my_thread_os_id.h

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/* Copyright (c) 2015, 2025, Oracle and/or its affiliates.
 
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.
 
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   as designated in a particular file or component or in included license
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   permission to link the program and your derivative works with the
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   the program or referenced in the documentation.
 
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License, version 2.0, for more details.
 
   You should have received a copy of the GNU General Public License
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   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
/**
  @file include/my_thread_os_id.h
  Portable wrapper for gettid().
*/
 
#ifndef MY_THREAD_OS_ID_INCLUDED
#define MY_THREAD_OS_ID_INCLUDED
 
#include "my_config.h"
#include "my_macros.h"
#include "my_thread.h"
#ifndef _WIN32
#include <sys/syscall.h>
#include <unistd.h>
#endif
 
#ifdef HAVE_PTHREAD_GETTHREADID_NP
#include <pthread_np.h> /* pthread_getthreadid_np() */
#endif                  /* HAVE_PTHREAD_GETTHREADID_NP */
 
#ifdef HAVE_PTHREAD_THREADID_NP
#include <pthread.h>
#endif /* HAVE_PTHREAD_THREADID_NP */
 
typedef unsigned long long my_thread_os_id_t;
 
/**
  Return the operating system thread id.
  With Linux, threads have:
  - an internal id, @c pthread_self(), visible in process
  - an external id, @c gettid(), visible in the operating system,
    for example with perf in linux.
  This helper returns the underling operating system thread id.
*/
static inline my_thread_os_id_t my_thread_os_id() {
#ifdef HAVE_PTHREAD_THREADID_NP
  /*
    macOS.
 
    Be careful to use this version first, and to not use SYS_gettid on macOS,
    as SYS_gettid has a different meaning compared to linux gettid().
  */
  uint64_t tid64;
  pthread_threadid_np(nullptr, &tid64);
  return (pid_t)tid64;
#else
#ifdef HAVE_SYS_GETTID
  /*
    Linux.
    See man gettid
    See GLIBC Bug 6399 - gettid() should have a wrapper
    https://sourceware.org/bugzilla/show_bug.cgi?id=6399
  */
  return syscall(SYS_gettid);
#else
#ifdef _WIN32
  /* Windows */
  return GetCurrentThreadId();
#else
#ifdef HAVE_PTHREAD_GETTHREADID_NP
  /* FreeBSD 10.2 */
  return pthread_getthreadid_np();
#else
#ifdef HAVE_INTEGER_PTHREAD_SELF
  /* Unknown platform, fallback. */
  return pthread_self();
#else
  /* Feature not available. */
  return 0;
#endif /* HAVE_INTEGER_PTHREAD_SELF */
#endif /* HAVE_PTHREAD_GETTHREADID_NP */
#endif /* _WIN32 */
#endif /* HAVE_SYS_GETTID */
#endif /* HAVE_SYS_THREAD_SELFID */
}
 
#endif /* MY_THREAD_OS_ID_INCLUDED */