#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
	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 assigns tasks --
	close(pipefd[0]);

	for(int t=0; t<total_tasks; t++){
		write(pipefd[1], &t, sizeof(t));
	}
	close(pipefd[1]);

	//--root waits workers
	while(wait(nullptr)>0);

	std::cout << "\nAll tasks completed \n";

	return 0;
}