Function butex_wait_from_pthread

src/bthread/butex.cpp:612–668

}

static int butex_wait_from_pthread(TaskGroup* g, Butex* b, int expected_value,
                                   const timespec* abstime, bool prepend) {
    TaskMeta* task = NULL;
    ButexPthreadWaiter pw;
    pw.tid = 0;
    pw.sig.store(PTHREAD_NOT_SIGNALLED, butil::memory_order_relaxed);
    int rc = 0;
    
    if (g) {
        task = g->current_task();
        task->current_waiter.store(&pw, butil::memory_order_release);
    }
    b->waiter_lock.lock();
    if (b->value.load(butil::memory_order_relaxed) != expected_value) {
        b->waiter_lock.unlock();
        errno = EWOULDBLOCK;
        rc = -1;
    } else if (task != NULL && task->interrupted) {
        b->waiter_lock.unlock();
        // Race with set and may consume multiple interruptions, which are OK.
        task->interrupted = false;
        errno = EINTR;
        rc = -1;
    } else {
        if (prepend) {
            b->waiters.Prepend(&pw);
        } else {
            b->waiters.Append(&pw);
        }
        pw.container.store(b, butil::memory_order_relaxed);
        b->waiter_lock.unlock();

#ifdef SHOW_BTHREAD_BUTEX_WAITER_COUNT_IN_VARS
        bvar::Adder<int64_t>& num_waiters = butex_waiter_count();
        num_waiters << 1;
#endif
        rc = wait_pthread(pw, abstime);
#ifdef SHOW_BTHREAD_BUTEX_WAITER_COUNT_IN_VARS
        num_waiters << -1;
#endif
    }
    if (task) {
        // If current_waiter is NULL, TaskGroup::interrupt() is running and
        // using pw, spin until current_waiter != NULL.
        BT_LOOP_WHEN(task->current_waiter.exchange(
                         NULL, butil::memory_order_acquire) == NULL,
                     30/*nops before sched_yield*/);
        if (task->interrupted) {
            task->interrupted = false;
            if (rc == 0) {
                errno = EINTR;
                return -1;
            }
        }
    }
    return rc;
}