qemu-aio.h revision 2910f183ddd5286911bc1e3499ea93cb57de8b75 
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 */
21typedef int (AioFlushHandler)(void *opaque);
22
23/* Runs all currently allowed AIO callbacks of completed requests in the
24 * respective AIO backend. Returns 0 if no requests was handled, non-zero
25 * if at least one queued request was handled. */
26typedef int (AioProcessQueue)(void *opaque);
27
28/* Flush any pending AIO operation. This function will block until all
29 * outstanding AIO operations have been completed or cancelled. */
30void qemu_aio_flush(void);
31
32/* Wait for a single AIO completion to occur.  This function will wait
33 * until a single AIO event has completed and it will ensure something
34 * has moved before returning. This can issue new pending aio as
35 * result of executing I/O completion or bh callbacks. */
36void qemu_aio_wait(void);
37
38/* Register a file descriptor and associated callbacks.  Behaves very similarly
39 * to qemu_set_fd_handler2.  Unlike qemu_set_fd_handler2, these callbacks will
40 * be invoked when using either qemu_aio_wait() or qemu_aio_flush().
41 *
42 * Code that invokes AIO completion functions should rely on this function
43 * instead of qemu_set_fd_handler[2].
44 */
45int qemu_aio_set_fd_handler(int fd,
46                            IOHandler *io_read,
47                            IOHandler *io_write,
48                            AioFlushHandler *io_flush,
49                            void *opaque);
50
51#endif
52