Function erase_from_butex

src/bthread/butex.cpp:511–542

}

inline bool erase_from_butex(ButexWaiter* bw, bool wakeup, WaiterState state) {
    // `bw' is guaranteed to be valid inside this function because waiter
    // will wait until this function being cancelled or finished.
    // NOTE: This function must be no-op when bw->container is NULL.
    bool erased = false;
    Butex* b;
    int saved_errno = errno;
    while ((b = bw->container.load(butil::memory_order_acquire))) {
        // b can be NULL when the waiter is scheduled but queued.
        BAIDU_SCOPED_LOCK(b->waiter_lock);
        if (b == bw->container.load(butil::memory_order_relaxed)) {
            bw->RemoveFromList();
            bw->container.store(NULL, butil::memory_order_relaxed);
            if (bw->tid) {
                static_cast<ButexBthreadWaiter*>(bw)->waiter_state = state;
            }
            erased = true;
            break;
        }
    }
    if (erased && wakeup) {
        if (bw->tid) {
            ButexBthreadWaiter* bbw = static_cast<ButexBthreadWaiter*>(bw);
            get_task_group(bbw->control, bbw->tag)->ready_to_run_general(bbw->task_meta);
        } else {
            ButexPthreadWaiter* pw = static_cast<ButexPthreadWaiter*>(bw);
            wakeup_pthread(pw);
        }
    }
    errno = saved_errno;
    return erased;
}

struct WaitForButexArgs {
    ButexBthreadWaiter* bw;