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/**
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
* SPDX-License-Identifier: Apache-2.0.
*/
#ifndef AWS_IO_ASYNC_STREAM_H
#define AWS_IO_ASYNC_STREAM_H
/**
* THIS IS AN EXPERIMENTAL AND UNSTABLE API
* TODO: logging
* TODO: modify API to return byte-bufs, instead of filling in the provided byte-buf?
* this would avoid a copy in the use-cases we know of, but it's more complex
* TODO: vtable acquire()/release()?
* TODO: protect against simultaneous reads?
* TODO: check results of vtable->read() (i.e. 0 byte reads not allowed)?
* this would require 1 or 2 additional allocations per read
*/
#include <aws/io/io.h>
#include <aws/common/ref_count.h>
AWS_PUSH_SANE_WARNING_LEVEL
struct aws_async_input_stream;
struct aws_byte_buf;
struct aws_future_bool;
struct aws_input_stream;
struct aws_async_input_stream {
const struct aws_async_input_stream_vtable *vtable;
struct aws_allocator *alloc;
struct aws_ref_count ref_count;
void *impl;
};
struct aws_async_input_stream_vtable {
/**
* Destroy the stream, its refcount has reached 0.
*/
void (*destroy)(struct aws_async_input_stream *stream);
/**
* Read once into the buffer.
* Complete the read when at least 1 byte is read, the buffer is full, or EOF is reached.
* Do not resize the buffer (do not use "aws_byte_buf_xyz_dynamic()" functions)
* Do not assume that buffer len starts at 0.
* You may assume that read() won't be called again until the current one completes.
* You may assume that the buffer has some space available.
* Return a future, which will contain an error code if something went wrong,
* or a result bool indicating whether EOF has been reached.
*/
struct aws_future_bool *(*read)(struct aws_async_input_stream *stream, struct aws_byte_buf *dest);
};
AWS_EXTERN_C_BEGIN
/**
* Initialize aws_async_input_stream "base class"
*/
AWS_IO_API
void aws_async_input_stream_init_base(
struct aws_async_input_stream *stream,
struct aws_allocator *alloc,
const struct aws_async_input_stream_vtable *vtable,
void *impl);
/**
* Increment reference count.
* You may pass in NULL (has no effect).
* Returns whatever pointer was passed in.
*/
AWS_IO_API
struct aws_async_input_stream *aws_async_input_stream_acquire(struct aws_async_input_stream *stream);
/**
* Decrement reference count.
* You may pass in NULL (has no effect).
* Always returns NULL.
*/
AWS_IO_API
struct aws_async_input_stream *aws_async_input_stream_release(struct aws_async_input_stream *stream);
/**
* Read once from the async stream into the buffer.
* The read completes when at least 1 byte is read, the buffer is full, or EOF is reached.
* Depending on implementation, the read could complete at any time.
* It may complete synchronously. It may complete on another thread.
* Returns a future, which will contain an error code if something went wrong,
* or a result bool indicating whether EOF has been reached.
*
* WARNING: The buffer must have space available.
* WARNING: Do not read again until the previous read is complete.
*/
AWS_IO_API
struct aws_future_bool *aws_async_input_stream_read(struct aws_async_input_stream *stream, struct aws_byte_buf *dest);
/**
* Read repeatedly from the async stream until the buffer is full, or EOF is reached.
* Depending on implementation, this could complete at any time.
* It may complete synchronously. It may complete on another thread.
* Returns a future, which will contain an error code if something went wrong,
* or a result bool indicating whether EOF has been reached.
*
* WARNING: The buffer must have space available.
* WARNING: Do not read again until the previous read is complete.
*/
AWS_IO_API
struct aws_future_bool *aws_async_input_stream_read_to_fill(
struct aws_async_input_stream *stream,
struct aws_byte_buf *dest);
AWS_EXTERN_C_END
AWS_POP_SANE_WARNING_LEVEL
#endif /* AWS_IO_ASYNC_STREAM_H */
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