ObjQueue.cpp

/*=============================================================================
Description: A thread safe queue using boost::mutex library to do so.

Author: J. Nolan Hager (JNHager)

NOTE (JNhager): boost::mutext::scoped_lock locks all resources in the same 
  scope until that scope has resolved. This means all scopes within will be 
  locked as well.

=============================================================================*/
#ifndef _ObjQueue_
#define _ObjQueue_

#include <iostream>
#include <string>
#include <queue>

#include "boost/thread.hpp"
#include "boost/thread/mutex.hpp"

using namespace std;

namespace  objQueue
{
  
  template <typename objData>
  class ObjQueue
  {
  private:
    std::queue<objData> _threadQueue;
    mutable boost::mutex _qMutex;
    boost::condition_variable conditionVar;
    int _maxItemCount;
    int _itemCount;

  public:
    ObjQueue()
    {
      _maxItemCount = -1;
      _itemCount = 0;
    };
    ObjQueue(int maxItemCount)
    {
      _maxItemCount = maxItemCount;
      _itemCount = 0;
    }
    ~ObjQueue(){};

    bool empty() const 
    {
      boost::mutex::scoped_lock lock(_qMutex);
      return _threadQueue.empty();
    }

    //NOTE (JNHager): This will return false till the queue has an item. This will allow 
    //                this class to be used with multiple threads and not sleeping them all.
    bool pop(objData& data)
    {
      boost::mutex::scoped_lock lock(_qMutex);
      
      if(_threadQueue.empty()) { return false; }

      data = _threadQueue.front();
      _threadQueue.pop();
      _itemCount--;
      return true;
    }

    int count() const
    {
      boost::mutex::scoped_lock lock(_qMutex);
      return _itemCount;
    }

    bool push(objData data)
    {
      boost::mutex::scoped_lock lock(_qMutex);
      if(_maxItemCount == -1 || _itemCount < _maxItemCount){
        _threadQueue.push(data);
        _itemCount ++;
        return 1;
      }
      return 0;
    }
  };

}

#endif