Intel® oneAPI DPC++/C++ Compiler Developer Guide and Reference

Developer Guide and Reference

Contents

Example for lio_listio Function

The following example illustrates how the
lio_
listio()
 function can be used. 
int aio_ex_5(HANDLE fd)
{
  static struct aiocb   aio[2];
  static struct aiocb  *aio_list[2] = {&aio[0], &aio[1]};
   int               i, ret;
 
/*
 ** Data initialization and Synchronously writing
*/
 IC_AIO_DATA_INIT(aio[0], fd, "rec#1\n", strlen("rec#1\n"), 0)
 IC_AIO_DATA_INIT(aio[1], fd, "rec#2\n", strlen("rec#2\n"),
 aio[0].aio_nbytes)
 aio[0].aio_lio_opcode = aio[1].aio_lio_opcode = LIO_WRITE;
 ret = lio_listio(LIO_WAIT, aio_list, 2, 0);
 if (ret) return ret;
 
 return 0;
}/* aio_ex_5 */
Result upon execution:
-bash-3.00$ ./a.out
-bash-3.00$ cat dat
rec#1
rec#2
-bash-3.00$
Remarks:
  1. In the example, the
    IC_AIO_DATA_INIT
     is defined as follows: 
    #define IC_AIO_DATA_INIT(_aio, _fd, _dat, _len, _off)\
  {memset(&_aio, 0, sizeof(_aio)); \
   _aio.aio_fildes = _fd;          \
   _aio.aio_buf    = _dat;         \
   _aio.aio_nbytes = _len;         \
   _aio.aio_offset = _off;}
  2. The file descriptor
    fd
     is obtained as: 
    HANDLE fd = CreateFile("dat",
   GENERIC_READ | GENERIC_WRITE,
   FILE_SHARE_READ,
   NULL,
   OPEN_ALWAYS,
   FILE_ATTRIBUTE_NORMAL/*|FILE_FLAG_OVERLAPPED*/,
   NULL);
  3. The
    aio_lio_opcode
     refers to the field of each
    aiocb
     structure that specifies the operation to be performed. The supported operations are
    LIO_READ
     (do a 'read' operation),
    LIO_WRITE
     (do a 'write' operation), and
    LIO_NOP
     (do no operation); these symbols are defined in
    <aio.h>
    .

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.