(OnEntryRemoved<K, V>* listener) {
mListener = listener;
}
template<typename K, typename V>
void GenerationCache<K, V>::clear() {
if (mListener) {
for (uint32_t i = 0; i < mCache.size(); i++) {
sp<Entry<K, V> > entry = mCache.valueAt(i);
if (mListener) {
(*mListener)(entry->key, entry->value);
}
}
}
mCache.clear();
mYoungest.clear();
mOldest.clear();
}
template<typename K, typename V>
bool GenerationCache<K, V>::contains(K key) const {
return mCache.indexOfKey(key) >= 0;
}
template<typename K, typename V>
K GenerationCache<K, V>::getKeyAt(uint32_t index) const {
return mCache.keyAt(index);
}
template<typename K, typename V>
V GenerationCache<K, V>::getValueAt(uint32_t index) const {
return mCache.valueAt(index)->value;
}
template<typename K, typename V>
V GenerationCache<K, V>::get(K key) {
ssize_t index = mCache.indexOfKey(key);
if (index >= 0) {
sp<Entry<K, V> > entry = mCache.valueAt(index);
if (entry.get()) {
detachFromCache(entry);
attachToCache(entry);
return entry->value;
}
}
return NULL;
}
template<typename K, typename V>
bool GenerationCache<K, V>::put(K key, V value) {
if (mMaxCapacity != kUnlimitedCapacity && mCache.size() >= mMaxCapacity) {
removeOldest();
}
ssize_t index = mCache.indexOfKey(key);
if (index < 0) {
sp<Entry<K, V> > entry = new Entry<K, V>;
addToCache(entry, key, value);
return true;
}
return false;
}
template<typename K, typename V>
void GenerationCache<K, V>::addToCache(sp<Entry<K, V> > entry, K key, V value) {
entry->key = key;
entry->value = value;
mCache.add(key, entry);
attachToCache(entry);
}
template<typename K, typename V>
V GenerationCache<K, V>::remove(K key) {
ssize_t index = mCache.indexOfKey(key);
if (index >= 0) {
return removeAt(index);
}
return NULL;
}
template<typename K, typename V>
V GenerationCache<K, V>::removeAt(ssize_t index) {
sp<Entry<K, V> > entry = mCache.valueAt(index);
if (mListener) {
(*mListener)(entry->key, entry->value);
}
mCache.removeItemsAt(index, 1);
detachFromCache(entry);
return entry->value;
}
template<typename K, typename V>
V GenerationCache<K, V>::removeOldest() {
if (mOldest.get()) {
ssize_t index = mCache.indexOfKey(mOldest->key);
if (index >= 0) {
return removeAt(index);
}
}
return NULL;
}
template<typename K, typename V>
void GenerationCache<K, V>::attachToCache(sp<Entry<K, V> > entry) {
if (!mYoungest.get()) {
mYoungest = mOldest = entry;
} else {
entry->parent = mYoungest;
mYoungest->child = entry;
mYoungest = entry;
}
}
template<typename K, typename V>
void GenerationCache<K, V>::detachFromCache(sp<Entry<K, V> > entry) {
if (entry->parent.get()) {
entry->parent->child = entry->child;
}
if (entry->child.get()) {
entry->child->parent = entry->parent;
}
if (mOldest == entry) {
mOldest = entry->child;
}
if (mYoungest == entry) {
mYoungest = entry->parent;
}
entry->parent.clear();
entry->child.clear();
}
}; // namespace android
#endif // ANDROID_UTILS_GENERATION_CACHE_H
|
