1 /* 2 * Copyright 2020 Google LLC 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 FCP_BASE_PROCESS_UNIQUE_ID_H_ 18 #define FCP_BASE_PROCESS_UNIQUE_ID_H_ 19 20 #include <atomic> 21 22 namespace fcp { 23 24 // Threadsafe class for creating IDs that are unique per-process. 25 class ProcessUniqueId { 26 public: 27 // Threadsafe method for getting a new unique ID, intended to be cheap. 28 static ProcessUniqueId Next(); value()29 uint64_t value() { return value_; } 30 31 private: ProcessUniqueId(uint64_t value)32 explicit constexpr ProcessUniqueId(uint64_t value) : value_(value) {} 33 // Value of the unique ID. 34 uint64_t value_; 35 }; 36 37 } // namespace fcp 38 39 #endif // FCP_BASE_PROCESS_UNIQUE_ID_H_ 40