/*

 * Copyright 2017 The Abseil Authors.

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      https://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

// Interface for getting the current ThreadIdentity, creating one if necessary.

// See thread_identity.h.

//

// This file is separate from thread_identity.h because creating a new

// ThreadIdentity requires slightly higher level libraries (per_thread_sem

// and low_level_alloc) than accessing an existing one.  This separation allows

// us to have a smaller //absl/base:base.

#ifndef ABSL_SYNCHRONIZATION_INTERNAL_CREATE_THREAD_IDENTITY_H_

#define ABSL_SYNCHRONIZATION_INTERNAL_CREATE_THREAD_IDENTITY_H_

#include "absl/base/config.h"

#include "absl/base/internal/thread_identity.h"

#include "absl/base/optimization.h"

#include "absl/base/port.h"

namespace absl {

ABSL_NAMESPACE_BEGIN

namespace synchronization_internal {

// Allocates and attaches a ThreadIdentity object for the calling thread.

// For private use only.

base_internal::ThreadIdentity* CreateThreadIdentity();

// Returns the ThreadIdentity object representing the calling thread; guaranteed

// to be unique for its lifetime.  The returned object will remain valid for the

// program's lifetime; although it may be re-assigned to a subsequent thread.

// If one does not exist for the calling thread, allocate it now.

inline base_internal::ThreadIdentity* GetOrCreateCurrentThreadIdentity() {

  base_internal::ThreadIdentity* identity =

      base_internal::CurrentThreadIdentityIfPresent();

  if (ABSL_PREDICT_FALSE(identity == nullptr)) {

    return CreateThreadIdentity();

  }

  return identity;

}

}  // namespace synchronization_internal

ABSL_NAMESPACE_END

}  // namespace absl

#endif  // ABSL_SYNCHRONIZATION_INTERNAL_CREATE_THREAD_IDENTITY_H_