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/* Copyright (c) 2013 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ASYNC_APPEND_H
#define ASYNC_APPEND_H 1
#include <stddef.h>
/* This module defines a simple, abstract interface to asynchronous file I/O.
* It is currently used only for logging. Thus, for now the interface only
* supports appending to a file. Multiple implementations are possible
* depending on the operating system's degree and form of support for
* asynchronous I/O.
*
* The comments below document the requirements on any implementation.
*
* Thread-safety
* =============
*
* Only a single thread may use a given 'struct async_append' at one time.
*/
/* Creates and returns a new asynchronous appender for file descriptor 'fd',
* which the caller must have opened in append mode (O_APPEND). If the system
* is for some reason unable to support asynchronous I/O on 'fd' this function
* may return NULL. */
struct async_append *async_append_create(int fd);
/* Destroys 'ap', without closing its underlying file descriptor. */
void async_append_destroy(struct async_append *ap);
/* Appends the 'size' bytes of 'data' to 'ap', asynchronously if possible. */
void async_append_write(struct async_append *ap,
const void *data, size_t size);
/* Blocks until all data asynchronously written to 'ap' with
* async_append_write() has been committed to the point that it will be written
* to disk barring an operating system or hardware failure. */
void async_append_flush(struct async_append *ap);
#endif /* async-append.h */
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