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/*

 * 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"

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 (AioFlushHandler)(void *opaque);

/* Runs all currently allowed AIO callbacks of completed requests in the

 * respective AIO backend. Returns 0 if no requests was handled, non-zero

 * if at least one queued request was handled. */

typedef int (AioProcessQueue)(void *opaque);

/* 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. */

void qemu_aio_wait(void);

/*

 * Runs all currently allowed AIO callbacks of completed requests. Returns 0

 * if no requests were handled, non-zero if at least one request was

 * processed.

 */

int qemu_aio_process_queue(void);

/* 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].

 */

int qemu_aio_set_fd_handler(int fd,

                            IOHandler *io_read,

                            IOHandler *io_write,

                            AioFlushHandler *io_flush,

                            AioProcessQueue *io_process_queue,

                            void *opaque);

#endif