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- [/
- / Copyright (c) 2003-2019 Christopher M. Kohlhoff (chris at kohlhoff dot com)
- /
- / Distributed under the Boost Software License, Version 1.0. (See accompanying
- / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- /]
- [section:AsyncRandomAccessReadDevice Buffer-oriented asynchronous random-access
- read device requirements]
- In the table below, `a` denotes an asynchronous random access read device
- object, `o` denotes an offset of type `boost::uint64_t`, `mb` denotes an object
- satisfying [link boost_asio.reference.MutableBufferSequence mutable buffer sequence]
- requirements, and `h` denotes an object satisfying [link
- boost_asio.reference.ReadHandler read handler] requirements.
- [table Buffer-oriented asynchronous random-access read device requirements
- [[operation] [type] [semantics, pre/post-conditions]]
- [
- [`a.get_executor()`]
- [A type satisfying the [link boost_asio.reference.Executor1 Executor requirements].]
- [Returns the associated I/O executor.]
- ]
- [
- [`a.async_read_some_at(o, mb, h);`]
- [`void`]
- [
- Initiates an asynchronous operation to read one or more bytes of data
- from the device `a` at the offset `o`. The operation is performed via the
- `io_service` object `a.get_io_service()` and behaves according to [link
- boost_asio.reference.asynchronous_operations asynchronous operation]
- requirements.\n
- \n
- The mutable buffer sequence `mb` specifies memory where the data should
- be placed. The `async_read_some_at` operation shall always fill a buffer
- in the sequence completely before proceeding to the next.\n
- \n
- The implementation shall maintain one or more copies of `mb` until such
- time as the read operation no longer requires access to the memory
- specified by the buffers in the sequence. The program must ensure the
- memory is valid until:\n
- \n
- [mdash] the last copy of `mb` is destroyed, or\n
- \n
- [mdash] the handler for the asynchronous read operation is invoked,\n
- \n
- whichever comes first.\n
- \n
- If the total size of all buffers in the sequence `mb` is `0`, the
- asynchronous read operation shall complete immediately and pass `0` as
- the argument to the handler that specifies the number of bytes read.
- ]
- ]
- ]
- [endsect]
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