Throttle Example using a circular queue (Push all but 2 less than maxSize; then pop all but 2 of current size), C++ (clang)

Throttle Example using a circular queue (Push all but 2 less than maxS...

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//Throttle Example using a circular queue
using namespace std;
#include <queue>
#include <thread>
#include <mutex>
#include <condition_variable>
#include <iostream>
#include <unistd.h>
#include "time.h"
#include "sys/time.h"

template <typename T>
class Queue
{
 public:

Queue(int iMaxSize)
  {
      head = -1;
      tail = -1;
      maxSize = iMaxSize; 
      data = new T[iMaxSize];
  }
  
  Queue(const Queue& aQueue)
  {
      if(this != &aQueue)
      {
          head = aQueue.head;
          tail = aQueue.tail;
          maxSize = aQueue.maxSize;
          data = new T[maxSize];
          for(int iCnt = 0; iCnt < maxSize; iCnt++)
          {
              data[iCnt] = aQueue.data[iCnt];
          }
      }
  }

T pop()
  {
    std::unique_lock<std::mutex> mlock(mutex_);
    while (isEmpty())
    {
      cond_.wait(mlock);
    }
      
    if(head == -1)
    {
        std::cerr << "Queue Underflow!!" << std::endl;    
    }
    else
    {
        T item = data[head];
 
        if(head == tail)
        {
            head = -1;
            tail = -1;
        }
        else if(head == maxSize-1)
        {
            head = 0;
        }
        else
        {
            head++;
        }
        return item;
    }       
  }

void push(const T& item)
  {
    std::unique_lock<std::mutex> mlock(mutex_);
    if((head == 0 && tail == maxSize - 1) || (head == (tail + 1)))
    {
        std::cerr << "Queue Overflow!!" << std::endl;        
    }
    else
    {
        if(tail == -1)
        {
            tail = 0;
            head = 0;
        }
        else if(tail == maxSize - 1) 
        {
            tail = 0;
        }
        else
        {
            tail++;
        }
    }
    data[tail] = item;
    mlock.unlock();
    cond_.notify_one();
  }
  
  int size()
  {
    if(head == -1 && tail == -1)
    {
        return 0;
    }
    else
    {    
        return abs(tail - head + 1);
    }
  }
  
  bool isEmpty()
  {
    if(head == -1 && tail == -1)
    {
        return true;
    }  
    else
    {
      return false;
    }
  }
    
  bool isFull()
  {
    if((head == 0 && tail == maxSize - 1) || (head == (tail + 1)))
    {
        return true;
    }
    else
    {
        return false;
    }
  }  
  int getHead()
  {
      return head;
  }
  int getTail()
  {
      return tail;
  }
 private:
  std::mutex mutex_;
  std::condition_variable cond_;
  int head;
  int tail;
  int maxSize;
  T* data;
};

class Timer
{
    public:
     static long long get_time_ms()
     {
        struct timeval t;
        gettimeofday(&t, NULL);
        return (long long)((t.tv_sec + (t.tv_usec / 1000000.0)) * 1000.0);    
     }
};

class LeakyBucket
{
    public:
     LeakyBucket(int maxRate) : maxRate_(maxRate)
     {
         this->minTime_ = (long)(maxRate_);
         this->lastSchedAction_ = (long long) Timer::get_time_ms();
     }
     const int getMaxRate()
     {
         return maxRate_;
     }
     const long getMinTime()
     {
         return minTime_;   
     }
     const long long getLastSchedAction()
     {
         return lastSchedAction_;
     }
     void consume()
     {
         long long curTime = Timer::get_time_ms();
         long long timeLeft;
         
         timeLeft = lastSchedAction_ + (minTime_ * 1000) - curTime;
         std::cerr << "Time Left = " << timeLeft << std::endl << std::flush;
         if(timeLeft > 0) 
         {
             lastSchedAction_ += (minTime_ * 1000);
         }
         else 
         {
             lastSchedAction_ = curTime;
         }
         if(timeLeft <= 0) 
         {
            return;
         }
         else 
         {
             sleep((int)((timeLeft+1)/1000));
         }
         return;
     }
    private:
     int maxRate_;
     long minTime_;
     long long lastSchedAction_;
     
};

int main()
{
    const int MAXQUEUESIZE = 400; // Maximum size of Queue
    Queue<int> queue = Queue<int>(MAXQUEUESIZE);
    const int MAXFLOWRATE = 2;  // Time interval at which to pick up items from the queue
    const int MAXCONCURRENTREQUESTRATE = 80; // Maximum picked out of queue for processing at any given time
    
    // Fill in all but 2 elements less than MAXQUEUESIZE
    for(int iCnt = 0; iCnt < MAXQUEUESIZE - 2; iCnt++)
    {
        queue.push(iCnt+1);
    }
    
    std::cerr << "Size of Queue = " << queue.size() << std::endl << std::flush;
    std::cerr << "Head = " << queue.getHead() << std::endl << std::flush;
    std::cerr << "Tail = " << queue.getTail() << std::endl << std::flush;
    LeakyBucket leakyBucket = LeakyBucket(MAXFLOWRATE);
    std::cerr << "Time : " << Timer::get_time_ms() << std::endl << std::flush;
    bool bForcedBreak = false;    
    // Fetch all but two elements from the queue subject to its current size; force break when just 2 elements are remaining
    while(queue.isEmpty() == false && bForcedBreak == false)
    {
        for(int iCnt = 0; iCnt < MAXCONCURRENTREQUESTRATE; ++iCnt)    
        {
            if(queue.isEmpty() == false)
            {
                std::cerr << "Fetched value :" << queue.pop() << std::endl << std::flush;
                
                if(queue.size() == 2)
                {
                    bForcedBreak = true;
                    break;
                }
            }
            else
            {
                break;
            }
        }
        if(queue.isEmpty() == false)
        {
            leakyBucket.consume();
            std::cerr << "Fetching next set !!" << std::endl << std::flush;
            std::cerr << "Time : " << Timer::get_time_ms() << std::endl << std::flush;
        }
        
    }
    std::cerr << "Head = " << queue.getHead() << std::endl << std::flush;
    std::cerr << "Tail = " << queue.getTail() << std::endl << std::flush;
    std::cerr << "Done with fetching all values !!" << std::endl  << std::flush;
    return 0;
}

Show compiler warnings [ + ] Compiler args [ + ] Show input
Compilation time: 0.82 sec, absolute running time: 9.06 sec, cpu time: 0 sec, memory peak: 3 Mb, absolute service time: 9.95 sec

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Error(s):

Size of Queue = 398
Head = 0
Tail = 397
Time : 1416727890672
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Time Left = 1999
Fetching next set !!
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Fetching next set !!
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Time Left = 1998
Fetching next set !!
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Fetching next set !!
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Time Left = 2997
Fetching next set !!
Time : 1416727899675
Head = 396
Tail = 397
Done with fetching all values !!

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