#include <stdio.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <time.h>
#include <fcntl.h>

//struct timeval {
//	time_t      tv_sec;     /* seconds */
//	suseconds_t tv_usec;    /* microseconds */
//};
// stolen from lmbench
#define uint64 unsigned long long
void
tvsub(struct timeval * tdiff, struct timeval * t1, struct timeval * t0)
{
        tdiff->tv_sec = t1->tv_sec - t0->tv_sec;
        tdiff->tv_usec = t1->tv_usec - t0->tv_usec;
        if (tdiff->tv_usec < 0 && tdiff->tv_sec > 0) {
                tdiff->tv_sec--;
                tdiff->tv_usec += 1000000;
                //assert(tdiff->tv_usec >= 0);
        }

        /* time shouldn't go backwards!!! */
        if (tdiff->tv_usec < 0 || t1->tv_sec < t0->tv_sec) {
                tdiff->tv_sec = 0;
                tdiff->tv_usec = 0;
        }
}

tvdelta(struct timeval *start, struct timeval *stop)
{
        struct timeval td;
        uint64  usecs;

        tvsub(&td, stop, start);
        usecs = td.tv_sec;
        usecs *= 1000000;
        usecs += td.tv_usec;
        return (usecs);
}

void write_file(char *file)
{
	int fd = open(&file[0], O_WRONLY|O_CREAT);
	if (fd < 0) {
		perror("open error");
		exit(fd);
	}
	write(fd, "foo");
	close(fd);
}

const uint64 USECS_PER_SEC = 1000000;
int run_openbench(int run_seconds)
{
	pid_t pid = getpid();
	char bufa[100];
	char bufb[100];
	int ret;
	int i;
	struct timeval start;
	struct timeval end;
	uint64 useconds = run_seconds * USECS_PER_SEC;
	uint64 running_for;
	uint64 last_running_for;

	printf("openbench running (pid %d)\n", pid);
	sprintf(&bufa[0], "/ram/openbench.%d", pid);
	sprintf(&bufb[0], "/ram1/openbench.%d", pid);
	uint64 opens = 0;
	int warmup = 1;
	gettimeofday(&start, NULL);
	do {
		int loops = 100000;
		for (i=0; i< loops; i++) {
			write_file(&bufa[0]);
			write_file(&bufb[0]);
			opens++;
		}
		ret = unlink(&bufa[0]);
		if (ret)
			perror("unlink error");
		ret = unlink(&bufb[0]);
		if (ret)
			perror("unlink error");
		gettimeofday(&end, NULL);
		running_for = tvdelta(&start, &end);
		if (running_for - last_running_for > USECS_PER_SEC) {
			if (warmup)
				printf("warmup ");
			printf("[%5d] opens/sec: %d\n", pid, opens*USECS_PER_SEC/running_for);
			fflush( stdout );
			last_running_for = running_for;
		}
		if (warmup && running_for > run_seconds/5*USECS_PER_SEC) {
			gettimeofday(&start, NULL);
			opens = 0;
			warmup = 0;
		}
	} while (running_for < useconds);
	printf("[%5d] total opens/sec: %d\n", pid, opens*USECS_PER_SEC/running_for);
	return 0;
}

int main(int argc, char **argv)
{
	int run_seconds = atoi(argv[1]);
	int nr_children = 4;
	int i;
	int status;
	
	for (i=0; i < nr_children; i++) {
		int pid = fork();
		if (pid)
			continue;
		run_openbench(run_seconds);
		//printf("pid: %d done\n", getpid());
		exit(0);
	}
	while ((status = wait(-1)) > 0 ) {
		printf("status: %d\n", status);
	}
}