#include <stdio.h>
#include <sys/types.h>
#include <sched.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <time.h>

#define GOD_PRIORITY 100000
#define ONE_PRIORITY 500
#define TWO_PRIORITY 10
#define THREE_PRIORITY 105
#define FOUR_PRIORITY 75

void loop() 
{ 
	int i, j;
	for(i=0;i<10000;++i)
		for(j=0;j<100000;++j) {}
}

int main(int argc, char **argv)
{
	pid_t pid, pid2, pid3, pid4;
	int i, j, time;
	char files[4][40];
	FILE *in[4];
	FILE *out;
	struct sched_param param;
	unsigned int begin;
	
	char line[1000];
	int stime;
	
	param.sched_priority = 23;
	setgid(GOD_PRIORITY);
	sched_setscheduler( 0, 3, &param );

	pid=pid2=pid3=-1;
	begin=clock();
	
	setgid(ONE_PRIORITY);
	pid=fork();
	if(pid>0) 
	{
		setgid(TWO_PRIORITY);
		pid2=fork();
	}
	if(pid2>0) 
	{
		setgid(THREE_PRIORITY);
		pid3=fork();
	}
init:	
	if(pid==0)
	{
		loop();
		printf("1 FINISHED\n");
		printf("Time elapsed(uS): %u\n",clock()-begin);
		exit(0);
	}
	else if(pid2==0)
	{
		loop();
		printf("2 FINISHED\n");
		printf("Time elapsed(uS): %u\n",clock()-begin);
		exit(0);
	}
	else if(pid3==0)
	{
		loop();
		printf("3 FINISHED\n");
		printf("Time elapsed(uS): %u\n",clock()-begin);
		exit(0);
	}
	else if(pid4==0)
	{
		loop();
		printf("4 FINISHED\n");
		printf("Time elapsed(uS): %u\n",clock()-begin);
	}
	else
	{
		
		setgid(GOD_PRIORITY);
		
		time=1;
		
		sprintf(files[0],"/proc/%d/stat",pid);
		sprintf(files[1],"/proc/%d/stat",pid2);
		sprintf(files[2],"/proc/%d/stat",pid3);
		
		out=fopen("RESULTS","w");
		while(1)
		{
				
			fprintf(out,"%d\n",time);
			for(i=0;i<4;++i)
			{
				if((in[i]=fopen(files[i],"r")))
				{
					
					fgets(line,1000,in[i]);
					
					strtok(line," \n");
					
					for(j=0;j<12;++j) strtok(NULL," \n");
					stime=atoi(strtok(NULL," \n"));
					
					
					fprintf(out,"%d) %d\n",i+1,(int)stime);
					fclose(in[i]);
					
				}
				else fprintf(out,"NOT RUNNING\n");
			}
			
			time++;
			fprintf(out,"\n");	


			waitpid(-1, NULL, WNOHANG);
			if(kill(pid,0) == -1 && kill(pid2,0)==-1 && kill(pid3,0)==-1 && kill(pid4,0)==-1) break;
			//wait(NULL);
			//exit(1);
			usleep(1000000);
			if(time==5) 
			{
				setgid(FOUR_PRIORITY);
				pid4=fork();
				if(pid4==0) goto init;
				setgid(GOD_PRIORITY);
				sprintf(files[3],"/proc/%d/stat",pid4);
			}
			
		}
		
		
		fclose(out);
		exit(0);
	}
}