threadingwin.cpp

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        LOG_ERROR("ThreadIdentifier %u was found to be deadlocked trying to quit", threadID);

    CloseHandle(threadHandle);
    clearThreadHandleForIdentifier(threadID);

    return joinResult;
}

void detachThread(ThreadIdentifier threadID)
{
    ASSERT(threadID);
    
    HANDLE threadHandle = threadHandleForIdentifier(threadID);
    if (threadHandle)
        CloseHandle(threadHandle);
    clearThreadHandleForIdentifier(threadID);
}

ThreadIdentifier currentThread()
{
    return static_cast<ThreadIdentifier>(GetCurrentThreadId());
}

bool isMainThread()
{
    return currentThread() == mainThreadIdentifier;
}

Mutex::Mutex()
{
    m_mutex.m_recursionCount = 0;
    InitializeCriticalSection(&m_mutex.m_internalMutex);
}

Mutex::~Mutex()
{
    DeleteCriticalSection(&m_mutex.m_internalMutex);
}

void Mutex::lock()
{
    EnterCriticalSection(&m_mutex.m_internalMutex);
    ++m_mutex.m_recursionCount;
}
    
bool Mutex::tryLock()
{
    // This method is modeled after the behavior of pthread_mutex_trylock,
    // which will return an error if the lock is already owned by the
    // current thread.  Since the primitive Win32 'TryEnterCriticalSection'
    // treats this as a successful case, it changes the behavior of several
    // tests in WebKit that check to see if the current thread already
    // owned this mutex (see e.g., IconDatabase::getOrCreateIconRecord)
    DWORD result = TryEnterCriticalSection(&m_mutex.m_internalMutex);
    
    if (result != 0) {       // We got the lock
        // If this thread already had the lock, we must unlock and
        // return false so that we mimic the behavior of POSIX's
        // pthread_mutex_trylock:
        if (m_mutex.m_recursionCount > 0) {
            LeaveCriticalSection(&m_mutex.m_internalMutex);
            return false;
        }

        ++m_mutex.m_recursionCount;
        return true;
    }

    return false;
}

void Mutex::unlock()
{
    --m_mutex.m_recursionCount;
    LeaveCriticalSection(&m_mutex.m_internalMutex);
}

bool PlatformCondition::timedWait(PlatformMutex& mutex, DWORD durationMilliseconds)
{
    // Enter the wait state.
    DWORD res = WaitForSingleObject(m_blockLock, INFINITE);
    ASSERT(res == WAIT_OBJECT_0);
    ++m_waitersBlocked;
    res = ReleaseSemaphore(m_blockLock, 1, 0);
    ASSERT(res);

    LeaveCriticalSection(&mutex.m_internalMutex);

    // Main wait - use timeout.
    bool timedOut = (WaitForSingleObject(m_blockQueue, durationMilliseconds) == WAIT_TIMEOUT);

    res = WaitForSingleObject(m_unblockLock, INFINITE);
    ASSERT(res == WAIT_OBJECT_0);

    int signalsLeft = m_waitersToUnblock;

    if (m_waitersToUnblock)
        --m_waitersToUnblock;
    else if (++m_waitersGone == (INT_MAX / 2)) { // timeout/canceled or spurious semaphore
        // timeout or spurious wakeup occured, normalize the m_waitersGone count
        // this may occur if many calls to wait with a timeout are made and
        // no call to notify_* is made
        res = WaitForSingleObject(m_blockLock, INFINITE);
        ASSERT(res == WAIT_OBJECT_0);
        m_waitersBlocked -= m_waitersGone;
        res = ReleaseSemaphore(m_blockLock, 1, 0);
        ASSERT(res);
        m_waitersGone = 0;
    }

    res = ReleaseMutex(m_unblockLock);
    ASSERT(res);

    if (signalsLeft == 1) {
        res = ReleaseSemaphore(m_blockLock, 1, 0); // Open the gate.
        ASSERT(res);
    }

