xref: /freebsd/contrib/llvm-project/libc/src/__support/threads/callonce.h (revision bb722a7d0f1642bff6487f943ad0427799a6e5bf)
1*bb722a7dSDimitry Andric //===-- Types related to the callonce function ----------------------------===//
2*bb722a7dSDimitry Andric //
3*bb722a7dSDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4*bb722a7dSDimitry Andric // See https://llvm.org/LICENSE.txt for license information.
5*bb722a7dSDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6*bb722a7dSDimitry Andric //
7*bb722a7dSDimitry Andric //===----------------------------------------------------------------------===//
8*bb722a7dSDimitry Andric 
9*bb722a7dSDimitry Andric #ifndef LLVM_LIBC_SRC___SUPPORT_THREADS_CALLONCE_H
10*bb722a7dSDimitry Andric #define LLVM_LIBC_SRC___SUPPORT_THREADS_CALLONCE_H
11*bb722a7dSDimitry Andric 
12*bb722a7dSDimitry Andric #include "src/__support/macros/config.h"
13*bb722a7dSDimitry Andric #include "src/__support/macros/optimization.h" // LIBC_LIKELY
14*bb722a7dSDimitry Andric 
15*bb722a7dSDimitry Andric // Plaform specific routines, provides:
16*bb722a7dSDimitry Andric // - OnceFlag definition
17*bb722a7dSDimitry Andric // - callonce_impl::callonce_fastpath for fast path check
18*bb722a7dSDimitry Andric // - callonce_impl::callonce_slowpath for slow path execution
19*bb722a7dSDimitry Andric #ifdef __linux__
20*bb722a7dSDimitry Andric #include "src/__support/threads/linux/callonce.h"
21*bb722a7dSDimitry Andric #else
22*bb722a7dSDimitry Andric #error "callonce is not supported on this platform"
23*bb722a7dSDimitry Andric #endif
24*bb722a7dSDimitry Andric 
25*bb722a7dSDimitry Andric namespace LIBC_NAMESPACE_DECL {
26*bb722a7dSDimitry Andric 
27*bb722a7dSDimitry Andric // Common definitions
28*bb722a7dSDimitry Andric using CallOnceCallback = void(void);
29*bb722a7dSDimitry Andric namespace callonce_impl {
30*bb722a7dSDimitry Andric int callonce_slowpath(CallOnceFlag *flag, CallOnceCallback *callback);
31*bb722a7dSDimitry Andric } // namespace callonce_impl
32*bb722a7dSDimitry Andric 
callonce(CallOnceFlag * flag,CallOnceCallback * callback)33*bb722a7dSDimitry Andric LIBC_INLINE int callonce(CallOnceFlag *flag, CallOnceCallback *callback) {
34*bb722a7dSDimitry Andric   if (LIBC_LIKELY(callonce_impl::callonce_fastpath(flag)))
35*bb722a7dSDimitry Andric     return 0;
36*bb722a7dSDimitry Andric 
37*bb722a7dSDimitry Andric   return callonce_impl::callonce_slowpath(flag, callback);
38*bb722a7dSDimitry Andric }
39*bb722a7dSDimitry Andric } // namespace LIBC_NAMESPACE_DECL
40*bb722a7dSDimitry Andric 
41*bb722a7dSDimitry Andric #endif // LLVM_LIBC_SRC___SUPPORT_THREADS_CALLONCE_H
42