1 //===--- Thread Identifier Header --------------------------------*- C++-*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef LLVM_LIBC_SRC___SUPPORT_THREADS_IDENTIFIER_H 10 #define LLVM_LIBC_SRC___SUPPORT_THREADS_IDENTIFIER_H 11 12 #ifdef LIBC_FULL_BUILD 13 #include "src/__support/threads/thread.h" 14 #endif // LIBC_FULL_BUILD 15 16 #include "hdr/types/pid_t.h" 17 #include "src/__support/OSUtil/syscall.h" 18 #include "src/__support/macros/optimization.h" 19 #include <sys/syscall.h> 20 21 namespace LIBC_NAMESPACE_DECL { 22 namespace internal { 23 get_tid_cache()24LIBC_INLINE pid_t *get_tid_cache() { 25 #ifdef LIBC_FULL_BUILD 26 return &self.attrib->tid; 27 #else 28 // in non-full build mode, we do not control the fork routine. Therefore, 29 // we do not cache tid at all. 30 return nullptr; 31 #endif 32 } 33 gettid()34LIBC_INLINE pid_t gettid() { 35 pid_t *cache = get_tid_cache(); 36 if (LIBC_UNLIKELY(!cache || *cache <= 0)) 37 return syscall_impl<pid_t>(SYS_gettid); 38 return *cache; 39 } 40 force_set_tid(pid_t tid)41LIBC_INLINE void force_set_tid(pid_t tid) { 42 pid_t *cache = get_tid_cache(); 43 if (cache) 44 *cache = tid; 45 } 46 47 } // namespace internal 48 } // namespace LIBC_NAMESPACE_DECL 49 50 #endif // LLVM_LIBC_SRC___SUPPORT_THREADS_IDENTIFIER_H 51