    EnterCriticalSection (&mutex.m_internalMutex);

    return !timedOut;
}

void PlatformCondition::signal(bool unblockAll)
{
    unsigned signalsToIssue = 0;

    DWORD res = WaitForSingleObject(m_unblockLock, INFINITE);
    ASSERT(res == WAIT_OBJECT_0);

    if (m_waitersToUnblock) { // the gate is already closed
        if (!m_waitersBlocked) { // no-op
            res = ReleaseMutex(m_unblockLock);
            ASSERT(res);
            return;
        }

        if (unblockAll) {
            signalsToIssue = m_waitersBlocked;
            m_waitersToUnblock += m_waitersBlocked;
            m_waitersBlocked = 0;
        } else {
            signalsToIssue = 1;
            ++m_waitersToUnblock;
            --m_waitersBlocked;
        }
    } else if (m_waitersBlocked > m_waitersGone) {
        res = WaitForSingleObject(m_blockLock, INFINITE); // Close the gate.
        ASSERT(res == WAIT_OBJECT_0);
        if (m_waitersGone != 0) {
            m_waitersBlocked -= m_waitersGone;
            m_waitersGone = 0;
        }
        if (unblockAll) {
            signalsToIssue = m_waitersBlocked;
            m_waitersToUnblock = m_waitersBlocked;
            m_waitersBlocked = 0;
        } else {
            signalsToIssue = 1;
            m_waitersToUnblock = 1;
            --m_waitersBlocked;
        }
    } else { // No-op.
        res = ReleaseMutex(m_unblockLock);
        ASSERT(res);
        return;
    }

    res = ReleaseMutex(m_unblockLock);
    ASSERT(res);

    if (signalsToIssue) {
        res = ReleaseSemaphore(m_blockQueue, signalsToIssue, 0);
        ASSERT(res);
    }
}

static const long MaxSemaphoreCount = static_cast<long>(~0UL >> 1);

ThreadCondition::ThreadCondition()
{
    m_condition.m_waitersGone = 0;
    m_condition.m_waitersBlocked = 0;
    m_condition.m_waitersToUnblock = 0;
    m_condition.m_blockLock = CreateSemaphore(0, 1, 1, 0);
    m_condition.m_blockQueue = CreateSemaphore(0, 0, MaxSemaphoreCount, 0);
    m_condition.m_unblockLock = CreateMutex(0, 0, 0);

    if (!m_condition.m_blockLock || !m_condition.m_blockQueue || !m_condition.m_unblockLock) {
        if (m_condition.m_blockLock)
            CloseHandle(m_condition.m_blockLock);
        if (m_condition.m_blockQueue)
            CloseHandle(m_condition.m_blockQueue);
        if (m_condition.m_unblockLock)
            CloseHandle(m_condition.m_unblockLock);
    }
}

ThreadCondition::~ThreadCondition()
{
    CloseHandle(m_condition.m_blockLock);
    CloseHandle(m_condition.m_blockQueue);
    CloseHandle(m_condition.m_unblockLock);
}

void ThreadCondition::wait(Mutex& mutex)
{
    m_condition.timedWait(mutex.impl(), INFINITE);
}

bool ThreadCondition::timedWait(Mutex& mutex, double absoluteTime)
{
    double currentTime = WTF::currentTime();

    // Time is in the past - return immediately.
    if (absoluteTime < currentTime)
        return false;

    // Time is too far in the future (and would overflow unsigned long) - wait forever.
    if (absoluteTime - currentTime > static_cast<double>(INT_MAX) / 1000.0) {
        wait(mutex);
        return true;
    }

    double intervalMilliseconds = (absoluteTime - currentTime) * 1000.0;
    return m_condition.timedWait(mutex.impl(), static_cast<unsigned long>(intervalMilliseconds));
}

void ThreadCondition::signal()
{
    m_condition.signal(false); // Unblock only 1 thread.
}

void ThreadCondition::broadcast()
{
    m_condition.signal(true); // Unblock all threads.
}

} // namespace WTF