//#define _GNU_SOURCE
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <assert.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <libaio.h>



int main(int argc, char *argv[])
{
  int err, fd;
  char *p;
  unsigned long long int total_read_bytes= 0;
  struct timespec timeout = {1, 100};
  io_context_t libaio;
  struct iocb **pcb, *laiocb;
  fd = open(argv[1], O_RDONLY | O_DIRECT);
  assert(fd >= 0);
  int nr_requests= atoi(argv[2]);
  int io_unit_kb= atoi(argv[3]);
  struct io_event events[nr_requests];
  unsigned long long int BLOCK = io_unit_kb * 1024;
  pcb= (struct iocb**)malloc(nr_requests*sizeof(struct iocb*));
  laiocb= (struct iocb*)malloc(nr_requests*sizeof(struct iocb));
  err = io_queue_init(nr_requests, &libaio);
  assert(!err);
  err = posix_memalign((void **)&p, BLOCK, BLOCK);
  assert(!err);
  while(1) {
    for(int i=0; i< nr_requests; i++) {
      pcb[i] = &laiocb[i];
      io_prep_pread(&laiocb[i], fd, p, BLOCK, total_read_bytes+ i * BLOCK);
      io_set_callback(&laiocb[i], (io_callback_t)(i+1));
    }
    err = io_submit(libaio, nr_requests, pcb);
    assert(err >= 0);
    io_getevents(libaio, nr_requests, nr_requests, events, &timeout);
    total_read_bytes+= nr_requests * BLOCK;
  }
}