1 /* 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> 22 #include <utils/threads.h> 23 24 namespace android { 25 // --------------------------------------------------------------------------- 26 27 template <typename TYPE> 28 class Singleton 29 { 30 public: getInstance()31 static TYPE& getInstance() { 32 Mutex::Autolock _l(sLock); 33 TYPE* instance = sInstance; 34 if (instance == 0) { 35 instance = new TYPE(); 36 sInstance = instance; 37 } 38 return *instance; 39 } 40 41 protected: ~Singleton()42 ~Singleton() { }; Singleton()43 Singleton() { }; 44 45 private: 46 Singleton(const Singleton&); 47 Singleton& operator = (const Singleton&); 48 static Mutex sLock; 49 static TYPE* sInstance; 50 }; 51 52 /* 53 * use ANDROID_SINGLETON_STATIC_INSTANCE(TYPE) in your implementation file 54 * (eg: <TYPE>.cpp) to create the static instance of Singleton<>'s attributes, 55 * and avoid to have a copy of them in each compilation units Singleton<TYPE> 56 * is used. 57 */ 58 59 #define ANDROID_SINGLETON_STATIC_INSTANCE(TYPE) \ 60 template class Singleton< TYPE >; \ 61 template< class TYPE > Mutex Singleton< TYPE >::sLock; \ 62 template<> TYPE* Singleton< TYPE >::sInstance(0); 63 64 65 // --------------------------------------------------------------------------- 66 }; // namespace android 67 68 #endif // ANDROID_UTILS_SINGLETON_H 69 70