Method lockForWrite

kdevplatform/language/duchain/duchainlock.cpp:110–153

}

bool DUChainLock::lockForWrite(uint timeout)
{
    Q_D(DUChainLock);

    //It is not allowed to acquire a write-lock while holding read-lock

    Q_ASSERT(d->ownReaderRecursion() == 0);

    if (d->m_writer.loadRelaxed() == QThread::currentThread()) {
        //We already hold the write lock, just increase the recursion count and return
        d->m_writerRecursion.fetchAndAddRelaxed(1);
        return true;
    }

    QElapsedTimer t;
    if (timeout) {
        t.start();
    }

    while (1) {
        //Try acquiring the write-lcok
        if (d->m_totalReaderRecursion.loadRelaxed() == 0 && d->m_writerRecursion.testAndSetOrdered(0, 1)) {
            //Now we can be sure that there is no other writer, as we have increased m_writerRecursion from 0 to 1
            d->m_writer = QThread::currentThread();
            if (d->m_totalReaderRecursion.loadRelaxed() == 0) {
                //There is still no readers, we have successfully acquired a write-lock
                return true;
            } else {
                //There may be readers.. we have to continue spinning
                d->m_writer = nullptr;
                d->m_writerRecursion = 0;
            }
        }

        if (!timeout || t.elapsed() < timeout) {
            QThread::usleep(uSleepTime);
        } else {
            //Fail!
            return false;
        }
    }

    return false;
}

void DUChainLock::releaseWriteLock()
{