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