#define _GNU_SOURCE
#define _XOPEN_SOURCE 500
#include <sched.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <assert.h>

#define BUFLEN 4096

static char wistmpfile[] = "/mnt/willitscale.XXXXXX";

char *testcase_description = "Same file pwrite";

char *buf;
#define FILE_SIZE (4096*1024)
void testcase_prepare(void)
{
	int fd = mkstemp(wistmpfile);

	assert(fd >= 0);
	assert(pwrite(fd, "X", 1, FILE_SIZE-1) == 1);
	buf = mmap(NULL, FILE_SIZE, PROT_READ|PROT_WRITE,
			       MAP_SHARED, fd, 0);
	assert(buf != (void *)-1);
	close(fd);
}

void testcase(unsigned long long *iterations)
{
	int cpu = sched_getcpu();
	int fd = open(wistmpfile, O_RDWR);
	off_t offset = sched_getcpu() * BUFLEN;
	long counter = 0;
	long counterread = 0;
	long *counterbuf = (void *)&buf[offset];

	printf("offset: %ld\n", offset);
	printf("       buf: %p\n", buf);
	printf("counterbuf: %p\n", counterbuf);
	assert(fd >= 0);

	while (1) {
		int ret;
		if (cpu == 1) {
			ret = madvise(buf, FILE_SIZE, MADV_DONTNEED);
			continue;
		}
	
		*counterbuf = counter;
		posix_fadvise(fd, offset, BUFLEN, POSIX_FADV_DONTNEED);
		ret = pread(fd, &counterread, sizeof(counterread), offset);
		assert(ret == sizeof(counterread));

		if (counterread != counter) {
			printf("cpu: %d\n", cpu);
			printf("    counter %ld\n", counter);
			printf("counterread %ld\n", counterread);
			printf("*counterbuf %ld\n", *counterbuf);
			while(1);
		}
		counter++;	
		(*iterations)++;
	}
}

void testcase_cleanup(void)
{
	unlink(wistmpfile);
}