xref: /illumos-kvm-cmd/qemu-aio.h (revision 68396ea9)
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 /* 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. */
26 typedef 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. */
30 void 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. */
36 void qemu_aio_wait(void);
37 
38 /*
39  * Runs all currently allowed AIO callbacks of completed requests. Returns 0
40  * if no requests were handled, non-zero if at least one request was
41  * processed.
42  */
43 int qemu_aio_process_queue(void);
44 
45 /* Register a file descriptor and associated callbacks.  Behaves very similarly
46  * to qemu_set_fd_handler2.  Unlike qemu_set_fd_handler2, these callbacks will
47  * be invoked when using either qemu_aio_wait() or qemu_aio_flush().
48  *
49  * Code that invokes AIO completion functions should rely on this function
50  * instead of qemu_set_fd_handler[2].
51  */
52 int qemu_aio_set_fd_handler(int fd,
53                             IOHandler *io_read,
54                             IOHandler *io_write,
55                             AioFlushHandler *io_flush,
56                             AioProcessQueue *io_process_queue,
57                             void *opaque);
58 
59 #endif
60