#define _GNU_SOURCE
#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <libaio.h>
#include <errno.h>
#include <unistd.h>

int main(int argc, char *argv[])
{
	const char *outputfile=argv[1];
	io_context_t ctx;
	int output_fd;
	const int nr = 4;
	struct iocb _io[nr];
	struct iocb *io[16] = {
		&_io[0],
		&_io[1],
		&_io[2],
		&_io[3],
	};
	struct io_event e[nr];
	struct timespec timeout;
	int ret;
	char *content;
	unsigned size = 2*1024 * 1024;

	posix_memalign((void **)&content, 4096, nr * size + 512);

	memset(&ctx,0,sizeof(ctx));
	if(io_setup(10, &ctx) != 0) {
		printf("io_setup error\n");
		return -1;
	}

	if((output_fd = open(outputfile, O_DIRECT, 0644)) < 0) {
		perror("open error");
		io_destroy(ctx);
		return -1;
	}
	io_prep_pread(io[0], output_fd, content + 4, size, 0);
	io_prep_pread(io[1], output_fd, content + size, size, size * 2);
	io_prep_pread(io[2], output_fd, content + size * 2, size, size * 4);
	io_prep_pread(io[3], output_fd, content + size * 3, size, size * 8);

	ret = io_submit(ctx, nr, io);
	if(ret != nr) {
		io_destroy(ctx);
		printf("io_submit error %d\n", ret);
		return -1;
	}

	while(1) {
		timeout.tv_sec=0;
	        timeout.tv_nsec=500000000;
	        if (io_getevents(ctx, nr, nr, e, &timeout) == nr) {
	            close(output_fd);
	            break;
	        }
	        printf("haven't done\n");
	        sleep(1);
	}
	io_destroy(ctx);
	return 0;
}