#include <iostream>
#include <unistd.h>
#include <sys/wait.h>
#include <cstdlib>
#include <ctime>

void random_task(int id) {
	srand(time(0));
	int delay=1+rand()%3;
	std::cout << "PID:" << getpid()
	<< "task " << id 
	<< " delay :" << delay << "s\n";
	sleep(delay);
}

int main() {
	int total_tasks=10;
	int k=4;
	int pipefd[2];
	pipe(pipefd);

	pid_t rootpid=getpid();

	//-- create workers --
	for (int w=0;w<k;w++) 
		fork();
	//--workers assigned tasks
	if (getpid()!=rootpid) 
	{
		close(pipefd[1]);
		int task;
		while (read(pipefd[0], &task, sizeof(task))>0)
		{
			random_task(task);
		}
		close(pipefd[0]);
		_exit(0);
	}
	//--root pid 
	close(pipefd[0]);
	for (int t=0;t<total_tasks;t++) {
		write(pipefd[1],&t,sizeof(t));
	}
	close(pipefd[1]);
	while(wait(0) >0) ;
	std::cout << "All tasks completed \n";
	return 0;
}