std::thread中获取当前线程的系统id

std::thread不提供获取当前线程的系统id的方法，仅可以获取当前的线程id，但是我们可以通过建立索引表的方式来实现

std::mutex m;
std::map<std::thread::id, pid_t> threads;
void add_tid_mapping()
{
  std::lock_guard<std::mutex> l(m);
  threads[std::this_thread::get_id()] = syscall(SYS_gettid);
}
void wrap(void (*f)())
{
  add_tid_mapping();
  f();
}

而后用其创建线程

std::thread t1(&wrap, &SayHello);

然后用如下方式获取线程id

pid_t tid = 0;
while (tid == 0)
{
  std::lock_guard<std::mutex> l(m);
  if (threads.count(t1.get_id()))
    tid = threads[t1.get_id()];
}

转自：https://stackoverflow.com/questions/15708983/how-can-you-get-the-linux-thread-id-of-a-stdthread