C++ MessageQueue::front方法代码示例

void
RPCChannel::DebugAbort(const char* file, int line, const char* cond,
                       const char* why,
                       const char* type, bool reply) const
{
    printf_stderr("###!!! [RPCChannel][%s][%s:%d] "
                  "Assertion (%s) failed.  %s (triggered by %s%s)\n",
                  mChild ? "Child" : "Parent",
                  file, line, cond,
                  why,
                  type, reply ? "reply" : "");
    // technically we need the mutex for this, but we're dying anyway
    DumpRPCStack("  ");
    printf_stderr("  remote RPC stack guess: %lu\n",
                  mRemoteStackDepthGuess);
    printf_stderr("  deferred stack size: %lu\n",
                  mDeferred.size());
    printf_stderr("  out-of-turn RPC replies stack size: %lu\n",
                  mOutOfTurnReplies.size());
    printf_stderr("  Pending queue size: %lu, front to back:\n",
                  mPending.size());

    MessageQueue pending = mPending;
    while (!pending.empty()) {
        printf_stderr("    [ %s%s ]\n",
                      pending.front().is_rpc() ? "rpc" :
                      (pending.front().is_sync() ? "sync" : "async"),
                      pending.front().is_reply() ? "reply" : "");
        pending.pop_front();
    }

    NS_RUNTIMEABORT(why);
}

Uint32 Sum(const MessageQueue& q)
{
    Uint32 sum = 0;

    for (const Message* m = q.front(); m; m = m->getNext())
    {
	const Alarm* a = (const Alarm*)m;
	sum += a->getKey();
    }
    return sum;
}

bool
RPCChannel::OnMaybeDequeueOne()
{
    // XXX performance tuning knob: could process all or k pending
    // messages here

    AssertWorkerThread();
    mMonitor->AssertNotCurrentThreadOwns();

    Message recvd;
    {
        MonitorAutoLock lock(*mMonitor);

        if (!Connected()) {
            ReportConnectionError("RPCChannel");
            return false;
        }

        if (!mDeferred.empty())
            MaybeUndeferIncall();

        MessageQueue *queue = mUrgent.empty()
                              ? mNonUrgentDeferred.empty()
                              ? &mPending
                              : &mNonUrgentDeferred
                              : &mUrgent;
        if (queue->empty())
            return false;

        recvd = queue->front();
        queue->pop_front();
    }

    if (IsOnCxxStack() && recvd.is_rpc() && recvd.is_reply()) {
        // We probably just received a reply in a nested loop for an
        // RPC call sent before entering that loop.
        mOutOfTurnReplies[recvd.seqno()] = recvd;
        return false;
    }

    CxxStackFrame f(*this, IN_MESSAGE, &recvd);

    if (recvd.is_rpc())
        Incall(recvd, 0);
    else if (recvd.is_sync())
        SyncChannel::OnDispatchMessage(recvd);
    else
        AsyncChannel::OnDispatchMessage(recvd);

    return true;
}

void TestMessageQueue2()
{
    MessageQueue q;

    Uint32 sum = 0;

    for (Uint32 i = 1; i <= 5; i++)
    {
	q.enqueue(new Alarm(i));
	sum += i;
    }
    assert(sum == 15);

    while (!q.isEmpty())
	q.remove(q.front());

    assert(q.getCount() == 0);
}

void TestMessageQueue1()
{
    MessageQueue q;

    Uint32 sum = 0;

    for (Uint32 i = 1; i <= 5; i++)
    {
	q.enqueue(new Alarm(i));
	sum += i;
    }

    assert(Sum(q) == sum);

    // Test removing from the middle:
    Message* m = q.findByKey(3);
    assert(m != 0);
    q.remove(m);
    assert(Sum(q) == sum - 3);
    assert(q.getCount() == 4);

    // Test removing from the front:
    q.remove(q.front());
    assert(Sum(q) == sum - 3 - 1);
    assert(q.getCount() == 3);

    // Test removing from the front:
    q.remove(q.back());
    assert(Sum(q) == sum - 3 - 1 - 5);
    assert(q.getCount() == 2);

    // Test dequeue:
    m = q.dequeue();
    assert(m->getKey() == 2);
    assert(Sum(q) == sum - 3 - 1 - 5 - 2);
    assert(q.getCount() == 1);

    // Test dequeue:
    m = q.dequeue();
    assert(m->getKey() == 4);
    assert(Sum(q) == sum - 3 - 1 - 5 - 2 - 4);
    assert(q.getCount() == 0);
}