1// Copyright 2017 The Abseil Authors.
2//
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// https://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#ifndef ABSL_BASE_INTERNAL_PER_THREAD_TLS_H_
16#define ABSL_BASE_INTERNAL_PER_THREAD_TLS_H_
17
18// This header defines two macros:
19//
20// If the platform supports thread-local storage:
21//
22// * ABSL_PER_THREAD_TLS_KEYWORD is the C keyword needed to declare a
23// thread-local variable
24// * ABSL_PER_THREAD_TLS is 1
25//
26// Otherwise:
27//
28// * ABSL_PER_THREAD_TLS_KEYWORD is empty
29// * ABSL_PER_THREAD_TLS is 0
30//
31// Microsoft C supports thread-local storage.
32// GCC supports it if the appropriate version of glibc is available,
33// which the programmer can indicate by defining ABSL_HAVE_TLS
34
35#include "absl/base/port.h" // For ABSL_HAVE_TLS
36
37#if defined(ABSL_PER_THREAD_TLS)
38#error ABSL_PER_THREAD_TLS cannot be directly set
39#elif defined(ABSL_PER_THREAD_TLS_KEYWORD)
40#error ABSL_PER_THREAD_TLS_KEYWORD cannot be directly set
41#elif defined(ABSL_HAVE_TLS)
42#define ABSL_PER_THREAD_TLS_KEYWORD __thread
43#define ABSL_PER_THREAD_TLS 1
44#elif defined(_MSC_VER)
45#define ABSL_PER_THREAD_TLS_KEYWORD __declspec(thread)
46#define ABSL_PER_THREAD_TLS 1
47#else
48#define ABSL_PER_THREAD_TLS_KEYWORD
49#define ABSL_PER_THREAD_TLS 0
50#endif
51
52#endif // ABSL_BASE_INTERNAL_PER_THREAD_TLS_H_
53