consumer_producer

cons.cc

// Compiled with: g++ -Wall -std=c++14 -pthread

#include <iostream>
#include <mutex>
#include <thread>
#include <condition_variable>
#include <queue>
#include <thread>
#include <vector>
using namespace std;


priority_queue<int> pqueue;
mutex m;
condition_variable var;
bool finished = false;
const int max_count = 5;


void producer() {
    vector<int> items = { 1, 2, 3, 4, 5, 6 ,7, 8, 9, 10 };
    size_t index = 0;
    while (index < items.size()) {
        unique_lock<mutex> lk(m);
        while(pqueue.size() < max_count && index < items.size()) {
            pqueue.push(items[index]);
            index++;
            var.notify_all();
        }
        
        cout << "wait to drain .. " << endl;
        var.wait(lk, [] { return pqueue.size() < max_count;}); 
        
    }
    
     unique_lock<mutex> lk(m);
     finished = true;
     var.notify_all(); 
}


void worker_thread() {
 
    while(1) {   
 
     unique_lock<mutex> lk(m); 
     var.wait(lk, []{return finished || !pqueue.empty();});
     cout << "awake: " << endl;
     while(!pqueue.empty()) {
         int val = pqueue.top();
         pqueue.pop();
          cout << "processed: " << val << endl;  
     }
     //signal that queue is drained   
     var.notify_one();    

     if (finished) break;   
        
    } 
}

int main(){
    cout << "Hello, World!" << endl;
    
    thread t1(worker_thread);
    thread t2(producer);
    
    
    t2.join();
    t1.join();
    
     cout << "This is the End" << endl;
    return 0;
}