Re: Exchanging data betwwen threads?

"Solang" <solang@verizon.net> wrote in message
news:DHotm.3060$tl3.1065@nwrddc01.gnilink.net...


A simple method is to create a queue; example pseudo-code typed in news
reader, please forgive any typos:
_______________________________________________________________________
struct node
{
    node* m_next;
};

class queue
{
    node* m_head;
    node* m_tail;

public:
    queue()
    : m_head(NULL)
    {

    }

public:
    void push(node* n)
    {
        n->m_next = NULL;

        if (! m_head)
        {
            m_head = n;
        }

        else
        {
            m_tail->m_next = n;
        }

        m_tail = n;
    }

    node* pop()
    {
        node* n = m_head;

        if (n)
        {
            m_head = n->m_next;
        }

        return n;
    }
};

class thread_safe_queue
{
    mutex m_mutex;
    cond m_cond;
    queue m_queue;

public:
    void push(node* n)
    {
        {
            mutex::guard lock(m_mutex);

            m_queue.push(n);
        }

        m_cond.signal();
    }

    node* pop()
    {
        node* n;

        {
            mutex::guard lock(m_mutex);

            while (! (n = m_queue.pop()))
            {
                m_cond.wait(lock);
            }
        }

        return n;
    }
};
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Or, if you prefer semaphores:
_______________________________________________________________________
class thread_safe_queue
{
    mutex m_mutex;
    semaphore m_sem;
    queue m_queue;

public:
    void push(node* n)
    {
        {
            mutex::guard lock(m_mutex);

            m_queue.push(n);
        }

        m_sem.post();
    }

    node* pop()
    {
        m_sem.wait();
        mutex::guard lock(m_mutex);

        return m_queue.pop();
    }
};
_______________________________________________________________________