#include <u.h>
#include <libc.h>

enum {
	Ios	= 1000,		/* number of ios / test */
	Nanoi	= 1000000000,	/* 1/nano */
	Microi	= 1000000,
};

enum {
	Read	= 1<<0,
	Write	= 1<<1,
};

static int otab[4] = {
[Read]		OREAD,
[Write]		OWRITE,
[Read|Write]	ORDWR,
};

static char *rwtab[4] = {
[Read]		"read",
[Write]		"write",
[Read|Write]	"rdwr",
};

void
rio(int fd, uvlong byte0, uvlong bytes, uint ss, int rw)
{
	char *buf;
	int i;
	uvlong maxlba, lba, t, x;
	long (*io)(int, void*, long, vlong);

	maxlba = (bytes - byte0) / ss;
	if(rw == Read)
		io = pread;
	else if(rw == Write)
		io = pwrite;
	else{
		io = nil;		/* compiler noise */
		sysfatal("not prepared to mix read/write yet");
	}

	buf = malloc(ss);
	if(buf == nil)
		sysfatal("malloc");

	srand(nsec());
	t = -nsec();
	for(i = 0; i < Ios; i++){
		lba = frand()*maxlba;	/* awful.  no vlnrand() */
		io(fd, buf, ss, byte0 + lba*ss);
	}
	t += nsec();
	free(buf);

	print("%s %lld.%03lld\n", rwtab[rw], t/Nanoi, (t%Nanoi)/Microi);
	x = (uvlong)Ios*(uvlong)Nanoi*100;
	x /= t;
	print("%lld.%02lld iops\n", x/100, (x%100));
}

void
usage(void)
{
	fprint(2, "usage: randomio [-rw] [-o offset] [-s sectorsz] [file ...]\n");
	exits("usage");
}

void
main(int argc, char **argv)
{
	int i, byte0, fd, rw, ss;
	uvlong bytes;
	Dir *d;

	rw = 0;
	ss = 512;
	byte0 = 0;
	ARGBEGIN{
	case 'r':
		rw |= Read;
		break;
	case 'w':
		rw |= Write;
		break;
	case 'o':
		byte0 = atoi(EARGF(usage()));
		break;
	case 's':
		ss = atoi(EARGF(usage()));
		break;
	default:
		usage();
	}ARGEND;

	if(rw == 0)
		rw = Read;

	for(i = 0; i < argc; i++){
		d = dirstat(argv[i]);
		if(d == nil)
			sysfatal("dirstat: %r");
		bytes = d->length;
		free(d);

		fd = open(argv[i], otab[rw]);
		if(fd == -1)
			sysfatal("open: %r");

		if(rw & Read)
			rio(fd, byte0, bytes, ss, Read);
		if(rw & Write)
			rio(fd, byte0, bytes, ss, Write);
		close(fd);
	}
	exits("");
}