qemu/qemu-aio.h

/*
 * QEMU aio implementation
 *
 * Copyright IBM, Corp. 2008
 *
 * Authors:
 *  Anthony Liguori   <aliguori@us.ibm.com>
 *
 * This work is licensed under the terms of the GNU GPL, version 2.  See
 * the COPYING file in the top-level directory.
 *
 */

#ifndef QEMU_AIO_H
#define QEMU_AIO_H

#include "qemu-common.h"
#include "qemu-char.h"
#include "event_notifier.h"

typedef struct BlockDriverAIOCB BlockDriverAIOCB;
typedef void BlockDriverCompletionFunc(void *opaque, int ret);

typedef struct AIOPool {
    void (*cancel)(BlockDriverAIOCB *acb);
    int aiocb_size;
    BlockDriverAIOCB *free_aiocb;
} AIOPool;

struct BlockDriverAIOCB {
    AIOPool *pool;
    BlockDriverState *bs;
    BlockDriverCompletionFunc *cb;
    void *opaque;
    BlockDriverAIOCB *next;
};

void *qemu_aio_get(AIOPool *pool, BlockDriverState *bs,
                   BlockDriverCompletionFunc *cb, void *opaque);
void qemu_aio_release(void *p);

/* Returns 1 if there are still outstanding AIO requests; 0 otherwise */
typedef int (AioFlushEventNotifierHandler)(EventNotifier *e);

/* Flush any pending AIO operation. This function will block until all
 * outstanding AIO operations have been completed or cancelled. */
void qemu_aio_flush(void);

/* Wait for a single AIO completion to occur.  This function will wait
 * until a single AIO event has completed and it will ensure something
 * has moved before returning. This can issue new pending aio as
 * result of executing I/O completion or bh callbacks.
 *
 * Return whether there is still any pending AIO operation.  */
bool qemu_aio_wait(void);

#ifdef CONFIG_POSIX
/* Returns 1 if there are still outstanding AIO requests; 0 otherwise */
typedef int (AioFlushHandler)(void *opaque);

/* Register a file descriptor and associated callbacks.  Behaves very similarly
 * to qemu_set_fd_handler2.  Unlike qemu_set_fd_handler2, these callbacks will
 * be invoked when using either qemu_aio_wait() or qemu_aio_flush().
 *
 * Code that invokes AIO completion functions should rely on this function
 * instead of qemu_set_fd_handler[2].
 */
void qemu_aio_set_fd_handler(int fd,
                             IOHandler *io_read,
                             IOHandler *io_write,
                             AioFlushHandler *io_flush,
                             void *opaque);
#endif

/* Register an event notifier and associated callbacks.  Behaves very similarly
 * to event_notifier_set_handler.  Unlike event_notifier_set_handler, these callbacks
 * will be invoked when using either qemu_aio_wait() or qemu_aio_flush().
 *
 * Code that invokes AIO completion functions should rely on this function
 * instead of event_notifier_set_handler.
 */
void qemu_aio_set_event_notifier(EventNotifier *notifier,
                                 EventNotifierHandler *io_read,
                                 AioFlushEventNotifierHandler *io_flush);

#endif