00001 /* 00002 * Copyright 2017 The Abseil Authors. 00003 * 00004 * Licensed under the Apache License, Version 2.0 (the "License"); 00005 * you may not use this file except in compliance with the License. 00006 * You may obtain a copy of the License at 00007 * 00008 * https://www.apache.org/licenses/LICENSE-2.0 00009 * 00010 * Unless required by applicable law or agreed to in writing, software 00011 * distributed under the License is distributed on an "AS IS" BASIS, 00012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 00013 * See the License for the specific language governing permissions and 00014 * limitations under the License. 00015 */ 00016 00017 // Interface for getting the current ThreadIdentity, creating one if necessary. 00018 // See thread_identity.h. 00019 // 00020 // This file is separate from thread_identity.h because creating a new 00021 // ThreadIdentity requires slightly higher level libraries (per_thread_sem 00022 // and low_level_alloc) than accessing an existing one. This separation allows 00023 // us to have a smaller //absl/base:base. 00024 00025 #ifndef ABSL_SYNCHRONIZATION_INTERNAL_CREATE_THREAD_IDENTITY_H_ 00026 #define ABSL_SYNCHRONIZATION_INTERNAL_CREATE_THREAD_IDENTITY_H_ 00027 00028 #include "absl/base/internal/thread_identity.h" 00029 #include "absl/base/port.h" 00030 00031 namespace absl { 00032 namespace synchronization_internal { 00033 00034 // Allocates and attaches a ThreadIdentity object for the calling thread. 00035 // For private use only. 00036 base_internal::ThreadIdentity* CreateThreadIdentity(); 00037 00038 // Returns the ThreadIdentity object representing the calling thread; guaranteed 00039 // to be unique for its lifetime. The returned object will remain valid for the 00040 // program's lifetime; although it may be re-assigned to a subsequent thread. 00041 // If one does not exist for the calling thread, allocate it now. 00042 inline base_internal::ThreadIdentity* GetOrCreateCurrentThreadIdentity() { 00043 base_internal::ThreadIdentity* identity = 00044 base_internal::CurrentThreadIdentityIfPresent(); 00045 if (ABSL_PREDICT_FALSE(identity == nullptr)) { 00046 return CreateThreadIdentity(); 00047 } 00048 return identity; 00049 } 00050 00051 } // namespace synchronization_internal 00052 } // namespace absl 00053 00054 #endif // ABSL_SYNCHRONIZATION_INTERNAL_CREATE_THREAD_IDENTITY_H_