1 /* 2 * Copyright (c) 2021 Huawei Device Co., Ltd. 3 * Licensed under the Apache License, Version 2.0 (the "License"); 4 * you may not use this file except in compliance with the License. 5 * You may obtain a copy of the License at 6 * 7 * http://www.apache.org/licenses/LICENSE-2.0 8 * 9 * Unless required by applicable law or agreed to in writing, software 10 * distributed under the License is distributed on an "AS IS" BASIS, 11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 * See the License for the specific language governing permissions and 13 * limitations under the License. 14 */ 15 #include <atomic> 16 17 #include "log_print.h" 18 #include "runtime_context_impl.h" 19 #include "version.h" 20 21 namespace DistributedDB { GetInstance()22RuntimeContext *RuntimeContext::GetInstance() 23 { 24 static char instMemory[sizeof(RuntimeContextImpl)]; 25 static std::mutex instLock_; 26 static std::atomic<RuntimeContext *> instPtr = nullptr; 27 // For Double-Checked Locking, we need check insPtr twice 28 if (instPtr == nullptr) { 29 std::lock_guard<std::mutex> lock(instLock_); 30 if (instPtr == nullptr) { 31 // Use instMemory to make sure this singleton not free before other object. 32 // This operation needn't to malloc memory, we needn't to check nullptr. 33 instPtr = new (instMemory) RuntimeContextImpl; 34 LOGI("DistributedDB Version : %s", SOFTWARE_VERSION_STRING.c_str()); 35 } 36 } 37 return instPtr; 38 } 39 } // namespace DistributedDB 40 41