blob: 7cc4c18be919aef78b2b2e346f28009b6966f8ac [file] [log] [blame]
Mathias Agopian6b35f972009-04-10 14:24:30 -07001/*
2 * Copyright (C) 2007 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#ifndef ANDROID_UTILS_SINGLETON_H
18#define ANDROID_UTILS_SINGLETON_H
19
20#include <stdint.h>
21#include <sys/types.h>
Colin Cross17b5b822016-09-15 18:15:37 -070022#include <utils/Mutex.h>
Mathias Agopian6b35f972009-04-10 14:24:30 -070023#include <utils/threads.h>
Romain Guy5cd32472011-10-12 13:48:51 -070024#include <cutils/compiler.h>
Mathias Agopian6b35f972009-04-10 14:24:30 -070025
26namespace android {
27// ---------------------------------------------------------------------------
28
29template <typename TYPE>
Romain Guy5cd32472011-10-12 13:48:51 -070030class ANDROID_API Singleton
Mathias Agopian6b35f972009-04-10 14:24:30 -070031{
32public:
33 static TYPE& getInstance() {
34 Mutex::Autolock _l(sLock);
35 TYPE* instance = sInstance;
36 if (instance == 0) {
37 instance = new TYPE();
38 sInstance = instance;
39 }
40 return *instance;
41 }
Romain Guy4e306232010-09-08 18:04:33 -070042
43 static bool hasInstance() {
44 Mutex::Autolock _l(sLock);
45 return sInstance != 0;
46 }
Mathias Agopian6b35f972009-04-10 14:24:30 -070047
48protected:
Colin Cross17b5b822016-09-15 18:15:37 -070049 ~Singleton() { }
50 Singleton() { }
Mathias Agopian6b35f972009-04-10 14:24:30 -070051
52private:
53 Singleton(const Singleton&);
54 Singleton& operator = (const Singleton&);
55 static Mutex sLock;
56 static TYPE* sInstance;
57};
58
Colin Cross17b5b822016-09-15 18:15:37 -070059template <typename TYPE>
60Mutex Singleton<TYPE>::sLock;
61
62template <typename TYPE>
63TYPE* Singleton<TYPE>::sInstance;
64
Mathias Agopiand8c95cc2009-04-17 14:15:18 -070065/*
66 * use ANDROID_SINGLETON_STATIC_INSTANCE(TYPE) in your implementation file
67 * (eg: <TYPE>.cpp) to create the static instance of Singleton<>'s attributes,
68 * and avoid to have a copy of them in each compilation units Singleton<TYPE>
69 * is used.
Mathias Agopian24ed9052010-05-28 15:13:30 -070070 * NOTE: we use a version of Mutex ctor that takes a parameter, because
71 * for some unknown reason using the default ctor doesn't emit the variable!
Mathias Agopiand8c95cc2009-04-17 14:15:18 -070072 */
73
Mathias Agopian24ed9052010-05-28 15:13:30 -070074#define ANDROID_SINGLETON_STATIC_INSTANCE(TYPE) \
Chih-Hung Hsiehc777f212014-12-10 13:55:21 -080075 template<> ::android::Mutex \
76 (::android::Singleton< TYPE >::sLock)(::android::Mutex::PRIVATE); \
77 template<> TYPE* ::android::Singleton< TYPE >::sInstance(0); \
78 template class ::android::Singleton< TYPE >;
Mathias Agopiand8c95cc2009-04-17 14:15:18 -070079
80
Mathias Agopian6b35f972009-04-10 14:24:30 -070081// ---------------------------------------------------------------------------
82}; // namespace android
83
84#endif // ANDROID_UTILS_SINGLETON_H
85