create_thread_identity.h (2160B)
1 /* 2 * Copyright 2017 The Abseil Authors. 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 * https://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 // Interface for getting the current ThreadIdentity, creating one if necessary. 18 // See thread_identity.h. 19 // 20 // This file is separate from thread_identity.h because creating a new 21 // ThreadIdentity requires slightly higher level libraries (per_thread_sem 22 // and low_level_alloc) than accessing an existing one. This separation allows 23 // us to have a smaller //absl/base:base. 24 25 #ifndef ABSL_SYNCHRONIZATION_INTERNAL_CREATE_THREAD_IDENTITY_H_ 26 #define ABSL_SYNCHRONIZATION_INTERNAL_CREATE_THREAD_IDENTITY_H_ 27 28 #include "absl/base/internal/thread_identity.h" 29 #include "absl/base/port.h" 30 31 namespace absl { 32 ABSL_NAMESPACE_BEGIN 33 namespace synchronization_internal { 34 35 // Allocates and attaches a ThreadIdentity object for the calling thread. 36 // For private use only. 37 base_internal::ThreadIdentity* CreateThreadIdentity(); 38 39 // Returns the ThreadIdentity object representing the calling thread; guaranteed 40 // to be unique for its lifetime. The returned object will remain valid for the 41 // program's lifetime; although it may be re-assigned to a subsequent thread. 42 // If one does not exist for the calling thread, allocate it now. 43 inline base_internal::ThreadIdentity* GetOrCreateCurrentThreadIdentity() { 44 base_internal::ThreadIdentity* identity = 45 base_internal::CurrentThreadIdentityIfPresent(); 46 if (ABSL_PREDICT_FALSE(identity == nullptr)) { 47 return CreateThreadIdentity(); 48 } 49 return identity; 50 } 51 52 } // namespace synchronization_internal 53 ABSL_NAMESPACE_END 54 } // namespace absl 55 56 #endif // ABSL_SYNCHRONIZATION_INTERNAL_CREATE_THREAD_IDENTITY_H_