/*** A thread safe queue.
 * From: http://www.justsoftwaresolutions.co.uk/threading/implementing-a-thread-safe-queue-using-condition-variables.html
 * Author: Anthony Williams
 */

#ifndef __TQUEUE_H__
#define __TQUEUE_H__

#include <queue>
#include <vector>
#include <boost/thread/mutex.hpp>
#include <boost/thread/condition.hpp>

template < class T, class Container = std::vector<T>, class Compare = std::less<typename Container::value_type> >
class pqueue : public std::priority_queue<T,Container,Compare>
{
    public:
    const T& front() const
    {
        return std::priority_queue<T,Container,Compare>::top();
    }

};

template< typename Data, class Container = std::queue<Data> >
class concurrent_queue
{
private:
    Container the_queue;
    mutable boost::mutex the_mutex;
    boost::condition cond_not_empty;
    boost::condition cond_not_full;

public:
    void push(Data const& data)
    {
        boost::mutex::scoped_lock lock(the_mutex);
        the_queue.push(data);
        lock.unlock();
        cond_not_empty.notify_one();
    }

    void push_if_not_full( Data const& data, const unsigned int max )
    {
        boost::mutex::scoped_lock lock(the_mutex);
        while( the_queue.size() >= max )
        {
            cond_not_full.wait(lock);
        }
        the_queue.push(data);
        lock.unlock();
        cond_not_empty.notify_one();
    }

    bool empty() const
    {
        boost::mutex::scoped_lock lock(the_mutex);
        return the_queue.empty();
    }

    typename Container::size_type size() const
    {
        return the_queue.size();
    }

    bool try_pop(Data& popped_value)
    {
        boost::mutex::scoped_lock lock(the_mutex);
        if(the_queue.empty())
        {
            return false;
        }

        popped_value=the_queue.front();
        the_queue.pop();
        cond_not_full.notify_one();
        return true;
    }

    void wait_and_pop( Data &popped_value )
    {
        boost::mutex::scoped_lock lock(the_mutex);
        while(the_queue.empty())
        {
            cond_not_empty.wait(lock);
        }

        popped_value = the_queue.front();
        the_queue.pop();
        cond_not_full.notify_one();
    }

};

#endif // __TQUEUE_H__