#include <assert.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <sys/uio.h>
#include <time.h>
#include <stdlib.h>
#include <unistd.h>

#define _COUNT_BUFS 8
#define _BUF_LEN 64

time_t test_std_read() {
	int fd = open("book.txt", O_RDONLY);
        char buf[_BUF_LEN] ;
	ssize_t nr;
        time_t start_std = clock();
        while ( (nr=read(fd, buf, _BUF_LEN))!=0)
        	write(STDOUT_FILENO, buf, _BUF_LEN);
	write(STDOUT_FILENO, buf, _BUF_LEN);
	time_t time_std = clock() - start_std;
	close(fd);
	return time_std;
}
time_t test_v_read() {
	char memory_seg[_COUNT_BUFS][_BUF_LEN];
        struct iovec segments[_COUNT_BUFS];
        int fd = open("book.txt", O_RDONLY);
        assert(fd!=-1);
       	ssize_t nr;
        time_t start = clock();
        for(int i=0; i<_COUNT_BUFS; i++) {
                  segments[i].iov_base = memory_seg[i];
                  segments[i].iov_len = sizeof(memory_seg[i]);
        }
        while ( (nr = readv(fd, segments, _COUNT_BUFS))!=0)
        	writev(STDOUT_FILENO, segments, _COUNT_BUFS);
        writev(STDOUT_FILENO, segments, _COUNT_BUFS);
        time_t time_v = clock() - start;
	close(fd);
	return time_v;
}
int main() {
	time_t t1 = test_std_read();
	system("clear");
	time_t t2 = test_v_read();
	system("clear");
	printf("time to standart read = %ld\n", t1);
	printf("time to readv = %ld\n", t2);

	return 0;
}