qemu-aio.h

   1 /*
   2  * QEMU aio implementation
   3  *
   4  * Copyright IBM, Corp. 2008
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #ifndef QEMU_AIO_H
  15 #define QEMU_AIO_H
  16
  17 #include "qemu-common.h"
  18 #include "qemu-char.h"
  19
  20 /* Returns 1 if there are still outstanding AIO requests; 0 otherwise */
  21 typedef int (AioFlushHandler)(void *opaque);
  22
  23 /* Flush any pending AIO operation. This function will block until all
  24  * outstanding AIO operations have been completed or cancelled. */
  25 void qemu_aio_flush(void);
  26
  27 /* Wait for a single AIO completion to occur.  This function will until a
  28  * single AIO opeartion has completed.  It is intended to be used as a looping
  29  * primative when simulating synchronous IO based on asynchronous IO. */
  30 void qemu_aio_wait(void);
  31
  32 /* Register a file descriptor and associated callbacks.  Behaves very similarly
  33  * to qemu_set_fd_handler2.  Unlike qemu_set_fd_handler2, these callbacks will
  34  * be invoked when using either qemu_aio_wait() or qemu_aio_flush().
  35  *
  36  * Code that invokes AIO completion functions should rely on this function
  37  * instead of qemu_set_fd_handler[2].
  38  */
  39 int qemu_aio_set_fd_handler(int fd,
  40                             IOHandler *io_read,
  41                             IOHandler *io_write,
  42                             AioFlushHandler *io_flush,
  43                             void *opaque);
  44
  45 #endif