#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <asm/unistd.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/mman.h>

#define GB (1024 * 1024 * 1024)

int do_posix_fallocate(char *name, off_t len)
{
	int r, fd;
	struct timeval tv1, tv2;

	unlink(name);
	fd = open(name, O_RDWR|O_CREAT, S_IRUSR|S_IWUSR);
	if (fd < 0) {
		perror("open");
		return -1;
	}

	printf("posix-fallocate run time:\n");
	gettimeofday(&tv1, NULL);
	r = posix_fallocate(fd, 0, len);
	close(fd);
	gettimeofday(&tv2, NULL);
	if (r < 0)
		return r;
	printf("\tseconds:microseconds: %llu:%llu\n", tv1.tv_sec, tv1.tv_usec);
	printf("\tseconds:microseconds: %llu:%llu\n", tv2.tv_sec, tv2.tv_usec);
	printf("\t(approx %us)\n", tv2.tv_sec - tv1.tv_sec);

	return 0;
}

#if 1
int do_fallocate(char *name, off_t len)
{
	int r, fd;
	struct timeval tv1, tv2;

	unlink(name);
	fd = open(name, O_RDWR|O_CREAT, S_IRUSR|S_IWUSR);
	if (fd < 0) {
		perror("open");
		return -1;
	}

	printf("fallocate run time:\n");
	gettimeofday(&tv1, NULL);
	r = syscall(__NR_fallocate, fd, 0, len);
	close(fd);
	gettimeofday(&tv2, NULL);
	if (r < 0) {
		perror("fallocate");
		return r;
	}
	printf("\tseconds:microseconds: %llu:%llu\n", tv1.tv_sec, tv1.tv_usec);
	printf("\tseconds:microseconds: %llu:%llu\n", tv2.tv_sec, tv2.tv_usec);
	printf("\t(approx %us)\n", tv2.tv_sec - tv1.tv_sec);

	return 0;
}
#endif

int do_mmap(char *name, off_t len)
{
	int fd;
	struct timeval tv1, tv2;
	char *addr;

	unlink(name);
	fd = open(name, O_RDWR|O_CREAT, S_IRUSR|S_IWUSR);
	if (fd < 0) {
		perror("open");
		return -1;
	}
	/* memset has to have the mmap'ed file backed by something on
	 * disk -- bus error otherwise */
	lseek(fd, len - 1, SEEK_SET);
	write(fd, "0", 1);

	addr = mmap(NULL, len, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
	if (addr == MAP_FAILED) {
		perror("mmap");
		return -2;
	}

	printf("mmap run time:\n");
	gettimeofday(&tv1, NULL);
	memset(addr, 0, len);
	munmap(addr, len);
	close(fd);
	gettimeofday(&tv2, NULL);

	printf("\tseconds:microseconds: %llu:%llu\n", tv1.tv_sec, tv1.tv_usec);
	printf("\tseconds:microseconds: %llu:%llu\n", tv2.tv_sec, tv2.tv_usec);
	printf("\t(approx %us)\n", tv2.tv_sec - tv1.tv_sec);

	return 0;
}

int do_write_chunks(char *name, off_t len, size_t chunk_size)
{
	int fd;
	struct timeval tv1, tv2;

	unsigned long long remain = len;
	char *zeros;

	zeros = calloc(1, len);

	unlink(name);
	fd = open(name, O_RDWR|O_CREAT, S_IRUSR|S_IWUSR);
	if (fd < 0) {
		perror("open");
		return -1;
	}

	printf("%llu-sized chunk run time:\n", chunk_size);
	gettimeofday(&tv1, NULL);
	while (remain) {
		int bytes = chunk_size;
		if (bytes > remain)
			bytes = remain;
		if ((bytes = write(fd, zeros, bytes)) < 0) {
			perror("write");
			return -2;
		}
		remain -= bytes;
	}
	close(fd);
	gettimeofday(&tv2, NULL);

	printf("\tseconds:microseconds: %llu:%llu\n", tv1.tv_sec, tv1.tv_usec);
	printf("\tseconds:microseconds: %llu:%llu\n", tv2.tv_sec, tv2.tv_usec);
	printf("\t(approx %us)\n", tv2.tv_sec - tv1.tv_sec);
	free(zeros);

	return 0;
}

int main(int argc, char **argv)
{
	char *basename;
	char *filename;

	if (argc < 2) {
		printf("usage: %s base-dir\n", argv[0]);
		return -1;
	}

	basename = argv[1];

	sprintf(filename, "%s/file-pf", basename);
	do_posix_fallocate(filename, 1 * GB);

#if 0
	sprintf(filename, "%s/file-pf", basename);
	do_fallocate(filename, 1 * GB);
#endif

	sprintf(filename, "%s/file-mmap", basename);
	do_mmap(filename, 1 * GB);

	sprintf(filename, "%s/file-chunk4", basename);
	do_write_chunks(filename, 1 * GB, 4 * 1024);

	sprintf(filename, "%s/file-chunk8", basename);
	do_write_chunks(filename, 1 * GB, 8 * 1024);

	return 0;
}